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Climate Science: A Culture of Predictions

Site Information


Matthias Heymann
Dania Achermann
Gabriel Henderson
Janet Martin-Nielsen


Greg A. Good
Matthias Heymann
Dania Achermann
Gabriel Henderson

Web Design

Nathan Cromer

We are also grateful to


Material on this site is copyright ©2018 American Institute of Physics.

Site Map

  • Climate Science: A Culture of Predictions
    • Introduction
      • Brief Intro
      • Trajectories
      • Climate Projections
      • Climatology or Climate Science
      • Spider Charts
    • Research Directions and Institutions
      • Climatalogical Traditions
        • Classical Climatology
        • Modernizing Climatology
        • Medical and Bioclimatology
        • Historical Climatology
      • Modern Climate Research
        • Physics of the Atmosphere
        • Climate Modeling
        • Institutions of Climate Science
        • Programs and Policies
      • Climate Conferences
        • Changes of Climate 1961
        • SCEP 1970
        • SMIC 1971
        • World Climate Conference 1979
      • Global Scale Research
      • Regional Scale Research
    • Climate Researchers
      • Modernizers of Climatology
        • Hermann Flohn
        • Hubert Lamb
        • Helmut Landsberg
        • Hans W. Ahlmann
      • Movers of Heuristic Climate Modeling
        • Syukuro Manabe
        • John Mason
      • Movers of Predictive Climate Modeling
        • William W. Kellogg
        • Stephen H. Schneider
        • James E. Hansen
        • Bert Bolin


Brief Introduction to Climatology

A web exhibition on history of climate modelling

This website examines the emergence and predominance of climate modelling as a culture of prediction. It shows that the interests in climate and the research directions to investigate climate have been diverse and changed enormously during the twentieth century.

From the 1970s on, climate modeling has played a major role in forging a scientific consensus about climatic change. One of its most important results have been climate projections. Based on simulations with complex Earth System Models such projections have become an iconic product of this thriving science. However, scientific consensus tends to hide the conflicts, complex negotiations and tangible interests behind the consensus itself. This exhibition attempts to show fundamental and contested changes in climate science by taking a look at a few crucial representatives of climate science and many relevant documents.

Changing research interest in climate

The history of climate research in the twentieth century experienced crucial changes. Its path has not been a linear one but paved with negotiations of the questions which types of knowledge are important, which epistemic standards are used to judge that knowledge, and which applications of that knowledge are regarded as useful and socially relevant.

This web exhibition shows the enormous breadth of diverse ideas, interests and research approaches in climate throughout the twentieth century. Climate research has included disciplines as diverse as geography and geology on one side and physics on the other side.

The priorities and focus, though, changed considerably, first, from a geography-oriented to a physics based approach, and second, from a heuristic to a predictive use of climate models. If we imagine the trajectories of all climate researchers depicted as a flow diagram, it resembles one, in which the flow of the majority of scientists changed sides (see figure below).

Focus in the first half of the 20th century still clearly was on the left side, geography-oriented climatology, whereas it moved in the second half of the century to the right side, to physics-oriented atmospheric and climate modeling.

Exemplary personalities and institutions in climate research

The exhibition deliberately focuses on few exemplary personalities and institutions to highlight the diversity of interests and values to which scientists subscribed and the tensions and conflicts to which diverging conceptions of climate research gave rise to.

This exhibition is based on work and results in the research project “Shaping Cultures of Prediction: Knowledge, Authority and the Construction of Climate Change” at Aarhus university in Denmark.


The figures below illustrate the diversity and the changes of interests in time. Each arrow roughly represents the scientific interest of individual researchers or institutions ranging between a "classical" geography based approach towards climate (left) and the physics and model-based approach (right) changing in time (downwards). From around the 1970s on, a further division in the use of climate models is represented: in either a heuristic or a predictive way.


Professional trajectories of climate researchers depicted as a flow diagram. Click on the graph to follow the introductory animation!

The range of interests in climate spans a large range, but the focus of interests (indicted by a large desity of arrows) would show a shift of focus in time towards the physics-based, modelling-oriented approach. The individual climate researchers featuring our work represent this diversity of positions and interests.

trajectories with flohn

Change in interests over time of Hermann Flohn (shown in red).

Climate Projections

Climate projections as message

Climate projections have become a major task of climate modeling. The interest in predicting future climate change is of relatively recent origin and emerged during the 1970s. Climate projections consist of enormously complex data collection, data processing and simulation efforts. As the vast amount of data resulting from simulations is difficult to understand, interpret and communicate, climate modelers have contributed two unique inventions: 1) the definition of a global mean temperature as an artificial parameter and 2) the depiction of global mean temperature change on a graph as a powerful graphical language (see also William W. Kellogg and James E. Hansen). Both inventions originated from the mid-1970s, but quickly became a part of the emerging scientific culture of climate prediction.

This is a selection of figures that show different projections of climate change into the future; a genealogy of climate projections:

Climate projections are important, because they provide relevant scientific information about climate change. They tell us that future climate will change. These projections are based on computer simulations with complex Earth-System Models. Most of them suggest that global mean temperature may rise several degrees in the decades to come. These projections have gained significant scientific and political authority and raised enormous attention.

Climate projections as a historical phenomenon

At the same time, climate projections raise further questions and invite to further analysis. While projections of climate change vary according to assumptions regarding future socio-economic developments, estimates about likely future warming remained more or less stable since about four decades.

This web-exhibition takes a different look at climate projections: it grasps them as a historical phenomenon. Climate projections have emerged at a certain point in time within specific historical contexts. They are based on specific scientific methods. They have been crafted by scientists of particular disciplines in specific ways, furnished with specific types of information. They respond to particular questions and interests...

Climatolgy or Climate Science

Climatology in the nineteenth and early twentieth century was radically different from the climate science we know today. It was a geographical science applying a holistic, descriptive methodology focusing on the collection and analysis of comprehensive sets of observational data. Its major interests included the investigation of spatial variations of climates and local interactions between climate, life and human beings. Some scientists referred to this discipline as “classical climatology” in order to distinguish it from attempts of modernizing climatology around the mid-twentieth century or from the radically different characteristics of modern climate research in more recent decades.

The climate science we know today is, in contrast, a physical science, pursuing rather a physics of the atmosphere with a focus on quantitative mathematical understanding of atmospheric phenomena based on the laws of physics. It investigates causal relations and temporal variations of atmospheric phenomena, such as in the case of global climate change. Climate science, in addition, is not a coherent discipline, but comprises a large variety of research domains ranging from paleo-archeology (investigating climates of the distant past) to climate modeling (simulating projections of climate in the distant future).

These deep-reaching and fundamental differences should be captured by preserving a clear distinction between the terms “climatology” on the one side and “climate science” and “climate research” on the other side. These terms, however, tend to be confused and often used synonymously in many languages. In this exhibition we strictly keep this distinction and suggest the table below as a rough guideline. The relevance of this distinction becomes visible in labels such as the “World Climate Research Program,” which was not (and deliberately not called) a world climatology program. “Climate research” is a broad concept, of which climatology is still a (small) part that usually refers to the collection and analysis of observational data.

Climatology (mainly pre-1950) Climate science (post-1950)
  • geographical science
  • climate conceived as local and stable in time
  • focus on descriptive approach
  • data collection and analysis as main methodology
  • physical science
  • climate conceived as global and changing in time
  • focus on casual understanding
  • mathematical modling as main methodology

Spider Charts

Spider charts

The following spider chart emphasises this dynamics of the discipline and the changes of scientific interests in climate. It clearly shows the shift of focus towards a physical understanding of climate and the use of climate models as a heuristic or predictive tool. Click on the chart to find out more.

Spider chart of 1960s

Graphic representation of interests in 1960s.

Spider chart of 1970s

Graphic representation of interests in 1970s.

Definitions of the spider axes:

Climate modeling: This axis of the spider chart shows how strong a climate researcher was interested in developing and using climate models (for a short description of climate modelling click here).

Heuristic modeling: This axis of the spider chart shows how strongly a climate researcher was interested in heuristic modeling, which describes the use of climate models as a research tool to investigate and better understand the atmosphere (for a short description of heuristic modelling click here).

Predictive modeling: This axis of the spider chart shows how strongly a climate researcher was interested in predictive modeling, which describes the use of climate models as a predictive tool (for a short description of predictive modelling click here). The results of these calculations are often represented in charts like these.

Modernizing climatology: This axis of the spider chart shows how strong the interest was in "modernizing" climatology from the 1950s onwards (for a short description of attempts of modernizing climatology click here).

Classical climatology: This variable shows how strong the interest in the approach of the classical climatology was (for a short description of classical climatology click here).

Historical climatology: This axis visualizes the interest in studying climatic changes of the past (for a short description of historical climatology click here).

Regional/small scale: This label shows to what extent regional or small scales were the predominant geographical scales of interest in the investigation of climate (see also Regional/small scale research of climate).

Global/large scale: This label shows to what extent large or even global scales were the predominant geographical scales of interest in the investigation of climate (see also Global/large scale research of climate).

Research Directions and Institutions

Climatological Traditions

Classical Climatlogy

The term “classical climatology” describes a specific interest in climate from the mid-19th century to the early 20th century. Typically, scholars like Alexander von Humboldt or Julius von Hann are considered to have set the theoretical basis for this type of climate research (Heymann 2009). As Humboldt explained:

The term climate denotes in its most general sense all changes of the atmosphere which directly affect our organs.1

And the Austrian Meteorologist Julius von Hann later specified in his Handbook of Climatology:

What we understand as climate is the totality of meteorological phenomena which describe the average state of the atmosphere over a specific location on earth.2

The focus of classical climatology was hence on collecting as many meteorological observation data as possible to investigate climatological problems. Statistical averages of meteorological data described the climates of different locations on earth. These data served the investigation of specific climatic phenomena (such as the Indian monsoon) and the construction of climate classifications. The climate was, according to the climatological paradigm, understood as a static (within human time scales) and a represented spatial concept. Climatology was a quantitative and descriptive discipline. Research programs in climatology included the exploration and description of climates on all regions on earth, an understanding of climatic phenomena based on local and regional geographical factors and the interactions between human activities and climate.

Well into the 1930s, climatology was conceived as a sub-discipline of geography. In Europe as well as the United States, climatologists were typically educated in geographical departments in order to develop maps of climate regimes. One prominent representative of classical climatology was Wladimir Köppen. He developed one of the first and most influential classification systems of terrestrial climates since 1884, which is still in use today. Countless new editions of climate classifications and climate maps were published during the late 19th and early 20th centuries. According to contemporaries, the colossal new edition of the “Handbook of Climatology,” edited by Köppen and his younger colleague Rudolf Geiger between 1930 and 1936, was deemed “the crowning achievement of the classical period of climatology."3

“Als Begrenzung des Gegenstands darf gelten, dass alles das an meteorologischem Wissen in das Buch gehört, was geographische Gesichtspunkte enthält, und nur so weit, als dieses der Fall ist. Es sind also nur solche Fakten zu behandeln, von deren geographischer Verbreitung man bereits eine Vorstellung hat […]. Auch die Klimate des freien Ozeans und die der höheren Luftschichten werden kürzer besprochen, sowohl weil das Material viel spärlicher ist, als auch weil dies nicht Räume ständigen Aufenthalts von Menschen sind.“4

Reproduction of the Wladimir Köppen’s climate charts from 1954.

This is a reproduction of the Wladimir Köppen’s climate charts from 1954.

1: Humboldt, Alexander von, Kosmos. Entwurf einer physischen Weltbeschreibung, vol. 1. Stuttgart/Tübingen: Cottascher Verlag, 1845.

2: Hann, Julius, Handbuch der Klimatologie, vol. 1.3. Stuttgart: Engelhorn, 1908.

3: Landsberg, Helmut, Review of Climatology, 1951-1955, Meteorological Research Reviews 3:12 (1957), p. 3.

4: Translated from German original. Humboldt, Alexander von, 1845: Kosmos. Entwurf einer physischen Weltbeschreibung, vol. 1. Stuttgart/Tübingen: Cottascher Verlag, page 340

Modernizing Climatology

Classical climatology had been challenged and expanded since the early-twentieth century by a number of developments – first, the “discovery” of the third (vertical) dimension of the atmosphere, i.e. the investigation of higher layers of the atmosphere with the help of balloon ascents, which became increasingly important with the emergence of air traffic; second, the increasing physical understanding of atmospheric processes and its quantitative description by physical laws; third, increasing evidence of the globally connected atmospheric circulation, which proved the influence of large-scale processes on small scale atmospheric phenomena; fourth, evidence of climatic fluctuations within human time scales, which undermined the idea of a static climate.

Many climatologists contributed to expanding the traditional focus of classical climatology. Wladimir Köppen, for example, took an interest in the investigation of higher layers of the atmosphere since the late 19th century and coined the name “aerology” for this new sub-discipline. With the introduction of new technologies such as radiosondes and aeroplanes, the amount of observational data from the upper atmosphere grew exponentially. Such data helped to bring the whole atmosphere into focus and to identify the larger context of regional climatic phenomena and its relations. Similarly, the emergence of dynamic meteorology, for example the development of physical concepts and descriptions by Vilhelm Bjerknes and his Bergen School of meteorology, improved the dynamic understanding of weather and climate and its dependence on large scale circulation patterns.1 In addition, a pronounced warming episode in the Nordic hemisphere, especially in the polar areas between about the 1920s and 1940s raised interest in climatic fluctuations within human timescales.

Around mid-century, leading climatologists advocated a modernization of climatology and urged to get beyond the purely descriptive approach of classical climatology. The traditional, purely empirical focus appeared “underdeveloped” and “unsystematic.”2 Hubert Lamb in England, Helmut Landsberg in the USA and Hermann Flohn in Germany all attempted to modernize climatology in different ways and aimed for a more dynamic and theoretical perspective on the atmosphere. Landsberg demanded a “new climatology."3 He pursued what he called a “renaissance” of climatology by making it more useful for agriculture and industry. Lamb became a pioneer of historical climatology, the analysis of historical data about climatic fluctuations and its impacts on human societies. Flohn realized early a fragmentation of climatology into different directions: the traditional geography-oriented and a new physics-based climatology. He demanded the integration of the physical and geographical traditions into one coherent, more powerful discipline which he called “modern climatology."4

The climatic manifestations are intimately related to the general circulation of the atmosphere. Theories of the general circulation should be capable of explaining the climatic mean states.5

These new approaches were all conceived not as entirely new disciplines, but as extensions of the classical approach to align it with new knowledge of the atmosphere and make it more relevant for science and society. Climatologists such as Landsberg, Lamb and Flohn were very productive and successful in their individual efforts, but their larger ambitions failed. Physics-based mathematical modelling and numerical simulation of weather and climate soon prevailed. The geographical tradition and identity of climatology with its focus on observation and local difference and detail became increasingly marginalized. While Köppen’s climate classification persisted and his climate maps remained hanging on classroom walls for many decades, attention had moved on to other topics such as weather prediction and climate change and research fields such as climate modeling.

illustration of a theory of the global circulation with the distribution of pressure on the surface of the earth

This is an illustration6 of a theory of the global circulation with the distribution of pressure on the surface of the earth (full line) and in higher altitudes (dashed line), and with the wind systems (arrow lines). This theory indicates the existence of the equatorial westerlies (dashed line) which were understood as being a cause of regional phenomena like the monsoon. The drawing visualises the “transition from surface to space” resulting in the modernisation efforts. It shows a dynamic, three-dimensional atmosphere and large-scale climate systems such as the westerlies, the trade wind and the Intertropical Convergence Zone.

example of a high altitude weather map from the northern hemisphere by Richard Scherhag

An example of a high altitude weather map from the northern hemisphere by Richard Scherhag, showing the pressure changes in an altitude of 500 mb (5000 meter) and on the earth’s surface on the day of the 15th Feb. 1962. Such maps were a novel working tools in the 1930s because until then, only weather maps from the surface of the earth were provided (enclosure to: Scherhag, Richard 1962: Einführung in die Klimatologie, 2. Aufl. Braunschweig: Georg Westermann Verlag).

