The significant regions where humans grow their food are temperate zones in Europe, northern North America, and rain-fed areas of the sub-tropics and the tropics. According to new research recently profiled in The Conversation, these regions will experience flash droughts in the coming years and decades.
What is a flash drought? I haven't heard of it before, you might think. It is a new phenomenon due to rising global temperatures and drought as rainfall distribution changes due to anthropogenic climate change. This is not your daddy's drought that takes years or decades to form. A flash drought can develop within days or months and is difficult to prepare for or predict, much like a flash flood which most are familiar with.
Sometimes a monstrous tyrant can cause a flash drought and a flash flood at the same time. I am talking of Vladimir the Bloody, where war crimes against the Ukrainian people resulted in the bombing of the Kakhovka dam and draining its reservoir. The reservoir irrigates Ukraine's wheat fields, one of Earth's most extensive bread baskets that will plunge parts of Ukraine into devastating drought—more on this topic below the fold.
Flash drought occurrence has been increasing over the past two decades—currently, 42 percent of flash droughts form within five days. Soil moisture evaporates in our new climate almost instantaneously. Extreme droughts could benefit farmers during harvest when dry soils allow farm machinery to operate without getting stuck in the mud; however, if the deficiency occurs while corn is silking, for example, the grain will not form, and the crop will be lost. In the southern plains of the United States, winter wheat seeds need to be in the ground for harvest in the Spring; soil evaporation at that time would be lethal to seedlings.
These droughts are devastating for wildlife.
The Conversation is a creative commons site that summarizes the study published by the American Meteorological Society on the flash drought's impact on the world's food baskets. Jeffery Bassa writes:
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 a 53% annual chance of a flash drought by 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 caused US$2.6 billion in agricultural damage in the U.S. alone.
All droughts begin when precipitation stops. What’s interesting about flash droughts is how fast they 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 can increase 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.
In our new study, we used climate models and data from the past 170 years to 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 emissions can reduce the risk significantly, but we found flash droughts would still increase by about 6% worldwide under a low-emissions scenario.
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 carries more 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.
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In the near term, it appears that Ukraine will suffer an enormous loss of agriculture. From The Guardian:
As Ukrainians along the Dnipro struggled to survive after the dam collapse, Ukraine’s ministry of agrarian policy and food predicted an even greater disaster next year, with global implications, as a result of the loss of the Kakhovka reservoir, one of the largest in Europe, and its impact on some of Ukraine’s most fertile regions.
The ministry said the loss of water in the reservoir and the four major canals it feeds would mean an almost complete loss of irrigation systems in the Kherson region, three-quarters lost in Zaporizhzhia, and one-third lost in Dnipropetrovsk.
“The destruction of the Kakhovskaya [dam] will mean that the fields in the south of Ukraine may turn into deserts as early as next year,” the ministry said in a statement.
The head of Ukraine’s hydroelectric corporation, Ihor Syrota, said the Kakhovka hydro power station had been totally destroyed and it would take five years to build a new one. The first priority, Syrota said, was to block off the dam as soon as the area was liberated, so the Kakhovka reservoir could begin to fill again, and provide the region with drinking water. While that was being done, the Dnipro’s waters would be held back by the dams further upstream.
“We will accumulate water in our upper reservoirs,” Syrota said. “Once we have freed up these areas, we will start damming and filling the Kakhovka reservoir and provide it with all the necessary water to mitigate this environmental disaster that we are witnessing today.”