Regional impacts of climate stabilisation across multiple global warming levels

The 2015 Paris Agreement adopted by 192 parties states the goal of limiting global warming to well below 2, preferably 1.5 degrees Celsius above pre-industrial levels. These goals imply an ambition to stay at or below these levels long-term. Evidence is beginning to emerge that regional patterns of change at given global warming levels (GWLs) can be very different between transiently warming through given GWLs and stabilising at those same GWLs.

In this presentation, we explore regional climate change across multiple variables, with a particular focus on regional precipitation change. Using a novel ensemble of six 500-years long fixed concentration simulations across various levels of warming between 1.5 and 5 degrees above pre-industrial with the CMIP6-generation Earth System Model UKESM1.0, we show that precipitation trends opposite in sign to transient climate change projections occur in several regions at the same GWLs. Such differences have important implications for climate change risk assessments and adaptation discussions, which typically only include transient projections. Here, we provide examples where a transient and stabilised climate differ and discuss the possible mechanisms driving these differences.