1: Bergeron, Tor 1930: Richtlinien einer dynamischen Klimatologie, Meteorologische Zeitschrift , pages 246-262.

2: Godske, C.L. 1959: Information, Climatology, and Statistics, Geografiska Annaler 41:2-3, page 85.

3,5: Landsberg, Helmut 1957: Review of Climatology, 1951-1955, Meteorological Research Reviews 3:12 (July 1957), pages 1-43.

4:Flohn, Hermann 1950b: Scherhags ’Neue Methoden der Wetteranalyse und Wetterprognose’ und die Entwicklung der dreidimensionalen Synoptik, Meteorologische Rundschau 3:1-2, page 19.

6: Flohn, Hermann 1950a: Neue Anschauungen über die allgemeine Zirkulation der Atmosphäre und ihre klimatische Bedeutung. Erdkunde, Nr. 4, 3/4. S. 147.

Medical and Bioclimatology

The notion of “bioclimatology” or “medical climatology” entails the investigation of the influence of climate on living organism such as plants, animals and the human body. In the first half of the 20th century, when climatology generally expanded within meteorological services and at universities, bioclimatology was a growing field of research.1 The goal was to investigate and understand the effect of different climates on the origin and distribution of diseases as well as their healing qualities.2 Examples were problems such as the dispersal of pollens and its relation to the proliferation of species and ailments like hay fever. Not only meteorological services but also and spas and sanatoriums maintained bioclimatological research stations. In the early 20th century, the German chemist Carl Dorno (1865-1942) founded bioclimatology as a research discipline, because his daughter suffered from tuberculosis.3

Bioclimatology prospered particularly in Germany during the 1930s when, under Nazi rule, new research institutions in agricultural and bioclimatology were established.4 In this context, German climatologist Hermann Flohn started his professional career in a bioclimatological unit of the German Reichswetterdienst (Imperial Weather Service). Also Helmut Landsberg in his career had an interest in bioclimatology. As assistant of the German geophysicist Franz Linke (1878-1944) at the University of Frankfurt he served as an editor of the journal Bioklimatische Beiblätter, a supplement to the leading scientific journal Meteorologische Zeitschrift.5 Also later, after Landsberg had fled to the United States in 1934, he continued to publish in this bioclimatological supplement.6

As sub-disciplines of classical climatology, bioclimatology and medical climatology (along with further sub-disciplines such as urban climatology and agrometeorology) exemplify the climatological focus on the relation of climate and human culture and life. Interest in these disciplines peaked in the interwar period, whereas they lost attention significantly in the postwar era. Today, bioclimatological research includes the investigation of problems such as heat transfer in human and animal bodies, metabolic processes and the impact of climate on insect populations that transmit malaria, dengue fever and other diseases.7

Heliotherapy in Switzerland

Images of children being treated by heliotherapy in Swiss mountains. Source: Transactions of the American Climatological and Clinical Association, vol. 30. Philadelphia 1914.

1: Heymann, Matthias 2009: „Klimakonstruktionen. Von der klassischen Klimatologie zur Klimaforschung“, NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin, vol. 17: 2, pp. 171-197.

2: Borchardt, Werner 1930: Einfluss des Klimas auf den Menschen I: Medizinische Klimatologie. Handbuch der Klimatologie in fünf Bänden. Wladimir Köppen, Rudolf Geiger (eds.). Berlin.

3: Dorno, Carl 1920: Klimatologie im Dienste der Medizin. Tagesfragen aus den Gebieten der Naturwissenschaften und der Technik, vol. 50. Wiesbaden: Springer.

4: Flohn, Hermann, Ratje Mügge 1962: Denkschrift zur Lage der Meteorologie. Ausschuss für angewandte Forschung der Deutschen Forschungsgemeinschaft, Denkschrift part 6. Wiesbaden.

5: Keil, Karl 1985: "Linke, Franz", in: Neue Deutsche Biographie 14, pp. 629 f. [online version]; URL:

6: Flohn, Hermann 1992: „Meteorologie im Übergang. Erfahrungen und Erinnerungen (1931–1991)“, Bonner Meteorologische Abhandlungen 40.

7a: Baer, Ferdinand 2005: “Bioclimatology”, in: Encyclopedia of World Climatology. John E. Oliver (ed.). Dordrecht: Springer, pp. 158-165.

7b: Kalkstein, Laurence S. 2005: „Human Helath and Climate”, in: Encyclopedia of World Climatology. John E. Oliver (ed.). Dordrecht: Springer, pp. 407-411.

Historical Climatology

Until the first half of the 20th century, mainly geologists and a few biologists studied climates and climate changes of the distant past, what was often referred to as paleoclimatology. This research rested upon studying fossils or geomorphological features like moraines and landscape peculiarities such as erratic blocks from which climatic features and information on the ice ages could be derived.1 Around 1900, paleoclimatological studies in geology thrived, before it entered years of stagnation.2

From the mid-20th century onwards, a rising number of scientists from other disciplines such as physics, chemistry and biology discovered paleoclimatology as a field of study. They investigated tree rings, ice cores, ocean and lake sediments, fossilized pollen, moraines, or bones and used them as proxies to retrieve information about the climate in the distant past. Paleoclimatology evolved into a highly interdisciplinary field.

At that time, a few climatologists began to take a stronger interest in the history of climates and climatic changes. The idea of the static character of climate (at least within human time scales) of classical climatology had still prevailed in the first half of the twentieth century. Around 1940, evidence from meteorological records and glaciological investigations had accumulated that the northern Hemisphere, particularly the polar areas, experienced a significant warming episode between about the 1920s and 1940s. This early twentieth-century warming undermined the idea of static climates and raised many questions: How common were significant climatic changes within only a few decades? Which were its causes? And what impacts did they have on human societies?

English climatologist Hubert H. Lamb pioneered the systematic investigation of historical weather observation series as far back as possible and became one of the founders of historical climatology. He considered the study of past weather data and the reconstruction of past climatic changes as a key to the understanding weather and climate and the atmospheric processes governing it:

The aim of meteorology in this quest for the facts of the past is to identify the true nature of the weather events and the atmospheric circulation processes at work.3

Lamb collected, studied and evaluated a vast amount of old data series along with other information on weather to reconstruct regional variations and fluctuations of temperature, precipitation and other climatic features as far back as the 18th century. Lamb’s interest, however, was not limited to the reconstruction of past climates. He also engaged in the investigation of the relation of fluctuating climates and human societies culture and life. Lamb, thus, maintained a core interest and tradition in classical climatology: a comprehensive perspective on climate and its relation to human life.

Lamb’s historical climatology seemed an outdated specialty to his superior, director of the Britisch Meteorological Office, John Mason, since the mid-1960s. Lamb, consequently, left the MetOffice and founded the Climatic Research Unit at the University of Eastern Anglia in Norwich (UK) in 1971.4 Its first aim was to “establish further knowledge of the history of climate (in the recent and distant past)” and, hence, continue and expand historical climatology.5

About two decades later, historical climatology proved to be a most important discipline – although for different reasons than Lamb’s. Data about the past climates turned out to be crucial for the testing and validation of global climate models. Lamb, ironically, had always remained very skeptical and reluctant about mathematical modeling and numerical simulation. He deplored that climate modeling gained priority, whereas the interest in the relations of climate and human conditions, which remained paramount to him, largely passed into oblivion. Today, climate science and climate models rest to a large degree on data established in historical climatology.

1: Fairbridge, Rhodes W. 2009: “History of Paleoclimatology”, Encyclopedia of Paleoclimatology and Ancient Environments, Vivien Gornitz (ed.). Dordrecht: Springer, pp. 414-438.

2: Schwarzbach, Martin 1949: „Das Klima der Vorzeit als Tagungsthema der Hauptversammlung 1951“, Geologische Rundschau 37: 1, pp. 139-140.

3: Lamb, Hubert H. 1977: Climate: Present, past and future, vol. 2: Climatic history and the future. London, page 22.

4: Martin-Nielsen, Janet 2015: “Ways of Knowing Climate. Hubert H. Lamb and Climate Research in the UK”, Wiley Interdisciplinary Reviews: Climate Change 6:5, pp. 465-477.

5: Lamb, Hubert H. 1972: “New Climatic Research Unit at Norwich, England”, Quaternary Research 2:4, page 593.

Climatological Traditions

Physics of the Atmosphere

In the nineteenth and early twentieth-century, climatology was largely conceived a climatological science and taught in geographical programs. At the same time, however, theoretical meteorologists and physicists attempted to describe atmospheric processes based on physical laws. This domain in meteorology generally came to be called “dynamic meteorology”. Due to the complexity of the atmosphere, its quantitative understanding and mathematical description proved enormously difficult.

A significant step forward was the work of Norwegian physicist Vilhelm Bjerknes. Bjerknes developed a foundational framework for the quantitative description of atmospheric processes, hoping to make meteorology an exact science of the atmosphere. In 1904, he published a famous paper laying out the basis for a solution to the problem of weather prediction. Seven non-linear partial differential equations with the seven main physical parameters—temperature, pressure, density, humidity, and wind velocity in three directions—describing the hydro- and thermodynamic properties of the atmosphere and in principle the state of the atmosphere at any point in time and space.

Vilhelm Bjerknes

"Image of Vilhelm Bjerknes" courtesy of the Bjerknes family is licensed under CC BY-SA 4.0

These so-called “primitive equations” proved a revolutionary step. First, they bore the promise of a comprehensive physical understanding of the atmosphere and represented a boost for dynamic meteorology. Second, they represented an important push in reversing priorities in meteorology and climatology in the long term: a priority of physical theory in describing the atmosphere. Meteorology and climatology had primarily built on a strong empirical tradition of data collection, which many atmospheric scientists later considered rather obscure and dull. Third, climatology was a discipline strongly interested in the interactions of human and climate: in questions related to climate and agriculture, climate and human health, but also the impact of human action on local climates.

Climate scientists Willliam Welch Kellogg on climatology1:

... the subject of climatology changed completely around the late 1960s and 1970s. it went from a subject which was just usually taught in the geography department and had to do with statistics of the weather to a physically-based theory of climate ... So, from a relatively-obscure and rather dull subject, climatology became a very exciting field of new research involving some of the best brains in the business and some of the fastest computers.

Bjerknes “primitive equations,” however, proved to be far from primitive, because they had no analytical solution. Only with the help of complex numerical approximation the equations could be solved. These numerical approximations required such an enormous amount of computations that they were effectively feasible only with the help of computers. After the World War II, when computers available, so-called numerical modeling and simulation experienced a very quick rise. An example was the development of numerical weather prediction (NWP) and climate modeling.

6 primitive equations in modern notation

The main six “primitive equations” by Vilhelm Bjerknes in modern notation.

1: Earl Droessler, Interview William W. Kellogg, American Meteorological Society, University Corporation for Atmospheric Research, August 18, 1988.

Edwards, Paul N. A Vast Machine: Computer Models, Climate Data, and the Politics of Global Warming. Cambridge, MA: MIT Press, 2010.

Fleming, James R. Inventing Atmospheric Science, Cambridge MA: MIT Press, 2016.

Gramelsberger, Gabriele. “Conceiving Meteorology as the Exact Science of the Atmosphere: Vilhelm Bjerknes’s Paper of 1904 as a Milestone.” Meteorologische Zeitschrift 18 (2009): 669–73.

Harper, Kristine. Weather by the Numbers: The Genesis of Modern Meteorology. Cambridge, MA: MIT Press, 2008.

Lynch, Peter. The Emergence of Numerical Weather Prediction, Richardson’s Dream. Cambridge, UK: Cambridge University Press, 2005.

Nebeker, Frederik. Calculating the Weather: Meteorology in the 20th Century. San Diego: Academic Press, 1995.

Climate Modeling

Basics of Climate Modeling

Climate modeling emerged in the late 1950s based on the development of weather models. It remained a very small research domain with only five pioneering centers pursuing the development of climate models before 1970. Since about the 1970s, climate models have become a key instrument in climate research.

The most comprehensive and common type of climate models are so-called “General Circulation Models (GCM),” which evolved from numerical weather prediction models developed in the 1950s.These models are computer programs based on the physical laws which simulate major features of the behaviour of the atmosphere and other earth systems. In other words, climate models are a simplified representation of the climate system in a purely mathematical language. They serve to compute the state and the change of the climate system in terms of properties such as temperature, pressure, wind, moisture etc. For doing so, the atmosphere and the oceans are broken up into a three dimensional grid, for each of which the atmospheric properties are computed.

schematic for global atmohspheric model

From: NOAA courtesy of Wikimedia.

Versions of climate models can be used to study and better understand atmospheric and climatic processes and their interactions [see “heuristic use of climate models”]. Versions of climate models can, alternatively, be dedicated to compute projections of future (or past) climates [see “predictive use of climate models”].

As climate models simulate the earth’s climate system, they are used for many virtual experiments. One example is the investigation of the rise of future CO2 concentrations (along with other potential changes) and the consequences of these changes in the virtual climate system. This is a most important research strategy, because such experiments cannot be pursued in the laboratory or in the real world. Hence, climate models represent a virtual laboratory.

While climate models are very powerful research tools, they also suffer from significant limitations. They do not represent the climate system in a realistic way. The spatial resolution of global climate models is usually limited to several hundred kilometres. Smaller scale processes have to be represented in a simplified and generalized manner called parameterization. Hence, scientists have to test and validate climate models and their behavior very carefully by comparing data sets based on simulations with data sets based on observation and by comparing model behavior with other models. A large part of research activities are hence invested into the improvement of the models.

Approximation in Climate Modeling

Vilhelm Bjerknes description of the physics of the atmosphere with quantitative equations – his so-called “primitive equations” – based on physical laws represented a powerful tool. Yet, the fact that the primitive equations had no analytical solutions strongly reduced their effectiveness and required the means of approximation. Approximation is a common strategy used by scientists to circumvent unsurmountable mathematical or experimental problems. Scientists prefer to be exact, however, and usually take exactitude as a norm of their profession.

