Climate change has aggravated California’s devastating drought, causing between 8 and 27 percent of the dry conditions afflicting the nation’s most populous state, a study released on Thursday has found.
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As the clock ticks for national governments to reach a deal to reduce harmful emissions ahead of this year’s United Nations Climate Change conference in Paris, Governor Brown continues to focus on building and broadening collaboration amongst cities, states and provinces, at the “subnational level”. Over the past 250 years, greenhouse concentrations have increased 40 percent in the atmosphere, and are now at their highest rate in at least 800,000 years, according to measurements of air bubbles in ice cores from Antarctica.
“As time goes on precipitation will be less able to make up for the intensified warmth”, Williams said. The Triple-R, as it’s been dubbed, has been lingering over the Pacific Ocean and steering storms away from California’s coast.
Firefighters in California also are battling a fierce wildfire season that officials say has turned wilder and more unsafe because of bone-dry conditions from the drought.
Speaking to the paper’s significance, Jonathan Overpeck, co-director of the Institute of the Environment at the University of Arizona, said: “It’s important to have quantitative estimates of how much human-caused warming is already making droughts more severe”. “In the absence of global warming, there would still be a drought in California, it would be just be less severe”. Noah Diffenbaugh, professor of environmental earth system science at Stanford University, said the latest study complements his ongoing research on a persistent high-pressure system called the “ridiculously resilient ridge”.
The Sierra snowpack is virtually all melted and farmers are pumping groundwater wells so heavily that the ground in the Central Valley is sinking 2 inches a month, cracking roads and threatening the California Aqueduct, a main north-south water canal.
“The real driver of the drought of course has been the drop in precipitation”, Seager said in an interview. The scientists said the most likely range is about 15 percent to 20 percent.
“Recent drought was naturally driven and modestly intensified by warming”, the report says in a summary of it findings.
Other research bolsters the case for a connection between warming and the intensity of the drought.
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The paper on the California drought echoes a growing body of research that has cited the effects of human emissions, but scientists not involved in the work described it as more thorough than any previous effort because it analyzed almost every possible combination of data on temperature, rainfall, wind speed and other factors that could be influencing the severity of the drought. “There’s evidence going back to the Paleo record that you really don’t find anything comparable to this over the past thousand years”.
