‘Megadrought’ in the West could become worst drought in history, scientists say

The western United States and northern parts of Mexico could experience a record-breaking megadrought, according to the Earth Institute at Columbia University.

“A new study says the time has arrived: a megadrought as bad or worse than anything even from known prehistory is very likely in progress, and warming climate is playing a key role,” the Earth Institute said.

Scientists based the study on modern weather observations, 1,200 years of tree-ring data and many climate models, according to Earth Institute.

“Earlier studies were largely model projections of the future,” author Park Williams, bioclimatologist at Columbia University, said in the news release. “We’re no longer looking at projections, but at where we are now. We now have enough observations of current drought and tree-ring records of past drought to say that we’re on the same trajectory as the worst prehistoric droughts.”

The study looked at nine states in the western U.S.: Oregon, Idaho, Wyoming, California, Nevada, Utah, Colorado, Arizona and New Mexico, according to a map from Science.

“Their conclusion: as measured against the worst 19-year increments within the previous episodes, the current drought is already outdoing the three earliest ones,” Earth Institute said. “The fourth, which spanned 1575 to 1603, may have been the worst of all — but the difference is slight enough to be within the range of uncertainty.”

Thanks to recent rainfall, none of the western states are currently experiencing extreme drought, according to Drought Monitor. Parts of Oregon, northern California and Washington, however, are experiencing severe drought.

The researchers say that rising temperatures are responsible for about half of the severity of the current drought, according to the Earth Institute.

“It doesn’t matter if this is exactly the worst drought ever,” author Benjamin Cook of the Lamont and the Goddard Institute for Space Studies, said to the Earth Institute. “What matters is that it has been made much worse than it would have been because of climate change.”

The drought could continue for the foreseeable future as temperatures will continue to rise, researchers said.

“Because the background is getting warmer, the dice are increasingly loaded toward longer and more severe droughts,” Williams told the Earth Institute. “We may get lucky, and natural variability will bring more precipitation for a while. But going forward, we’ll need more and more good luck to break out of drought, and less and less bad luck to go back into drought.”

What does the megadrought mean for the West?

Researchers say the effects are palpable. Major water sources, like the Colorado River and Lake Mead, have begun shrinking already, according to researchers. Lake Mead, though up from last year, is still 131 feet below full, according to the Lake Mead Water Level.

Wildfires also continue to breakout across the West., researchers point out.

As temperatures continue to rise, the warmer conditions will make droughts worse, causing them to go on for longer and be more widespread, scientists say.

This story was originally published April 20, 2020 at 1:56 PM with the headline "‘Megadrought’ in the West could become worst drought in history, scientists say."