Near- and long-term global warming of current emissions

Human activities influence the climate in a range of ways. While emissions of CO2 from burning of fossil fuels is the dominant factor behind the present rapid global warming, many other gases and particles also contribute. These may have short or long atmospheric lifetimes, and thus have climate impacts that are important in the near- or long-term, or both. They may also be either warming or cooling, and several climate perturbing substances may be emitted from the same sources. Consequently, determining the full impact of a given mitigation measure, aimed at reducing emissions if a given substance, is not trivial. In the present report, commissioned by the Norwegian Ministry of Climate and Environment, we discuss the near- and long-term climate impacts of present emissions of long-lived greenhouse gases (here defined as CO2 and N2O), and a range of short-lived climate forcers. Based on this, we discuss the potential for optimal mitigation strategies across regions and sectors, including co-benefits for health and agriculture.