The fate of Amazonian ecosystems over the coming century arising from changes in climate, atmospheric CO2, and land use

Ke Zhang; Andrea D de Almeida Castanho; David R Galbraith; Sanaz Moghim; Naomi M Levine; Rafael L Bras; Michael T Coe; Marcos H Costa; Yadvinder Malhi; Marcos Longo; Ryan G Knox; Shawna McKnight; Jingfeng Wang; Paul R Moorcroft

doi:10.1111/gcb.12903

The fate of Amazonian ecosystems over the coming century arising from changes in climate, atmospheric CO_2, and land use

Glob Chang Biol. 2015 Jul;21(7):2569-2587. doi: 10.1111/gcb.12903. Epub 2015 May 12.

Authors

Ke Zhang^{1

2

3}, Andrea D de Almeida Castanho^{4

5}, David R Galbraith⁶, Sanaz Moghim⁷, Naomi M Levine^{1

8}, Rafael L Bras^{7

9}, Michael T Coe⁴, Marcos H Costa¹⁰, Yadvinder Malhi¹¹, Marcos Longo¹, Ryan G Knox¹², Shawna McKnight⁷, Jingfeng Wang⁷, Paul R Moorcroft¹

Affiliations

¹ Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA.
² Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, Norman, OK, USA.
³ Hydrometeorology & Remote Sensing (HyDROS) Laboratory, School of Civil Engineering and Environmental Sciences, University of Oklahoma, Norman, OK, USA.
⁴ The Woods Hole Research Center, Falmouth, MA, USA.
⁵ Department of Agricultural Engineering, Federal University of Ceará, Fortaleza, Brazil.
⁶ School of Geography, University of Leeds, Leeds, UK.
⁷ School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
⁸ Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA.
⁹ School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
¹⁰ Department of Agricultural and Environmental Engineering, Federal University of Vicosa, Viçosa, Minas Gerais, Brazil.
¹¹ Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, UK.
¹² Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.

PMID: 25704051
DOI: 10.1111/gcb.12903

Abstract

There is considerable interest in understanding the fate of the Amazon over the coming century in the face of climate change, rising atmospheric CO₂ levels, ongoing land transformation, and changing fire regimes within the region. In this analysis, we explore the fate of Amazonian ecosystems under the combined impact of these four environmental forcings using three terrestrial biosphere models (ED2, IBIS, and JULES) forced by three bias-corrected IPCC AR4 climate projections (PCM1, CCSM3, and HadCM3) under 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 are primarily determined by the direction and severity of projected changes in regional precipitation: 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 climate-driven changes in fire frequency are predicted to cause additional aboveground biomass loss and reductions in forest extent. The relative impact of land use and fire dynamics compared to climate and CO₂ impacts varies considerably, depending on both the climate and land-use scenario, and on the terrestrial biosphere model used, highlighting the importance of improved quantitative understanding of all four factors - climate change, CO₂ fertilization effects, fire, and land use - to the fate of the Amazon over the coming century.

Keywords: Amazon; CO2 fertilization; biomass; climate change; deforestation; fire; land use; terrestrial biosphere model; water stress.