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AGU 2009 Joint Assembly: Global change, local impacts

Level 7 of the Metro Toronto Convention Centre is situated above Level 8, and Level 6 is higher still. Once you find your way around, it’s seems the perfect place to study atmospheric inversions and other climatological phenomena. That’s what is happening at the centre this week during the Joint Assembly of the American and Canadian Geophysical Unions, along with a half-dozen other Earth and space science societies.

This annual event, once known as AGU Spring Meeting, has attracted some 2,500 presentations, ranging from Atmospheric Science to Volcanology, and the ones touching on climate change turn up under a variety of headings. Climate change may occur globally, but it impacts locally, and regional impacts were the topic of numerous presentations Monday at Joint Assembly.

The issue facing researchers and policy makers alike is scaling down the results of global climate models to make useful predictions for specific locales, like cities, counties, or watersheds, predicting how climate change may affect local populations, industries, and wildlife.

In the US state of New Hampshire, for example, the multimillion dollar ski industry depends upon a large and consistent snowpack. Cameron Wake of the University of New Hampshire said that to be economically viable, ski operators must count on a season of at least 100 days, ideally including Christmas week. But, a group of regional scientists estimates that by 2100, New Hampshire will warm between 1.9o and 6.9o Celsius, the extremes of several models tested. The greatest warming will be in winter. Also, there will be more rain and less snow in winter, and anticipated droughts will further reduce the number of days with snow on the ground. By the 100-day standard, Wake said, and even with snowmaking equipment, almost all New England ski areas will be vulnerable by 2100.

New York City has always prided itself on its water supply. New Yorkers turn the tap and enjoy mountain spring water piped from protected watersheds far upstate. But will climate change affect the quality of that water—currently four million liters for nine million customers daily—in years to come? The city is actively addressing that question, said Mark Zion of New York’s Environmental Protection Agency.

Stressing that he was presenting very preliminary results from Phase I of an ongoing modeling study, Zion outlined a future in which eutrophication (excessive nutrient load from land-based runoff) and turbidity, both of which are infrequent issues now, become much more common. By 2100, he said, air temperature in the watersheds will be higher, especially in winter; reservoirs will overflow, affecting downstream communities and farms; water temperature will increase, especially in summer, and the chlorophyll level will rise in summer and fall. All of this must be studied carefully, Zion said, as models are refined in the light of experience.

Climate change is also affecting wildlife, and researchers at North Carolina State University and the U.S. Geological Survey are particularly concerned about the future of bird populations in the southeastern US, a prime migration route and breeding area. Alexa McKerrow of North Carolina State College described two projects currently underway. One seeks to predict forest fire potential, based on projected temperatures and convective precipitation, in an effort to provide resource managers with viable options to protect the habitat of priority species in the Southern Atlantic Migratory Bird Initiative.

The second, and larger, study focuses on land birds, using occupancy models to assess the possibility of future local extinctions. The study looks at the great expected expansion of urban areas, along with anticipated sea level rise and other environmental factors. The work is delicate, said McKerrow, as Bobwhite quails require habitat that burns regularly, obviously difficult as humans move farther into the landscape.

Other regional climate issues will be discussed tomorrow, as Joint Assembly continues.

Harvey Leifert is a freelance science writer


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