B22A-06:
The Fate of Amazonian Ecosystems over the Coming Century Arising from Changes in Climate, Atmospheric CO2 and Land-use
Tuesday, 16 December 2014: 11:35 AM
Paul R Moorcroft, Harvard Univ, Cambridge, MA, United States, Ke Zhang, University of Oklahoma Norman Campus, Norman, OK, United States, Andrea D de Almeida Castanho, UFC Federal University of Ceará, Fortaleza, Brazil, David Galbraith, University of Leeds, School of Geography, Leeds, LS2, United Kingdom, Sanaz Moghim, Georgia Institute of Technology Main Campus, Atlanta, GA, United States, Naomi Marcil Levine, University of Southern California, Los Angeles, CA, United States, Rafael L Bras, Georgia Tech, Atlanta, GA, United States, Michael Thomas Coe, The Woods Hole Research Center, Falmouth, MA, United States, Marcos Heil Costa, UFV Federal University of Vicosa, Vicosa, Brazil, Yadvinder Malhi, Oxford University, Environmental Change Institute, Oxford, United Kingdom, Marcos Longo, EMBRAPA Brazilian Agricultural Research Corportation, Campinas, Brazil, Ryan G Knox, Lawrence Berkeley National Laboratory, Berkeley, CA, United States, Shawna L McKnight, Georgia Institute of Technology, Atlanta, GA, United States and Jingfeng Wang, GA Ins of Tech-Civil & Env Eng, Atlanta, GA, United States
Abstract:
There is considerable interest and uncertainty regarding the expected fate of the Amazon over the coming century in face of the combined impacts of climate change, rising atmospheric CO2 levels, and on-going land transformation in the region. In this analysis, we explore the fate of Amazonian ecosystems under projected climate, CO2 and land-use change in the 21st century using three state-of-the-art terrestrial biosphere models (ED2, IBIS, and JULES) driven by three representative, bias-corrected GCM climate projections (PCM1, CCSM3, and HadCM3) under the SRES A2 scenario, coupled with two land-use change scenarios. We assess the relative roles of climate change, CO2 fertilization, land-use change, and fire in driving the projected changes in Amazonian biomass and forest extent. Our results indicate that the impacts of climate change depend strongly on the direction and severity of projected changes in precipitation regimes within the region: under the driest climate projection, climate change alone is predicted to reduce Amazonian forest cover by an average of 14%; however, the models predict that CO2 fertilization will enhance vegetation productivity and alleviate climate-induced increases in plant water stress, and as a result sustain high biomass forests, even under the driest climate scenario. Land-use change and changes in fire frequency are predicted cause additional aboveground live biomass loss and changes in forest extent. The relative impact of land-use and fire dynamics versus the impacts of climate and CO2 on the Amazon varies considerably, depending on both the climate and land-use scenarios used and on the terrestrial biosphere model, highlighting the importance of improved understanding of all four factors -- future climate, CO2 fertilization effects, fire and land-use -- to the fate of the Amazon over the coming century.
