Twenty-first century atmospheric change and deforestation: Potential impacts on tropical forests

This chapter quantifies the relative roles of carbon dioxide (CO2), temperature, rainfall, and deforestation on the future extent and condition of tropical rainforests, and examines the magnitude of their feedbacks on atmospheric CO2 concentrations. A dynamic global vegetation model is applied using multiple scenarios of tropical deforestation (extrapolated from two estimates of current rates) and multiple scenarios of changing climate (derived from four independent off-line general circulation model simulations). Results show that deforestation is likely to produce large losses of carbon, despite the uncertainty concerning exact deforestation rates. Estimates of additional carbon emissions during the 21st century, for all climate and deforestation scenarios, range from 101 to 367 Gt C, resulting in CO2 concentration increases above background values by between 29 and 129 ppm. Notwithstanding this range of uncertainty, continued tropical deforestation will most certainly play a very large role in the build-up of future greenhouse gas concentrations.