Sierra Summit

Conversations and observations about California's mountains

September 28, 2009
Arctic warming (it's about more than polar bears)
musk ox1.jpg
Climate change is especially severe in the Arctic - and it's not just polar bears that are feeling the heat. 
That's the conclusion of an article in Science magazine this month (Sept. 09) that combs the scientific literature for information about the ecological impacts of warming in the Arctic - and here are some of the findings: 
  • Unusually early spring rains in northern Canada have led to the melting and collapse of birth lairs of ringed seals, leaving pups exposed on bare ice. 
  • The northward expansion of moths in Scandanavia has led to the severe defoliation of birch forests.
  • Shrub species are moving north, too, threatening plant diversity. But so far, grazing by caribou and musk ox - such as this one I saw in Canada's Northwest Territories in 2004 -  has slowed the advance. 
  • Increased melting of winter snows in Norway has led to a rapid increase in reindeer population, through increased fecundity and less starvation. Elsewhere, less snow-cover has been associated with the collapse of small mammal populations, including lemmings. 
  • Plants are blooming up to 20 days earlier over the past decade in some places.
It makes sense that colder landscapes - those attuned to cycles of snowfall and snow melt - would be among the first to exhibit the impacts of warming. We have one of those landscapes here in California, too - the majestic Sierra Nevada, a glistening white water tower, wildlife sanctuary and recreational bonanza - much of it tied to life around the freezing point. Stay tuned as I explore, in periodic blog posts, the impact of climate change across the Sierra Nevada, California's cold zone. 

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About Sierra Summit

The Author
Tom Knudson lives in the Sierra Nevada and travels widely throughout the range. His hobbies include fly-fishing, backpacking and cross-country skiing. He is the recipient of numerous journalistic awards, including two Pulitzer Prizes, one for a 1992 Sacramento Bee series "Sierra in Peril," a watershed work about environmental threats to the mountain range. E-mail Tom at

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