BERKELEY, Calif. — Over the past few weeks, California has gone from extreme drought to unrelenting flooding, experiencing a form of “whiplash” that its governor said is “proof that the climate crisis is real."
Gov. Gavin Newsom, who declared a state of emergency for the state last week in response to a succession of storms fueled by atmospheric rivers of moisture, connected the dots Tuesday between climate change and the storms that have so far been blamed in the deaths of at least 17 people and are expected to result in damages of close to $1 billion.
The sudden juxtaposition from the worst drought in state in 1,200 years to the third rainiest 15-day period on record, behind storms that befell California in 1862 and 1866, has left many Americans wondering how climate change can be blamed for both seemingly contradictory events.
Peter Gleick, a climate scientist and the founder of the Pacific Institute in Oakland, Calif., told Yahoo News that while it will take time to assess how the current storms in the state have been influenced by climate change, the switch from one extreme to another is consistent with global warming.
“We don’t know until we’ve looked at the data exactly how climate change is influencing these storms that are now hitting California, but we do know that all weather today is influenced by human-caused climate change," Gleick said. “We have ideas for how the current events are being influenced by climate change. We understand the mechanisms, but it’s often weeks or even months afterward before we can look at the data and see exactly what happened.”
Using historical data, statistics, climate models and comparisons of atmospheric greenhouse-gas concentrations, climate scientists have already begun examining how climate change has affected the storms that have unloaded half of California's annual rainfall average in just 16 days. But Gleick stressed that the current body of scientific knowledge already points to certain conclusions about what California is now enduring.
“We know that temperatures are going up around the world and we know that a warmer atmosphere holds more water. We know that the Arctic is being severely disrupted by climate change and the ice is disappearing and that is influencing the jet stream and the pressure systems in the Pacific [Ocean],” he said. “All of those factors make storms more extreme. So when I say that I’m confident that the current storms we’re seeing are influenced by climate change, it’s because I’m confident that all weather today is influenced by climate change. I’m not saying climate change is causing these storms, but it is certainly influencing them.”
Attributing individual weather events solely to climate change is usually too simplistic, according to most climate scientists, but climate change does make extreme precipitation events more likely.
For instance, a study by an international team of scientists and published Wednesday in the journal Advances in Atmospheric Sciences found that ocean temperatures in 2022 were the hottest ever recorded. That fact, in turn, has resulted in a variety of consequences for the world's weather, including the super-charging of rains like the ones battering California.
“Warmer oceans mean there is more potential for bigger precipitation events, like we’ve seen this past year in Europe, Australia, and currently on the west coast of the U.S.” Michael Mann, a climate scientist at the University of Pennsylvania and one of the study’s authors, told the Guardian.
In November, prior to the arrival of the heavy rains, UCLA climate scientist Daniel Swain co-authored a study that found that, thanks to climate change, the chances of a mega-flood on a par with the one that struck California in 1862, killing thousands, had doubled.
“I guarantee you that most people in California are not thinking that one of the biggest risks of a warming climate is the risk of extreme flooding. But that is one of the things that I would highlight as the largest risks in California,” Swain told Yahoo News for its series “Finding Safe Haven in the Climate Change Future.”
While the current California storms are not as severe as in 1862, the excess moisture in the atmosphere due to rising global temperatures has increased the possibility that a catastrophic event of that magnitude will recur, even as the risk of extreme drought is also pushed higher due in part to faster rates of evaporation.
“We’re now no longer able to avoid some of the consequences of climate change. It’s here, it’s not hypothetical. It’s our new day-to-day reality and it’s going to get worse,” Gleick said.