Start Date/Time: Monday, February 04, 2013, 12:00 PM
Ending Date/Time: Monday, February 04, 2013, 1:00 PM
Location: Hitchcock Hall 132
Dr. Abigail L. S. Swann,
Assistant Professor Department of
Atmospheric Sciences & Department of Biology
University of Washington
In this talk I will show that the addition of forests over large spatial scales in the northern mid latitudes warms the Northern Hemisphere and alters global circulation patterns in climate model experiments. An expansion of dark forests increases the absorption of solar energy and increases surface temperature, particularly in regions where the land surface is unable to compensate with evapotranspiration flux due to water limitation. Atmospheric circulation re-distributes the anomalous energy absorbed in the northern hemisphere, in particular towards the south, through altering the Hadley circulation, resulting in the northward displacement of the tropical rain-bands. Precipitation decreases over parts of the Amazon basin affecting productivity and increases over the Sahel and Sahara regions in Africa. We find that the response of climate to afforestation in mid latitudes is determined by the amount of soil moisture available to plants with the greatest warming found in water limited regions. Mid latitude afforestation is found to have a small impact on modeled global temperatures and on global CO2, but asymmetric heating from the increase in forest cover is capable of driving unintended and undesirable changes in circulation and precipitation. The ability of vegetation to affect remote circulation has implications for strategies for climate mitigation.