The relative contribution and physical drivers of internal variability in recent Arctic sea ice loss remain open questions, leaving up for debate whether global climate models used for climate projection lack sufficient sensitivity in the Arctic to climate forcing. Here, through analysis of large ensembles of fully coupled climate model simulations with historical radiative forcing, we present an important internal mechanism arising from low-frequency Arctic atmospheric variability in models that can cause substantial summer sea ice melting in addition to that due to anthropogenic forcing. This simulated internal variability shows a strong similarity to the observed Arctic atmospheric change in the past 37 years. Through a fingerprint pattern matching method, we estimate that this internal variability contributes to about 40-50% of observed multi-decadal decline in Arctic sea ice. Our study also suggests that global climate models may not actually underestimate sea ice sensitivities in the Arctic, but have trouble fully replicating an observed linkage between the Arctic and lower latitudes in recent decades. Further improvements in simulating the observed Arctic-global linkage are thus necessary before the Arctic's sensitivity to global warming in models can be quantified with confidence.
1.Univ Calif Santa Barbara, Dept Geog, Santa Barbara, CA 93106 USA 2.Univ Calif Santa Barbara, Earth Res Inst, Santa Barbara, CA 93106 USA 3.Univ Washington, Appl Phys Lab, Polar Sci Ctr, Seattle, WA 98105 USA 4.NOAA, Climate Predict Ctr, College Pk, MD USA 5.Univ Washington, Dept Earth & Space Sci, Seattle, WA 98195 USA 6.Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA 7.Princeton Univ, Cooperat Inst Climate Sci, Princeton, NJ 08544 USA 8.Lawrence Livermore Natl Lab, Livermore, CA USA 9.Geophys Fluid Dynam Lab, Princeton, NJ USA
Recommended Citation:
Ding, Qinghua,Schweiger, Axel,L',et al. Fingerprints of internal drivers of Arctic sea ice loss in observations and model simulations[J]. NATURE GEOSCIENCE,2019-01-01,12(1):28-+