In atmospheric and climate modeling and simulation approximation became a necessity, an unavoidable need, a deeply inscribed practice in this research field to which scientists had to resort. The main problem of meteorology is that a model consisting of seven partial differential equation is far too complex to derive an algebraically exact solution. Thus, numerically computing the equations for a discrete spatial grid and time step is the only way to achieve results. British scientist Lewis Fry Richardson was the first to attempt making the primitive equations operational with the help of approximation. During World War I, Richardson defined a spatial grid and applied a numerical approximation scheme for solving the primitive equations. Richardson’s grid and approximate solution of difference equations represented a move from local precision to averaged information.

Richardson’s approach was pointing the way ahead, but could be pursued effectively only when computers became available due to the enormous computational effort it requires. This is the reason atmospheric scientists have to make use of the fastest super-computers available, in order to compute weather development faster than the real weather evolves and the development of climate for many decades into the future.

representation of Ricahrdsons numerical approximations of weather prediction

A representation of the grid on which Lewis Fry Richardson performed his numerical approximation of a weather prediction for 20 May 1910.1

The limited spatial resolution of climate models has remained a significant challenge to the very day, even though the spatial resolution could be improved significantly with increasing computer power. Small scale processes such as clouds, convection and radiation transport (among many others) cannot be modeled explicitly, because their size is smaller than the model grid. The global climate models, so-to-speak, cannot see realistic clouds.

Small scale processes, instead, have to be approximated with so-called parameterizations, artificial auxiliary constructions, which professedly were not (and could not be) a realistic representation. No climate model can work without such parameterizations. This limitation has caused significant frustration. A group of scientists around climate modeler David Randall described it as “ironic that we cannot represent the effects of the small-scale processes by making direct use of the well-known equations that govern them.”2

Many other types of approximation enter climate modeling and simulation. These comprise simplified representations of atmospheric processes due to lack of knowledge or lack of data or limitations of the availability and quality of input data, which scientists have to work around. Why, then, do weather and climate modeling work in spite of approximations being at the core of it. The performance of models can, in fact, only be tested by comparison of simulated and observed data. Due to an enormous amount of testing experiments, modelers gain a lot of knowledge about the performance and limits of their models. Furthermore, the evaluation of climate models has become a core task of the Intergovernmental Panel on Climate Change (see here the chapter Evaluation of Climate Models in the latest IPCC report).

1: Richardson, Lewis Fry. Weather Prediction by Numerical Process. Cambridge: Cambridge University Press, 1922, p. iii (reprint: 2007, online:

2: Randall, David, Marat Khairoutdinov, Akio Arakawa, and Wojceich Grabowski. “Breaking the Cloud Parameterization Deadlock.” Bulletin of the American Meteorological Society 84 (2003): 1547–64.

Edwards, Paul N. A Vast Machine: Computer Models, Climate Data, and the Politics of Global Warming. Cambridge, MA: MIT Press, 2010.

Heymann, Matthias. “Constructing Evidence and Trust: How Did Climate Scientists’ Confidence in Their Models and Simulations Emerge.” In The Social Life of Climate Change Models: Anticipating Nature, 203–24. New York: Routledge, 2012.

Lynch, Peter. The Emergence of Numerical Weather Prediction, Richardson’s Dream. Cambridge, UK: Cambridge University Press, 2005.

Nebeker, Frederik. Calculating the Weather: Meteorology in the 20th Century. San Diego: Academic Press, 1995.

Heuristic Climate Modeling

Climate models initially served purely heuristic purposes. This means that models were developed and used to investigate and better understand the processes governing climate and its variations. Historically, an ingenious inventor of heuristic modeling was Jule Charney. Charney was hired by the famous mathematician John von Neumann in 1948 as a young and bright meteorologist for the so-called Meteorology Project. His task was to help develop numerical weather prediction at the Institute of Advanced Study in Princeton.

Charney promoted the concept of experimenting with models of different complexity, including deliberately simplified models, which were not realistic, but helped to investigate specific processes or questions. He suggested a hierarchy of models in which specialized simple models could serve for testing the understanding of individual processes, which represented only a part of the complex atmospheric interactions. The model space served as a laboratory for experimentation. The models resembled an idealized experimental apparatus in the laboratory. Running experiments with this apparatus allowed valuable insights, informed theoretical reasoning and improved scientific understanding.1

It was such type of experiment, which meteorologist Norman Phillips, one of Charney’s associates in the Meteorology Project, undertook in 1955. Phillips wanted to test whether a weather forecasting model could be used to simulate atmospheric conditions over a longer period of time than a few days. Phillips results proved surprisingly successful and produced patterns of atmospheric circulation, which resembled observed patterns. These results provoked enormous excitement. When Phillips was invited to deliver a seminar on his experiment to the Royal Meteorological Society in 1956, British Meteorologist Eric Eady grasped the importance of this work in and wrote:

Numerical integrations of the kind Dr. Phillips has carried out give us a unique opportunity to study large-scale meteorology as an experimental science.2

Complex systems like weather and climate had become accessible to quantitative understanding based on the laws of physics. Phillips’s approach became the foundation for the development of so-called General Circulation Models (GCMs), atmospheric models which represented large-scale processes in the atmosphere and served for investigating and understanding the emergence of different climates. Climate modelers of the first generation such as Joseph Smagorinsky and Syokuro Manabe at Princeton and Yale Mintz and Akio Arakawa at the University of California, who started climate modeling efforts in the late 1950s, had purely heuristic interests.3 They strove to tackle the problem of climate piece by piece and contribute to what climate scientists William W. Kellogg and Stephen H. Schneider later called a “theory of climate.”4

1: Dahan, D.Amy. 2001. History and Epistemology of Models: Meteorology as a Case Study (1946–1963). Archive for the History of the Exact Sciences 55, pp. 395–422.

2: Lewis, John M. 2000. Clarifying the dynamics of general circulation: Phillips’s 1956 Experiment, in: David A. Randall, General circulation model development, past, present, future (San Diego: Academic Press), pp. 91-125.

3: Heymann, Matthias, Nils Randlev Hundebøl. 2017. From heuristic to predictive: Making climate models political instruments, in: Matthias Heymann, Gabriele Gramelsberger and Martin Mahoney (eds.): Knowledge and Authority: Epistemic and Cultural Shifts in Computer-based Environmental Science (New York: Routledge), pp. 100-119.

4: Kellogg, William W., Stephen H. Schneider 1974. Climate Stabilization: For Better or For Worse? Science 186, pp. 1163–72.

Predictive Climate Modeling

Mathematical models can be developed and used for different purposes. Whereas in heuristic modeling model development and use predominantly serves heuristic purposes such as the investigation and better understanding of atmospheric and climate processes, predictive modeling aims at the production of predictive knowledge such as future projections of climate change. These categories – heuristic vs. predictive – were not commonly used among scientists, but are historians’ categories to bring attention to the motivations of scientists as they sought to employ climate models.1

The different scopes of heuristic and predictive modeling are important, because they involve different research priorities, practices and strategies. Climate models and data need to be developed and adjusted specifically for this scope. he first generation of climate modelers comprised predominantly theoretical meteorologists, who were interested in investigating atmospheric processes and improving its physical understanding. They pursued heuristic modeling and did not take an interest in producing predictions of future climate.

The path to predictive modeling was paved by concerns about climate warming due to rising CO2 concentrations. In a time of social unrest and rising environmentalism around 1970, a new generation of climate scientists such as William W. Kellogg and Stephen H. Schneider gave climate modeling a fundamentally new interpretation. NCAR Atmospheric Division Director William Welch Kellogg wrote in 1971 that

... there is the haunting realization that man may be able to change the climate of the planet Earth. This, I believe, is one of the most important questions of our time, and it must certainly rank near the top of the priority list in atmospheric science.2

Kellogg and Schneider concluded that climate models should be developed and used in order to simulate projections of future climate. Even though they were aware that climate models were still very simple and had to be improved, they strongly demanded to develop and pursue predictive climate modeling. Schneider described the dilemma of using imperfect models for prediction 1956 in a popular book as follows:

The real problem is: If we choose to wait for more certainty before actions are initiated, then can our models be improved in time to prevent an irreversible drift toward a future calamity? (...) This dilemma rests, metaphorically, in our need to gaze into a very dirty crystal ball; but the tough judgment to be made here is precisely how long we should clean the glass before acting on what we believe we see inside.3

1a: Dahan, D.Amy. 2001. History and Epistemology of Models: Meteorology as a Case Study (1946–1963). Archive for the History of the Exact Sciences 55, pp. 395–422.

1b: Heymann, Matthias, Nils Randlev Hundebøl. 2017. From heuristic to predictive: Making climate models political instruments, in: Matthias Heymann, Gabriele Gramelsberger and Martin Mahoney (eds.): Knowledge and Authority: Epistemic and Cultural Shifts in Computer-based Environmental Science (New York: Routledge), pp. 100-119.

2: Kellogg, WilliamW. 1971. Predicting the climate, in: Matthews, William H., William W. Kellogg, W. D. Robinson (eds.), Man’s Impact on the Climate (Cambridge, MA: MIT Press): 123-132.

3: Schneider, S.H. 1976. The Genesis Strategy: Climate and Global Survival (New York: Plenum Press).

Institutions of Climate Science

Early Pioneers of Climate Modeling

Climate modeling remained a very small research domain during the late 1950s and 1960s. The pioneering effort was an experiment pursued by Norman Phillips, a team member of the Meteorology Project led by Jule Charney, which developed the first numerical weather prediction in 1950. In 1955, Phillips simulated a much longer forecast period of 30 days with a further simplified version of the weather model. His simple model calculated circulation patterns for a dry version of the atmosphere, neglecting thermodynamics and involving many other unrealistic abstractions in order to reduce the amount of computations.

While this was only an experiment and not a simulation based on a realistic situation, it turned out to be surprisingly successful, because it produced patterns of the atmospheric circulation similar to the observed global circulation. Phillips concluded that “the verisimilitude of the forecast flow patterns suggests quite strongly that [the model] contains a fair element of truth.”1

Research team of the Meteorology Project

Research team of the Meteorology Project, Institute for Advanced Study, Princeton, 1952. Jule Charney left, Norman Phillips second left.

The experiment was path-breaking in two ways and raised a lot of enthusiasm: first, it showed that computer based simulation could serve to simulate atmospheric phenomena; second, it proved that “[n]umerical integration of this kind ... give[s] us [the] unique opportunity to study largescale meteorology as an experimental science,” as British meteorologist Eric Eady concluded in 1956.2

With his remark, Eady grasped the revolutionary power of atmospheric simulation. Experimentation with so-called General Circulation Models (GCMs), representations of virtual atmospheres in the computer model, served in the following years the development of heuristic modeling. This research program was dedicated to developing a quantitative theoretical understanding of atmospheric and climatic processes. Appropriately, many of the first research groups pursuing heuristic modeling were named laboratories – suggesting the pursuit of experimental science. Some scientists referred to these modeling efforts as the development of comprehensive climate theory.

Around 1960, three separate groups in the USA began to build – more or less independently – many-leveled, three-dimensional GCMs based on the primitive equations of Bjerknes and Richardson: the General Circulation Research Section of the U.S. Weather Bureau (later Geophysical Fluid Dynamics Laboratory, GFDL, in Princeton), the University of California in Los Angeles, and the Lawrence Livermore National Laboratory. In 1964, a fourth group at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, initiated a climate modeling effort. Outside the USA only the UK Meteorological Office began to build a climate model in 1963. All these groups focused on improving the understanding of atmospheric and climatic processes.

Particularly influential climate modeling pioneers became the Japanese theoretical meteorologists Syukuro Manabe at GFDL and Akio Arakawa at the University of California modeling groups. Manabe made very significant contributions to treating radiative transfer, convection and thermal equilibrium. He also was one of the first to couple atmospheric models with ocean models in the late 1960s. Arakawa became famous for his “wizardry with numerical methods”, as climate modeling historian Paul N. Edwards3 expressed it. His contributions included numerical schemes for stable integration over a long period of time, cloud processes and their parameterization and the representation of the atmospheric boundary layer.

Syukuro Manabe at GFDL.

Syukuro Manabe at GFDL.

1: Phillips, Norman, The general circulation of the atmosphere: A numerical Experiment, Quarterly Journal of the Royal Meteorological Society 82 (1956), pp. 123–164.

2: Lewis, John M., Clarifying the dynamics of the general circulation, Phillips’s 1956 experiment, Bulletin of the American Meteorological Society 79 (1998), pp. 39-60.

3: Edwards, Paul N. A Vast Machine: Computer Models, Climate Data, and the Politics of Global Warming. Cambridge, MA: MIT Press, 2010.

Weart, Spencer. General Circulation Models of Climate. In: The Discovery of Global Warming. A hypertext history of how scientists came to (partly) understand what people are doing to cause climate change. Online at:

British Meteorological Office

The Meteorological Office (shortly called the Met Office) is the United Kingdom's national weather service. The Met Office was established in 1854 as a small department within the Board of Trade. Until 1965 it had grown to about 3800 staff, in 2017 it employed about 2100 staff.1 Its major task was to provide meteorological and climatological information across all timescales, particularly weather forecasts and, later, forecasts of climate change. Through-out its history the Met Office had the reputation to pursue a policy of academic cautiousness and diligence.

John Mason

Met Office director John Mason.2

In the postwar era, the Met Office expanded its research profile, established a comprehensive set of experimental facilities and installations including laboratories, cold chambers and wind tunnels and engaged in a variety of research directions ranging from experimental and theoretical meteorology to historical climatology. Since the late 1940s, it pursued research in numerical weather prediction (NWP). While the pioneering USA and Sweden started operational NWP already in the mid-1950s, it only became operational much later in the UK. Under its new director John Mason the Met Of-fice provided daily weather forecasts based on numerical simulations since November 1965, even though Met Office officials were still doubtful of the maturity of NWP.

Mason transformed the culture at the Met Office deeply. He focused operations systematically on numerical simulation, whereas other fields of activity were strongly reduced or closed. Under his directorship, the Met Office a world-wide leading center for weather prediction. Mason also strong-ly supported numerical modeling of climate and climate change. The Met Office was the first center outside the USA to pursue research on climate modeling since 1963, although on a small scale only. By 1968, the Met Office’s climate modelers had a 5-level model which included a radiation transfer scheme as well as the effects of surface friction, mountain drag, and latent heat released during the condensation of water vapor to form clouds.

Due to the lack of a computer, the Met Office climate model could only be tested in the USA at IBM and at the Geophysical Fluid Dynamics Laboratory. The situation improved not before 1971, when the Met Office’s new IBM 360/195 computer was installed at its headquarters in Bracknell. The modelers were encouraged by their ability to reproduce what Meteorological Office Director John Mason called “essential features” of the general circulation despite having only crude repre-sentations of processes below the synoptic scale.3

A hallmark of the Met Office climate modeling efforts during the 1970s became its cautious devel-opment and interpretation. The climate modeling group focused on heuristic modeling using climate models “almost like a laboratory,” as one of the modelers expressed it, to conduct experiments in a controlled setting and to pursue specific research questions.4 The Met Office’s early climate modeling publications and internal discussions emphasized weaknesses and problems with the models, and warned explicitly not to place too much weight on results from model experiments.

John Mason strongly endorsed this line and resolutely tried to fend off demands of applying the climate model for predictive purposes. Despite these reservations, however, the Met Office’s climate models soon entered the political arena. When the development of the Concorde caused debates about potential atmospheric pollution and climatic effects in the early 1970s, a new 13-level climate model was applied to study the effects of supersonic transport on global mean surface temperature (which was found to be negligible).

