A research team led by Prof. BI Haibo from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) has revealed that accelerated warming in the North Pacific has contributed to a significant slowdown in Arctic summer sea ice loss since 2007. Their findings were recently published in Communications Earth & Environment.

While global mean surface temperatures have surged, breaching the 1.5°C threshold set by the Paris Agreement in 2024, the September minimum extent of Arctic sea ice has not hit a new record low since 2012. Between 2007 and 2024, the trend in September sea ice area was nearly zero, marking a stark contrast to the steep decline observed from 1979 to 2006.

By combining observational data and numerical modeling, the researchers identified a key driver: the North Pacific Ocean. A pronounced warming trend in North Pacific sea surface temperatures (SSTs) has triggered an atmospheric Rossby wave train, a large-scale pattern of atmospheric waves, that propagates into the Arctic.

This wave train induces a negative phase of the summertime Arctic Dipole (AD), a climate pattern defined by specific pressure distributions over the Arctic. The resulting atmospheric circulation brings cooler air to the region, reduces downward longwave radiation, and alters surface wind patterns. These changes have boosted sea ice concentration in two critical areas: the central Arctic Ocean near 180°W and the Canadian Arctic Archipelago, with annual increases of 0.4% and 1.1%, respectively.

Though some regions, such as the Greenland Sea and the northern Laptev Sea, continue to see sea ice decline, the gains in the central Arctic and Canadian Arctic Archipelago have partially offset these losses. This regional variability explains why the overall retreat of Arctic sea ice has slowed.

To isolate the impact of North Pacific SST anomalies, the researchers further conducted climate model simulations. The results confirmed that warming in the Pacific alone can generate the same atmospheric wave patterns observed in the Arctic, leading to localized cooling and sea ice growth.

Prof. BI noted, "This slowdown is likely a temporary phenomenon, driven by the interaction between natural climate variability and human-induced warming." He added that the North Pacific warming itself is largely linked to greenhouse gas emissions, highlighting the complex interplay between anthropogenic forcing and natural climate cycles.

Current climate models, including those from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and Phase 6 (CMIP6), struggle to replicate the observed summer teleconnections between the Pacific and the Arctic. This suggests a need to improve these models to better predict near-term changes in sea ice.

"Understanding these processes is crucial for refining future projections of Arctic sea ice," Prof. BI added. "While the long-term decline is expected to continue, periods of stabilization remind us that natural variability can modulate—but not stop—the effects of climate change."

The study emphasizes the importance of integrating oceanic teleconnections into climate models to enhance predictions of Arctic sea ice loss.