Regional Estimates of the Transient Climate Response to Cumulative Carbon Emissions

English Abstract:

The Transient Climate Response to cumulative Emissions (TCRE) is a new metric that quantifies the response of the climate system to anthropogenic CO2 emissions. Defined as the ratio between the global mean temperature change and the amount of CO2 emitted into the atmosphere, the TCRE accounts for interactions between human activity, the climate and the Earth's carbon cycle dynamics.

It is now well known that the TCRE metric is fairly stable in time, that is, approximately independent of the emission pathway. While this has been widely shown in terms of the global mean surface air temperature from observational data as well as in results from state-of-the-art Earth System Models, this study shows that the TCRE stability hypothesis also applies locally in a broad diversity of regions. The largest source of uncertainty affecting the TCRE residing in the sensitivity of the climate-carbon system, we hence attribute a range of confidence to the TCRE spatial pattern based on an ensemble of twelve Earth System Models from the CMIP5 archive. Brought together, the global and regional estimates of the TCRE form a simple but powerful set of tools for synthesizing complex climate models output to non-expert users and hence nourish current discussions for mitigating greenhouse gases emissions.