Since the mid-1970s, the British government put increasing pressure on the Met Office to enter cli-mate prediction and produce politically useful information on future global warming. The interest of the government had less to do with concern about climate change than concern about British indus-try in the case demands for emission reduction would turn up. Mason, however, kept to his cautious attitude and rejected repeated demands for several years, until he felt forced to give in in 1978 un-der the threat of severe funding cuts. Mason ordered the Met Office’s climate modelers to investi-gate the effects of a sudden doubling of carbon dioxide over a complete annual cycle.

The results of these modeling experiments showed that the rise of global mean surface temperature strongly depended on assumptions for sea-surface temperatures and ranged from 0.4 degrees with constant sea-surface temperatures to 2.7 degrees in the case of a sea-surface temperatures increased by 2 degrees. “The ‘true’ answers probably lie somewhere in between”, said Mason in 1979, “but confident estimates will require combined atmosphere/ocean models with a comprehensive treat-ment of the interaction between them.”5

These climate modeling efforts quickly lost importance, however, when Margaret Thatcher came in office as British Prime Minister in 1979. Thatcher did not see a political priority in the CO2 problem and, for the time being, stopped the Met Office’s reluctant efforts. Only in 1988, Thatcher radically changed her mind, accepted the risks of climate change and took the decision to establish the Had-ley Centre for Climate Prediction and Research.

1-2: Browning, Keith A., Sir (Basil) John Mason CB. 18 August 1923 – 6 January 2015, Biographical Memoirs of the Fellows of the Royal Society 62 (2016), pp. 359-380, online available at

3-5: Martin Nielsen, Janet, Computing the Climate: When Models Became Political, Historical Studies in the Natural Sciences 48 (2018), forthcoming.

Agar, Jonathon, “Future Forecast – Changeable and Probably Getting Worse”: The UK Govern-ment’s Early Response to Anthropogenic Climate Change, Twentieth Century British History 26:4 (2015), pp. 602–628.

Martin Mahony, Mike Hulme, Modelling and the Nation: Institutionalising Climate Prediction in the UK, 1988–92, Minerva 54:4 (2016), pp. 445-470.

Met Office, Diversity Data 2017, available online at (last accessed 3 January 2018).

Climate Research Unit

The Climatic Research Unit (CRU) is one of the world's leading institutions concerned with the study of natural and anthropogenic climate change. It is part of the School of Environmental Sci-ences at the University of East Anglia in Norwich and was founded in 1972 by Hubert Horace Lamb. The early priority of CRU was to expand and extend the research program in historical climatology set up by Lamb at the British Meteorological Office since the 1950s. Lamb led CRU until his retirement in 1978, when Tom Wigley succeeded as director.

Hubert Horace Lamb

Hubert Horace Lamb, founder of the Climatic Research Unit.1

The foundation of CRU was related to Lambs deep conflict with the director of the Met Office, John Mason. Mason focused research and operations of the Met Office on numerical simulation approaches and withdrew any support to Lamb’s work in historical climatology. Lamb eventually left the Met Office in 1971 to continue his research program at CRU, which he established with the help of among others Sir Graham Sutton, who had already supported his research as former director of the Meteorological Office and Lord Solly Zuckerman, who served as an adviser to the Universi-ty of East Anglia.

The aim of research at CRU was to reconstruct and improve knowledge of the past climatic record over as much of the globe and as far back in time as possible, and to analyze that record to better understand climatic variation and change and its relation to human history. Lamb and his new col-leagues aimed explicitly to develop “a wide field of academic liaisons with archaeologists, histori-ans, palaeobotanists, glaciologists, geologists and geophysicists, oceanographers and others” – an aim which spoke to Lamb’s views of climatology as a discipline and which set the CRU starkly apart from the Met Office under Mason. In Lamb’s opinion, climatology was fundamentally an in-terdisciplinary subject.

During the 1970s, CRU repeatedly suffered from severe funding problems, however. Initial spon-sors included British Petroleum, the Nuffield Foundation and Royal Dutch Shell. Later the Rocke-feller Foundation, the U.S. Department of Energy and the British Wolfson Foundation provided important contributions. Notably, the British Natural Environment Research Council refused to fund the Climatic Research Unit. Lamb later complained that “the research funds made available have been of the order of twenty to fifty times as much to the theoretical work as to construction and analysis of the actual past record of climate” (Lamb 1982, p. 14). Physics-based theoretical modeling work had clearly outclassed empiricism-focused historical climatology.2

CRU Building

Building of the Climate Re-search Unit built in 1986 with funds from the Wolfson Foundation. It was renamed Hubert Lamb Building in 2006.3

Within two years of opening, the CRU had a core staff of nine (five scientists), by Lamb’s re-tirement in the autumn of 1978, it employed 29 scientific staff. Lamb hired experts in environmental science, statistics, languages and linguistics, biology, history and geography, as well as mathematics, physics and meteorology – a pattern which underlines the interdisciplinarity central to Lamb’s vision of climate research. The bulk of the CRU’s scientific work in the 1970s focused deriving and quan-tifying temperature and rainfall data from historical sources (numerical, textual, visual and proxy) and examining the cycles and probabilities of extreme weather phenomena (e.g., floods, droughts, severe winters and winds). By 1974, the CRU had produced weather charts for Europe, and for much of the Atlantic and the eastern seaboard of the United States, over the past two centuries.

Lamb and his colleagues saw themselves as the torchbearers of an older tradition of climatological work – one immersed in historical and geographical ways of seeing the world – and as the saviors of that tradition. At Lamb’s retirement in 1978, however, CRU had little in the way of secure long-term funding, practically no government support, and a high turnover of scientific staff. The CRU’s scientists felt that their work did not receive the understanding or respect it deserved.

Lamb’s successor Tom Wigley adjusted in 1978 CRU’s research strategy and started the production of the world's land-based, gridded temperature data set – which was needed for numerical climate simulation. This work, expanded in 1986 to include the marine areas, involved many person-years of painstaking data collection, checking and homogenization and, in hindsight, according to CRU’s own assessment, “probably had the largest international impact” (CRU, undated).

CRU had acquired a strong reputation with its accomplishments in climate research, when it was hit by a coordinated hacker attack in November 2009. More than 4,000 emails and documents were stolen. The scandal was exploited by climate skeptics, who coined the term “Climategate”, and re-ceived intense media coverage. It caused a severe loss of trust in climate science in general and CRU in particular, even though subsequent investigations exonerated CRU from any charges and fully reinstated its scientific integrity.

1,3-4: Climatic Research Unit, History of the Climatic Research Unit, available online at (last accessed 4 January 2018).

2: Lamb, Hubert H., Climate, History and the Modern World, London and New York: Methuen, 1982.

Leiserowity, Anthony A. et al., Climategate, Public Opinion, and the Loss of Trust, American Be-havioral Scientist 57:6 (2012), pp. 818–837, online available at (last accessed 4 January 2018).

Martin Nielsen, Janet, Foundation of the CRU, unpublished manuscript, Aarhus University, 2016.

Max Planck Institute for Meteorology

Institutionalisation of model-based climate research in Germany

The Max Planck Institute for Meteorology (MPI-M) in Hamburg is operated by the Max Planck Society, a state-funded research institution beyond university walls. It was officially inaugurated in February 1975. The major goal of the new institute was to develop climate models, integrating ocean-atmosphere interaction, and investigate natural climatic change.

The history of the foundation of the MPI-M is a relatively short one. It only took a few months for the board of the Max Planck Society to decide on the foundation and to appoint a director. Until 1974, meteorological research was hardly represented in the Society’s programme. None of its institutes pursued specific climatological or meteorological research. But in late 1973, the Max Planck Society received an offer from the Fraunhofer Society to take over one of their institutes, which pursued basic research in maritime and radiometeorology. This offer initiated a debate within the Max Planck Society whether meteorology was a topic important enough to be included in the Society’s agenda.

Several experts in the field of climatology, meteorology and atmospheric sciences were invited to this discussion, including Hermann Flohn, Christian Junge, and Bert Bolin. Flohn had already advocated for years that Germany needed an institution that focused on climate change research, because neither the German universities nor the German Weather Service encouraged theoretical meteorology and studies on long-term climate variations.

Internationally, smog, acid rain and extreme climate events reinforced an environmental awareness. Debates about the risks of economic growth and environmental pollution resulted in initiatives and theories like the Club of Rome or the Gaia Hypothesis, and created the notion of the earth as a complex interconnected system. It was the setting in which several conferences on climate change took place in the USA. In Germany, the social-liberal government introduced in 1973 a Federal Office of Environmental Matters (the later Federal Environmental Agency).

Research on climate gained more and more interest also in Germany, but at this point there was still no research institution in Germany that focused entirely on climate science. When the discussion at the Max Planck Society was initiated it promptly decided to fill this gap.

The MPI-M founding process indicates just how much climate research was considered to be relevant. Traditionally, a Max Planck institute is set up for an individual outstanding and established researcher who receives the opportunity to develop his research interest by building up his own institute, also called the “Harnack Principle” (Renn et al. 2014). But in the case of the MPI-M the Society first decided to set up the institute and then search for an eligible director. This “topic first” approach and the fast founding process show the enormous interest the subject enjoyed.

The research of this new institute focused entirely on the development of climate models including ocean-atmosphere interrelations, and on model-based climate prediction. The awareness that the ocean-atmosphere interactions were crucial for the understanding of climate had grown, and it influenced the choice of the director and the research agenda: appointed director was Klaus Hasselmann, a German physicist and oceanographer with experience in ocean modelling instead of climate modelling.

Chronology of the founding process:

October 1973: offer to take up the Fraunhofer Institute
November 1973: consultation with external experts in meteorology/climatology
15 March 1974: senate’s decision on the foundation of a new institute for meteorology, search for an eligible director
20 July 1974: appointment of Klaus Hasselmann as director
February 1975: official foundation, start of work
5 December 1975: ceremonial inauguration act

Programs and Policies

Global Atmospheric Research Program

On 25 September 1961, President Kennedy gave an address to the 16th session of the United Nations General Assembly. His address focused on disarmament and the control of nuclear weapons. As part of his initiative he proposed international collaboration in space and the atmospheric sciences, notably “cooperative efforts between all nations in weather prediction and eventually in weather control.”1 The UN Assembly subsequently passed two resolutions inviting Member States, the World Meteorological Organization (WMO) and the International Council on Scientific Unions (ICSU) to organize a collaborative research program to advance weather forecasting capabilities and weather and climate modification.

UN Resolution 1721 (XVI), 20 December 1961
“The General Assembly …
1. Recommends to all Member States and to the World Meteorological Organization and other appropriate specialized agencies the early and comprehensive study, in the light of developments in outer space, of measures;
(a) To advance the state of atmospheric science and technology so as to provide greater knowledge of basic physical forces affecting climate and the possibility of large-scale weather modification;
(b) To develop existing weather forecasting capabilities and to help Member States make effective use of such capabilities through regional meteorological centres.”2

The US National Academy of Science developed the outline of an international atmospheric research program, which focused on Jule Charney’s idea to improve global observations and data collection to improve numerical computer modeling of weather and climate. The lack of appropriate atmospheric data with global coverage represented a major impediment for advancing weather prediction and climate simulation. Interests in the atmosphere were diverse, however, and negotiations within ICSU proved difficult and lengthy. The diplomatic skills of Swedish climate scientist Bert Bolin eventually helped to establish the Global Atmospheric Research Program (GARP) in 1967 on the basis of the American plans.

GARP was defined as the study of the physical processes in the atmosphere that are essential for an understanding of “large-scale fluctuations which control changes of the weather and the general circulation of the atmosphere”. It “would lead to increasing the accuracy of [weather] forecasting from one day to several weeks” and “a better understanding of the physical basis of climate.”3 GARP was a huge international undertaking and organized large-scale field experiments such as the GARP Atlantic Tropical Experiment (GATE) and the global weather experiment called First GARP Global Experiment (FGGE), each with many subprograms.

FGGE included the use of four geo-stationary satellites for observation of the tropics and subtropics and two polar orbiting satellites to achieve global coverage. In addition, poor data coverage in the Southern Oceans was improved by free-floating buoys communicating with the world data centers via satellite. Another element were high-flying drifting balloons providing data for comparison with satellite observations and in situ measurements. According to Bolin “FGGE greatly advanced our knowledge.”4 GARP existed for 15 years until 1982, when it was replaced by the World Climate Research Program.

GARP contributed significantly to making the atmospheric sciences a truly global and cooperative effort. It was an important step in making numerical modeling of weather and climate an international research priority and expand and adjust global observation systems to the needs of weather and climate models.

1: Kennedy, John F. Address at U.N. General Assembly, 25 September 1961, John F. Kennedy Presidential Library and Museum, Film and transcript online at:

2: UNOOSA website at:

3: Bolin, Bert, Introduction. In: Joint Organizing Committee, An Introduction to GARP, GARP Publication Series No. 1, WMO and ICSU: Geneva, 1969.

3: Bolin, Bert, A history of the science and politics of climate change, The role of the Intergovernmental Panel on Climate Change, Cambridge: Cambridge University Press, 2007.

National Academy of Science

Founded in 1863 as a result by an Act of Congress, the U.S. National Academy of Sciences (NAS) is charged with “providing independent, objective advice to the nation on matters related to science and technology."1 In this mission the NAS had a significant share in the expansion of the atmospheric and climate sciences in the postwar period and the provision of advice on issues related to climate including global climate change.

US NAS Building

Building of the U.S. National Academy of Sciences.2

Already in the 1930s, the NAS contributed to funding the MIT meteorology program for purchasing a research aircraft for measurements in the higher atmosphere. In 1956, an Advisory Committee on Meteorology was established at the NAS, renamed Committee on Atmospheric Sciences (CAS) in summer 1958. This committee assembled some of the leading atmospheric sciences in the USA and was instrumental in the creation of a national institute for atmospheric research. In 1960, the Na-tional Center for Atmospheric Research (NCAR) was founded in Boulder, Colorado. It became one of the leading centers of atmospheric sciences in the world, a magnet for young atmospheric scien-tists from many countries and home to influential climate researchers such as William W. Kellogg and Stephen H. Schneider.

The NAS was also involved in ambitions of weather and climate modification. This topic electrified scientists and politicians during the 1950s and 60s and shaped perceptions and directions of atmos-pheric research in this era. The goal of weather and climate prediction, for example, served as a step to the bigger goal of weather and climate modification. The NAS published influential reports on weather and climate modification in 1966 and 1973. Another report titled The Atmospheric Sciences and Man’s Needs3 formulated research recommendations for the 1970s. It dedicated a chapter to weather and climate modification, whereas global warming due to carbon dioxide emis-sions, called “inadvertent modification”, was treated on only one page and considered a non-issue.

Cover page of NAS Report

Cover page of NAS Report on weather and climate modification published in 1966.4

Important activities of the Committee on Atmospheric Sciences were also the expansion of educa-tion in meteorology and atmospheric sciences and of international cooperation. Through CAS, in fact, the NAS was a crucial player in the formulation and establishment of the Global Atmospheric Research Program (GARP) in 1967. Weather and climate modelers urgently needed better obser-vational data of the atmosphere with global coverage. New technologies such as rockets and satel-lites promised improved surveillance of the state of the atmosphere, which GARP was to harness.

