Over the past several hundred thousand years, global atmospheric levels of carbon dioxide have remained relatively stable, averaging 280 parts per million (ppm) and varying between 180 and 300 ppm through several ice ages. But over the past 60 years, the carbon dioxide concentration in the atmospheric has risen steadicly, at an accelerating rate from decade to decade, to the current level of 392 ppm.
Why should we care? There is a strong causal link (shown by ice core and other scientific studies) between atmospheric concentrations of “greenhouse gases” such as carbon dioxide and global surface temperatures. Moreover, scientists who study the earth’s history have discovered periods in the Earth’s history, tens and hundreds of millions of years ago, when high concentrations of greenhouse gases apparently led to global warming and mass extinctions of the earth’s biota as much of the planet became uninhabitable. In the current period of rapidly rising atmospheric CO2, we are already seeing dramatic evidence of ecosystem change. Among many recent examples of climate-caused ecosystem change, two widely publicized ones include coral reefs bleaching and dying as the oceans warm and become more acidic, and dramatic losses of summer ice cover on the Arctic Ocean as the poles warm.
Why should we care? Well, if you live in the Arctic, or if you live on a low-lying island in the ocean, or if you live in an area suffering from climate-caused drought, or if you live an an area where the forests are dead all around you (e.g., southern British Columbia and many areas in the Rocky Mountains), or if you fish for salmon in Alaskan rivers, you care. But for those of us living in temperate regions it is often hard to perceive, and thus to care about, the relatively slow incremental changes that are occurring due to rising levels of atmospheric CO2 and a changing climate. Scientists have only recently started to focus on impacts of climate change on a regional or local level in the temperate parts of the world.
A new study by Dr. Curt Stager and Mary Thill sheds light on climate impacts that have already occurred in the Lake Champlain Basin and what impacts are to be expected in the near future. Funded by The Nature Conservancy, the research was an effort to find out how climate change might affect the aquatic habitat in one relatively small region. Their research showed that average temperatures have risen 2°F in just the past 30 years and that winter ice cover is significantly less extensive than in the past. For example, in the 19th century the lake failed to freeze over only three times, while between 1970 and 2007 it failed to freeze over 18 times.
No one can precisely predict future climates, but a host of climate models do a demonstrably and increasingly good job of doing so. An on-line tool is available, Climate Wizard, which allows anyone to easily access leading climate change information from 16 leading climate models and visualize the impacts anywhere on the planet. Report authors Stager and Thill applied Climate Wizard to the Champlain basin to develop a deeper understanding of how climate change might impact the basin and what resource managers could do. The good news is that many of their recommendations are things that we are already doing or should be doing: reduce pollution inputs, monitor environmental conditions and vulnerable species, be flexible and adaptive and prepared for varying lake levels, and prevent alien species invasions. As the authors state, dealing proactively with potential climate change impacts in the basin will be less costly and more effective than trying to respond after the fact.
The same thought process applies at the global level where I began this commentary. Climate change is real. It is going to get much warmer within the next 50-100 years. There is strong scientific consensus (e.g., Intergovernmental Panel on Climate Change reports) that the primary cause of the dramatically rising atmospheric concentration of greenhouse gases are human emissions. But this is good news, in a sense, as it means that unlike past episodes of climate change linked to volcanic eruptions and meteor impacts, we can control our future – if we take steps soon to reduce greenhouse gases before large areas of the planet become uninhabitable.
The steps we should be taking – reducing our dependence on foreign oil, eliminating the burning of coal until its combustion is clean and non-polluting, using renewable energy sources, eating locally grown food, driving hybrid and electric cars, and reducing our heating and electric bills – are things that we should do regardless, even if all the climate scientists are all wrong (inconceivable to me). These steps amount to taking out relatively cheap insurance to ensure that our grandchildren inherit a healthy planet – just in case the scientists are correct.
Curt Stager and Mary Thill’s full report is available here.
Graph: Lake Champlain ice dates, courtesy Curt Stager.