The Dust Bowl of the 1930s in the American Great Plains demonstrated the severe (but in this case temporary) potential for harm from climate change, caused by humans through poor agricultural practices. Terrible dust storms were accompanied by unprecedented drought and heat from sun warming the dessicated soil; the failure of farms drove a large-scale migration of refugees.

1935 photos from Russell Lord, "To Hold This Soil",
Miscellaneous Publication No. 321, U.S. Department of Agriculture, 1938.
Courtesy National Oceanic and Atmospheric Administration/Department of Commerce.