A new study in Science (Eric Post, et al., Ecological Dynamics Across the Arctic Associated with Recent Changes, 325 Science 1355-1358 (2009) could be a very good potential reading for students on the impacts of climate change, as it emphasizes the fact that climate change is already occurring, discusses some of the impacts that I feel are under-emphasized, including phenological impacts and biogeochemical changes, and provides a portent of anticipated impacts in other parts of the world, including the impacts of shifts in species’ distribution. The article may be a bit technical for some students, but it’s a great way to get them to grapple with the scientific aspects of this issue, including extremely complex ecological dynamics potentially associated with climate change, many of which might not be immediately obvious to them.
Among the most important take-aways from the article:
- Arctic warming rates now exceed the century-scale warming that occurred during the Pleistocene-Holocene transition, a period which witnessed widespread shifts in vegetation and faunal extinctions across the Arctic;
- During the past two or three decades seasonal minimal sea ice extent throughout the Arctic has declined by 45,000 square kilometers annually, an area the size of New Jersey;
- Among the serious impacts already manifesting themselves from rapid climate change in the region include the following:
- Unusually early spring rain in the Canadian Arctic had led to melting, collapse and washout of birth lairs of ringed seals, imperiling newborn pups;
- Polar bears are experience rapid declines in birth rates and survival due to loss of sea ice habitat;
- Enhanced lake stratification associated with warming has changed the migration pattern of some fish species and increased likelihood of species inhabiting fish-less lakes, altering lake ecosystems;
- Changes in plant growing seasons have resulted in a trophic mismatch with caribou, threatening survival of calves.
- The future threats posed by climate change in the region include:
- Shifts in species composition could affect land-atmosphere greenhouse gas balances, creating feedbacks that we currently only poor understand;
- Shifts in species may profoundly alter simple Arctic ecosystems; this appears already to be occurring in terms of species of geometric moths and the decline of Arctic fox with northward expansion of th rnage of red foxes
- Projected warming of as much as 6C in the fjords of northeast Greenland could substantially change the dynamics of species dependent on aquatic productivity;
- Given the relative simplicity of the Arctic ecosystem, and consequent limited functional redundancy, losses of individual species may have very immediate consequences for ecosystem processes