Do global warming targets limit heatwave risk?

Climate change mitigation targets are often described in terms of annually averaged global mean temperature increases. However local interpretation of impacts resulting from these targets are required if the public is to have a sound appreciation of their consequences. Some of the largest impacts are likely to arise from changes in extreme events, for example heatwaves and floods. This article estimates future regional heat extreme changes consistent with specific global warming targets, using a new and presently unique ensemble of physically plausible climate simulations. We find that a subset of ensemble members giving globally averaged temperature increases of 2.0 +/- 0.5 degrees C shows a wide range of changes in regional temperature extremes. For example, changes in extreme single-day hot events range between 2 and 6 degrees C for large parts of Europe, North America and Asia for this target. Plausible variations in the model representation of forest roughness length, vegetation root depth and boundary layer cloud make the largest individual contributions to the spread of changes found in different parts of the world. However, a wide range of processes contribute to the uncertainties in the regional changes, particularly through their direct or indirect influences on the simulation of soil moisture. Citation: Clark, R. T., J. M. Murphy, and S. J. Brown (2010), Do global warming targets limit heatwave risk?, Geophys. Res. Lett., 37, L17703, doi: 10.1029/2010GL043898.