Climate change driving multiple extreme weather events happening at once

·2 min read

Story at a glance

  • Rising temperatures are occurring alongside an increase in the ferocity and frequency of wildfires in the United States.

  • Whether these two scenarios, along with intense droughts, feed into each other was previously unknown.

  • Researchers modeled the intensity of a June 2021 heatwave in the absence of a simultaneous drought to see what effect each event had on the other.

As the country gears up for another blistering summer, it may be unsurprising for some to see  an uptick in severe droughts and wildfires alongside increased temperatures.

This is because climate change is helping create conditions that increase the likelihood of multiple extreme weather events occurring at once, according to new research published this month in Geophysical Research Letters. In some cases, these events could even create feedback loops and work to amplify conditions.

Using satellite observation and numerical experiments, researchers evaluated the record-breaking heatwave that took place in the southwest United States during June of 2021.

The Water Research Forecasting (WRF) model was employed to test for land-atmosphere feedbacks during the heatwave, they explained. Simulations from the model revealed a modest positive drought-heat effect, indicating “a small but systematic positive feedback of drought on heat,” authors wrote.

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Despite the modest impact of the drought on the heatwave, the event did coincide with up to four degrees of increased temperatures in some affected regions. Though this was not a clear answer as to whether the drought elevated heat, the drought did increase demand for evaporation which in turn compounded the water stress in the dry areas.

Similar cascading events likely contributed to the historic size of this year’s New Mexico wildfire, researchers said.

“With more extremes happening, the possibility of an extreme drought plus a heat wave and even a fire, together, the odds are just better that it’s going to happen,” said study co-author Benjamin Zaitchik in a press release.

“Understanding how a compound event can lead to a cascade where you end up in a record-shattering situation that can be really damaging for people and ecosystems is something that many climate scientists are trying to understand.”

Records will continue to be shattered in the future Zaitchik warned, adding earlier springs and drier conditions already exacerbate the risk for a heat-drought-fire cascade.

Regions’ climatic and ecological context should be taken into account when assessing future risks, authors concluded.

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