Impacts of natural and anthropogenic forcings on historical and future changes in global-land surface air temperature in CMIP6–DAMIP simulations

In this study, the impacts of natural and anthropogenic forcings on historical changes and future projections in global-land surface air temperature (GLSAT) are investigated using climate model simulations from the Detection and Attribution Model Intercomparison Project (DAMIP) in the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The results show that the increase in GLSAT can be largely attributed to human activities. The effect of anthropogenic forcing (ANT) can be robustly detected and separated from the response to the natural external forcing (NAT) since about 1970–1990s. Well-mixed greenhouse gases is the primary contributor to anthropogenic climate warming. ANT contributes a robust warming trend of 0.1–0.2 °C per decade for global landmass during 1951–2020, along with a stronger warming in 2011–2020 (relative to 1901–1930) of 1.0–1.6 °C. These attributable warming largely encompass the observed warming trend of ~0.18 °C per decade in 1951–2012 and the observed warming of 1.59 °C in 2011–2020 (relative to 1850–1900) for global landmass reported in IPCC AR5 and AR6, respectively. The observed warming changes since 1951 or recent decade are primarily attributed to the GHG-forcing. The anthropogenic warming is projected to increase by 3–6 °C for most of global landmass under the SSP2-4.5 scenario, especially in the high latitudes of the Northern Hemisphere by the late of 21st century, along with an increase in the mean and widespread flattening of the probability distribution functions (PDFs) of temperature anomalies. In contrast a cooling effect of ~0.7°C in 2011–2020, the anthropogenic aerosols (AA) forcing is projected to cool the global land by around 0.6°C by the late of the 21st century.