A Seminar On the Importance of Land Surface Processes On the Global Climate System

I thank Jim Angel, the Illinois State Climatologist, for alerting me to this seminar. While most of us cannot attend, the topic is of considerable interest to us.


The Illinois State Water Survey Presents
Center for Atmospheric Sciences Seminar

A butterfly flaps its wings: The unintended regional and global
consequences of Amazonian deforestation

Peter Snyder
Department of Atmospheric Sciences
University of Illinois at Urbana-Champaign

Tuesday, April 3 2007 2:00 – 3:00 PM
Illinois Room – ISWS Conference Room
Coffee and Cookies at 1:45 PM


Although it has been established that the biosphere has an influence on the atmosphere at local and regional scales, there is widespread disagreement over whether the biosphere is capable of influencing the global climate through large-scale changes to the atmospheric general circulation. Numerous studies have already identified the regional climate response to human modification of the landscape through changes to the biophysical exchanges of energy, water, and momentum between the land surface and the atmosphere. However, we still do not understand whether land use and land cover change are capable of influencing remote regions through teleconnection processes. Furthermore, given a specific surface forcing, it is not entirely clear where the response will occur, how strong it will be, or how large a surface forcing is required in order for a climate response to be felt globally. Tropical deforestation is one example of a surface forcing that has the potential to influence the global climate. Several studies have suggested that significant changes to the Northern Hemisphere climate may occur as a result of selective tropical deforestation in the Amazon basin, yet most of these studies have focused on the climate response in the extratropics with little explanation of the mechanisms responsible for propagating the signal out of the tropics. This has led to disagreement over whether these mechanisms are real or are, in fact, artifacts generated by “noise” in climate models.

I will present results from a coupled atmosphere-biosphere model, CCM3-IBIS (Community Climate Model, version 3 – Integrated Biosphere Simulator), to illustrate the potential influence of theoretical land use and land cover change on the global climate by way of atmospheric teleconnections. The results suggest that pan-tropical and Amazonian deforestation can have a strong influence on the Northern Hemisphere general circulation by way of changes to synoptic-scale dynamics and land-atmosphere feedbacks both in the Amazon and in Asia. The result is a large warming across parts of Asia in boreal winter. While theoretical, this approach illustrates the potentially important processes connecting regional land surface changes in the tropics to climate changes in far-removed regions.

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