For most of us spring is a time of renewal, a time when flowers bloom, when the sun shines, and life generally replenishes itself. As global temperatures rise, however, the timing of spring's arrival is subtly changing; it's moving back and the repercussions may be more serious than you think.

 

Winter can be a harsh time for animals and many have adapted unique strategies for survival. Some hibernate, tucking themselves away for a long winter nap; others migrate, choosing to spend the cold months in sunny south. In either case, these animals rely on specific seasonal cues to tell them when to come and when to go.

 

For some animals, like the marmot, these cues are based on air temperature. These plump little rodents typically enter a state of torpor, lowering their body temperature and metabolic rates as they sleep away the winter. Then, in spring when air warms up, they wake up and head out, hungry for a snack.

 

Ecologists have found, however, that Colorado's marmots are now waking up a full month earlier than they did twenty years ago, a change which may be attributed to global warming. The early risers are finding themselves facing deep snow and no food, since many plants rely on changes in photoperiod rather than temperature to put up shoots and flowers.

 

And marmots aren't the only ones affected. The timing of some annual bird migrations has also changed. According to a study cited by the Environmental Protection Agency, the American robin now arrives a full two weeks earlier, and British swallows are returning to their spring feeding grounds up to eight weeks early. While these birds may move in response to food availability, other long-distance migrants are finding that their annual sojourns are slowly becoming out of synch with the plants and bugs on which they feed, leaving them without the food to fuel their epic flights.

 

This spring, as you enjoy the return of all things green, take a moment to think about the ways in which we impact the world around us. Think about what one degree warmer actually means, not to you, but to a marmot, or a bird, or a butterfly whose vitality depends on the regularity of something as simple and fundamental as the seasons.