Dependence of the radiative forcing of the climate system on fossil fuel type

Abstract:

Climate change mitigation strategies are greatly directed towards the reduction of CO₂ emissions and other greenhouse gases from fossil fuel combustion to limit warming to 2º C in this century. For example, the Clean Power Plan aims to reduce CO₂ emissions from the power sector by 32% of 2005 levels by 2030 by increasing power plant efficiency but also by switching from coal-fired power plants to natural gas-fired power plants. It is important to understand the impact of such fuel switching on climate change. While all fossil fuels emit CO₂, they also emit other pollutants with varying effects on climate, health and agriculture. First, The emission of CO₂ per joule of energy produced varies significantly between coal, oil and natural gas. Second, the complexity that the co-emitted pollutants add to the perturbations in the climate system necessitates the detangling of radiative forcing for each type of fossil fuel. The historical (1850-2011) net radiative forcing of climate as a function of fuel type (coal, oil, natural gas and biofuel) is reconstructed. The results reveal the significant dependence of the CO₂ and the non-CO₂ forcing on fuel type. The CO₂ forcing per joule of energy is largest for coal. Radiative forcing from the co-emitted pollutants (black carbon, methane, nitrogen oxides, organic carbon, sulfate aerosols) changes the global mean CO₂ forcing attributed to coal and oil significantly. For natural gas, the CO₂-only radiative forcing from gas is increased by about 60% when the co-emitted pollutants are included.