La Nina Means Not Enough Water To Seriously Dent Western Drought As Winter Draws To A Close [View all]

[hatrack]

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Now the West is in the winter wet season, but due, in part, to the La Niña weather pattern, too little rain and snow is falling to make up for the preceding dry months. Some rain and snow may still fall, but the National Weather Service’s seasonal forecast projects that drought conditions will persist across the Western US through May, the end of the current forecast period. “We do have some time to maybe put a dent in some of these deficits that we’ve seen through the winter,” said Fuchs. “Now the idea that we are going to catch up completely — that’s going to be tough.” The trajectory of this drought episode remains unclear, but scientists say that it is actually part of a bigger megadrought — a decades-long dry spell, punctuated by severe droughts.

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While natural variability has been a factor in recent droughts, the current megadrought is also being driven by climate change, according to the study. Higher temperatures, caused by greenhouse gases, have increased evaporation and decreased precipitation in the spring across the region. The researchers
were able to identify that climate change accounted for 46 percent of the drought’s severity.

Without climate change, there still would have been a drought, but “anthropogenic warming was critical for placing 2000–2018 on a trajectory consistent with the most severe past megadroughts,” they wrote. The current megadrought, which they traced from 2000 through 2018, was the second driest 19-year episode in the 1,200-year record. This finding is not just important for how we understand the current crisis, but also for the coming decades in the Western US as temperatures continue to climb.

The latest National Climate Assessment, authored by 13 US federal agencies in 2018, laid out a grim future for the Southwestern states: Rising temperatures will increase the likelihood of megadroughts in the region and make droughts more frequent and severe, according to the scientific literature cited. While annual precipitation in the Southwest may not necessarily decrease, the hotter annual temperatures will burn off more moisture, contributing to droughts, the researchers explained in the Science tree ring study.

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https://www.vox.com/2021/3/13/22324813/drought-california-snow-rain-west-colorado-wildfire-farms-water-climate-change