Extreme drought in Colorado could come every 6 years -- instead of every 1,000 -- due to climate change, study finds

For a two-year period, an extreme drought across Colorado and much of the West dried farmers’ fields, lowered water levels in reservoirs, fueled extreme wildfires and left streams dangerously low.

Historically, an exceptional drought like the one that plagued the Western U.S. from 2020 to 2022 happened less than once every 1,000 years.

But warmer temperatures caused by climate change could make similar megadroughts occur once every six years by the end of the century if humans continue business as usual, according to research published earlier this month in the journal Science Advances.

“The droughts of today and the droughts of the future are not going to look like the droughts of the past,” said Joel Lisonbee, a scientist with the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder working at the National Oceanic and Atmospheric Administration and the National Integrated Drought Information System.

He and a team of other researchers with UCLA and NOAA wanted to know whether the megadrought that plagued the West from 2000 to 2022 was a natural variation in weather or fueled by climate change. They also examined the extreme drought that occurred from 2020 to 2022 in deeper detail.

The findings? Higher temperatures caused by climate change made conditions significantly worse.

Even if precipitation patterns don’t change in the future, higher temperatures alone will drive increased drought. Droughts will last longer, cover wider areas and become more extreme as the climate warms, according to the study.

During the 2020-to-2022 drought, increased evaporation accounted for 61% of the severity across the West while lack of precipitation accounted for 39%, according to the research.

In Colorado, the drought in those years fueled the state’s three largest wildfires on record, which collectively burned more than 541,000 acres. Even after those fires were extinguished, damage to the environment caused mudslides that blocked Interstate 70 and triggered deadly flash flooding.

Dry conditions helped feed the 2021 Marshall fire in Boulder County, even in December. It destroyed more than 1,000 homes and stands as the most destructive wildfire in state history.

Smoke from fires here and across the West on some days plunged air quality on the Front Range to some of the worst in the world.

In 2020, every Colorado county experienced severe drought. In 2021, Gov. Jared Polis declared an emergency for the drought affecting 21 counties on the Western Slope.

“If that period was not as hot as it was, we would’ve still had a drought but it would’ve been far less severe,” Lisonbee said.

Increased temperatures also created a cyclical feedback loop.

Warmer atmospheres can hold more water vapor before releasing the water as rain or snow. So as the planet warms, more water will evaporate from the surface and then remain in the atmosphere longer, reducing precipitation.

“This is not something you could build bigger reservoirs or something to prevent because when the atmosphere warms, it will just suck up more moisture everywhere,” said Rong Fu, a UCLA professor of atmospheric and oceanic sciences and the corresponding author of the study. “The only way to prevent this is to stop temperature increase, which means we have to stop emitting greenhouse gasses.”

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