What really caused the Dust Bowl?

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Thursday, 21 January 2010: 4:30 PM
B216 (GWCC)
Jeffrey A. Lee, Texas Tech University, Lubbock, TX; and T. E. Gill

The most severe wind erosion in the history of the United States happened during the 1930s in a region known as the “Dust Bowl.” Agricultural lands were badly degraded over an area of hundreds of thousands of square kilometers, and dust storms originating in the Dust Bowl core region carried massive amounts of mineral aerosols eastward across North America and into the Atlantic Ocean. Over the years, evaluations of the Dust Bowl disaster generally have approached it from the perspective of it either being an anthropogenic (land management) phenomenon or a short-term climatic fluctuation (an extreme drought).

From a land management point of view, certain tillage practices prevalent in the southern Great Plains in the 1930s degraded soil aggregate stability. The economic depression, coupled with the drought, prevented most farmers from managing the soil to reduce erosion through other forms of tillage and maintaining a crop cover. From a climate perspective, the drought of the 1930s was associated with a decadal-scale breakdown of the ENSO, a bidecadal oscillation possibly forced by solar cycles, and widespread sea surface temperature anomalies (cool Pacific and warm Atlantic). Their result strongly reduced rainfall over the Plains, while atmosphere-land surface interactions may have further suppressed precipitation, especially during the warm season.

However, an objective evaluation of the Dust Bowl suggests that it was not strictly either an anthropogenic or natural phenomenon. The drought of the 1950s in the same region was at least as extreme, but accompanied by nowhere nearly as much dust. Major dust storms have occurred in the region before and since the 1930s, but not always during periods of extreme drought. We review many of the different ascribed “causes” of the Dust Bowl and how they may have contributed to this catastrophe. We suggest that the Dust Bowl be best considered as an unfortunate convergence of inappropriate land use practices in a region experiencing a climatic extreme. Lessons learned from the Dust Bowl should be considered to prevent future disasters in the southern Great Plains with predicted climatic changes.