Understanding Multiple Environmental Stresses Report of a Workshop (2007) / Chapter Skim
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2 Drought
2 Drought
Pages 15-26
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From page 15... ...
Drought risk is a product of a region's exposure to natural hazards and its vulnerability to extended periods of water shortage. Drought is different from many other natural hazards in that it does not begin and end swiftly.
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From page 16... ...
In general, western North America has seen significant warming over the last 100 years, particularly in the last couple of decades. The recent period of unprecedented population increase in the western United States coincided with one of the wettest periods on record.
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From page 17... ...
1 The paleoclimate record, seen through proxy records such as tree rings, coral, and boreholes in ice, allows scientists to estimate precipitation amounts back much farther than the past few hundred years of instrument records, and it is clear that significant droughts are not solely a modern phenomenon (Cook et al., 2004; Woodhouse and Overpeck, 1998)
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From page 18... ...
, and dry winters are favored in La Niña years.4 More recently, studies have confirmed that anomalous sea surface temperature (SST) patterns, particularly in the tropics and the Indo-Pacific, can explain both 20th-century and earlier droughts, and research has identified strong statistical associations between decadal modes of Pacific and Atlantic variability with decadal patterns of wet and dry conditions over North America (McCabe et al., 2004; Hoerling and Kumar, 2003)
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From page 19... ...
The longer the drought, the wider the range of ecosystem and societal effects that cascade from primary to tertiary impacts as time lengthens and spatial scales widen. Terrestrial ecosystems respond not only to temperature but particularly to decreasing soil moisture that in turn induces woody plant mortality, rapid canopy change, and increased soil erosion.8 Drought-induced tree mortality results in heightened vulnerability to fires.
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From page 20... ...
Enhancing our knowledge of the hazard will require a complex, integrated early warning system that incorporates climate, soil, and water supply factors such as precipitation, temperature, soil moisture, snowpack, reservoir and lake levels, groundwater levels, and streamflow. The implementation of the National Integrated Drought Information System (NIDIS)
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From page 21... ...
This is a critical research need. In addition to improved seasonal forecasts, there is need for improved methods of probability risk assessments that rely on reconstructions of past climates and account for climatic nonstationarity to calculate the occurrence and return probabilities of drought (Enfield and Cid-Serrano, forthcoming)
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From page 22... ...
. The principles of risk management can be promoted by encouraging the improvement and application of seasonal and shorter-term forecasts, developing integrated monitoring and drought early warning systems and information delivery systems, developing preparedness plans at various levels of government, adopting mitigation actions and programs, and creating a safety net of emergency response programs that ensure timely and targeted relief.
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From page 23... ...
. Many governments are striving to learn how to employ proper risk management techniques to reduce societal vulnerability to drought and therefore lessen the impacts associated with future drought events.
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From page 24... ...
Key components of this bill included an emphasis on risk management, preparedness planning, and improvement of the nation's drought monitoring system and forecasting capabilities. A project, the National Integrated Drought Information System (NIDIS)
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From page 25... ...
This would improve monitoring and early warning systems to provide better and more timely and reliable information to decision makers; address data gaps in drought monitoring and enhance networks, particularly for soil moisture, snowpack, and groundwater; and develop new monitoring and assessment tools/ products that will provide resource managers at all levels with proper decisionsupport tools at higher resolution. • Help the scientific and policy communities and resource managers better understand drought as a complex natural hazard.
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From page 26... ...
for the phasein and phase-out of drought mitigation and response programs and actions during drought events. Work could be done to develop vulnerability profiles for various economic sectors, population groups, and regions and to identify appropriate mitigation actions for reducing vulnerability to drought for critical sectors.
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