Since the 1970s, NAS provided important reviews about the problem of global warming and open research questions to be tackled. An influential contributions was the so-called Charney Report from 1979. Commissioned by the NAS and headed by Jule Charney, a study group consisting of high ranking scientists investigated the state of knowledge about a future global warming. Based on fu-ture projections of climate with two climate models by Syukuro Manabe and James E. Hansen the study group cautiously concluded that it “finds no reason to doubt that climate changes will result and no reason to believe that these changes will be negligible.”5

1: NAS mission statement:

2: NAS website:

3: National Academy of Sciences, The Atmospheric Sciences and Man’s Needs: Priorities for the Fu-ture, Washington: NAS, 1971

4: National Academy of Sciences, Weather and Climate Modification, Problems and Prospects: Final Report of the Panel on Weather and Climate Modification, Vol. 1–2, NAS: Washington, 1966.

5: Charney, Jule G. et al. 1979. Carbon Dioxide and Climate: A Scientific Assessment (Washington, DC: National Academy of Sciences).

National Academy of Sciences, Weather and Climate Modification, Problems and Progress, NAS: Washington, 1973.

US National Climate Program

First conceived in 1975, American legislators sought to pass a national climate program to reduce the negative impacts of climatic variability. The central idea was that states would work in concert with the federal government to monitor and analyze climatic fluctuations in the hope that such efforts could lead to accurate climate predictions. Given the elimination of the State Climatology Program in 1973 during the Nixon administration, state climatologists, business and agricultural interests, as well as state officials argued vehemently for a program that strengthened the role of local interests in national decision making. State climatologists, many of whom testified in support of climate legislation, were especially critical of what appeared to be federal inaction on climate-related matters.

While influential members of the U.S. Congress – in consultation with various constituencies – concluded that something should be done, prominent officials within the Carter administration advocated for a more restrained approach to climate governance. Instead of providing grants to local and state officials, who then would distribute the funds to state climatologists and other climate-related services tailored to individual state needs, the administration argued for a more centralized research program suited to improving the reliability of climate predictions. The Office of Science and Technology Policy, as well as the Office of Management and Budget, relied on the opinions not only of agency heads but on the views as presented within federally-sponsored scientific reports.

Despite the reluctance of the administration to support congressional efforts to pass a service-oriented climate program, President Carter signed the legislation into law in September 1978. This legislation marked the first time that climate had acquired a distinctly legal and political identity within the United States, and as such its passage also marks the first time that climate deliberations sparked policy disagreements between different branches of the American government.

Climate Conferences

Changes of Climate 1961

From 2 to 7 October 1961 the Rome Symposium “Changes of Climate” was organized by the United Nations Educational, Scientific and Cultural Organization (UNESCO) and the World Meteorological Organization (WMO). 115 scientists from 36 countries participated and 45 papers were given in nine different working sessions. The conference highlighted a strong interest in climatic changes that had recently emerged (find full conference proceedings here1). Climate was mostly conceived as stable within human timescales in the tradition of classical climatology. In the mid-twentieth century, this understanding had eroded.

The conference took place as part of UNESCO’s Arid Zone Program. After its foundation in 1945, UNESCO took a strong interest in problems related to natural resources and the protection of nature. The dramatic dustbowl in the Western United States during the 1930s and similar events in Australia and Southern Africa, drought related famine in India, and the French obsession with the desiccating effects of deforestation in North and West Africa made climatic problems of arid zones an international focus of interest. UNESCO wanted to contribute to better knowledge about arid zones and solutions to its climatic challenges.

Buried machinery in South Dakota, United States

Buried machinery in South Dakota, United States, during the Dust Bowl in 1936.1 (Source: Wikipedia).

In 1949 UNESCO established the Arid Zone Program, which in 1956 evolved into the Arid Lands Major Project, one of UNESCO’s three so-called “Major Projects”. In this program, UNESCO sought to facilitate a comprehensive interdisciplinary approach to the problem of deserts and to produce an international community of arid zone researchers. The program comprised the collection and dissemination of information on Arid Zone hydrology and related fields – such as climatology, biology, ecology, geology, soil science and engineering – and the organization of international conferences on topics such as hydrology and underground water (Ankara 1952), renewable energy sources (New Delhi 1954) and climatology and microclimatology (Canberra 1956).

The Symposium “Changes on Climate” represented a major synthesizing event. ”The problem of climatic fluctuations is one of extreme complexity and one which relates to many disciplines,” stated the foreword of the proceedings. “The purpose of the symposium was to bring together scientists who have contributed to the subject from such fields as meteorology, oceanography, geomorphology, geography, hydrology, botany, geology and even archaeology, so as to obtain a coherent and comprehensive picture of present knowledge, theories and implications of climatic change” (UNESCO 1961, Foreword). Accordingly, the contributions to this conference covered a wide range of research domains.

The conference represented a striking example of the comprehensive approach and holistic ambitions that had characterized climatology in the nineteenth and early twentieth century. This ambition soon was to be abandoned to be replaced by a focus on physical approaches and numerical modeling and simulation. Two conferences on problems of climatic change organized just a decade later, the Study of Critical Environmental Problems in 1970 and the Study on Man’s Impact on Climate, clearly made manifest fundamental changes in the study of climate.

1: UNESCO, Changes of Climate, Proceedings of the Rome Symposium organized by Unesco and the World Meteorological Organization, Paris: UNESCO, 1963.

2: A South Dakota farm during the Dust Bowl, 1936. Sloan (?) - United States Department of Agriculture; Image Number: 00di0971 Wikipedia.

SCEP 1970

Two very unusual conferences played a significant role in making the problem of climate change visible: the Study of Critical Environmental Problems (SCEP) in 1970 and the Study of Man’s Impact on the Climate (SMIC) in 1971. These conferences were major events that helped put problems of climate change in focus as a potentially significant environmental problem. They were initiated and organized by Carroll Louis Wilson, professor of management at the Massachusetts Institute of Technology (MIT) with an extraordinary personality. Wilson was a man of action and an outstanding organizer. Born in 1910, he had made a remarkable career as an administrator, businessman and university professor with excellent contacts and ties to the worlds of politics and business.

The Study of Critical Environmental Problems (SCEP) for the first time highlighted potential changes of climate as an important environmental issue. It was a study conference lasting over the whole month of July 1970. Its approximately seventy participants came from universities, corporations, laboratories, and federal agencies in the USA. These participants embraced a panoply of disciplines: meteorology, atmospheric chemistry, oceanography, biology, ecology, physics, engineering, economics, the social sciences, and law. They had the task to discuss and synthesize the state of knowledge on four topics: 1) Climatic Effects, 2) Ecological Effects, 3) Monitoring and 4) Implications of Change. William Kellogg chaired the work group on Climatic Effects.

“A thorough understanding and reliable prediction of the influence of atmospheric pollutants on climate requires the mathematical simulation of atmosphere-ocean systems, including the pollutants.”1

The study report emphasized that participants “acted as individuals, not as representatives of the agencies or organizations with which they were affiliated” (SCEP 1970, p. xiv). This autonomy helped to relieve the participants from consideration of official narratives and duties. Likewise, it allowed Carroll Wilson to shape the event and its major product, the SCEP report, according to his ambitions. The SCEP report was published very quickly in October 1970. It provided a comprehensive assessment of environmental problems. The report suggested the adoption of the principle of precaution and included calls for “corrective action.” A language of concern set the tone from the outset. The conference was concluded with a press conference. In addition, a comprehensive volume of SCEP background papers was published in spring 1971.2

“This is a collection that most meteorologists should read, especially those concerned with environmental problems.”3.

1: SCEP (Study of Critical Environmental Problems). 1970. Man’s Impact on the Global Environment: Assessment and Recommendation for Action (Cambridge, MA: MIT Press).

2: Matthews, William H., William W. Kellogg, G. D. Robinson (eds.). 1971. Man’s impact on the climate. Collected background papers of SCEP (Cambridge: MIT Press).

3: Landsberg, Helmut E. 1972. Review of Kellogg et al. Man’s Impact on Climate, Bulletin of the American Meteorological Society 53:2, pp. 162-163.

SMIC 1971

Should preventive or remedial action be necessary, it will almost certainly require effective cooperation among the nations of the world. SMIC was developed to assist in that process by providing an international scientific consensus on what we know and do not know and how to fill the gaps.1

Right after the successful SCEP Conference in 1970, its organizer Carroll Wilson and his closest collaborators decided for a second, international conference of the same type with a sole focus on climate problems, the Study of Man’s Impact on Climate (SMIC). Wilson wanted to inspire international cooperation, reach an international consensus and address an international audience. SMIC took place for a period of three weeks from 28 June to 16 July 1971 at the conference center Wijk close to Stockholm and was hosted by the Swedish Royal Academy of Sciences. The study conference was financed for the most part by the U.S. National Science Foundation. This time, 30 scientists from 14 countries participated, among them notable experts such as Belgian Jacques van Miegham, one of the principal architects of the International Geophysical Year, Mikhail Ivanovich Budyko, leading climatologist from the Soviet Union, Hermann Flohn, the leading climatologist in Germany, and Syokuro Manabe, one of the outstanding climate modeling pioneers in the USA.

The SMIC Report was published quickly and distributed widely. It served the scientific preparation of the 1972 UN Conference on the Human Environment in Stockholm, which was a milestone in the development of international environmental politics. The Report had the ambition “to be definitive and authoritative in assessing the status of our present knowledge and in recommending the needed programs.” On more than 300 pages it provided a comprehensive account of the state of knowledge about climate. It emphasized the urgency of responses to the risk of warming due to rising carbon dioxide concentrations. Its recommendations included the improvement of models (with detailed suggestions) and its “expanded use” for modeling experiments including the long term prediction of climate change.2 The SMIC meeting also revealed the contested character of much of the available climate knowledge. William Kellogg, one of its organizers, attempted to overcome an “apparent impasse in the assembled group between two opposing schools of thought: the climate 'coolers' and the climate 'warmers'.”3 This attempt failed, however.

In spite of disagreement whether a future warming or a future cooling was to be expected, the SCEP and SMIC reports exemplified an intellectual and ideological sea change from an era defined by military and geopolitical reasoning and logic in the early Cold War to an era that was strongly influenced by environmental concern (Hare 1972). Climate was reinterpreted as a condition of the human environment that could change and demanded urgent attention. Furthermore, SCEP and SMIC were important social experiences for many of the participants and presaged changes in the culture of climate science.

It is now quite clear that climatology in particular, and physical geography in general, is going to be remade as a result of the innovations of the environmental movement ... The volumes under review here are essential documents in the rethinking process now under way.4

1-2: SMIC (Study of Man’s Impact on the Climate), Man’s Impact on the Climate, Cambridge: MIT Press, 1971.

3: Kellogg, William W., Mankind's Impact on Climate: The Evolution of an Awareness, Climatic Change 10 (1987), pp. 113-136.

4: Hare, F. Kenneth, Man’s impact on the global environment, Annals of the Association of American Geographers 62:3 (1972), pp. 520-522.

World Climate Conference 1979

On 12-23 February 1979 the World Climate Conference, A Conference of Experts on Climate and Mankind, took place in Geneva. The World Meteorological Organization (WMO) had taken increased interest in issues related to climate and climate change since the early 1970s and organized or sponsored a number of smaller meetings. On its 29th session the Executive Committee of the WMO decided to convene the World Climate Conference “(a) To review knowledge of climatic change and variability, due both to natural and anthropogenic causes; and (b) To assess possible future climatic changes and variability and their implications for human activities” (WMO 1979, p. vii; the full proceedings of the conference can be found here).1

During the 1970s, concerns increased that the emission and rising concentration of carbon dioxide in the atmosphere may cause a future climate change. The World Climate Conference represented a visible and politically influential response to these concerns. Robert M. White, Chairman of the Conference, provided in his opening Keynote a broad overview on diverse problems related to climate ranging from pressures on agriculture and food production and deadly famines due to climatic fluctuations to the problem of global climate change. “If natural climate disasters had not been enough to motivate governments and the scientific community to action, the ominous possibilities for man-induced climatic changes would have triggered our presence here,” he concluded.2

In the first week of the World Climate Conference invited speakers presented “comprehensive and authoritative Overview Papers covering current knowledge of climate and the interactions between climate variability and change and human society” to an audience of 350 participants from all parts of the world. In the second week, invited experts assessed the present understanding of climate and its interactions with mankind and formulated general recommendations for international action. Major topics comprised climate data, applications of knowledge of climate, studies of the impact of climate on human activities and research on climate change and variability. These themes were the major components of the planned World Climate Research Program.

Another topic, however, was looming as a major issue of interest in many of the discussions. "The Conference noted that there was an additional issue of special importance that pervades all the above-mentioned components: The problem of possible human influences on climate." As one major outcome, the conference published a “Declaration of the World Climate Conference.3” The declaration included “An Appeal to Nations” (see box) and emphasized the political challenge by carbon dioxide emissions and global climate change.

An appeal to nations

An Appeal to Nations scanned excerpt.

The “Declaration of the World Climate Conference” concluded: “It is possible that some effects on a regional and global scale may be detectable before the end of this century and become significant before the middle of the next century. This time scale is similar to that required to redirect, if necessary, the operation of many aspects of the world economy, including agriculture and the production of energy.”

1: WMO, Proceedings of the World Climate Conference, A Conference of Experts on Climate and Mankind, Geneva, 12 - 23 February 1979, Geneva: WMO, 1979.

2: White, Robert M., Climate at the Millenium, Keynote Address, in: WMO, Proceedings of the World Climate Conference, pp. 1-11.

3: WMO, Declaration of the World Climate Conference, online available at:

Global Scale Research

The observation of winds in the atmosphere raised the question of large scale movements of air masses. In the 18th century, George Hadley, an English lawyer and amateur meteorologist, proposed a tropical atmospheric circulation with warm air rising near the equator, flowing poleward at 10–15 kilometers above the surface and descending in the subtropics.1 This so-called Hadley cell could explain the trade winds. Interest in global circulation phenomena continued, but its systematic use to understand climatic phenomena only began in the 20th century.

Comparison of modern and sketch recreation of a Hadley Cell.

Comparison of modern diagram2 and recreation of original sketch of a Hadley cell.

Classical climatology took an opposite approach and attempted to understand climatic phenomena from a local perspective through local investigation (see also Regional/small scale research of climate). When higher layers of the atmosphere became a matter of intensive investigation in the early 20th century, the climatological buttom-up approach from the local to the global became challenged. Large scale circulation patterns had a tremendous impact on climatic phenomena such as tropical rain belts, subtropical deserts and the monsoon. Climatologists such as Hermann Flohn, who made significant contributions to the understanding of the monsoon, attempted to modernize climatology and integrate local and large scale approaches in climatology (see modernizing climatology).

