Arctic Winter Temperature Variations Correlated With ENSO Are Dependent on Coincidental Sea Ice Changes.

The El Niño Southern Oscillation (ENSO) is a well‐known modulator of global climate and is correlated with observed temperature variations over the Barents‐Kara Sea (BKS). However, the origins and causality of this observed correlation are unclear. Here, we show that historical climate model simulations, on average, fail to reproduce the observed ENSO‐BKS correlation. However, individual realizations do show a relationship as observed. We find that the internal variability of BKS sea ice is the main factor between realizations that reproduce the ENSO‐BKS correlation and those that do not. Furthermore, we find that atmospheric model simulations prescribed with observed sea ice variability reproduce the ENSO‐BKS correlation. We conclude that ENSO‐correlated winter BKS temperature variations are dependent on coincidental sea ice changes. Plain Language Summary: Naturally occurring changes in the tropical Pacific Ocean, for example, the El Niño Southern Oscillation or ENSO, are known to affect weather and climate all across the planet. The influence of ENSO on Europe and North America is relatively well known but if and how ENSO affects Arctic weather and climate is less clear. In this study, we identify a correlation between ENSO and winter temperatures in the Arctic focusing specifically on the Barents and Kara Seas. We then examine a large collection of climate model experiments to see if they reproduce the observed correlation. We find that models, on average, do not. However, a small selection of the model experiments do show a correlation as large or larger than observed. The experiments that do reproduce the observed correlation are those that, by chance, have sea ice variations similar to observed; or are experiments in which sea ice is constrained to perfectly match observations. We conclude that Barents and Kara Sea winter temperature variations are primarily governed by local sea ice changes, which by coincidence, may on occasion correlate with ENSO. Key Points: Observed near‐surface air temperature variations over the Barents‐Kara Sea (BKS) are correlated with El Nino Southern Oscillation (ENSO)Models can reproduce the ENSO‐BKS correlation, but only in realizations that have similar or identical sea ice variations as observedSea ice variations are the proximal cause of ENSO‐correlated BKS temperature changes and may be a manifestation of internal variability [ABSTRACT FROM AUTHOR]