Melting Arctic ice drives weather shifts, study says — and maybe California downpours
Melting ice in the Arctic Ocean is driving weather changes as far afield as the equator, newly published research reveals — and those changes may fuel downpours that later drench California.
The study shows that the accelerating ice melt near the North Pole is linked to weather changes in the equatorial Pacific Ocean, researchers from the Scripps Institution of Oceanography at the University of California, San Diego, said in a news release. Researchers note that the Pacific Ocean drives weather patterns worldwide, including in California.
The findings were published Monday in the journal “Proceedings of the National Academy of Sciences,” with researchers calling the study “the first time that researchers have looked at both world regions together in this context.”
Researchers said the study finds “strong evidence that the ice melt sets a chain of events in motion that sends cold air equatorward in the upper atmosphere.”
Each summer, up to twice as much Arctic sea ice melts as used to melt during the 20th century, researchers said. And as more Arctic ice has melted, trade winds have intensified near the equator in the Central Pacific Ocean, the study found.
“There’s a definite relationship and a change in tropical Pacific climate,” Charles Kennel, a physicist and the former director of Scripps, said in a statement. “There’s now a network of consistent correlations.”
Here’s how the Arctic melt influences the Pacific: As sea ice turns into water amid hotter conditions, there’s more dark Arctic Ocean water exposed to the sun — and that water absorbs roughly 93 percent of sunlight, unlike the ice that was once there and bounced away the sun’s rays, according to researchers.
That means water temperatures go up, Kennel said. The warm air rises in the atmosphere, reaching the boundary of the troposphere and the stratosphere above it, researchers said.
“It’s like applying a candle to the bottom of the atmosphere; you set off convection that rises to high altitudes and once it gets up there it has no place to go, so it gradually moves southward,” Kennel said, according to Mongabay, an environmental news site.
And that has global implications.
“This movement goes hand in hand with contortions of typical weather patterns that have caused frigid ‘polar vortex’ weather in the U.S. Midwest and deadly flooding in Asia in recent years,” researchers said. “Though many researchers had thought that air originating in the Arctic couldn’t make it to the equator, Kennel and [co-author Elena] Yulaeva said their work suggests it does.”
But how would thosechanges influence California’s weather?
The San Francisco Chronicle reported that the Arctic-fueled wind and weather shift in the Pacific “in turn, triggers El Niño weather events and the violent ‘atmospheric rivers’ that bring deluges of rain, sometimes causing havoc in the Bay Area.”
El Niño and La Niña, patterns of warm equatorial water in the Pacific, impact weather worldwide, the researchers said — meaning “the melt of Arctic sea ice could have a global reach by influencing the influencer of weather set in motion around the world.”
And while “classical El Niños feature build-ups of warm water at the eastern end of the Pacific Ocean off South America, … El Niños starting in the Central Pacific Ocean are the ones that respond to the arrival of Arctic air near the equator,” the researchers said.
The researchers also said that “since so much of California’s rain comes from atmospheric river storms that develop in the Central Pacific, the Arctic-Tropics connection merits further study.”
This story was originally published January 27, 2020 at 8:11 PM with the headline "Melting Arctic ice drives weather shifts, study says — and maybe California downpours."
