A dwindling ice pack in the Arctic may lead to a more meager snowpack in the Rockies, according to two new studies.
The disappearing Arctic ice pack – which is likely to reach record lows this summer – may lead to a shift in the jet stream that will pull winter storms north in coming decades.
“In the Rockies, we see about 17 percent less rain and snow, and … a lot of your water comes from that,” said Lisa Sloan, a professor of earth sciences at the University of California at Santa Cruz who ran the computer-modeling study.
“It was a result we were just astounded by,” she said.
The new findings, based on eight climate models, buttress earlier work published in Geophysical Research Letters by Sloan and Jacob Sewall, also a University of Santa Cruz researcher.
“In seven of eight, they produce this very dry bull’s-eye in the Western U.S., and it’s wetter in southern Alaska, the Canadian Rockies,” Sewall said. “This result appears very robust. … If you want anything better, you need to sit around and wait 50 years and watch.”
Some of the Arctic sea-ice data used in the study come from the National Snow and Ice Data Center in Boulder. There, polar researcher Mark Serreze has been watching the floating ice cover shrink for the last five years, a trend not seen in the previous 25 years of satellite records.
Not only is ice retreating, Serreze said, but what ice is left appears to be much thinner, and this summer’s low point in September will likely be a record- breaker.
“We’re getting to some kind of tipping point here,” Serreze said during a conference at the Denver Federal Center last week. “The sea ice can’t recover.”
That prediction inspired Sewall and Sloan to run computer models forward in two scenarios: average winter ice cover and a melting of about 20 percent, which is expected by 2050.
With part of its computer-generated ice cover gone, the relatively warm Arctic Ocean poured heat into the frigid air, changing regional pressure systems and sending ripples through the wavy jet stream, Sewall said.
Winter storms headed farther north, drying the West and dampening Canada.
In their models, Sewall and Sloan ignored the fact that the greenhouse gas carbon dioxide is likely to continue to increase in the atmosphere, possibly causing greater warming. “If you add that, greenhouse warming is going to cause increased temperature and more drying of the soil. The results could potentially be quite bad,” Sewall said.
Richard Alley, a climate researcher at Pennsylvania State University, said the new Arctic-West link is tantalizing, but it needs more confirmation.
“This is one of those things we’d better figure out,” he said. “Because if we go to a completely ice-free Arctic, we have a very different world.”
Staff writer Katy Human can be reached at 303-820-1910 or at khuman@denverpost.com.