ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 35, JANUARY 2018, 75–84 • Original Paper • Recent Increased Warming of the Alaskan Marine Arctic Due to Midlatitude Linkages James E. OVERLAND ∗1 , Muyin WANG 1,2 , and Thomas J. BALLINGER 3 1 NOAA/Pacific Marine Environmental Laboratory, Seattle WA 98115, USA 2 Joint Institute for the Study of Atmosphere and Oceans/University of Washington, Seattle WA 98115, USA 3 Department of Geography, Texas State University, San Marcos TX 78666, USA (Received 29 January 2017; revised 15 July 2017; accepted 3 August 2017) ABSTRACT Alaskan Arctic waters have participated in hemispheric-wide Arctic warming over the last two decades at over two times the rate of global warming. During 2008–13, this relative warming occurred only north of the Bering Strait and the atmospheric Arctic front that forms a north–south thermal barrier. This front separates the southeastern Bering Sea temperatures from Arctic air masses. Model projections show that future temperatures in the Chukchi and Beaufort seas continue to warm at a rate greater than the global rate, reaching a change of +4 ◦ C by 2040 relative to the 1981–2010 mean. Offshore at 74 ◦ N, climate models project the open water duration season to increase from a current average of three months to five months by 2040. These rates are occasionally enhanced by midlatitude connections. Beginning in August 2014, additional Arctic warming was initiated due to increased SST anomalies in the North Pacific and associated shifts to southerly winds over Alaska, especially in winter 2015–16. While global warming and equatorial teleconnections are implicated in North Pacific SSTs, the ending of the 2014–16 North Pacific warm event demonstrates the importance of internal, chaotic atmospheric natural variability on weather conditions in any given year. Impacts from global warming on Alaskan Arctic temperature increases and sea-ice and snow loss, with occasional North Pacific support, are projected to continue to propagate through the marine ecosystem in the foreseeable future. The ecological and societal consequences of such changes show a radical departure from the current Arctic environment. Key words: Alaska, North Pacific, Arctic, warm advection, polar vortex Citation: Overland, J. E., M. Wang, and T. J. Ballinger, 2018: Recent increased warming of the Alaskan marine Arctic due to midlatitude linkages. Adv. Atmos. Sci., 35(1), 75–84, https://doi.org/10.1007/s00376-017-7026-1. 1. Introduction This paper provides an update on the major climate changes in the marine Alaskan Arctic over the past decade (Wood et al., 2013; Ballinger and Sheridan, 2014; Overland et al., 2014a; Cassano et al., 2015). At the decadal/regional scale of climate change, Fig. 1 shows the 13-month running mean surface air temperature (SAT) anomalies for Barrow, Alaska (red), and areal averages for the Northern Hemisphere land area (blue), relative to a baseline period of 1981–2010. Temperature anomalies at Barrow are predominantly positive since 2003, and in winter 2015–16 are roughly four times the magnitude of the Northern Hemisphere mean temperature in- crease. Alaskan Arctic waters participate in the hemispheric- wide warming of the Arctic over the last two decades. Addi- tional warming of Alaskan Arctic coastal waters from autumn 2014 through autumn 2016 can be attributed to the shift to warm ocean temperature anomalies in the North Pacific and ∗ Corresponding author: James E. OVERLAND Email: james.e.overland@noaa.gov associated shifts to southerly winds over Alaska. Such North Pacific contributions subside after autumn 2016, but green- house gas (GHG) and regional Arctic feedback contributions remain. Arctic air and ocean surface temperature increases coin- cide with the expansion of sea-ice-free areas, increases in the mobility of sea ice, shifts in ocean currents, and biological impacts at all trophic levels from primary productivity in- creases through loss of walrus habitat Wassmann (2015). In the following sections, we track atmospheric changes in the Alaskan Arctic, compare them relative to the Bering Sea, as- sess future climate projections, and address Alaskan Arctic temperature increases since August 2014 due to warming in the North Pacific. 2. Regional climate of the maritime Alaskan Arctic The Pacific Arctic discussed here is defined as regions north of 66 ◦ N, which covers the area north of the Bering © Institute of Atmospheric Physics/Chinese Academy of Sciences, and Science Press and Springer-Verlag GmbH Germany 2018