Slow-down in summer warming over Greenland in the past decade linked to central Pacific El Niño

Greenland warming and ice loss have slowed down since the early 2010s, in contrast to the rest of the Arctic region. Both natural variability and anthropogenic forcing contribute to recent Greenland warming by reducing cloud cover and surface albedo, yet most climate models are unable to reasonably simulate the unforced natural variability. Here we show that a simplified atmospheric circulation model successfully simulates an atmospheric tele-connection from the tropics towards Greenland, which accounts for Greenland cooling through an intensified cyclonic circulation. Synthesis from observational analysis and model experiments indicate that over the last decade, more central Pacific El Niño events than canonical El Niño events have generated the atmospheric teleconnection by shifting the tropical rainfall zone poleward, which led to an intensified cyclonic circulation over Greenland. The intensified cyclonic circulation further extends into the Arctic Ocean in observations, whereas the model does not show a direct remote forcing from the tropics, implying the contribution of an indirect atmospheric forcing. We conclude that the frequent occurrence of central Pacific El Niño events has played a key role in the slow-down of Greenland warming and possibly Arctic sea-ice loss.

Shinji Matsumura, Koji Yamazaki, Kazuyoshi Suzuki