A new study has confirmed what scientists have been warning about for a long time. Climate change has exacerbated the megadrought gripping the American West so much that the last two decades are now the driest the region has seen in 1,200 years.
It’s a figure researchers have touted before, when they pointed out that between 2012 and 2016, Western states experienced their worst dry spell in more than a millenia. But since the beginning of the 21st century, when the drought conditions began, the situation has worsened far more quickly than previous models anticipated, according to a study published Monday in the journal Nature Climate Change. It’s the latest evidence that the baseline researchers use to help understand the world’s complex weather systems continues to change faster than their understanding of it.
“This study supports what scientists keep telling me: We’ve moved past any semblance of a ‘new normal,’” said Liza Gross, the West Coast reporter for Inside Climate News, where she has covered how heat and drought have affected one of the world’s most profitable agriculture industries. “Things are changing so rapidly that it’s hard to establish the kind of baseline scientists need to predict future events. Each event seems to shatter past records.”
In fact, scientists have pushed back on using such phrases as “the new normal” to describe what they’re observing. That’s because that phrase implies predictability, Gross said, and Monday’s research shows how the goalpost keeps moving. “If anything, they said, it’s a new abnormal,” she added.
The study also showed that human-caused global warming contributed significantly to the severity of today’s dry conditions. By combining observational climate data with measurements of tree rings, which are wider apart in wet years and thinner in dry ones, researchers were able to link tree ring width to past moisture content in the soil. With that, the authors said they could determine that although the West would have still experienced a drought without climate change, its severity would have been about 60 percent less than what it is today if humans weren’t rapidly heating the planet.
The region’s ongoing drought has especially complicated matters for the seven states that depend on the Colorado River for their water needs. Monday’s news comes as water levels at the nation’s two largest reservoirs, Lake Mead and Lake Powell, are at their lowest levels ever recorded. Just how those states—as well as Native American tribes, the federal government and even Mexico—are allowed to use the Colorado River are determined by a contract that will expire in 2026, setting up a looming showdown over what future management of the river should look like. Researchers have said those dry conditions could persist for years to come.
The region’s powerful agriculture industry is also sure to weigh in on the negotiations. Farming has become increasingly expensive as climate change supercharges floods and extreme rain, while elongating drought conditions at the same time. A recent analysis based on government data found that insurance payments to farmers have risen more than 400 percent for drought-related losses and nearly 300 percent for losses from rains and flooding, from 1995 to 2020.
The drought is also contributing to the massive damage that increasingly destructive wildfires are causing in Western states. The worst U.S. wildfire season on record took place in 2020, burning more than 10 million acres across several states and costing $16.5 billion.
So, what’s the take away from all this? “The worst-case scenario keeps getting worse,” Park Williams, the study’s lead author and a climate hydrologist at the University of California, Los Angeles, told The Associated Press. “We need to be preparing for conditions in the future that are far worse than this.”
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