Anthropogenic Influence on Long-Term Surface Air Temperature Trends: Attribution of Temperature Changes Across East Asia

Abstract

Climate change is an ongoing process impacting ecosystem functions and human health; East Asia (EA) is one of the most vulnerable regions being influenced by such changes. This study examines the long-term variability of surface air temperatures (SATs) across EA using the new Coupled Model Intercomparison Project Phase 6 (CMIP6) datasets. Historical simulations (20th century) and future (21st century) SAT projections were investigated based on multi-model ensemble simulations. We also demonstrate the contribution of external and natural (NAT) forcings to SAT change. This study mainly focuses the effect of anthropogenic forcings (ANT) on EA climate for a long period (1850-2100). Our simulations show that SAT in EA increased by 0.031 °C/decade during the period 1850–2014 owing to combined ANT and NAT (‘ALL=ANT+NAT’) forcings, while an increase of 0.08 °C/decade can be attributed to greenhouse gas (GHG) emissions. The ANT forcing rapidly increased after the third industrial revolution (after 1969). Consequently, SAT change accelerated to 0.255 °C/decade and 0.268 °C/decade owing to ALL and GHG forcings, respectively. Human-induced GHG emissions and land use were the dominant factors driving SAT warming during the study period, and will contribute to substantial future warming trends. Furthermore, optimal fingerprinting method demonstrates the significance of ANT influences on climate change in EA. ANT forcing was clearly detected and distinct from NAT forcing in a two-signal analysis. In a three-signal analysis, GHG was clearly detected for EA region in separation from ANT and NAT influences. The shared socioeconomic pathway emission scenarios (SSP1–2.6, SSP2–4.5, and SSP5–8.5) showed future projections (warming trends) from 2015–2100. This analysis suggests that climate change could be mitigated by restricting anthropogenic factors (especially GHG) and land use/activities in EA.