June 14, 2023
Farmers Worldwide Face a Soaring Risk of Flash Droughts, New Research Shows
Flash droughts develop fast, and when they hit at the wrong time, they can devastate a region’s agriculture.
They’re alsobecoming increasingly commonas the planet warms.
In a new study published May 25, 2023,wefoundthat the risk offlash droughts, which can develop in the span of a few weeks, is on pace torise in every major agriculture regionaround 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 as much as a53% annual chance of a flash droughtby the final decades of this century. The result would put food production, energy and water supplies under increasing pressure. The cost of damage will also rise. A flash drought in the Dakotas and Montana in 2017 causedUS$2.6 billion in agricultural damagein the U.S. alone.
How flash droughts develop
All droughts begin when precipitation stops. What’s interesting about flash droughts ishow fastthey reinforce 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 canincrease this “evaporative 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.
Global warming and flash droughts
In our new study, we used climate models anddata from the past 170 yearsto gauge the drought risks ahead under three scenarios for how quickly the world takes action to slow 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 49% and 53% annual chance of flash droughts, respectively, by the final decades of this century. Globally, the largest projected increases would be in Europe and the Amazon.
Slowing emissionscan reduce the risksignificantly, but we found flash droughts would still increase by about 6% worldwide under a low-emissions scenario.
Timing is everything for agriculture
We’ve lived through a number of flash drought events, and they’re not pleasant. People suffer. Farmers lose crops. Ranchers may have to sell off cattle. In 2022, a flash drought slowed barge traffic on the Mississippi River, which carriesmore than 90% of U.S. agriculture exports.
If a flash drought occurs at a critical point in the growing season, it could devastate an entire crop.
Corn, for example, is most vulnerable during its flowering phase,called silking. That typically happens in the heat of summer. If a flash drought occurs then, it’s likely to have extreme consequences. However, a flash drought closer to harvest can actually help farmers, as they can get their equipment into the fields more easily.
In the southern Great Plains,winter wheat最高风险在播种,在Septembe吗r to October the year before the crop’s spring harvest. When we looked at flash droughts in that region during that fall seeding period, we found greatly reduced yields the following year.
Ranches can also be hit hard by flash droughts. During thehuge flash drought in 2012in the central U.S., cattle ran out of forage and water became scarcer. If rain doesn’t fall during the growing season for natural grasses, cattle don’t have food, and ranchers may have little choice but tosell off part of their herds. Again, timing is everything.
It’s not just agriculture. Energy and water supplies can be at risk, too.Europe’s intense summer drought in 2022started as a flash drought that became a larger event as a heat wave settled in. Water levels fell so low in some rivers that power plants shut down because they couldn’t get water for cooling, compounding the region’s problems. Events like those are a window into whatcountries are already facingand could see more of in the future.
Not every flash drought will be as severe as what the U.S. and Europe saw in 2012 and 2022, but we’re concerned about what may be ahead.
Can agriculture adapt?
One way to help agriculture adapt to the rising risk is to improve forecasts for rainfall and temperature, which can help farmers as they make crucial decisions, such as whether they’ll plant or not.
When we talk with farmers and ranchers, they want to know what the weather will look like over the next one to six months. Meteorology is pretty adept at short-term forecasts that look out a couple of weeks, and at longer-term climate forecasts using computer models. But flash droughts evolve in a midrange window of time that is difficult to forecast.
We’re tackling the challenge of monitoring andimproving the lead time and accuracy of forecastsfor flash droughts, as are other scientists. For example, theUnited States Drought Monitorhas developed anexperimental short-term mapthat can display developing flash droughts. As scientists learn more about the conditions that cause flash droughts and about their frequency and intensity, forecasts and monitoring tools will improve.
Increasing awareness can also help. If short-term forecasts show that an area is not likely to get its usual precipitation, that should immediately set off alarm bells. If forecasters are also seeing the potential for increased temperatures, that heightens the risk for a flash drought’s developing.
Nothing is getting easier for farmers and ranchers as global temperatures rise. Understanding the risk from flash droughts will help them, and anyone concerned with water resources, manage yet another challenge of the future.
About the Authors
Jeff Basara is an Associate Professor of Meteorology, and Jordan Christian is a Postdoctoral Researcher in Meteorology, both at the University of Oklahoma.