Flash droughts develop fast, and when they hit at the wrong time, they can ruin a region's agriculture. They're also becoming increasingly common as the planet warms. In a study published in the journal Communications Earth& Environment, we found that the risk of flash droughts, which can develop in just a few weeks, is on the rise in every major agricultural region around the world in the coming decades.
In North America and Europe, cropland that had a 32% annual chance of a flash drought a few years ago could have a greater chance of a flash drought by the final decades of this century. That result would put food production, energy, and water supplies under increasing pressure. The cost of change will also rise. A flash drought in the Dakotas and Montana 2017 caused $2.6 billion in agricultural damage in America alone.
All droughts begin when rainfall stops. What's interesting about flash droughts is how fast they strengthen themselves, with some help from the warming climate. When the weather is hot and dry, soil loses moisture rapidly. Dry air extracts moisture from the land, and rising temperatures can increase this evaporative (蒸发的) demand. The lack of rain during a flash drought can further contribute to the feedback processes. Under these conditions, crops and vegetation begin to die much more quickly than they do during typical long-term droughts.
In our study, we used climate models and data from the past 170 years to assess the drought risks ahead under three conditions for how quickly the world takes action to slow the pace of global warming. If greenhouse gas emissions from vehicles, power plants, and other human sources continue at a high rate, we found that cropland in much of North America and Europe would have a 53% annual chance of flash droughts, by the final decades of this century. Globally, the largest increases in flash droughts would be in Europe and the Amazon. Slowing emissions can reduce the risk significantly, but we found flash droughts would still increase by about 6% worldwide under low emission conditions.