Climate modeling took from its very beginning a larger scale approach, and could not deal adequately with small-scale phenomena. Climate models are based on differential equations, which in principle describe the state of the atmosphere at every point in time and space. The solution of these equations, however, required an averaging of the state of the atmosphere in large grid cells covering the surface of the earth. These grid cells usually have a side length of several hundred kilometers. Smaller scale phenomena such as cloud formation and precipitation, hence, cannot be modeled in a realistic manner.

It is ironic that we cannot represent the effects of the small-scale processes by making direct use of the well-known equations that govern them.3

With the dissemination of general circulation models (and a raising awareness of global environmental problems) from the 1970s onwards, the attention increasingly moved away from local and regional detail to the global character of climate. A typical example of this globalization is the construction of the artificial parameter “global mean temperature” by James Hansen and others as a lead parameter to assess and predict global climate change (see climate projections). Coarse grid resolution and simplifications in climate models reinforced a reductionist approach which blurred regional and local characteristics (such as local topography etc.).

Global surface temperature diagram depicting temperature anomalies.

Global surface temperature diagram depicting temperature anomalies.4

1: Hadley, George: "Concerning the Cause of the General Trade-Winds", Philosophical Transactions 39, pp. 58-62.

2: Hadley cells within an idealized depiction of the Earth's atmospheric circulation as they may appear at equinox by Kaidor is liscened under CC BY-SA 3.0

3: Randall, D. et al. 2003: “Breaking the Cloud Parameterization Deadlock”, Bulletin of the American Meteorological Society 84, pp. 1547-1564.

4: Global Surface Temperature Anomaly December 2016 from the, already warmer than normal, 1951-1980 average. Source: NOAA,

Regional Scale Research

Scales matter significantly in the investigation of climate. Classical climatology typically pursued a small scale, regional approach by studying climates in specific geographical locations. It’s very methodological starting point is the local climate and its understanding, from which broader regional characteristics and patterns, like in Köppen’s climate maps (see classical climatology), were constructed. Classical climatology can be characterized by a bottom-up approach, which perceived detailed local information as the basis for generating knowledge about relations on the larger scale. This methodological approach also involved a comparably strong focus on local factors as an explanation for climatic features. In the early 20th century this approach was successfully pursued in climatological sub-disciplines such as microclimatology, bioclimatology and urban climatology.

The bottom-up research strategy in climatology was increasingly challenged since the early 20th century by new insights about large scale processes in the atmosphere such as a better understanding of the general circulation of the atmosphere and the importance of jet streams in high layers of the atmosphere, which have an influence on weather and climate at the surface of the earth. Many climatologists such as Hermann Flohn in Germany saw the importance of these dynamic, large scale processes and attempted to include them in their climatological reasoning (see modernizing climatology). Still, most climatologists kept to their observation-based, bottom-up methodology.

Some climatologists such as Hubert Lamb expressed reluctance to accept ambitious approaches in numerical modeling, which prioritized theoretical reasoning based on physical laws and approximations on large geographical scales (see also Global/large scale research of climate). In their eyes, these approaches neglected local detail and, hence, much of the complexity of climatic phenomena. After about 1950, these views increasingly represented a minority position, because the focus of research shifted towards computer-based numerical simulation and a more global view on climate.

Climate Researchers

Modernizers of Climatology

Hermann Flohn

Hermann Flohn

Hermann Flohn was academically raised in a tradition he later called “classical climatology”. He studied geography, meteorology, geophysics and geology in Frankfurt a.M. and Innsbruck, and received his PhD in geomorphology in 1934. After his graduation, Hermann Flohn first specialised in medical climatology. He became an assistant at the Hygienisches Institut of the University of Marburg/Lahn. A few months later he became an intern at the Reichsamt für Wetterdienst in Berlin and soon official in charge of its medical climatology section. At the age of 25 he was promoted head of the bioclimatological research station in Bad Elster, a small town at the Czech border. When World War II broke out in 1939 Flohn was called up to work at the weather service of the German Air Force, where he was mainly in charge of weather forecasting.

After the war, Flohn was detained and imprisoned for one year before he was classified as a “Mitläufer” (follower) of the NSDAP, convicted to 1000 Reichsmark (or 30 days of work) and thereafter politically cleared. Right after, in 1946, Flohn joined the Central Bureau for Weather Service in the US controlled zone in Bad Kissingen, an initially small successor of the once powerful Reichsamt für Wetterdienst. A few years later, from 1952 until 1961, he made a career in the newly founded Deutscher Wetterdienst (German Weather Service), in which he became head of the research department.

The monsoon, a regional climate phenomenon in the tropics and in East Asia became one of his main fields of interest. On the one hand, he investigated this wind as a “singularity” in the weather pattern; on the other hand, he more and more put it also in the context of larger scales atmospheric circulations.

In summer 1949, Flohn accompanied his mentor Ludwig Weickmann for a research trip to the USA. It was the beginning of an extensive travelling activity by Flohn. At the Weather Service, Flohn gathered a group of young first class theoreticians around him including Friedrich (Fritz) Wippermann (1922-2005) and Karl Heinz Hinkelmann (1915-1986) and established a research group on numerical weather prediction. Flohn eventually left the Service in 1961 to become full professor and director of the newly established Institute of Meteorology at the University of Bonn.

With his advancing career, Flohn developed a particular interest in human induced climate change. He became an often invited expert on conferences and symposia on climate change in Europe and the USA. His expertise and engagement made him also become an advisor, like his Swedish colleague Bert Bolin, when in 1974 the Max-Planck-Society decided to set up an Institute of Meteorology in Hamburg. Flohn was a strong supporter of the physical-mathematical approach towards climate as applied with computer models. But he also stuck to his conviction that climate is too complex to be understood, interpreted and predicted solely by such mathematical means.

In 1977, Hermann Flohn retired as professor in Bonn, but continued working and publishing in academia. At the same time, he strengthened his position as mediator between his scientific community and other disciplines as well as the public. He wrote for various journals and newspapers, where he warned of the danger of human-induced global warming.

“As a climatologist, I must confess, that to me this approach seems the most fascinating and rewarding one. It promises to be the base of a complete understanding of our present climate […].”

Flohn on numerical weather prediction 1965 (Flohn, Hermann 1965: Research Aspects of Long-Range Forecasting. In: WMO-IUGG symposium on research and development aspects of long-range forecasting, Boulder, Colorado. WMO Technical Note 66, page 4.

Hubert Lamb

Hermann Flohn

Hubert Horace Lamb was a leading British climatologist and pioneer of historical climatology. He was born on 22 September 1913 in Bedford, UK, and died on 28 June 1997. Lamb studied geography during the 1930s at Trinity College, University of Cambridge, and shared a life-long interest in history. In 1936 he joined the UK’s national weather service, the British Meteorological Office (shortly often referred to as MetOffice). During the war years he served at the Irish Meteorological Service on aviation forecasts.

After World War II, he joined the MetOffices climatology section in Harrow, in northwest London. In the basement of the Harrow office Lamb discovered archives of past weather observations in the world, which was perhaps the richest collection of its kind developed as a by-product of Britain’s colonial and exploratory history. With this discovery Lamb grasped the opportunity to pursue his interests in history and explore the climates of the past. He was one of the first to propose that climate could change within human experience and opposed the long-held orthodox view in classical climatology that climate could be treated as constant within time-scales of decades.

His life-long research focus became the question about the relationships between climate and human history. Lamb constructed monthly barometric pressure maps as far back in time and covering as much of the world as possible. He became fascinated by the timing, extent and causes of past climatic variations and explored its social and cultural impacts. Based on the investigation of past climatic data, Lamb developed theories about the Medieval Warm Period and the Little Ice Age. Lamb expanded his research program in historical climatology systematically. The reconstruction of past climates drew from results of many disciplines such as archaeology, history, paleobotany, glaciology, geology, geophysics, oceanography and others. Lamb was convinced that only such multi-disciplinary approach provided comprehensive knowledge about climatic changes.

The Met Office generously supported Lamb’s research efforts for more than a decade. When in 1965 British cloud physicist John Mason was appointed director of the Met Office, however, Lamb’s situation changed drastically. Mason transformed the culture at the Met Office deeply and focused operations systematically on numerical simulation, whereas other fields of activity were strongly reduced or closed. Lamb lost his scientific staff and financial support for his research in historical climatology.

Lamb strongly disagreed with Mason’s research strategy and criticized numerical simulation approaches. Raised in the empirical tradition of classical climatology, he put great emphasis on the collection of empirical information and was convinced that understanding the climate and its changes required a detailed analysis of past climates. In a paper in the journal Nature in 1969 he argued: “The computer models of atmospheric behavior and other climatic areas may be unrealistic, and may therefore proceed too far and too fast on faulty basic assumptions. Such developments should be preceded by acquiring fuller and firmer factual knowledge.”1

Numerical modelling, Lamb believed, reduced climate to a purely physical phenomenon with no associations to culture, geography, or human history – a reductionist approach that he found misguided at best and harmful at worst. A numerical, interpretation of climate, Lamb worried, negated other ways of knowing – ways which might prove crucial to a full understanding of climate.

Lamb’s ongoing conflict with Mason eventually convinced him to leave the Meteorological Office in 1971 after 36 years of service. Soloman Zuckerman, chief science advisor to the British government commented aptly that “Lamb does not fit in very well to the Meteorological Office, which is predominantly manned by people trained in the physical sciences.”2. In 1972, Lamb founded the Climatic Research Unit (CRU) at the School of Environmental Sciences, University of East Anglia in Norwich, with the help of Sir Graham Sutton, former director of the Meteorological Office and a supporter of Lamb’s research and Lord Solly Zuckerman, who served as an adviser to the University.

As director of CRU Lamb until his retirement in 1978, Lamb expanded his research program in historical climatology, even though CRU repeatedly suffered from funding problems. Initial sponsors included British Petroleum, the Nuffield Foundation and Royal Dutch Shell. Later the Rockefeller Foundation, the U.S. Department of Energy and the British Wolfson Foundation provided important contributions. Notably, the British Natural Environment Research Council refused to fund the Climatic Research Unit. Lamb complained repeatedly that throughout the 1970s numerical approaches received vastly more funding than historical climatology.

1: Lamb, Hubert H., The New Look of Climatology, Nature, 223 (1969), pp. 1209-1215.

2: Martin Nielsen, Janet, Ways of knowing climate: Hubert H. Lamb and climate research in the UK, WIREs Climate Change 6 (2015), pp. 465–477.

Lamb, Hubert H., Climate, History and the Modern World, London and New York: Methuen, 1982.

Martin-Nielsen, Janet, A New Climate: Hubert H. Lamb and Boundary Work at the UK Meteoro-logical Office, in: Matthias Heymann, Gabriele Gramelsberger and Martin Mahoney (eds.), Cultures of Prediction in Atmospheric and Climate Science: Epistemic and cultural shifts in computer-based modelling and simulation, New York: Routledge, 2017, pp. 85-99.

Helmut Landsberg

Helmut Erich Landsberg

Helmut Erich Landsberg was born in Frankfurt, Germany. As a doctoral student at Frankfurt University during the late 1920s, he was heavily involved in efforts to apply geophysical knowledge to practical problems in agriculture and aviation. After completing his doctorate in 1930 in seismology, he continued to work under the auspices of one of his advisers, meteorologist Franz Linke, who would eventually help him immigrate to the United States in 1934 after the rise of the Nazi Party. His first academic position was located at Pennsylvania State College, where he applied his seismological knowledge to practical problems. During these early years in the United States, he was not heavily involved in climatological research. But with the onset of America’s entry into World War II in 1941, he sought to put climatology to work. He worked with the Army Air Force to make bombing more precise, and his superiors praised his efforts as being uniquely integral to the success of bombing campaigns on the Pacific Front.

During the war, Landsberg began to think critically about the place of climatology in American society. Given that climatology had always been subservient to its mother discipline of meteorology, he worried that climatology would fall into old patterns once hostilities ended. Imagining a so-called “climatological renaissance” as early as 1943, he began to argue that the study of climate would be integral to maintaining a stable society in peacetime. This ambition lived with him for the remainder of the war, and afterward he used his expertise and connections to implement his vision. One would be hard-pressed to argue that climatology was seen generally as a useful discipline, and even Landsberg himself acknowledged often that attaining his goals would mean overcoming many intellectual and institutional barriers. Nonetheless, during the 1950s and 1960s, his efforts contributed to a growing awareness among America’s elites that climatology would be a useful discipline.

While Landsberg was clearly invested in maximizing the usefulness of climatology to human society, he wore multiple disciplinary hats – bioclimatologist, urban climatologist, microclimatologist. Omnipresent within the global climatological community, he gained recognition for being one of the most inspiring climatologists of the 20th century. While serving as director of the U.S. Weather Bureau’s Office of Climatology between 1955 and 1966, he argued often that studying the physics of the atmosphere would prove valuable in the long-term. Not only would the mathematization of the atmosphere provide the tools to predict future climate states, he believed that the momentum would usher in a world in which climatology would be seen as invaluable to human ambitions to provide sufficient levels of food, shelter, and stability.

While he always harbored a grand vision of climatology, Landsberg observed with great consternation the popularization of climate in contemporary affairs. Abhorring what he saw as the uptake of climate into popular culture and politics, he could not help but grow wary of claims about future climate-induced disaster. Contrary to claims that climate was becoming increasingly unstable during the 1970s, he instead argued that population growth combined with an unwillingness to consider climate in everyday decision making made the vagaries of climate appear more disruptive. “Some, who are not particularly familiar with the peculiarly complex mechanisms of the atmosphere have come forth with prophesies of impending climatic catastrophes,” he commented in 1976. While he acknowledged what appeared to be vacillations in climate parameters, things like temperature and precipitation, it seemed premature to equate such vacillations with long-term changes or to equate such changes as being the result of human activities.1

While Landsbeg had spent decades arguing for the value of climate understanding to human affairs, it seemed by the 1970s and early 1980s that genuine understanding had become secondary to the politics of alarm that swept across the country. Always envisioning climatology as a reticent discipline, he never felt comfortable in a society where climate change had become wrapped up into other salient issues that spilled out on the pages of national newspapers, including topics like anthropogenic global climate change and claims of an impending nuclear winter. While in retirement, it seemed integral to isolate climate from what he saw as the vulgarities of politics and popular culture, and he never found a solution that suited his style as a scientist. If there ever was a time when his own style contrasted with the ferment of the times, it was toward the end of his life. He passed away in December 1985 while attending a meeting of the World Meteorological Organization, a moment of passing that marked definitively the sunset of climate as a sensational topic of media intrigue and popular political debate. For him, this was not the vision set forth two decades earlier. As he articulated in light of the inauguration of John F. Kennedy,

Climatology is not a glamorous field. It does not produce what the newspaper jargon applied to science calls ‘exciting discoveries’ or ‘spectacular breakthroughs.’ Improved knowledge in this field will, however, assure better living for mankind... These ‘bread and butter’ goals may not fire the imagination nor kindle much enthusiasm but they will help us to the necessities of life.2

This quote, perhaps more than any other, illuminates the essence of Helmut Landsberg’s scientific life.

