Assessing the Role of Climate Sensitivity and Initial Conditions on AMOC and Surface Temperature Using the IGSM-CESM Framework

Abstract: This research provides insights into how climate sensitivity and initial conditions influence future projections of the Atlantic Meridional Overturning Circulation (AMOC), heat transport by the ocean, and surface temperature. 

Here, we employ a novel computational framework that links the emissions-driven Integrated Global System Model (IGSM)—a human–Earth system modeling framework—with the Community Earth System Model version 1 (CESM1), which has been enhanced to explore a wide range of plausible climate sensitivities. We use the IGSM-CESM1 framework to simulate a "Current Trends" (CT) scenario for 2081-2100, revealing that climate sensitivity affects long-term trends, while initial conditions influence short-term variability. 

Notably, higher climate sensitivity scenarios project greater future warming and more substantial weakening of the AMOC strength. A decline in AMOC strength under high climate sensitivity leads to a ~0.28 PW reduction in northward Atlantic OHT at ~40°N, underscoring its critical role in ocean heat transport.