Abstract/Summary

Following the Paris Agreement, there have been hundreds of studies researching the impacts of 1.5 °C and 2 °C of global warming above pre-industrial levels. Multiple methods have been developed to address the question of how regional climate change and impacts differ between global warming levels (GWLs), including pattern scaling1,2, time-slicing of existing climate projections3, single coupled-model experiments4 and multi-model atmosphere-only experiments5. The problem is that, while the Paris Agreement is not explicit, the intention is that global temperatures will be stabilized well below the 2 °C or, preferably, the 1.5 °C, GWL and will not continue to increase6, but the methods described above are based on transient projections in one form or another (Table 1) that do not reflect stabilized climates. This issue has come to the fore with the use of a time-sampling approach in transient simulations generating GWL-based climate projections in the Sixth Assessment Report of Working Group 1 (AR6 WG1) of the IPCC.