Book 2.indb - US Climate Change Science Program

The U.S. Climate Change Science Programmore, leaving little land fallow. When cropsdied again there was little in the way of “shelterbelts” or fallow fields to lessen wind erosion.This led to monstrous dust storms that removedvast amounts of top soil and caused hundredsof deaths from dust inhalation (Worster, 1979;Hansen and Libecap, 2004; Egan, 2006). As thedrought persisted year after year and conditionsin farming communities deteriorated, about athird of the Great Plains residents abandonedthe land and moved out, most as migrant workersto the Southwest and California, which hadnot been severely hit by the drought.The Dust Bowl disaster is a classic case ofhow a combination of economic and politicalcircumstances interacted with a natural eventto create a change of course in national andregional history. It was in the 1930s that theFederal Government first stepped in to providesubstantial relief to struggling farm communitiesheralding policies that remain to this day.The Dust Bowl drought also saw an end to thesettlement of the semi-arid lands of the UnitedStates based on individual farming familiesacting independently. In addition, wind erosionwas brought under control via collective action,organized within Soil Conservation Districts,while farm abandonment led to buyouts and alarge consolidation of land ownership (Hansenand Libecap, 2004). Ironically, the populationmigration to the West likewise provided themanpower needed in the armaments industryafter 1941 to support the U.S. World War IIeffort.Earlier droughts in the late 19th century havealso tested the feasibility of settlement of theWest based on provisions within the HomesteadAct of 1862. This act provided farmers withplots of land that may have been large enoughto support a family in the East but not enoughin the arid West, and it also expected themto develop their own water resources. Thedrought of the early to middle 1890s led towidespread abandonment in the Great Plainsand acceptance, contrary to frontier mythologyof “rain follows the plow” (Libecap andHansen, 2002), that if the arid lands were to besuccessfully settled and developed, the FederalGovernment was going to have to play an activerole. The result was the Reclamation Actof 1902 and the creation of the U.S. Bureau ofReclamation, which in the following decadesdeveloped the mammoth water engineeringworks that sustain agriculture and cities acrossthe West from the Great Plains to the PacificCoast (Worster, 1985).On a different level, the Great Plains droughtsof the 1850s and early 1860s played a role inthe combination of factors that led to the nearextinction of the American bison (West, 1995).Traditionally, bison tried to cope with droughtby moving into the better watered valleysand riparian zones along the great rivers thatflowed eastward from the Rocky Mountains.However, by the mid-19th century, these areashad become increasingly populated by NativeAmericans who had recently moved to theGreat Plains after being evicted from theirvillages in more eastern regions by settlersand the U.S. Army, thereby putting increasedhunting pressure on the bison herds for foodand commercial sale of hides. In addition, themigration of the settlers to California afterthe discovery of gold there in 1849 led to thevirtual destruction of the riparian zones used bythe bison for over-wintering and refuge duringdroughts. The 1850s and early 1860s droughtsalso concentrated the bison and their humanpredators into more restricted areas of the GreatPlains still suitable for survival. Drought did notdestroy the bison, but it did establish conditionsthat almost lead to the extinction of one ofAmerica’s few remaining species of megafauna(West, 1995; Isenberg, 2000).The most recent of the historical droughts,which began in 1998 and persists at the timeof writing, has yet to etch itself into the pagesof American history, but it has already createda tense situation in the West as to what it portends.Is it like the 1930s and 1950s droughtsand, therefore, likely to end relatively soon? Oris it the emergence of the anthropogenic dryingthat climate models project will impact thisregion—and the subtropics in general—withinthe current century and, quite possibly, withinthe next few years to decades? Breshears et al.(2005) noted that the recent Southwest droughtwas warmer than the 1950s drought and thehigher temperatures exacerbated droughtimpacts in ways that are consistent with expectationsfor the amplification of drought severityin response to greenhouse forcing. If thisChapter 380