Abstract The Pacific inflow to the Arctic traditionally brings heat in summer, melting sea ice; dense waters in winter, refreshing the Arctic’s cold halocline; and nutrients year‐round, supporting Arctic ecosystems. Bering Strait moorings from 1990 to 2019 find increasing (0.010 ± 0.006 Sv/yr) northward flow, reducing Chukchi residence times by ∼1.5 months over this period (record maximum/minimum ∼7.5 and ∼4.5 months). Annual mean temperatures warm significantly (0.05 ± 0.02°C/yr), with faster change (∼0.1°C/yr) in warming (June/July) and cooling (October/November) months, which are now 2°C to 4°C above climatology. Warm (≥0°C) water duration increased from 5.5 months (the 1990s) to over 7 months (2017), mostly due to earlier warming (1.3 ± 0.7 days/yr). Dramatic winter‐only (January–March) freshening (0.03 psu/yr) makes winter waters fresher than summer waters. The resultant winter density change, too large to be compensated by Chukchi sea‐ice processes, shoals the Pacific Winter Water (PWW) equilibrium depth in the Arctic from 100–150 to 50–100 m, implying PWW no longer ventilates the Arctic’s cold halocline at 33.1 psu.
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Arctic open-water periods are projected to lengthen dramatically by 2100
Abstract The shrinking of Arctic-wide September sea ice extent is often cited as an indicator of modern climate change; however, the timing of seasonal sea ice retreat/advance and the length of the open-water period are often more relevant to stakeholders working at regional and local scales. Here we highlight changes in regional open-water periods at multiple warming thresholds. We show that, in the latest generation of models from the Coupled Model Intercomparison Project (CMIP6), the open-water period lengthens by 63 days on average with 2 °C of global warming above the 1850-1900 average, and by over 90 days in several Arctic seas. Nearly the entire Arctic, including the Transpolar Sea Route, has at least 3 months of open water per year with 3.5 °C warming, and at least 6 months with 5 °C warming. Model bias compared to satellite data suggests that even such dramatic projections may be conservative.
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- Award ID(s):
- 1847398
- PAR ID:
- 10234889
- Date Published:
- Journal Name:
- Communications Earth & Environment
- Volume:
- 2
- Issue:
- 1
- ISSN:
- 2662-4435
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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