Inferring future warming in the Arctic from the observed global warming trend and CMIP6 simulations

The emergent constraint approach is a way of using multi-model ensembles to identify the linkage between current/past climate variability and future climate changes, which has been widely used for narrowing down the uncertainty of multi-model projections of future climate change. Climate models of the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) show a much stronger Arctic warming signal but with a larger inter-model spread. In this study, we find that the projected Arctic warming made by multi-models in CMIP6 is positively correlated with the simulated global warming trend during the period of 1981–2011 in historical runs. This enables us to tighter constraints to future warming in the Arctic by using the observed global warming during the instrument era. The fact that CMIP6 models tend to overestimate the trend of global mean surface temperature during 1981–2011, therefore, would imply a relative weak Arctic warming compared to the CMIP6 median warming projection.