Natural conditions, not human-caused emissions of greenhouse gases, are the driving force behind California’s three-year dry spell, scientists on a federal task force concluded Monday. But the report came under fire from some experts who said it downplayed other factors that have humanity’s fingerprints on them.
The evidence suggests a naturally induced “warm patch” of water in the western Pacific helped to create a high-pressure ridge that blocked precipitation from entering California, the experts said at a news conference to release the
report.
“We have been able to identify this as a mode of ocean forcing of atmospheric circulation that causes West Coast drought,” said Richard Seager, a climate model specialist at
Columbia University’s Lamont-Doherty Earth Observatory.
Other studies suggesting a global warming link are off the mark since they hadn’t spotted the warm patch’s influence, but that’s not to say emissions aren’t having other impacts, according to the task force assembled by the
National Oceanic and Atmospheric Administration.
“The report is not dismissive of global warming at all,” said Marty Hoerling, a meteorologist at NOAA’s Earth System Research Lab. “At the same time, drought is not a consequence of the warming planet to date.”