Regional Heterogeneity in the Rates of Warming from CO2 Emissions

Abstract:

While it is commonly understood that the magnitudes of global warming from anthropogenic emissions are and will be spatially heterogeneous, little work has been done exploring heterogeneity in the timing of effects from an emission of carbon dioxide (CO2). Using the results from the Coupled Model Intercomparison Project v5 (CMIP5) abrupt4xco2 experiment, we explore regional differences in the timing, as opposed to magnitude, of the warming from emissions of CO2. Our analysis reveals a surprisingly high amount of regional diversity in the pace of realization of the warming effect of a CO2 emission, with relatively accelerated warming for areas such as the eastern United States and Central Asia and a relatively long lag between emission and warming effect for Australia and Amazonia. Figure 1 shows the ratio of the ensemble median rate of warming in the first decade after a change in CO2 concentration to the rate of warming for the remainder of the first century. Because estimates of social cost of carbon implicitly assume similar timing of warming for all regions, the observed effects have important implications for climate policy.