Varying contributions of greenhouse gases, aerosols and natural forcings to Arctic land surface air temperature changes

The Arctic has warmed rapidly over the past century, with widespread negative impacts on local and surrounding environments. Previous studies have estimated the overall effects of individual groups of anthropogenic forcing agents on Arctic warming. However, the spatial patterns and temporal variabilities of the separate contributions of greenhouse gases (GHGs), natural forcing agents (NATs; solar radiation and volcanic activity combined) and other anthropogenic (OANT) forcing agents (which are dominated by aerosols) on Arctic land surface air temperatures remain underexamined. Here, we use CMIP6 (the Sixth Phase of the Coupled Model Intercomparison Project) models to quantify the separate contributions of GHGs, NATs and OANT forcing agents to Arctic land surface air temperature changes and analyze their spatial and temporal change patterns from 1915 to 2014. The results show that GHGs alone have warmed the Arctic by 2.72 degrees C/century (90% confidence interval: 1.42 degrees C-4.03 degrees C), 61.8% of which has been offset by OANT agents. The GHG-induced warming peaks are found in Ellesmere Island, Severnaya Zemlya and Svalbard (above 4 degrees C/century), while the largest cooling effects (above -2 degrees C/century) induced by OANT agents occurred in Krasnoyarsk Krai and Severnaya Zemlya. A further temporal evolution analysis indicates that the effects of GHGs and OANT forcings have been gradually and robustly detected over time; this increases our confidence in projecting future Arctic climate changes via CMIP6 models.