It's too early to say with certainty, but 2012 is shaping up as the year that winter forgot. All of December and the first week of January saw atypically mild temperatures throughout much of the U.S.--most dramatically in the usually harsh states of the far north and parts of the Plains. Fargo, N.D., hit 55F on Jan. 5, breaking a more-than-a-century-old record for the warmest day in January. In December, at least half the U.S. had temperatures at least 5F above normal. At the end of 2011, less than 20% of the lower 48 was covered with snow, compared with more than 50% at the end of 2010. Ski resorts face the possibility of a dry, warm winter leaving slopes bare.
Is climate change the culprit? It's important to remember that one season does not make a trend, and the warm temperatures of the past month and a half aren't driven by any single variable. The winters of 2011 and 2010 saw unusually heavy snowfall in much of the U.S., after all, and Europe experienced some of the coldest temperatures in its history. And even this winter, Alaska is being buried in snow--a stunning 67 in. in one town during a nine-day stretch. Still, it's undeniable that truly cold temperatures are becoming less and less common. In the U.S. since 1980, nearly every year has seen annual average temperatures higher than the long-term average.
To many people, that's not a bad thing. Extreme cold isn't just uncomfortable and inconvenient--it's also dangerous, particularly for older or poorer people who often can't protect themselves from the elements. But warmer winters can change nature in dangerous ways as well. Western bark beetles, which have ravaged pine trees in the West, are thriving because they're no longer being knocked out by very cold winters. A decline in mountain snowpack in the West can mean less water for dry states that are accustomed to meltwater runoff in the spring.
And then there's the less quantifiable, more lyrical value of winter--a cold and crystalline season that's beautiful and punishing all at once. "If we had no winter, the spring would not be so pleasant," said the early-American poet Anne Bradstreet. Climate change disrupts the rhythm of the seasons, that regular passage of time and temperature we assumed was fixed. It turns out we may be wrong, and winter as we know it could one day be a season of the past. As we keep altering the climate, who can tell what else might follow into unplanned obsolescence?