Stephen Sitch^a, Victor Brovkin^a, Werner von Bloh^a, Detlef van Vuuren^b, Bas Eickhout^b, and Andrey Ganopolski^a

Global Biogeochemical Cycles 19, GB2013, doi:10.1029/2004GB002311 (2005)

^aPotsdam Institute for Climate Impact Research (PIK), Telegrafenberg, P.O. Box 60 12 03, 14412 Potsdam, Germany.

^bNetherlands Environmental Assessment Agency (RIVM/MNP), Bilthoven, Netherlands.

Abstract

Climate-carbon cycle model CLIMBER2-LPJ is run with consistent fields of future fossil fuel CO₂ emissions and geographically explicit land cover changes for four Special Report on Emissions Scenarios (SRES) scenarios, A1B, A2, B1, and B2. By 2100, increases in global mean temperatures range between 1.7°C (B1) and 2.7°C (A2) relative to the present day. Biogeochemical warming associated with future tropical land conversion is larger than its corresponding biogeophysical cooling effect in A2, and amplifies biogeophysical warming associated with Northern Hemisphere land abandonment in B1. In 2100, simulated atmospheric CO₂ ranged from 592 ppm (B1) to 957 ppm (A2). Future CO₂ concentrations simulated with the model are higher than previously reported for the same SRES emission scenarios, indicating the effect of future CO₂ emission scenarios and land cover changes may hitherto be underestimated. The maximum contribution of land cover changes to future atmospheric CO₂ among the four SRES scenarios represents a modest 127 ppm, or 22% in relative terms, with the remainder attributed to fossil fuel CO₂ emissions.

Keywords: Earth system modeling, biosphere-atmosphere interaction, future land cover changes, SRES scenarios, atmospheric CO₂ concentration.