1: Landsberg, Helmut, “How is Our Climate Fluctuating,” Series 5, Box 1, Papers of Helmut Landsberg

2: Landsberg, Helmut, “Outline for Climatology, 1961-1970,” Series 3, Box 7, Papers of Helmut Landsberg

Hans W. Ahlmann

Hans Wilhelmsson Ahlmann

Hans Jakob Konrad Wilhelmsson Ahlmann was a Swedish glaciologists and one of the leading figures in this discipline. He became known for his studies of glaciers and the discovery that glaciers were retreating in the first half of the twentieth century due to a warming in the Northern hemisphere. Ahlmann was born on 14 November 1889. He studied geography at Stockholm University, where he also served as associate professor between 1915 and 1920 and professor of geography from 1929 to 1950. In 1950, Ahlmann was appointed Swedish ambassador in Oslo, where he served until 1956. Ahlmann died in 1974.

Ahlmann was a man of many talents and interests, both literary and artistic, and with a broad ranging interest in geography, stretching from fieldwork in Libya to a major study of the modern Stockholm region. In 1918, he started investigating the Horung massif glaciers in Jotunheimen in southern Norway. He was interested in the physiography of glaciers, its size and form and its changes in time due to meteorological factors.

He made this interest a systematic life-long occupation, studying further glaciers at two expeditions to Spitsbergen in 1931 and 1934, an expedition to the Vatnajökull glacier in Iceland in 1936 and an expedition to northeast Greenland to study the Fröya glacier in 1939. Ahlmann wanted to combine the tradition of scientific expeditions with stringent methodology and a strong focus on precision in quantitative field measurements. Historian Sverker Sörlin called his style of fieldwork a “culture of precision.”1

Ahlmann wanted to understand the processes of growth and retreat of glaciers by meteorological factors. He could show that glacier regimes depend more upon temperatures than upon precipitation. He became particularly famous and caused much public attention during the 1940s and 50s for making an opposite inference: his observation of shrinking glaciers and understanding of the ablation processes led him to postulate a significant polar warming, which he called an “embetterment of climate.”2

In May 1947, Hans Ahlmann travelled to the United States from Sweden to lecture on polar warming. In a lecture Geophysical Institute of the University of the University of California in Los Angeles, he reported that Arctic temperatures had risen by five degrees Celsius in recent decades. Ahlmann concluded that a melting of the ice sheets in Greenland and Antarctica, in case the warming was global in nature, would have catastrophic consequences. This lecture and its horrifying conclusions received coverage in leading public media such as the New York Times. In June 1947, Ahlmann was invited to a meeting at the Pentagon. The U.S. military authorities took great interest in Ahlmann’s conclusions, because a polar melting threatened U.S. national security interests. This episode helped to strongly increase the focus on research efforts in arctic regions in the USA.

1-2: Sörlin, Sverker, The Anxieties of a Science Diplomat: Field Coproduction of Climate Knowledge and the Rise and Fall of Hans Ahlmann’s “Polar Warming”, Osiris 26:1 (2011), pp. 66-88.

Ahlmann, Hans W., Glaciers in Jotunheim and Their Physiography, Geografiska Annaler, Vol. 4 (1922), pp. 1-57.

Doel, Ronald E., Quelle place pour les sciences de l'environnement physique dans l'histoire envi-ronnementale? Revue d’histoire moderne contemporaine 56:4 (2009), pp. 137-164.

Sörlin, Sverker, Narratives and counter-narratives of climate change: North Atlantic glaciology and meteorology, c.1930–1955, Journal of Historical Geography 35 (2009) 237–255.

Movers of Heuristic Climate Modeling

Syukuro Manabe

Syukuro Manabe

One of the leading pioneers in the first generation of climate modelers was Japanese meteorologist Syukuro Manabe. Manabe was born on 21 September 1931. He received a PhD in Meteorology from the University of Tokyo in 1958. In 1959 he moved to the USA and joined the General Circulation Research Laboratory, which was led by Joseph Smagorinsky and initially located in Washington D.C. In 1963, the Laboratory was renamed the Geophysical Fluid Dynamics Laboratory and in 1968 moved to Princeton University.

Manabe had experiences in weather prediction research in Japan and was an excellent theoretical meteorologist. Smagorinsky hired him to contribute to General Circulation Model (GCM) development. Building on the work of early pioneers of climate modeling such as Jule Charney and Norman Phillips, Manabe and Smagorinsky adopted a cautious heuristic modeling research strategy. According to climate modeling historian Paul N. Edwards, they pursued a “long-range view of the circulation modeling effort” and their “research strategy used GCMs to diagnose what remained poorly understood or poorly modeled.”1. “Strict attention to developing physical theory and numerical methods before seeking verisimilitude became a hallmark of the GFDL modeling approach.”2

Manabe, like his Japanese fellow climate modeler Akio Arakawa at the University of California, made very significant contributions to climate modeling by investigating and representing atmospheric processes, which had not yet been considered in GCMs. Manabe explored radiative transfer, convection and the thermal equilibrium in different heights of the atmosphere with a 1-dimensional model representing the vertical dimension of the atmosphere. Arakawa, in contrast, was interested in accounting for the effects of clouds on climate. Many of these processes occurred on much smaller spatial scales than GCMs could resolve. Hence, artificial schemes approximating these so-called sub-scale processes had to be developed for GCMs. These approximations are called “parameterizations” and have remained indispensable until today, even though they are major sources of model uncertainty (further details of the scientific work of Manabe and Arakawa are given in Weart 2017a3 and 2017b4).

By 1965 Manabe and his group had developed a three-dimensional global model with nine vertical levels. The model was still highly simplified, with no geography included, but able to provide quite realistic simulation results of processes such as transfer of heat and moisture. A Committee of the National Academy of Sciences concluded in 1966 that the best models simulated atmospheres with gross features "that have some resemblance to observation."5 Manabe was also an early pioneer of attempts to include the role of oceans in climate models. In the late 1960s, together with oceanographer Kirk Bryan, he developed a first coupled model consisting of an atmospheric GCMs with a simple ocean model.

coupled climate model

Simplified “geography” of Manabe’s coupled climate model. Manabe and Bryan made a globe by putting together three identical segments, each part land and part sea. The polar regions, hard to deal with mathematically, were cut off.6

While Manabe was a dedicated heuristic modeler who aimed at a physical understanding of the atmosphere and climate, he was also drawn into early attempts of climate prediction. In 1965, the U.S. Presidential Scientific Advisory Committee published a report on the state and problems of the environment (PSAC 1965). Joseph Smagorinsky was member of a working group that studied issues of climate for this report including rising carbon dioxide levels. Smagorinsky recalled in an interview that the committee meetings for the PSAC report prompted him to ask Manabe to add carbon dioxide to his radiation model in order to explore the impact of rising carbon dioxide levels.7

Syukuro Manabe und Richard Wetherald made the test and used their one-dimensional model to simulate what would happen if the level of carbon dioxide doubled. They came up with their famous result that global temperature according to their model simulations would rise roughly by 2°C, but added that this result was subject to great uncertainty.8 This result, though preliminary, simulated with a model and not validated by observation, became an important resource in the emerging climate change discourse. Oceanographer and climate researcher Wallace Broecker later recalled that it was this 1967 paper “that convinced me that this was a thing to worry about.”9

thermal equillibrium paper

Title and abstract of Manabe’s and Wetherald’s famous paper providing a first model-based estimate of climate change in the case of doubled carbon dioxide content in the atmosphere (the relevant sentence in the abstract is highlighted)10. For a discussion of the article see here.

1: Edwards, Paul N. (2010) A Vast Machine: Computer Models, Climate Data, and the Politics of Global Warming. Cambridge, MA: MIT Press.

2: Edwards, Paul N. (2011) History of Climate Modeling, WIREs Climate Change 2: 128-139.

3: Weart, Spencer (2017a) Basic Radiation Calculations. In: The Discovery of Global Warming. A hypertext history of how scientists came to (partly) understand what people are doing to cause climate change. Online at:

4,7,9: Weart, Spencer (2017b) General Circulation Models of Climate. In: The Discovery of Global Warming. A hypertext history of how scientists came to (partly) understand what people are doing to cause climate change. Online at:

5: National Academy of Sciences, Committee on Atmospheric Sciences Panel on Weather and Climate Modification (1966) Weather and Climate Modification: Problems and Prospects, 2 Vols. (Washington, DC: National Academy of Sciences).

6: Manabe, Syukuro, Kirk Bryan (1969). Climate Calculations with a Combined Ocean-Atmosphere Model, Journal of Atmospheric Sciences 26, pp. 786-89.

8,10: Manabe, Syukuro, and Richard T. Wetherald (1967). "Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity." Journal of Atmospheric Sciences 24, pp. 241-59.

John Mason

thermal equillibrium paper

Sir Basil John Mason, better known as John Mason, was an expert on cloud physics and powerful director of the British Meteorological Office from 1965 to 1983. He led the Met Office into the computer age and transformed it significantly “into a world centre for weather prediction.”1 Born on 18 August 1923, Mason studied physics at Nottingham University and continued as lecturer in meteorology from 1947 and professor of cloud physics from 1961 at Imperial College London. In 1965, Mason was appointed director of the Met Office at the age of 42. During his long career he received numerous awards for his outstanding accomplishments. In 1979, he was knighted (and, hence, entitled to use the prefix Sir to his name).

Mason was described as a “charismatic man”, who “possessed scientific vision, enthusiasm and an inspiring style of lecturing and advocacy that enabled him to recruit good scientists and raise the funds needed to achieve these ends, although his manifest self-belief and forthright manner upset some.”2 Already in the early 1950s (in his late twentieth), Mason built a scientific and a public lecturing career. He received a Rockefeller Travelling Fellowship for the USA (1951) and augmented his meagre salary as lecturer by appearing frequently on radio and television programs and giving public lectures in the UK and abroad. He published about 70 papers and books on cloud physics between 1950 and 1965 and helped to establish cloud microphysics as a coherent discipline. Mason also served in the Executive Council of the World Meteorological Organization and was a strong supporter of the Global Atmospheric Research Program.

As new director of the Met Office, Mason immediately put his stamp on this venerable institution with some 3800 staff. One of his first major decisions, taken just weeks after assuming directorship, was to make numerical weather prediction operational – a decision that went against the advice of his senior staff and represented the beginning of a strong commitment to numerical methods and computer modeling at the office. One month after the beginning of Mason’s tenure at 1 October 1965, on Monday, 2 November 1965, the Meteorological Office began issuing twice-daily numerical forecasts.

Met Office KDF9 Computer

Met Office KDF9 Computer in 1966, Met Of-fice Headquarters, Bracknell. Source: Met Office Archive

For Mason, the role of objectively implemented physical theory in meteorology and climate research was critical to the future of those disciplines: numerical methods, he argued “are objective, logical, mathematical exercises based on a firm structure of physical theory,” whereas traditional weather forecasting and historical-based climate work depended heavily on individual experience.4

In subsequent years, the Office invested heavily in computer modeling, namely, numerical weather forecasting and, soon thereafter, numerical modeling of climate. Computers, Mason wrote in 1967, herald the end of “a long period of steady but unspectacular development in meteorology.” With numerical techniques, he continued, the Meteorological Office stood on “the threshold of a new era, with unprecedented opportunities for increasing our scientific understanding of the atmosphere.”5 On Mason’s demand, recruitment at the office was steered toward the natural sciences and, within a year of his appointment, only candidates with a first or second class honors degree in mathematics or physics could be considered for Scientific Officer positions at the Meteorological Office. For researchers at the Met Office pursuing different research interests and approaches, such as climatologist Hubert H. Lamb, no more support was granted.

Within a decade of his appointment, the Met Office had been extensively modernized and firmly based “on the most advanced numerical models in operational use,” as Mason wrote. Similarly, Mason approached the problem of climate. “By far the most promising approach to understanding the prediction of climatic change lies in the construction of physico-mathematical models of the global circulation of the atmosphere and oceans treated as a combined geophysical system,” Mason explained in an article in 1976.6

In spite of his enthusiasm for numerical approaches, Mason and his staff regarded climate simulation a slowly developing research domain, in which at first an adequate understanding of atmospheric processes had to be gained. An application of the model for practical purposes was out of the question. Mason even rejected demands by the British government to come up with climate predictions for several years. “Our understanding of the mechanisms and causes of climatic trends and fluctuations is inadequate to allow their prediction,” he wrote in 1976.7 In contrast to scientists such as William W. Kellogg, Stephen H. Schneider and James E. Hansen in the USA, Mason did not share beliefs in risks of global warming. He remained cautious about the limitations of climate models and sought to protect the scientific authority of the MetOffice.

1: The Telegraph, Sir John Mason, meteorologist – obituary, 15 January 2015, online at (last accessed, 3 January 2018).

2: Browning, Keith A., Sir (Basil) John Mason CB. 18 August 1923 – 6 January 2015, Biographical Memoirs of the Fellows of the Royal Society 62 (2016), pp. 359-380, online available at

3,5: Martin-Nielsen, Janet, A New Climate: Hubert H. Lamb and Boundary Work at the UK Meteoro-logical Office, in: Matthias Heymann, Gabriele Gramelsberger and Martin Mahoney (eds.), Cultures of Prediction in Atmospheric and Climate Science: Epistemic and cultural shifts in computer-based modelling and simulation, New York: Routledge, 2017, pp. 85-99.

4: Martin Nielsen, Janet, Ways of knowing climate: Hubert H. Lamb and climate research in the UK, WIREs Climate Change 6 (2015), pp. 465–477.

6: Martin Nielsen, Janet, Computing the Climate: When Models Became Political, Historical Studies in the Natural Sciences 48 (2018), forthcoming.

Agar, Jonathon, “Future Forecast – Changeable and Probably Getting Worse”: The UK Govern-ment’s Early Response to Anthropogenic Climate Change, Twentieth Century British History 26:4 (2015), pp. 602–628.

Movers of Predictive Climate Modeling

William W. Kellogg

William Welch Kellogg

William Welch Kellogg was a climate scientist who made very significant contributions to the emerging culture of climate prediction during the 1970s. He was one of the first scientists who demanded predictive modeling, the use of climate models for the simulation of future climate prediction, since the early 1970s. He also popularized as one of the first climate scientists the use and dissemination of a simple graphical representations of future climate projections. Such graphs helped to convey the message of the risk of climate warming very effectively.

Kellogg was born in New York Mills, New York. He attended the Brooks School in North Andover, Massachusetts, and graduated from Yale in 1939 with a BA in physics. Kellogg continued graduate studies at U.C., Berkeley, among others with Jakob Bjerknes as teacher, whom he recalled as his “favorite professor at UCLA.”1 These studies were interrupted by World War II, when he served in the Air Force's new meteorological program. As a pilot and weather officer, with a strong passion for flying, he collected some of the first data on the dynamics of thunderstorms by flying B-25s into the heart of the storms.

After the war, while working on a PhD from UCLA, he joined the RAND Corporation in Santa Monica, California. He completed his thesis “The Atmosphere Above 100 Kilometers” in 1949. At the RAND Corporation he became one of the leading experts and proponents of satellites for meteorological research. He developed many of the concepts still in use today. In 1964, he was invited to join the National Center for Atmospheric Research at Boulder, Colorado, as director of the Laboratory of Atmospheric Sciences. In this position he was involved in a range of research activities including air pollution and the chemistry of the atmosphere and the development of meteorological models of the higher atmosphere.

