According to the findings of a recent study, climate change is responsible for an increase in the frequency and severity of droughts that emerge quickly in many regions of the world. These "flash droughts" are replacing more normal, slower ones, and since they are more difficult to foresee and plan for, their management may be more challenging.
The majority of significant droughts have a history of occurring on seasonal or annual time frames, typically as a consequence of the variable nature of large-scale climatic patterns such as El Nio (SN: 2/13/23). According to a paper that was published in the journal Science on April 14, researchers found that over the course of the past roughly sixty decades, there has been a change towards more droughts that emerge over the course of only a few weeks with little notice throughout the majority of the world.
Christine O'Connell, an ecosystem ecologist at Macalester College in St. Paul, Minnesota, who was not engaged in the study, states that "this conclusion has tremendous ramifications for ecosystem conservation and agriculture management." If there is a continued tendency towards flash droughts, would some plant species have a reduced ability to survive? What would it imply for the amount of carbon that may be stored in an ecosystem, as well as the biodiversity?"
Even flash droughts that don't turn into seasonal droughts can still wreak substantial harm to agriculture and contribute to other extreme weather events like wildfires and heat waves. Some flash droughts turn into seasonal droughts after a period of time. Damages of over $30 billion were incurred as a result of a severe flash drought that swept over the United States in the summer of 2012. Within a month, many of the impacted areas went from having normal circumstances to experiencing acute drought, and no climate models projected this to happen.
Past study has indicated that some regions are experiencing an increase in the frequency and severity of flash droughts. Nevertheless, it was not obvious if these droughts were taking the place of those with a slower start, which would imply that droughts that are normally slow to develop were happening more quickly, or whether both fast-onset and slow-onset droughts were growing in tandem.
In order to answer this question, Xing Yuan, a hydrologist from Nanjing University of Information Science and Technology in China, together with his colleagues, analysed soil moisture data collected from all over the world between the years 1951 and 2014. They differentiated between sudden and slow subseasonal droughts by examining the pace at which soils dried during the early time of drought onset. After that, they assessed how frequently each kind of drought happened and how far it travelled throughout the land.
According to the findings of the study, the rate at which droughts begin on subseasonal scales has accelerated in a significant portion of the planet. Yet according to the Intergovernmental Panel on Climate Change's Special Report on Extreme Events, the proportion of regions experiencing quick droughts as opposed to moderate droughts has grown in over 74 percent of the world's regions. The extent of the devastation was greatest in several areas, including South Australia, North and East Asia, the Sahel, Europe, and the western coast of South America.
The researchers discovered that human activity is having a significant impact on global trends by contrasting climate models that either included or excluded components like greenhouse gases. This allowed them to conclude that human activity is the primary driver of climate change. In scenarios with larger levels of emissions, these patterns become more pronounced, and the rate at which droughts begin to develop also quickens.
According to Yuan, the climate abnormalities that cause flash droughts, such as heat waves, are more severe than those that cause seasonal or interannual droughts. This results in severe droughts occurring in a shorter amount of time.
A period of low rainfall continues to be the primary cause of flash droughts, just as it is with the majority of droughts. The research demonstrates that an excessive amount of evapotranspiration, which is water flowing into the atmosphere from the soil and plants, plays a significant part in the development of severe droughts by hastening the drying up of the soil. According to the findings of the study, sudden droughts occur two to three times more frequently in humid regions such as the northwest of North America, Europe, and southern China than in other places.
The researchers predict that the frequency of flash droughts will continue to increase as the global average temperature continues to rise, which will result in increased evapotranspiration and decreased precipitation.
Mark Svoboda, a climatologist at the University of Nebraska–Lincoln who first coined the term "flash droughts" 20 years ago but was not involved in the new research, says the study is "very important as we are living in it now." Svoboda says this despite the fact that he was not a part of the new research. "We now have more data to validate my suspicion that the interaction of drought with winds, evapotranspiration, and heat waves in particular might truly lead to rapid onset drought," the author writes. "[T]here is a strong possibility that the drought could genuinely cause rapid onset drought."
It is difficult to predict flash droughts since the monitoring mechanisms that are already in place frequently are unable to record their start at short enough time intervals. Yuan asserts that "we need to enhance these systems" by doing research into the processes that underlie sudden droughts and enhancing simulations, maybe with the use of artificial intelligence.
According to Svoboda, overcoming these droughts requires not just an improved set of tools, but also a shift in mentality in order to be successful. "It is in our human instinct to avoid dealing with drought until we are actually experiencing it. Therefore, we propose taking preventative measures against drought rather than responding to it when it occurs.
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