Folger Specialist in Energy and Natural Resources Policy
Betsy A. Cody Specialist in Natural Resources Policy
Nicole T. Carter Specialist in Natural Resources Policy
is a natural hazard with potentially significant societal, economic, and
environmental consequences. Public policy issues related to drought range
from how to identify and measure drought to how best to prepare for,
respond to, and mitigate drought impacts, and who should bear such costs.
This report provides information relevant to drought policy discussions by describing
the physical causes of drought, drought history in the United States, examples
of regional drought conditions, and policy challenges related to drought.
What is drought? Drought is commonly defined as a lack of precipitation over an
extended period of time, usually a season or more, relative to some
long-term average condition. While the technology and science to predict
droughts have improved, regional predictions remain limited to a few
months in advance. History suggests that severe and extended droughts are
inevitable and part of natural climate cycles.
What causes drought? The physical conditions causing drought in the United States
are increasingly understood to be linked to sea surface temperatures
(SSTs) in the tropical Pacific Ocean. Studies indicate that
cooler-than-average SSTs have been connected to the severe western drought
in the first decade of the 21st century, severe droughts of the late 19th century,
and precolonial North American “megadroughts.” The 2011 severe drought in
Texas is thought to be linked to La Niña conditions in the Pacific Ocean.
What is the future of drought in the United States? The prospect of extended
droughts and more arid baseline conditions in parts of the United States
could suggest new challenges to federal water projects, which were
constructed largely on the basis of 20th century climate conditions. Some
studies suggest that the American West may be transitioning to a more arid
climate, possibly resulting from the buildup of greenhouse gases in the
atmosphere, raising concerns that the region may become more prone to
extreme drought it was in the 20th century. Some models of future climate
conditions also predict greater fluctuations in wet and dry years.
California’s 2007-2009 drought exacerbated ongoing tensions among competing
water uses. While drought is most common in California and the Southwest,
drought also can exacerbate water tensions in other regions. For example,
the 2007-2008 drought in the Southeast heightened a long-standing dispute
in the Apalachicola-Chattahoochee-Flint River (ACF) basin. Both California
and the ACF are again experiencing drought conditions, as are the Rio Grande
and Upper Colorado River basins.
What are some drought policy challenges? Although the impacts of drought can be
significant nationally as well as regionally, comprehensive national
drought policy does not exist. Developing such a policy would represent a
significant challenge because of split federal and non-federal
responsibilities, the existing patchwork of federal drought programs, and
differences in regional conditions and risks. While a comprehensive
national policy has not been enacted, Congress has considered and acted
upon some of the recommendations issued by the National Drought Policy
Commission in 2000. In coming years, Congress may review how federal agencies
such as the U.S. Army Corps of Engineers and the Bureau of Reclamation respond
to droughts. Congress may also assess other federal programs or choose to
reassess the National Drought Policy Commission’s recommendations.
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