Climate change increases the odds of worsening drought in many parts of the United States and the world in the decades ahead. Regions such as the U.S. Southwest are at particular risk.
There are a number of ways climate change may contribute to drought. Warmer temperatures can enhance evaporation from soil, making periods with low precipitation drier they would be in cooler conditions. Droughts can persist through a “positive feedback,” where very dry soils and diminished plant cover can further suppress rainfall in an already dry area. A changing climate can also alter atmospheric rivers (narrow streams of moisture transported in the atmosphere), which can especially disrupt precipitation patterns in the Western United States. A combination of shifting atmospheric rivers and warmer temperatures can also affect Western snowpack and melt, potentially decimating the water supply.
Threats Posed by Drought
The United States is historically susceptible to drought. Paleoclimate studies show major droughts in the distant past, while some more recent dry periods are still within living memory, such as the Dust Bowl of the 1930s or the drought of the 1950s. These historic examples serve as guideposts to highlight our vulnerabilities to drought as we move into a warmer and, in some places, drier future.
Severe drought can affect:
- Agriculture: Droughts affect livestock and crops, including cornerstone commodities like corn, soybeans, and wheat. In countries already facing food insecurity, cost spikes can lead to social unrest, migration, and famine.
- Transportation: Droughts can affect water levels on rivers of commerce like the Mississippi. Transport barges need at least nine feet of water, and to maintain this level, the U.S. Army Corps of Engineers had to blast, dredge, and clear obstructions on a key stretch of the Mississippi in 2013.
- Wildfires: Drought conditions and record heat have fueled damaging and sometimes deadly wildfires in the U.S. West. Millions of forested acres and thousands of homes have been lost over the past decade due to fires thriving in dry, stressed forests and the proximity of communities to fire-prone forests.
- Energy: Droughts can raise concerns about the reliability of electricity production from plants that require cooling water to maintain safe operations. Hydroelectric power may also become unavailable during droughts. When heat waves coincide with droughts, electricity demands can grow, compounding stress on the grid.
What can be done?
Governments and businesses must identify their vulnerability to drought and improve resilience. Actions like conserving water, enhancing water efficiency throughout landscapes, city plans, water infrastructure, identifying alternative water supplies, emergency planning for drought, and planting drought-resistant crops will help prepare for both future droughts and climate change.
Other actions that improve resilience to other stressors, like deploying green infrastructure for stormwater management or increasing energy efficiency in buildings (thereby using less water-cooled power), can improve resilience to drought as a co-benefit.
These steps will be most effective if they are combined with reductions in greenhouse gases that can minimize the ultimate magnitude of climate change.
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