The Short-Term Cooling but Long-Term Global Warming Due to Biomass Burning

Abstract

Biomass burning releases gases (e.g., CO2, CO, CH4, NOx, SO2, C2H6, C2H4, C3H8, C3H6) and aerosol particle components (e.g., black carbon, organic matter, K+, Na+, Ca2+, Mg2+, NH4+, H+, Cl?, H2SO4, HSO4?, SO42?, NO3?). To date, the global-scale climate response of controlling emission of these constituents together has not been examined. Here 10-yr global simulations of the climate response of biomass-burning aerosols and short-lived gases are coupled with numerical calculations of the long-term effect of controlling biomass-burning CO2 and CH4 to estimate the net effect of controlling burning over 100 yr. Whereas eliminating biomass-burning particles is calculated to warm temperatures in the short term, this warming may be more than offset after several decades by cooling due to eliminating long-lived CO2, particularly from permanent deforestation. It is also shown analytically that biomass burning always results in CO2 accumulation, even when regrowth fluxes equal emission fluxes and in the presence of fertilization. Further, because burning grassland and cropland yearly, as opposed to every several years, increases CO2, biofuel burning, considered a ?renewable? energy source, is only partially renewable, and biomass burning elevates CO2 until it is stopped. Because CO2 from biomass burning is considered recyclable and biomass particles are thought to cool climate, the Kyoto Protocol did not consider biomass-burning controls. If the results here, which apply to a range of scenarios but are subject to uncertainty, are correct, such control may slow global warming, contrary to common perception, and improve human health.