The economic commitment of climate change

Global projections of macroeconomic climate-change damages typically consider impacts from average annual and national temperatures over long time horizons. Using recent empirical findings from more than 1,600 regions worldwide over the past 40 years, this study projects sub-national damages from temperature and precipitation, including daily variability and extremes. Employing an empirical approach that provides a robust lower bound on the persistence of impacts on economic growth, the authors find that the world economy is committed to an income reduction of 19% within the next 26 years independent of future emission choices (relative to a no-climate-impact baseline; likely range 11–29% accounting for physical climate and empirical uncertainty). These damages already outweigh the mitigation costs required to limit global warming to 2 °C by roughly sixfold over this near-term time frame and thereafter diverge strongly depending on emission choices. Committed damages arise predominantly through changes in average temperature, but accounting for temperature variability and multiple precipitation dimensions increases estimates by ~50% and yields stronger regional heterogeneity. Committed losses are projected for almost all regions except very high latitudes, where reductions in temperature variability bring benefits. The largest committed losses occur at lower latitudes in regions with lower cumulative historical emissions and lower present-day income.

Maximilian Kotz, Anders Levermann, Leonie Wenz