Such was the case in 2015, the fourth-warmest year in the contiguous U.S., when a snow drought reduced the April snowpack in the Sierra Nevada mountain range to a mere 5% of its historical average water content - its lowest snowpack in 500 years. Rising temperatures increase the fraction of winter precipitation that falls as rain rather than snow and also shorten the cold season, so there’s less time for snow to even occur. Warming also diminishes snowfall, an essential water resource for the estimated 1.9 billion residents of the Northern Hemisphere who depend on snowpacks, or snow reservoirs that store water during the cooler months and release it when it’s needed in the warmer, drier months. Sign up for our weekly email newsletter and never miss a story. The climate is changing, and our journalists are here to help you make sense of it. What might have otherwise been a mild or moderate drought in a cooler world will become, in a warmer world, more severe as a result of increased evaporation. Higher air temperatures not only encourage drought conditions to build but also intensify them. (Ironically, this additional atmospheric moisture triggers heavier downpours in other regions, which explains why the overall trend in the U.S. As high air temperatures sap liquid water from soils and plant leaves, transforming it into atmospheric water vapor via a process called transpiration, ground-level drying will increase in some regions. For that reason, hotter weather can result in drier soils. Global warming increases the risk of drought in several ways.įor one, water generally evaporates more quickly at higher temperatures.
Drought Monitor/) Warmer temperatures lead to drying Drought conditions across the contiguous United States as of August 10, 2021.
Climate change, namely rising average temperatures driven by human-generated emissions of heat-trapping greenhouse gases, is contributing to droughts, too.
However, regional climate isn’t the only culprit in drought activity.
Because of the West’s largely semi-arid and desert climates, droughts are natural occurrences across the region. That’s particularly true in the Western United States. For tens of millions of Americans, drought has become an ever-present natural disaster.
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