Download Were there Modern-Day Dust Bowls? Evidence Suggests that

Were there Modern-Day Dust Bowls? Evidence Suggests that Recent Extreme
Droughts Contributed to Cropland Conversion in the United States
Phu V. Le1 (Author and Presenter)
Abstract
Climate and weather extremes have always been a critical problem for the sustainability of
US agriculture. In this study, we focus on the single most destructive event - extreme
droughts. We present the first evidence of the effect of severe drought condition on
farmland loss trend in the US in late twentieth century. By incorporating extreme drought
into the total productivity factor, we model the cropland conversion as a consequence of
weather shocks that produced permanent damages to the productive capacity of the soil,
such as losses of the topsoil from extreme drought events like the Dust Bowl.
The result indicates that extreme droughts and uncertainty regarding their long lasting effect
on soil productivity discourage sustainable agricultural use and accelerate irreversible
conversion out of agricultural production. This result also highlights a major threat to US
agriculture arising from climate change that may introduce significant agricultural regions to
extreme dry condition. The threat could be worse if future yield growth cannot keep up with
observed historical pattern. In addition, we suggest a potential mechanism in which
Ricardian approach [1,2] to estimating the impact of climate change, by assuming full
adaptation, may have underreported actual damages from the extremes. And we consider a
fat-tail climate change scenario that disproportionately increases the frequency or intensity of
extreme drought events could be particularly damaging to the US agricultural landscape.
The ultimate concern is that even with a projected increase in precipitation in all global
warming scenarios, drought affected areas have also been on the rise since the Dust Bowl,
and extreme droughts may experience a large percentage change. A very large population in
the US will be severely affected following dire prediction for drought and increased aridity in
the coming decades. This is especially problematic for studies using mean shift to project
long-term climate change impact. Such assumption on mean shift doesn’t account for a
possible scenario, one that has just grasped much attention recently, that more drying
condition may become prevalent even in as soon as 2030s, especially for most of the western
US [3,4]. Extreme drought damages soil, lowers productivity, reduces farming profit and
accelerate permanent farmland conversion to urban use. Facing highly anticipated drought
condition in the coming decades, the prospect of the US’ future agricultural landscape rests
squarely on the capability to spur higher agricultural productivity to compensate possible
damage from extreme droughts. The threat of yield plateau, or yield leveling out, could be
dramatic on agricultural sector.
Reference:
[1] Mendelsohn, Robert, William D. Nordhaus, and Daigee Shaw (1994), "The Impact of Global Warming on
Agriculture: A Ricardian Analysis," American Economic Review, Vol. 84(4), pp. 753-771.
1
Department of Agricultural and Resource Economics, University of California at Berkeley. A full paper is available upon
request at [email protected].
[2] Schlenker, Wolfram, Michael W. Hanemann, and Anthony C. Fisher (2005), “Will U.S. Agriculture Really
Benefit from Global Warming? Accounting for Irrigation in the Hedonic Approach,” American Economic
Review, Vol. 95(1), pp. 395–406.
[3] Dai, Aiguo (2011), “Drought under Global Warming: a Review,” Wiley Interdisciplinary Reviews: Climate
Change, Vol. 2, pp. 45-65.
[4] Dai, Aiguo (2011), “Characteristics and Trends in Various Forms of the Palmer Drought Severity Index
during 1900–2008,” Journal of Geophysical Research, Vol. 16, D12115, 2011.