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California drought linked with global warming

‘What we are seeing now is fundamentally different from previous mega-droughts, which were driven largely by precipitation’

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Global warming is likely to exacerbate droughts worldwide.

By Summit Voice

FRISCO — While drought conditions have eased across parts of the U.S. in recent months, conditions have worsened in the far West, and particularly in California, where water shortages will have consequences spreading far beyond the state’s borders.

And the western drought has global warming fingerprints all over, according to four researchers who discussed the links between climate change and drought at a teleconference organized by Climate Nexus, a communications group focused on highlighting the wide-ranging impacts of climate change.

The scientists stressed that higher average temperatures caused by a warming climate are making this a record-breaking drought.

“Western and Southwestern states are feeling the effects of reduced water supply, and these are the types of scenarios expected under climate change conditions,” said Dr. Thomas Piechota, interim vice president for research at the University of Nevada, Las Vegas. “Nevada now has clear indications of drought, and this extends to varying extents to the Colorado River basin and across the region,” said Piechota, lead author on the National Climate Assessment Southwest report.

“These are the type of conditions that the National Climate Assessment report characterized, and as snowpack and streamflow amounts continue to decline we will see decreased water supply for cities, agriculture and ecosystems,” he said.

Along with colleagues from California, Kansas and Arizona, Piechota stressed the importance of recognizing the drought’s connection to climate change, particularly its implications for local water supplies, agricultural productivity and long-term changes in land use across the West and Southwest.

Currently, about 97 percent of Nevada is experiencing drought, with nine counties in Nevada declared disaster areas. The federal government has declared parts of 10 other western and central states as natural disaster areas because of the drought: California, Arizona, Kansas, Texas, Utah, Arkansas, Hawaii, Idaho, Oklahoma and Colorado. Oregon, while not in the 11 state region of drought emergencies, also has severe drought conditions.

“The western portion of Kansas is now experiencing severe drought of exactly the type that we would expect from a changing climate,” said Kansas State University geography professor Dr. John Harrington Jr. “What’s happening in Kansas is part of a much larger trend. The climate system has fundamentally changed, with human-driven emissions permanently altering temperatures and precipitation patterns. Droughts like this will continue and get worse until climate change is addressed.”

In Kansas, nearly half (47 percent) of the state remains in drought, including 37 counties, according to the U.S. Drought Monitor. The winter wheat crop in particular is at risk from dry weather and rapid weather swings.

“What we are seeing now is fundamentally different from previous mega-droughts, which were driven largely by precipitation,” said Dr. Valerie Trouet, a tree-ring researcher at the University of Arizona. “Now, thanks to higher temperatures driven by climate change, droughts are increasingly temperature-driven, which makes even normal levels of precipitation less effective in relieving drought conditions.

“In the Sierra Nevada mountain range, for example, higher temperatures and very low snowpack will reduce springtime runoff and make forest fires even more likely,” she said.

Dr. Trouet also said the current conditions of severe drought in the West and bitter cold, ice and snow in the East and Southeast are related to the impact of global warming on the jet stream. With more warming, the jet stream is slowing down, she said. “The polar vortex is the flip side of the California drought.”

At least moderate drought covers about 58 and 80 percent of Arizona and New Mexico, respectively, according to NOAA. With so many wildfires and the continuing drought, state agencies are seeking to double their budgets to fight fires.

The experts emphasized that the drought is likely just the latest in a series of worsening extreme conditions in the West. They noted that the Southwest has heated up markedly in recent decades, and the period since 1950 has been hotter than any period of the same length in at least 600 years.

“The California drought is already as bad or worse than any drought in recent memory, and likely the worst the state has seen in seventy years,” said UC Berkeley professor Dr. Michael Hanemann.

“In previous droughts, Mother Nature has had no more than two dry winters in a row. We have now had two dry winters, but there is no guarantee that next winter will be wet. In fact, climate change makes it far more likely that we will have an unprecedented third dry winter. The implications of that for California’s water supplies, agriculture and people would be alarming to say the least,” Hanemann said.

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2 Responses

  1. The last century has been one of the wettest in the last 7,000 years for California … Climate change has made california wetter, less and weaker droughts

    http://www.mercurynews.com/science/ci_24993601/california-drought-past-dry-periods-have-lasted-more

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