As the Copenhagen convention on global climate change begins Monday, U.S. polls indicate that Americans are becoming less convinced that global climate change is real. Is this because we haven’t had dramatic heat waves in the past couple of years, or because the past two winters in New England have had more snow than in recent years, or is it simply because the sour economy has trumped all else and people are withdrawing into a cocoon where they focus only on present hardships and ignore the future?
Recently we have been further burdened with doubt as news reports cite a series of e-mails that have been labeled a conspiracy to suppress data among some climate scientists. To me these e-mails represent normal, but unfortunate, dialogue between scientists who are weighing the pros and cons of a mass of complex data that will be used to develop long-term predictions. But it certainly has provided fuel for those who have doubts that climate change is real.
Any or all of these reasons may be affecting our collective thinking, but I propose a more cogent reason is related to the diffuse and seemingly conflicting nature of the crisis. Yes, we have all heard that temperatures will rise several degrees, but we have also heard that some places may actually get cooler, or that sea ice near the poles is melting, but that only melting of ice caps will lead to sea level rise, or that globally we can expect drier conditions in some areas, but not in others. These seeming contradictions appear to be lulling us into complacency. And in places like Maine, folks who don’t live in a coastal plain may actually be hoping for a general warming trend.
What is often missed in climate change generalities are the real but unanticipated local changes that will likely occur. The natural world is a web of extremely complex interactions. Small changes in one factor can often lead to what scientists call amplification effects.
A classic example is now playing out in the northern polar region. Heat energy from the sun is mostly reflected back into the atmosphere when it strikes snow or ice (the albido effect). But once seawater or bare land is exposed, much of the sun’s energy is absorbed and now the warming curve rapidly increases. So far, we still have much of the winter ice in the aArctic seas, but we are rapidly losing seasonal (summer) ice, permitting more heat absorption by the ocean which in turn leads to thinner and thinner winter ice. We are approaching a tipping point.
But let’s bring the discussion back to Maine and just consider two wildlife species that we all directly or indirectly depend on for economic or recreational gain — white-tailed deer and brook trout. Native brook trout are the iconic fish species for Maine and draw many anglers to the state. Deer are either loved for hunting possibilities or disliked if they jump in front of our vehicles or eat our gardens. Populations of both deer and trout will be afected not so much by direct temperature changes but by indirect habitat modifications.
Climate modelers predict that Maine’s winters will become warmer but wetter. The past two winters were wetter (more snow) but did not reach, in most places, the subzero minimums that once characterized Maine. Even with warming temperatures Maine will still receive most winter precipitation in the form of snow, but it will be “wetter” since the temperatures will be closer to the freezing point. This will increase the winter burden on deer (deep, wet snow causes much greater mortality — especially of fawns). So, although the winters will be somewhat milder, this may not benefit the deer herds.
Since winter minimums will not be as low and because soil-insulating snow cover may be more persistent, trees and shrubs that are currently not adapted to Maine may migrate north. As a consequence, conifer numbers will decline as they face greater competition from broad-leaved deciduous trees. Conifers, such as spruce and fir, provide year-round shade along streams and brooks. If they are replaced by deciduous trees, we can expect more rapid spring snowmelt leading to increased siltation and trout habitat destruction. In summer, our native speckled alder along streams provides shade for trout and a staging area for caddis flies, a primary food source for brook trout.
During the past 50 years, another alder that was native south of here has been creeping into several counties in southern Maine. Will this alder replace speckled alder? Will it provide the same amenities for brook trout? We don’t know, but nature can be full of unwelcome surprises. Natural processes in ecosystems can adapt to change, but they may produce results that are culturally and economically less appealing.
Richard Jagels is a professor of forest biology at the University of Maine and the lead author of the “Forest” section of “Maine’s Climate Future,” published this year and available online at www.climatechange.umaine.edu/mainesclimatefuture/.