Human-induced climate change has led to an increase in flash droughts, which are expected to become more frequent and intense with future climate warming
Droughts can have a debilitating impact on water supplies, food production, and livelihoods, as well as the environment and human health. While droughts in the conventional sense tend to develop slowly over a period of time, a new study shows that there has been a transition to flash droughts, which develop or intensify much faster, making them more difficult to predict and prepare for.
Flash droughts can start with little warning and can soon intensify into severe droughts within a very short space of time, usually just a few weeks. They develop during periods of low rainfall, combined with abnormally high temperatures, winds, and solar radiation. This leads to a high rate of evapotranspiration, water moving from the earth’s surface into the atmosphere through evaporation from water bodies, surface soil, and capillary water, as well as transpiration from soils via plants.
The combination of low rainfall and a high evapotranspiration can quickly dry out soils. When these conditions persist for months, it can have a devastating impact on crops and natural ecosystems, and can trigger heat waves and wildfires that exacerbate the initial impact.
The Role of Climate Change
The authors of the study, which was recently published in Science, found that climate change is speeding up the rate at which droughts form, and flash droughts are likely to become the new normal as the climate becomes warmer in the future.
According to study co-author Justin Sheffield, professor of hydrology and remote sensing at the University of Southampton in the United Kingdom, the likelihood of rapid-onset flash droughts is likely to increase if greenhouse gas emissions increase in the future, making it increasingly difficult to mitigate against these risks and adapt to climate change impacts. Sheffield said:
Climate change has effectively sped up the onset of droughts. While it varies between different regions, there has been a global shift towards more frequent flash droughts during the past 64 years.
While conventional slow-forming droughts are easier for climatologists to forecast, flash droughts are somewhat trickier. This can hinder climate adaptation strategies, and can result in affected regions being inadequately prepared. Flash droughts may also adversely affect natural ecosystems, which may not be able to adapt in time to a sudden drop in water levels or extremely high temperatures.
The authors suggest that new approaches be developed to provide early warnings of flash drought events, and to improve our understanding of how flash droughts will impact both humans and natural ecosystems.
Preparing for Flash Droughts
While flash droughts give us little time to prepare for their impacts, there are measures we can take. Important strategies include improving water infrastructure, prudent management of fresh water, and looking for alternative sources of water.
Unconventional water sources such as desalinated seawater or brackish groundwater, and wastewater treated for reuse can be a lifeline in drought-prone areas and take pressure off of natural supplies of fresh water. Reusing wastewater for irrigation or to replenish aquifers can help restore freshwater habitats and ecosystems in times of drought.
Extending Access to Services With WaaS®
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