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05-26-2023

Flash droughts are increasing around the world due to warming climate

A severe and sudden weather phenomenon known as a flash drought is increasingly catching the attention of climate scientists due to its potential to significantly impact agricultural and ecological systems. The ripple effects of such events can resonate far beyond their immediate environments. 

A team of researchers at the University of Oklahoma is digging deeper into this concern, particularly focusing on how our ever-warming climate might influence the frequency of these flash droughts and the ensuing risks posed to global cropland.

The study, led by postdoctoral researcher Jordan Christian, takes center stage in the climate science community today with its publication in the journal Nature Communications Earth and Environment

How the study was conducted

“In this study, projected changes in flash drought frequency and cropland risk from flash drought are quantified using global climate model simulations,” said Christian. 

“We find that flash drought occurrence is expected to increase globally among all scenarios, with the sharpest increases seen in scenarios with higher radiative forcing and greater fossil fuel usage.”

Radiative forcing refers to the imbalance caused when more radiation penetrates the Earth’s atmosphere than leaves it. Activities like burning fossil fuels are substantial contributors to this imbalance and consequently to the warming climate. 

The escalating climate change threatens to provoke an upsurge in severe weather events, ranging from storms and flash flooding to the sudden droughts under study.

Christian provides further insight into the study’s results, explaining, “Flash drought risk over cropland is expected to increase globally, with the largest increases projected across North America and Europe.”

Predicting the future of flash droughts

“We anticipate a 1.5 times increase in the annual risk of flash droughts over croplands across North America by 2100, from the 2015 baseline of a 32% yearly risk in 2015 to 49% in 2100,” said Christian. “Europe, on the other hand, is expected to face the most significant increase in the most extreme emissions scenario, witnessing an increase from 32% to 53%, a 1.7 times increase in annual risk.”

Study co-author Professor Jeffrey Basara is Christian’s faculty advisor and leads the University of Oklahoma’s Climate, Hydrology, Ecosystems, and Weather research group. 

Next steps – finding a way to predict flash droughts

The team has been exploring ways to enhance flash drought identification and prediction since 2017 and has contributed numerous papers to notable scientific journals.

Basara elaborates on the practical implications of their findings, stating, “This study continues to emphasize that agricultural producers, both domestic and abroad, will face increasing risks associated with water availability due to the rapid development of drought. As a result, socioeconomic pressures associated with food production, including higher prices and social unrest, will also increase when crop losses occur due to flash drought.”

In summary, this groundbreaking research underscores the increasing threat of flash droughts in the context of a warming climate. The implications of such events are vast and extend to numerous societal sectors, bringing an imperative for further study and mitigating strategies to the forefront.

More about flash droughts

Flash droughts are rapid-onset drought events that can cause severe agricultural and ecological damage. These droughts develop quickly, often within a few weeks, leaving little time for preparation or mitigation. 

They are characterized by a sudden decrease in soil moisture and a rapid increase in evapotranspiration, which is the sum of evaporation from the land surface and transpiration from plants.

Flash droughts can occur in various climatic conditions but are most common in summer months, often coinciding with periods of high temperatures and low rainfall. They tend to result in acute water shortages, leading to a rapid deterioration of crop conditions. 

Because of their quick onset and severity, flash droughts can have devastating impacts on agriculture and ecosystems, leading to significant economic losses.

Different types of flash droughts 

There are generally two types of flash droughts: heatwave-dominant and precipitation-deficit dominant. Heatwave-dominant flash droughts are mainly caused by high temperatures, leading to increased evaporation and transpiration.

On the other hand, precipitation-deficit dominant flash droughts are triggered by significantly reduced rainfall over a period of time.

Climate change is thought to increase the likelihood of flash droughts, as rising global temperatures can intensify evaporation rates, alter rainfall patterns, and potentially increase the frequency of extreme weather events like heatwaves.

Predicting flash droughts is challenging due to their rapid onset and development. However, scientists are making strides in this area, using advanced climate models and real-time monitoring of soil moisture and atmospheric conditions to provide early warnings. 

Despite these advancements, further research is needed to understand the mechanisms of flash droughts fully and to improve our ability to predict and mitigate their impacts.

How climate change impacts and amplifies severe weather events

Climate change has a profound impact on severe weather events, leading to an increased frequency, intensity, and duration of such events. This is primarily due to the fact that a warmer atmosphere holds more moisture, which can fuel extreme weather.

Here are a few key examples of how climate change affects different types of severe weather:

Heatwaves

As the average global temperature increases due to climate change, heatwaves have become more frequent, intense, and prolonged. Heatwaves can lead to a range of health issues, from heat exhaustion and heatstroke to increased mortality rates, particularly among vulnerable populations.

Droughts and flash droughts

Rising temperatures increase evaporation rates, altering the hydrological cycle and potentially leading to more frequent and severe droughts, including flash droughts. Changes in precipitation patterns can also exacerbate drought conditions in certain regions.

Storms and hurricanes

Warmer ocean surface temperatures can fuel more intense storms and hurricanes. Increased water vapor in the atmosphere can lead to heavier rainfall during these events, increasing the risk of flooding.

Floods

With a warmer atmosphere capable of holding more moisture, rainfall patterns can change, potentially leading to more heavy rainfall events and, consequently, more flooding. Additionally, sea-level rise due to melting polar ice can increase the risk of coastal flooding.

Wildfires

Drier conditions and higher temperatures can increase the frequency and intensity of wildfires. These conditions can lead to more combustible vegetation and longer wildfire seasons.

Extreme cold events

While it may seem counterintuitive, climate change can also influence extreme cold events. Changes in atmospheric conditions can occasionally cause frigid polar air to spill into lower latitudes, leading to severe cold snaps.

In summary, climate change is leading to a wide range of changes in severe weather patterns. This increased frequency and severity of extreme weather events highlight the need for effective climate change mitigation and adaptation strategies.

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