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The food we eatDrought may threaten much of globe within decades

Published 21 October 2010

A new study, based on twenty-two computer climate models and a comprehensive index of drought conditions, as well as analyses of previously published studies, finds that most of the Western Hemisphere, along with large parts of Eurasia, Africa, and Australia, will be at risk of extreme drought this century; in contrast, higher-latitude regions from Alaska to Scandinavia are likely to become more moist

The United States and many other heavily populated countries face a growing threat of severe and prolonged drought in coming decades, according to a new study by the National Center for Atmospheric Research (NCAR) scientist Aiguo Dai. The analysis concludes that warming temperatures associated with climate change will likely create increasingly dry conditions across much of the globe in the next thirty years, possibly reaching a scale in some regions by the end of the century that has rarely, if ever, been observed in modern times.

Using an ensemble of twenty-two computer climate models and a comprehensive index of drought conditions, as well as analyses of previously published studies, the paper finds that most of the Western Hemisphere, along with large parts of Eurasia, Africa, and Australia, will be at risk of extreme drought this century.

In contrast, higher-latitude regions from Alaska to Scandinavia are likely to become more moist.

Dai cautioned that the findings are based on the best current projections of greenhouse gas emissions. What actually happens in coming decades will depend on many factors, including actual future emissions of greenhouse gases as well as natural climate cycles such as El Niño.

The new findings appear this week as part of a longer review article in Wiley Interdisciplinary Reviews: Climate Change. The study was supported by the National Science Foundation, NCAR’s sponsor.

We are facing the possibility of widespread drought in the coming decades, but this has yet to be fully recognized by both the public and the climate change research community,” Dai says. “If the projections in this study come even close to being realized, the consequences for society worldwide will be enormous.”

While regional climate projections are less certain than those for the globe as a whole, Dai’s study indicates that most of the western two-thirds of the United States will be significantly drier by the 2030s. Large parts of the nation may face an increasing risk of extreme drought during the century.

Other countries and continents that could face significant drying include:

  • Much of Latin America, including large sections of Mexico and Brazil
  • Regions bordering the Mediterranean Sea, which could become especially dry
  • Large parts of Southwest Asia
  • Most of Africa and Australia, with particularly dry conditions in regions of Africa
  • Southeast Asia, including parts of China and neighboring countries

The study also finds that drought risk can be expected to decrease this century across much of Northern Europe, Russia, Canada, and Alaska, as well as