Bering Strait Oceanic heat versus next year's Arctic sea ice

Please contact Rebecca Woodgate (woodgate@uw.edu) for use of any of this material

Abstract
Changing Arctic sea ice influences not just the Arctic and sub-Arctic, but arguably also lower latitudes, via disruption of weather patterns. Understanding the many drivers of sea-ice change is essential to predicting future sea ice. Oceanic heat entering the Arctic from the Pacific (which is all via the Bering Strait) is finally being recognized as one such important influence on Arctic sea ice, but prior studies have only focused on the same-year influence of this oceanic heat. Using total annual Bering Strait oceanic heat flux estimates from year-round in situ Bering Strait mooring measurements (1991 to 2024), we discovered a significant correlation (r = -0.58) between this annual heat flux and whole Arctic September (i.e., minimum) sea-ice extent in the following year. This correlation suggests the Bering Strait inflow has a significant lagged effect on Arctic sea ice, explaining about 1/3rd (r2) of the summer sea-ice variability. This correlation is widespread in the western Arctic, particularly the Russian shelf seas (regions important for Arctic shipping), where warm Pacific waters are usually found as a subsurface temperature maximum. As Pacific waters are near freezing when they leave the Arctic, most likely this lagged correlation arises from upward transfer of Pacific water heat thinning sea ice through winter, making it more vulnerable to melt-back the following spring. The regions of influence are consistent with plausible advection times for Pacific waters. Investigations showed that having Bering Strait oceanic heat information only until August (the duration compatible with annual mooring servicing in summer/fall) provides an equally good correlation, raising the intriguing possibility of an in situ observation-based prediction scheme for the following year's sea ice. These results highlight the importance of continued Bering Strait in situ measurements and the necessity of accurate simulation of Bering Strait fluxes in modeling studies of Arctic sea-ice change.

Figures
For details, see paper

Figure 1. Comparison of annual Bering Strait oceanic heat flux with whole-Arctic and regional sea-ice extents.

a) Arctic map showing the Bering Strait, the geographical regions of the Sea Ice Index (Fetterer et al., 2025) and the "polar hole" (dashed circle at 87.2degN) (Section 2.1.3), and (schematically) the Pacific Water inflow (blue arrows), with International Bathymetric Chart of the Arctic Ocean (IBCAO) v3 (Jakobsson et al., 2012) bathymetric contours every 1,000 m.

b) Time-series of whole-Arctic September sea-ice extent (thick black lines) and total annual Bering Strait oceanic heat flux (BS-OHF) per year (thin cyan line, with large dots) and (to illustrate the 1-year lagged correlation) advanced 1 year (thin dark-blue dashed line).

c) Summary table of all significant (p ≤ 0.05) correlations between BS-OHF (same year (0 yr) and 1 year prior (1 yr)) and the whole Arctic and regional sea-ice extents, with correlation values of magnitude greater than 0.5 in bold font. Dash in table indicates no significant correlation.
BS-OHF are the A3v4 product from the Bering Strait mooring project (for home page, see Data Accessibility section) and are calculated from Bering Strait A3 mooring temperature and velocity data (corrected for instrument depth and data drop-outs), relative to -1.9degC. Here, we have included an interannually constant addition of +1.55x10²⁰ J to account for extra heat due to the Alaskan Coastal Current (ACC) and stratification.

Figure 2: Mapped correlations of the Bering Strait heat flux and same year's monthly Arctic sea-ice concentrations.
For given month (panel), significant (p ≤ 0.05) correlations (see color bar) of that month's sea-ice concentration with the same year's total annual Bering Strait oceanic heat flux, showing also that month's minimum (purple solid line), maximum (pink dashed line) and mean (green dotted line) and sea-ice extent, defined as region with sea-ice concentrations greater than 15%. Dashed circle at 86.72degN indicates southern extent of data interpolated over the "Pole Hole" (Section 2.1.3). (Depth contours are every 1,000 m from IBCAO v3 (Jakobsson et al., 2012).)

Figure 3: Mapped correlations of the Bering Strait heat flux and following year's monthly Arctic sea-ice concentrations.
For given month (panel), significant (p ≤ 0.05) correlations (see color bar) of that month's sea-ice concentration with the previous year's total annual Bering Strait oceanic heat flux, showing also that month's minimum (purple solid line), maximum (pink dashed line) and mean (green dotted line) and sea-ice extent, defined as region with sea-ice concentrations greater than 15%. Dashed circle at 86.72degN indicates southern extent of data interpolated over the "Pole Hole" (Section 2.1.3). (Depth contours re every 1,000 m from IBCAO v3 (Jakobsson et al., 2012).)

Figure 4. Time-series of annual and part-year Bering Strait oceanic heat fluxes (without stratification/Alaskan Coastal Current contributions).
Time-series of (black solid line with dots) the total annual Bering Strait oceanic heat flux (HF) and the part-year heat fluxes, i.e., those summed from January through June (yellow solid line), January through July (orange dotted line) and January through August (red dash-dot line). Correlations of these part-year fluxes (Cum HF) to the total annual heat flux are given top left of figure and are all significant at the (p ≤ 0.05) level. All the heat fluxes in this figure neglect the combined contribution from stratification and the Alaskan Coastal Current (ACC) (as the data do not currently exist to compute the seasonal variability of those contributions for the whole timeseries) and thus the total annual means here differ from those in Figure 1b by the estimated (constant) annual contribution from stratification and the Alaskan Coastal Current, set at 1.55x10²⁰ J for Figure 1b.

