Drought and Climate Change

The U.S. Drought Monitor shows the extent of current drought conditions.

Click on the map above to go to the drought monitor site with a full report and statistics.

 

Drought and Climate Change

Recent U.S. droughts have been the most expansive in decades. At the peak of the 2012 drought, an astounding 81 percent of the contiguous United States was under at least abnormally dry conditions, resulting in an estimated $30 billion in damages. Climate change increases the odds of worsening drought in many regions of the U.S. and the world in the decades ahead.

The Link Between Climate Change and Drought

Global warming will increase the risk of drought in some regions, particularly in the Southwest United States. Even in regions that may not see changes in precipitation, warmer temperatures can increase water demands and evaporation, putting greater stress on water supplies.

Estimates of future changes in seasonal or annual precipitation in a particular location are subject to considerable uncertainty; more so than estimates of future warming. However, scientists are more confident that at the global scale, relatively wet places such as the tropics and the high latitudes will get wetter, while relatively dry places in the subtropics (where most of the world’s deserts are located) will become drier.

When droughts do occur, warmer temperatures can amplify their impacts. Droughts can persist through a “positive feedback,” where very dry soils and diminished plant cover can further suppress rainfall in an already dry area. Increased temperatures enhance evaporation from soils, making a periodic occurrence of drought worse than it would be under cooler conditions.

Threats to the U.S.

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.

Recent U.S. droughts have been the most expansive in decades. For example, in 2011, Texas experienced its driest 12 months ever. At one point, 80 percent of the state was rated at an “exceptional” level of drought. At the peak of the 2012 drought, an astounding 81 percent of the contiguous United States was under at least abnormally dry conditions. Severe drought can affect:

  • Agriculture: Droughts affect livestock and crops, including cornerstone commodities like corn, soybeans and wheat.  At the height of the 2012 drought, the U.S. Department of Agriculture declared a natural disaster over 2,245 counties, 71 percent of the United States.
  • Transportation: Recent droughts have had major impacts on water levels on the Mississippi River and the ability to move goods along the river. 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 between St. Louis, Mo., And Cairo, Ill.  
  • Wildfires: In the Southwest, drought conditions and record heat have fueled damaging and sometimes deadly wildfires in Arizona, Colorado and New Mexico. Millions of forested acres and thousands of homes have been lost over the past decade due to fires thriving in dry, stressed forest environments and because of 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. When heat waves coincide with droughts, electricity demands can grow, compounding stress on the grid.

Potential Global Problems

In recent years, droughts have struck several major breadbasket regions simultaneously, adding to food price instability. In countries already facing reduced food security, cost spikes can lead to social unrest, migration, and famine. Several price spikes have occurred over the last decade, often connected to crop failures or poor yield.  During the 2007-2008 crisis, the Food and Agriculture Organization of the United Nations estimated that high food prices increased the number of chronically hungry people in the word by 75 million.

How to Build Resilience

Governments and businesses must identify the vulnerabilities that droughts expose and take steps to improve resilience. Actions like using water more efficiently and developing more drought-resistant crops will help prepare us for both future droughts and climate change. 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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