https://www.pnas.org/doi/epdf/10.1073/pnas.2206742119
The Bering Strait was flooded 10,000 years before
the Last Glacial Maximum
Significance
The Bering Strait was a land bridge during the peak of
the last ice age (the Last Glacial Maximum, LGM), when
sea level was ~130 m lower than today. This study
reconstructs the history of sea level at the Bering
Strait by tracing the influence of Pacific waters in
the Arctic Ocean. We find that the Bering Strait was
open from at least 46,000 until 35,700 y ago, thus
dating the last formation of the land bridge to within
10,000 y of the LGM. This history requires that ice
volume increased rapidly into the LGM. In addition, it
appears that humans migrated to the Americas as soon as
the formation of the land bridge allowed for their passage.
Abstract
The cyclic growth and decay of continental ice sheets
can be reconstructed from the history of global sea level.
Sea level is relatively well constrained for the Last
Glacial Maximum (LGM, 26,500 to 19,000 y ago, 26.5 to
19 ka) and the ensuing deglaciation. However, sea-level
estimates for the period of ice-sheet growth before the
LGM vary by > 60 m, an uncertainty comparable to the
sea-level equivalent of the contemporary Antarctic Ice
Sheet. Here, we constrain sea level prior to the LGM by
reconstructing the flooding history of the shallow Bering
Strait since 46 ka. Using a geochemical proxy of Pacific
nutrient input to the Arctic Ocean, we find that the
Bering Strait was flooded from the beginning of our
records at 46 ka until 35.7+3.3−2.4 ka. To match this
flooding history, our sea-level model requires an ice
history in which over 50% of the LGM’s global peak ice
volume grew after 46 ka. This finding implies that global
ice volume and climate were not linearly coupled during
the last ice age, with implications for the controls on
each. Moreover, our results shorten the time window
between the opening of the Bering Land Bridge and the
arrival of humans in the Americas.
--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)