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The Arctic Ocean has experienced significant sea ice loss over recent decades, shifting towards a thinner and more mobile seasonal ice regime. However, the impacts of these transformations on the upper ocean dynamics of the biologically productive Pacific Arctic continental shelves remain underexplored. Here, we quantified the summer upper mixed layer depth and analyzed its interannual to decadal evolution with sea ice and atmospheric forcing, using hydrographic observations and model reanalysis from 1996 to 2021. Before 2006, a shoaling summer mixed layer was associated with sea ice loss and surface warming. After 2007, however, the upper mixed layer reversed to a generally deepening trend due to markedly lengthened open water duration, enhanced wind-induced mixing, and reduced ice meltwater input. Our findings reveal a shift in the primary drivers of upper ocean dynamics, with surface buoyancy flux dominant initially, followed by a shift to wind forcing despite continued sea ice decline. These changes in upper ocean structure and forcing mechanisms may have substantial implications for the marine ecosystem, potentially contributing to unusual fall phytoplankton blooms and intensified ocean acidification observed in the past decade
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CLIMATE CHANGE AT HIGH LATITUDES: AN ILLUMINATING EXAMPLE
A striking example is presented of a newly observed phenomenon in the ice‐covered Arctic Ocean that appears to be a consequence of changes in the physical forcing. In summer 2011, a massive phytoplankton bloom was observed north of the Bering Strait, between Russia and the United States, underneath pack ice that was a meter thick—in conditions previously thought to be inconducive for harboring such blooms. It is demonstrated that the changing ice cover, in concert with the resulting heat exchange between the atmosphere and ocean, likely led to this paradigm shift at the base of the food chain by altering the supply of nutrients and sunlight. Such early‐season under‐ice blooms have the potential to profoundly alter the Arctic food web.
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- Award ID(s):
- 1733564
- PAR ID:
- 10582719
- Publisher / Repository:
- DOI PREFIX: 10.16995
- Date Published:
- Journal Name:
- Zygon: Journal of Religion and Science
- Volume:
- 53
- Issue:
- 2
- ISSN:
- 1467-9744
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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