Figure 5: Comparison of correlations of heat to following year's sea-ice concentrations for annual versus year-to-August fluxes.

a) Focusing on the areas of greatest Bering Strait influence, August, September and October (panels), significant (p ≤ 0.05) correlations (see color bar) of that month's sea-ice concentration with the previous year's total annual Bering Strait oceanic heat flux, showing also that month's minimum (purple solid line), maximum (pink dashed line) and mean (green dotted line) and sea-ice extent, defined as region with sea-ice concentrations greater than 15%. Dashed circle at 86.72degN indicates southern extent of data interpolated over the "Pole Hole" (Section 2.1.3). (Depth contours are every 1,000 m from IBCAO v3 (Jakobsson et al., 2012).)

b) as per Figure 5a, but correlating the following year's monthly sea-ice concentrations with the Bering Strait heat flux summed only till August (i.e., the quantity that could be calculated following a September mooring turnaround).

Copyright: Polar Science Center, University of Washington, 2026

We gratefully acknowledge financial support for this work from the National Science Foundation (NSF).

Back to Bering Strait Homepage
Back to High Latitude Dynamics Homepage

	Figure 1. Comparison of annual Bering Strait oceanic heat flux with whole-Arctic and regional sea-ice extents. a) Arctic map showing the Bering Strait, the geographical regions of the Sea Ice Index (Fetterer et al., 2025) and the "polar hole" (dashed circle at 87.2degN) (Section 2.1.3), and (schematically) the Pacific Water inflow (blue arrows), with International Bathymetric Chart of the Arctic Ocean (IBCAO) v3 (Jakobsson et al., 2012) bathymetric contours every 1,000 m. b) Time-series of whole-Arctic September sea-ice extent (thick black lines) and total annual Bering Strait oceanic heat flux (BS-OHF) per year (thin cyan line, with large dots) and (to illustrate the 1-year lagged correlation) advanced 1 year (thin dark-blue dashed line). c) Summary table of all significant (p ≤ 0.05) correlations between BS-OHF (same year (0 yr) and 1 year prior (1 yr)) and the whole Arctic and regional sea-ice extents, with correlation values of magnitude greater than 0.5 in bold font. Dash in table indicates no significant correlation. BS-OHF are the A3v4 product from the Bering Strait mooring project (for home page, see Data Accessibility section) and are calculated from Bering Strait A3 mooring temperature and velocity data (corrected for instrument depth and data drop-outs), relative to -1.9degC. Here, we have included an interannually constant addition of +1.55x10²⁰ J to account for extra heat due to the Alaskan Coastal Current (ACC) and stratification.
Figure 2: Mapped correlations of the Bering Strait heat flux and same year's monthly Arctic sea-ice concentrations. For given month (panel), significant (p ≤ 0.05) correlations (see color bar) of that month's sea-ice concentration with the same year's total annual Bering Strait oceanic heat flux, showing also that month's minimum (purple solid line), maximum (pink dashed line) and mean (green dotted line) and sea-ice extent, defined as region with sea-ice concentrations greater than 15%. Dashed circle at 86.72degN indicates southern extent of data interpolated over the "Pole Hole" (Section 2.1.3). (Depth contours are every 1,000 m from IBCAO v3 (Jakobsson et al., 2012).)	Figure 3: Mapped correlations of the Bering Strait heat flux and following year's monthly Arctic sea-ice concentrations. For given month (panel), significant (p ≤ 0.05) correlations (see color bar) of that month's sea-ice concentration with the previous year's total annual Bering Strait oceanic heat flux, showing also that month's minimum (purple solid line), maximum (pink dashed line) and mean (green dotted line) and sea-ice extent, defined as region with sea-ice concentrations greater than 15%. Dashed circle at 86.72degN indicates southern extent of data interpolated over the "Pole Hole" (Section 2.1.3). (Depth contours re every 1,000 m from IBCAO v3 (Jakobsson et al., 2012).)
Figure 4. Time-series of annual and part-year Bering Strait oceanic heat fluxes (without stratification/Alaskan Coastal Current contributions). Time-series of (black solid line with dots) the total annual Bering Strait oceanic heat flux (HF) and the part-year heat fluxes, i.e., those summed from January through June (yellow solid line), January through July (orange dotted line) and January through August (red dash-dot line). Correlations of these part-year fluxes (Cum HF) to the total annual heat flux are given top left of figure and are all significant at the (p ≤ 0.05) level. All the heat fluxes in this figure neglect the combined contribution from stratification and the Alaskan Coastal Current (ACC) (as the data do not currently exist to compute the seasonal variability of those contributions for the whole timeseries) and thus the total annual means here differ from those in Figure 1b by the estimated (constant) annual contribution from stratification and the Alaskan Coastal Current, set at 1.55x10²⁰ J for Figure 1b.	Figure 5: Comparison of correlations of heat to following year's sea-ice concentrations for annual versus year-to-August fluxes. a) Focusing on the areas of greatest Bering Strait influence, August, September and October (panels), significant (p ≤ 0.05) correlations (see color bar) of that month's sea-ice concentration with the previous year's total annual Bering Strait oceanic heat flux, showing also that month's minimum (purple solid line), maximum (pink dashed line) and mean (green dotted line) and sea-ice extent, defined as region with sea-ice concentrations greater than 15%. Dashed circle at 86.72degN indicates southern extent of data interpolated over the "Pole Hole" (Section 2.1.3). (Depth contours are every 1,000 m from IBCAO v3 (Jakobsson et al., 2012).) b) as per Figure 5a, but correlating the following year's monthly sea-ice concentrations with the Bering Strait heat flux summed only till August (i.e., the quantity that could be calculated following a September mooring turnaround).

In situ data suggest one third of summer/fall Arctic sea-ice variability is related to the prior year's Bering Strait oceanic heat flux