In the Artic, a lot still goes unseen. Take the weird weather event of October 2003 that killed 20,000 musk oxen on Canada's Banks Island above the Arctic Circle. Rain fell for days atop 6 inches of snow and seeped through to the soil. When the temperature plunged, the rain froze into a thick layer of ice that persisted all winter. Browsers couldn't dig through to feed on lichens and mosses, and one-third of a 70,000-herd of musk oxen perished. "Starvation happened over a period of many months and no one knew until they went up to do the population count the next spring," says Thomas Grenfell, research professor of atmospheric sciences at the University of Washington. The closest weather station, 60 miles away, didn't record any rainfall at the time and few people recognized the oxen's distress.
Now Grenfell and Jaakko Putkonen, also of UW, have found evidence of the 2003 rain-on-snow occurrence in passive satellite microwave imagery. This could provide a signature to help detect similar events in the future, throughout the sparsely-populated Arctic, including in Alaska, northern Canada, Siberia, and Scandinavia. They looked for patterns in data from 10 different satellite microwave channels that correlated with rain-on-snow events. "The subtleties in the microwave levels mean there can be high error margins on this information, but the Banks Island event stood out like a sore thumb in the data," said Grenfell. He hopes satellite data might make up for a scarcity of weather stations and enable native people, who depend on musk oxen, reindeer and caribou, to get food to the herds to prevent mass starvation.
Not explicitly stated but worrying nontheless—expect more rain-on-snow events as the Arctic warms. Which means, this is what we've come to, essentially taming wildlife to keep it alive. Sad benchmark. The study will be published March 25 in Water Resources Research, a journal of the American Geophysical Union.
Julia Whitty is Mother Jones' environmental correspondent, lecturer, and 2008 winner of the John Burroughs Medal Award. You can read from her new book, The Fragile Edge, and other writings, here.