On the linearity of local and regional temperature changes from 1.5°C to 2°C of global warming

It is challenging to quantify changes across a small increment of global warming, so a pattern-scaling approach may be considered. Here we investigate the validity of such an approach by comprehensively examining how well local temperatures and warming trends in a 1.5 degrees C world predict local temperatures at global warming of 2 degrees C. Ensembles of transient coupled climate simulations from multiple models under different scenarios were compared and individual model responses were analyzed.

For many places, the multimodel forced response of seasonal-average temperatures is approximately linear with global warming between 1.5 degrees and 2 degrees C. However, individual model results vary and large contributions from nonlinear changes in unforced variability or the forced response cannot be ruled out. In some regions, such as East Asia, models simulate substantially greater warming than is expected from linear scaling.