For the first time, climate scientists have illustrated a direct cause-and-effect relationship between melting sea ice in the Arctic and the uptick in extreme weather events and "atmospheric rivers" on the Pacific Coast of the U.S.
According to a new paper out of the Scripps Institution of Oceanography, melting ice in the Arctic leads to more moisture getting blown across the Pacific on trade winds, which in turn causes warming ocean temperatures as in El Niños and major disruptions in wind and weather patterns at the equator. And, as the Chronicle reports from the study, which was published today in Proceedings of the National Academy of Sciences, global climate effects then occur in a chain reaction that begins with the decrease in the amount of sea ice around the North Pole.
"The Arctic is changing rapidly,” says Noah Diffenbaugh, a climate scientist at the Woods Institute for the Environment at Stanford University, in a statement to the Chronicle reacting to the study. "The most immediate impacts are for the ecosystem and people in the Arctic, but there is strong evidence of impacts on ... conditions that we experience here in California."
Scientists have long said that warming seas lead to changes in wind circulation patterns and consequent extreme weather in greater frequency. But the Scripps paper marks the first time that the direct causal link from the Arctic has been documented through computer modeling. Previously, scientists did not believe that air from the Arctic could reach as far as the equator, but the Scripps study illustrates that it does.
Saltwater freezes at 28.8 degrees Fahrenheit, and much of the Arctic Ocean beneath its ice sheets is just barely warmer than that. But as the ice melts, the surface temperature can warm quickly because the ice itself reflects the sun, and the less of it there is, the more of the sun's rays get absorbed into the water. It's believed that 40 percent of Arctic sea ice has disappeared in the past 40 years.
Scientists now predict that winter temperatures in the Arctic will rise 9 degrees over the next 30 years.
According to the study authors, "These results add to the evidence that loss of Arctic sea ice is having a major impact on climatic variability around the world. [And] The magnitude of Arctic sea ice loss and the strength of the Central Pacific trade winds are unprecedented in the instrumental record."
The warming wind patterns may be to blame for a much talked-about "blob" of warm water in the Pacific that appeared multiple times in the last several years, unconnected to El Niño patterns. That blob was blamed for a cascade of effects that included the dying off of kelp forests on the Pacific coast, which in turn caused the die-off of red abalone and an uptick in the deaths of sea otters who no longer had kelp to hide in from sharks.
So, brace yourself for more extreme weather for the rest of your lives, as the temperatures in the Arctic are expected to continue to rise even if the world's most ambitious carbon-reduction goals are met.