Pacific Warming Pattern Discrepancy Linked to Spurious Rainband in Climate Models | CU Experts

Abstract; The distinctive pattern of observed Pacific surface temperature trends, with cooling in the east and intensified warming in the west, departs from the more uniform warming anticipated by climate models. The apparent inability of climate models to simulate this warming pattern limits our ability to understand why it is occurring and to predict its wide‐ranging impacts. Here we demonstrate a link between climate models' Pacific warming pattern discrepancy and their simulation of a spurious Inter‐Tropical Convergence Zone (ITCZ) rainband south of the equator—commonly referred to as the “double‐ITCZ bias.” Models with reduced double‐ITCZ bias better simulate a key feedback pathway, leading to both stronger decadal variability and anthropogenically forced warming patterns more closely resembling observations. Our findings suggest that observed Pacific trends may contain a stronger forced component than previously recognized and that reducing the double‐ITCZ bias is critical for improving the reliability of climate projections.

VIVO