Co-benefits of Near-Term Climate Change Mitigation

While mitigation of carbon dioxide remains the principal climate target, addressing the so-called short-lived climate forcers including black carbon, tropospheric ozone, and methane offers significant co-benefits for near-term climate, human health, food security, and the cryosphere. Using IIASA’s GAINS (Greenhouse Gas and Air Pollution Interactions and Synergies) model we identified 14 specific emission control measures targeting black carbon and methane, an ozone precursor, that were selected because of their potential to reduce the rate of climate change over the next 20–40 years. Emission scenarios where these measures are applied globally by 2030 would reduce global warming potential from short-lived forcers about 60%, methane emissions by up to 45% and black carbon by over 70% beyond baseline projections. These mitigation scenarios were used in climate simulations, performed with GIS and ECHAM models, and for health impact assessment. In addition to climate benefits (estimated reduction of global mean warming of ~0.5°C by 2050), the findings indicate substantial co-benefits for air quality and public health worldwide avoiding 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increasing annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond. These projected benefits are independent of carbon dioxide mitigation measures