We've just cancelled our pre-Christmas family ski trip for the first time ever because of lack of snow. The Colorado high country is usually blanketed by three to six feet of snow by this time of year. In over 15 years of pre-Christmas, Colorado skiing we've had a range of conditions: some years we've had amazing snow-covered, uncrowded slopes, in other years we've had bitter cold with great snow, and in some years the snow was sparse -- but there was always enough to ski on.
This year, however, the normal October and November snows have not come and there is virtually no natural base to ski on. The ski areas are reported to have only ribbons of man-made snow (I'm writing this on December 9 when 9" of snow fell on some areas but only a few more inches are projected in the next 10 days). It's been unusually warm and sunny in the Colorado high country this fall. However, don't worry about skiers or the ski areas, but rather worry about what the snow is needed for: water -- for plants, wildlife, people, and agriculture, as well as insulation for hibernators.
Hibernation is an amazing adaptation that permits animals to survive long, cold winters without food by reducing their body temperature to a few degrees above freezing and their respiration and heart rate to an almost undetectable rate. Doing this reduces the amount of energy they need. The yellow-bellied marmots I study at the Rocky Mountain Biological Laboratory (RMBL) in Colorado burn about one gram of fat per day while they are in what is called 'deep torpor.'
Like many things, however, such adaptations are tuned to the environments in which animals evolved. In the case of marmots, and arctic and alpine ground squirrels, and Siberian hamsters, a good amount of snow is a necessary source of insulation. At our 9,500' Colorado study site, long-term snow records dating back to 1974 tell us that 2012 is breaking records. As of the week of December 8, 2012 has had the least snowfall to date (34") while the average is 101" by this time. However the warmth has melted the snowpack; the average snowpack this week is 24.5", while we only had 5" on the 8th this year. Photographs I've seen of the area show many areas with absolutely no snow, including the hillside near our cabin and some of the meadows under which marmots are hibernating.
Last year, after a record early melt-out in April, the snowpack evaporated quickly in the late spring. The lack of snow has consequences: plants dried out, flowers were killed because plants started flowering early only to be killed by frosts in May and June, and the natural spring that is the normal source of water for the RMBL dried out in August for the first time ever. And, I'm sure you remember the wildfires all over Colorado during the summer of 2012. Reservoirs that had finally begun to re-fill after a long drought, had their levels begin to drop again. These reservoirs provide water for the American West. If the lack of snow continues, prepare for another tinder-dry summer with limited water, and few, if any, flowers.
So where does this leave the hibernators? As I wrote above, snow provides insulation. This insulation makes the temperature in the burrows in which the marmots are hibernating warmer. And this warmth is essential. Hibernators have what's called a thermal-neutral zone: a temperature range in which it's neither too warm or too cold and in which the marmots can burn about one gram per day. If it's too hot, their metabolic rate is higher and they burn more fat. If it's too cold, they have to burn more fat to keep warm. A good blanket of snow makes it 'just right.'
My colleagues and I have studied the marmots since 1962 and we've created an important record of how the environment influences population size in marmots. We know that if the snowpack sticks around too long -- some marmots run of energy before the vegetation greens up. We know that late summer droughts also are important sources of marmot mortality because they can't gain sufficient fat to survive hibernation. We've not really looked at the effect of limited snowpack because this is an extremely rare event.
We've had a big die off the past two years: a crash from over 300 animals to 46. Why? Two winters ago we had record snowfall and this was followed by a low-snowpack year. Climate disruption is predicted to lead to increasingly variable annual weather. We've seen the effects of this with super-storms, fire-storms, and higher food prices. We know that these will become the new normal in given the failure to create effective controls on carbon consumption.
With respect to our marmots, we thought that the population began to increase with the birth of about 80 pups last summer. It's always exciting to arrive in the spring and figure out who survived hibernation and who did not, see who breeds and who doesn't, and see who disperses and who remains in their social groups. However, I fear for their survival this winter because they're hibernating without a good blanket.
What's the solution? Save a marmot -- send blankets to Colorado! Or, perhaps, more importantly, we can use this as a wake-up call and do whatever we can to work towards binding agreements to reduce our carbon consumption. The Doha talks were essentially a failure, agreeing only to extend the largely ineffective Kyoto Protocols. We need to do a better job; there isn't much time to waste.