this drought It may be feeding back into what is increasingly destroying the planet’s land, just as in a forest fire, thereby causing its accelerated expansion. The reason consists of reducing the evaporation of soil moisturethis supports the lack of rain and the expansion of dryness.
The greed of forest fires the fire’s ability to spread rapidly and destroy the surrounding vegetation. Now, scientists have concluded that there is another extreme environmental phenomenon, such as Droughts also have a self-propagating nature by expanding and multiplying the lack of water over large areas.
Unintentional wildfires and droughts, like any other, are two climate events that are unpredictable and unmanageable when they occur. However, although they are two completely different events, they may share some similarities, at least in terms of their spreading capacity.
“Up to 30% of the rain deficit may be due to the self-propagation of drought,” said research from the European Research Council’s (ERC) DRY-2-DRY project. According to the document published in the expert journal Nature Geoscience, run by the Hydroclimatic Extremes Laboratory of the University of Ghent in Belgium, reduced evaporation caused by dry soil can affect the energy balance of the earth’s surfacewith implications for local and downwind precipitation.
When evaporation is limited by soil moisture, the atmospheric water supply is depleted and it can spread in open time and space. According to the hypothesis put forward by the scientists, this mechanism could cause the drought to spread on its own.
In this sense, the United Nations (UN) He warned of extreme weather events such as global warming, pollution and drought, which he described as “the next epidemic”.
Lack of precipitation is usually manifested by dry soils. However, precipitation is not the only determinant. moisture. The land surface also plays a very active role in the formation of rain, as it provides moisture to the atmosphere through evaporation.
Therefore, when conducting this research, scientists asked themselves: What happens when much less water evaporates than usual?
Experts made the following assumption: The lack of evaporation from a moisture-deficient soil can allow drought to spread on its own.because they present a negative cycle in which they contribute less moisture for precipitation, not only locally, but also where moisture transported from dry soil is determined by favorable winds.
Until now, evidence of this self-propagating drought fueled by dry soils was an unproven guess. This new study reveals for the first time evidence confirming this hypothesis.
To ensure this, experts analyzed the 40 most important droughts of recent history. For each event, they tracked the weather over the drought zones as the area of influence expanded. This allowed them to calculate how much of the downwind precipitation deficits were due to dry soils.
Up to 30% of drought caused by self-replication
His conclusion was: In isolated months, up to 30% of the precipitation deficit can be caused by this self-propagating drought.. “In fact, drought behaves similarly to wildfires: as they spread downwind, igniting more and more fuel around them,” said Dominik Schumacher, lead author of the study. droughts do this by drying out the land surface, reducing their own rain resources. producing”.
For scientists, then, self-reproduction is strongest in subtropical arid areas like Australia and South Africa. In these areas, the limiting effect of low soil moisture on evaporation is stronger. By definition, water is already scarce in arid areas, but these areas contain a significant proportion of the world’s human population and are also widely used for agriculture.
Then, As drylands are expected to expand as a result of climate change, the self-propagating nature of droughts could lead to even greater events. and developing faster in the future, exacerbating water scarcity as well as the associated socio-economic and environmental consequences. According to experts, this is “the biggest alarm that should be given to find a way out of the processes themselves that prevents dry feedback”.
Reference work: https://www.nature.com/articles/s41561-022-00912-7
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