Robust but weak winter atmospheric circulation response to future Arctic sea ice loss

• Main Authors: Smith, DM, Eade, R, Andrews, MB, Ayres, H, Clark, A, Chripko, S, Deser, C, Dunstone, NJ, García-Serrano, J, Gastineau, G, Graff, LS, Hardiman, SC, He, B, Hermanson, L, Jung, T, Knight, J, Levine, X, Magnusdottir, G, Manzini, E, Matei, D, Mori, M, Msadek, R, Ortega, P, Peings, Y, Scaife, AA, Screen, JA, Seabrook, M, Semmler, T, Sigmond, M, Streffing, J, Sun, L, Walsh, A
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: eScholarship, University of California 2022
• Subjects: Climate Action; Arctic; North Atlantic; North Atlantic oscillation; Sea ice
• Online Access: https://escholarship.org/uc/item/27d5j2z0

The possibility that Arctic sea ice loss weakens mid-latitude westerlies, promoting more severe cold winters, has sparked more than a decade of scientific debate, with apparent support from observations but inconclusive modelling evidence. Here we show that sixteen models contributing to the Polar Amplification Model Intercomparison Project simulate a weakening of mid-latitude westerlies in response to projected Arctic sea ice loss. We develop an emergent constraint based on eddy feedback, which is 1.2 to 3 times too weak in the models, suggesting that the real-world weakening lies towards the higher end of the model simulations. Still, the modelled response to Arctic sea ice loss is weak: the North Atlantic Oscillation response is similar in magnitude and offsets the projected response to increased greenhouse gases, but would only account for around 10% of variations in individual years. We further find that relationships between Arctic sea ice and atmospheric circulation have weakened recently in observations and are no longer inconsistent with those in models.