His serious interest in the investigation of climate started only in 1970s, when he became involved in the organization of the Study of Critical Environmental Problems (SCEP) in 1970, which was initiated and organized by MIT professor Carroll Wilson. In this one-month study, Kellogg led the Work Group Climatic Effects of Man’s Activities. One year later, Kellogg was one of the organizers of the international follow-up meeting entitled Study of Man's Impact on Climate (SMIC) held in Sweden in 1971. The investigation of climate became Kellogg’s main focus until his retirement in 1987.2 While Kellogg was not an activist, he was concerned about the possibility of climate warming. As contributor to the SCEP and SMIC studies and as a consultant of the World Meteorological Organization, he was a very active lecturer and writer to public audiences, and became a strong supporter of using climate models for predictive purposes and projecting future climate in spite of model uncertainties.

1: William W. Vaughan and Dale Johnson, “Meteorological Satellites—The Very Early Years, Prior to Launch of TIROS-1,” Bulletin of the American Meteorological Society 75 (December 1994), p. 2297.

2: SCEP (Study of Critical Environmental Problems) (1970). Man's Impact on the Global Environment. Assessment and Recommendation for Action. Cambridge, MA: MIT Press;

List of key publications

Matthews, William H., William W. Kellogg, W. D. Robinson, eds. (1971). Man’s Impact on the Climate (Cambridge, MA: MIT Press)

Kellogg, WilliamW. (1971). Predicting the climate, in: Matthews, William H., William W. Kellogg, W. D. Robinson (eds.), Man’s Impact on the Climate (Cambridge, MA: MIT Press): 123-132.

Kellogg, William W., and Margaret Mead (1977). The Atmosphere: endangered and endangering. Fogarty International Center proceedings, no. 39 (Bethesda: U.S. Dept. of Health, Education, and Welfare, Public Health Service, National Institutes of Health).

Kellogg, WilliamW. (1977). Effects of Human Activities on Global Climate (Geneva: WMO Tech-nical Note 156).

Kellogg, William W., and Stephen H. Schneider (1974). "Climate Stabilization: For Better or for Worse?" Science 186: 1163-72.

Kellogg, William W., Robert Schware (1981). Climate Change and Society: Consequences of In-creasing Atmospheric Carbon Dioxide (Boulder, CO: Westview).

Kellogg, William W., Robert Schware (1982). Society, Science and Climate Change, Foreign Affairs, Vol. 60: 5, pp. 1076-1109.

Kellogg, William W. (1987). "Mankind's Impact on Climate: The Evolution of an Awareness." Climatic Change 10: 113-36.

List of key documents

1) WMO Report 1977: Kellogg, WilliamW. (1977). Effects of Human Activities on Global Climate (Geneva: WMO Technical Note 156).

2) Graph: Estimates of past and future variations of global mean temperature (Kellogg 1977: 24; republished many times in Kellogg’s later publications).

3) Popular article: Kellogg, W. W., Is mankind warming the earth? Bulletin of Atomic Scientists 34:2 (February 1978), pp. 10-19.

Stephen H. Schneider

Stephen H. Schneider

Stephen Henry Schneider was a leading climate researcher. He played a significant role as a scientific activist and in the development and propagation of predictive modeling. Schneider was an engineering student at Columbia University when he started a first modeling experiment in 1970 at the Goddard Institute of Space Studies (GISS), where he also met James Hansen. In April 1971, William Kellogg invited Schneider to serve as a rapporteur at the Study of Man’s Impact on the Climate (SMIC) in July 1971. In 1972, Schneider moved to the National Center of Atmospheric Research (NCAR) in Boulder, Colorado, to continue work about climate modeling and collaborate among others with William Kellogg. Schneider remained at NCAR until 1992 when he became professor at Stanford University, which remained his intellectual home for the rest of his life.

Steve was as tough as nails.1

Schneider was an enormously productive scientist. His interest also went far beyond process of climate and encompassed the impact of climates on the biosphere and on human societies. In 1977 he founded the influential journal Climatic Change to provide a broad platform for relevant scholarship from many disciplines. Schneider’s main scientific interest rested with climate models. He was excited about climate modeling which promised not only the opportunity of important scientific breakthroughs in the understanding of climate, but also a means to produce politically relevant future projections about climate change. Despite the imperfection of models, Schneider emphatically advocated predictive modeling.

Another outstanding characteristic of Schneider’s work was his strong engagement as popular writer and political activist. Already as a young postdoc at GISS he started to publish letters to the editor in the New York Times, which was not generally accepted and instigated a strong conflict with his director (Santer, Ehrlich 2010, p. 15). In 1976 Schneider published (with his wife, science writer Lynne E. Mesirow as co-author) a popular book about problems of climate variation and change and its relations to droughts and hunger (Schneider, Mesirow 1976). He expressed strong political concern about climate warming and emphasized the importance of climate models for climate prediction, even though these models involved significant uncertainties. One quote in this book neatly encapsulates Schneider’s scientific and political conviction:

Unfortunately, for the task of estimating the potential impact of human activities on climate the models are just about the only tools we have [italics in the original]. Should we ignore the predictions of uncertain models? … I think not – a political judgment, of course. … The real problem is: If we choose to wait for more certainty before actions are initiated, then can our models be improved in time to prevent an irreversible drift toward a future calamity? … This dilemma rests, metaphorically, in our need to gaze into a very dirty crystal ball; but the tough judgment to be made here is precisely how long we should clean the glass before acting on what we believe we see inside.2

1: Quoted by James Hansen in: Santer, B. D., Paul R. Ehrlich, Stephen Schneider, 1945-2010, Biographical memoir, Washington: National Academy of Science, 2010, p. 15.

2: Schneider, Stephen H., Lynne E. Mesirow, The Genesis Strategy: Climate and Global Survival, New York: Plenum Press, 1976. (Republished)

List of key documents

1) Graph: Projections of future global mean temperature to the year 2100 (Hansen et al. 1981, p. 963).

2) Statement of Dr. James Hansen, Director, NASA Goddard Institute of Space Studies, in: Hearing before the Committee on Energy and Natural Resources, First Session on the Greenhous effect and global climate change, June 23, 1988, Washington: U.S. Government Printing Office, 1988, p. 39-41 plus prepared statement by Dr. Hansen (7 pages).

James E. Hansen

James Edward Hansen

James Edward (Jim) Hansen is a leading climate researcher. He played a significant role in the emergence of predictive modeling. As an expert in solar radiation transfer in planetary atmospheres at the Goddard Institute of Space Studies of NASA, he began modelling radiative transfer in the Earth’s atmosphere in 1970. During the 1970s, Hansen became a leading climate modeling expert. In 1981 he and his collaborators published the first long term projections of climate based on model simulations in the journal Science (Hansen et al. 1981). Though this paper was very controversial, it set the stage of predictive modeling in the following years and decades.

Hansen was the son and one of seven children of a tenant farmer in Iowa. He studied physics and astronomy at the University of Iowa, among other with the outstanding scientist, James van Allen. In 1967 he joined the Goddard Institute for Space Studies (GISS) in New York as a postdoctoral candidate and specialized in theoretical work on radiative transfer in planetary atmospheres. Around 1970, Hansen joined a weather prediction modeling project based on Arakawa’s general circulation model and started focus on climate modeling in the following years.

Hansen developed ingenious modeling approaches by simplifying climate models for specific tasks. Many ambitious studies he pursued were based on a one-dimensional model, which only represented the vertical axis of the atmosphere. With this approach he could circumvent limits of computational power and apply the model for simulations of complex problems. He later explained his interests and ambitions in an interview with Spencer Weart:

“We’re taking the model and using it for climate applications. It’s hard to have enough time to work on the basic structure of the model and also use it”.

A one-dimensional model also served for the 1981 landmark paper in Science. In spite of a large amount of significant uncertainties, the authors developed trust in their model, because it reproduced past global mean temperature changes rather well. This achievement encouraged them to venture into simulating climate projections based on socio-economic assumptions regarding future CO2 emissions to the year 2100. In 1988 Hansen and his group published for the first time climate projections simulated with a three-dimensional climate model (Hansen et al. 1988).

Hansen became famous for his testimony before Congress in June 1988. In this summer the USA experienced an extraordinary heat wave. Hansen clearly expressed his conviction that climate warming was already happening:

Number one, the earth is warmer in 1988 than at any time in the history of instrumental measurements. Number two, the global warming is now large enough that we can ascribe with a high degree of confidence a cause and effect relationship to the greenhouse effect. And number three, our computer climate simulations indicate that the greenhouse effect is already large enough to begin to effect the probability of extreme events such as summer heat waves.
hansen testimony

Hansen’s famous testimony before Congress on 23 June 1988 (Hansen 1988, p. 39).

This testimony brought him ample press coverage as well as significant criticism. It caused a steep rise of public attention to global warming. “Global warming has began, Expert tells Senate,” titled the New York Times on its front page on June 24, 1988:

New York Times article about Hansen

Hansen making headlines.

The general agreement between modeled and observed temperature trends strongly suggests that CO2 and volcanic aerosols are responsible for much of the global temperature variation in the past century. Key consequences are: (i) empirical evidence that much of the global climate variability on time scales of decades to centuries is deterministic and (ii) improved confidence in the ability of models to predict future CO2 climate effects.
one dimensional climate model

Conclusions about simulations with a one-dimensional climate model (Hansen et al. 1981, p. 964).

Number one, the earth is warmer in 1988 than at any time in the history of instrumental measurements. Number two, the global warming is now large enough that we can ascribe with a high degree of confidence a cause and effect relationship to the greenhouse effect. And number three, our computer climate simulations indicate that the greenhouse effect is already large enough to begin to effect the probability of extreme events such as summer heat waves.
Hansen hearing before congress in 1988

Testimony before Congress on June 23, 1988 (Hansen 1988, p. 39)

Bert Bolin

Bert Rickard Johannes Bolin

Bert Bolin was a leading Swedish climate researcher. Since the 1950s he took an interest in carbon dioxide and became a pioneer in the investigation of the carbon cycle. Bolin played an extraordinary role as a science diplomat and contributed significantly to forming international collaboration in at-mospheric and climate research. He was one of the main organizers of the Global Atmospheric Re-search Program (GARP) in the 1960s and the Intergovernmental Panel on Climate Change (IPCC) in the 1980s. He served as chairman of the IPCC from 1988 to 1997. Bolin’s efforts were founda-tional for making climate warming a public and political issue.

Bolin was a student of Swedish meteorologist Carl-Gustaf Rossby at Stockholm University. During his doctorate he spent a year in 1950 at the Institute for Advanced Study in Princeton, New Jersey, where he worked with Jule Charney and others on the first computerized weather forecast. After Rossby’s sudden death in 1957 he succeeded him as director of the Meteorological Institute at the Stockholm University, where he became Professor of Meteorology in 1961. Already in 1959 Bolin made headlines in the New York Times, after he presented his research about the carbon cycle at the Annual Meeting of the U.S. National Academy of Science in Washington and predicted that the carbon dioxide content in the atmosphere may rise by 40 percent by the year 2000.1 Bolin also took a strong interest in atmospheric pollution and acidification due to sulphur dioxide emissions.

In the 1980s, Bolin contributed greatly to making climate change a political issue. He led a compre-hensive assessment supported by the United Nations Environment Program (UNEP) and the World Meteorological Organization (WMO), which formed a background for the International Conference on the Assessment of the Role of Carbon Dioxide and of other Greenhouse Gases in Climate Varia-tions and Associated Impacts in Villach, Austria, in 1985. In this report the authors summarized the state of knowledge and emphasized that “the urgency of the problem is of decisive importance in the establishment of a policy for action.”2 The Villach Conference was the catalyst for starting an international political process that led to the establishment of the IPCC in 1988. Bolin is best known for his efforts as chairman of the IPCC, which was awared the Nobel Peace Prize in 2007 just before Bolin’s death.

...the CO2 problem, or rather the problem of a possibly changing climate due to emissions of greenhouse gases into the atmosphere ... is one of many important environmental problems that must be addressed but in a long-term perspective probably the most important one.”3
Projections of carbon emissions in 2050

Projections of carbon emissions in 2050 based on a range of different investigations from the early 1980s (Source: Bolin et al. 1986a).

Scenarios for future atmospheric CO2 concentrations

Scenarios for future atmospheric CO2 concentrations (Source: Bolin 1986b).

comparison of results of recent assessments of the CO2 problem

A comparison of results of recent assessments of the CO2 problem.

In their 1986 SCOPE report, Bolin and his co-authors summarized assessments of the CO2 problem from the early 1980s. All these assessments provided estimates for global warming for the case of doubled CO2 content in the atmosphere based on climate simulations with different models. The report showed that despite imperfections of climate models, their predictive use had become a commonplace part in the culture of climate science.4

1: Bolin, Bert (1959), Atmospheric Chemistry and Broad Geophysical Relationships, Proceedings of the National Academy of Sciences of the United States of America,Vol. 45, No. 12, pp. 1663-1672.

2-4: Bolin, Bert, B. R. Döös, J. Jäger and R. A. Warrick, eds. (1986), The greenhouse effect, climatic change, and ecosystems, SCOPE-Report 29, Chichester: John Wiley & Sons.

List of key publications (focus until 1980s)

Bolin, Bert, Erik Eriksson (1959), Changes in the Carbon Dioxide Content of the Atmosphere and Sea Due to Fossil Fuel Combustion, In: The Atmosphere and the Sea in Motion, edited by Bert Bolin, New York: Rockefeller Institute Press, pp. 130-42.

Bolin, Bert, et al., eds. (1979), The Global Carbon Cycle. SCOPE Report No. 13. New York: John Wiley.

Bolin, Bert et al. , B. R. Döös, J. Jäger and R. A. Warrick, eds. (1986), The greenhouse effect, cli-matic change, and ecosystems, SCOPE-Report 29, Chichester: John Wiley & Sons.

Bolin, Bert, B. R. Döös, J. Jäger (1986a), The Greenhouse Effect, Climatic Change, and Ecosys-tems: A Synthesis of Present Knowledge, in: Bolin, Bert, B. R. Döös, J. Jäger and R. A. War-rick, eds., The greenhouse effect, climatic change, and ecosystems, SCOPE-Report 29, Chich-ester: John Wiley & Sons, ch. 1, (last accessed 26 February 2017)

Bolin, Bert (1986b), How Much CO2 Will Remain in the Atmosphere? The Carbon Cycle and Pro-jections for the Future, in: Bolin, Bert, B. R. Döös, J. Jäger and R. A. Warrick, eds., The greenhouse effect, climatic change, and ecosystems, SCOPE-Report 29, Chichester: John Wiley & Sons, ch. 3, (last accessed 26 February 2017)

Bolin, Bert (2007), A History of the Science and Politics of Climate Change. The Role of the Inter-governmental Panel on Climate Change, Cambridge: Cambridge University Press.

List of key documents

Scope Report 29

Bolin, Bert, B. R. Döös, J. Jäger and R. A. Warrick, eds. (1986), The greenhouse effect, climatic change, and ecosystems, SCOPE-Report 29, Chichester: John Wiley & Sons.