Tropical Indo-western Pacific forcing expedites warming in the northern Canadian-Greenland Arctic

Since the beginning of modern satellite monitoring around 1980, near-surface and tropospheric temperatures in the northern Canadian-Greenland Arctic have substantially warmed, with magnitudes comparable to those in the pan-Arctic. However, the main causes of this marked regional warming and its magnitude in future projections remain debated because of large inter-model spread across historical and future periods. Here, using a hierarchy of pacemaker experiments in which regional sea surface temperature anomalies are nudged toward observations, we reveal that the tropical Indo-western Pacific (IOWP) forcing amplifies warming in northern Canada and Greenland through the IOWP-Arctic teleconnection. Anomalous tropical IOWP warming remotely triggers enhanced subsidence and reduced total cloud cover, increasing incoming shortwave radiation and, consequently, near-surface and tropospheric temperature warming. Further, by observationally constraining future projected warming magnitudes with recent tropical IOWP warming trends, the upper bounds (95th percentile values) of near-term (2026–2055 minus 1981–2010) warming magnitudes in the northern Canadian-Greenland Arctic and pan-Arctic decrease by ~19.8% and ~18.3%, respectively, under the high-emission scenario. Our results highlight the potential of the tropical IOWP warm pool to enable reliable Arctic warming projections.