Rapid Sea Level Rise Quantified And Dated

We know that following the last glacial maximum, there was a rapid rise in sea level. But, when did it happen and how fast did it take place. A new study published in the journal Nature (abstract reproduced here), tightens these estimates:

[T]he last deglaciation was punctuated by a dramatic period of sea-level rise, of about 20 metres, in less than 500 years. . . . Here we show that MWP-1A [meltwater pulse 1A] started no earlier than 14,650 years ago and ended before 14,310 years ago, making it coeval with the Bølling warming. Our results, based on corals drilled offshore from Tahiti . . . reveal that the increase in sea level at Tahiti was between 12 and 22 metres, with a most probable value between 14 and 18 metres, establishing a significant meltwater contribution from the Southern Hemisphere.

Thus, there was about 16 meters of seawater level surge in the South Pacific Ocean in less than 340 years. Pinning down this surge in sea levels allows for more accurate timing of key events in modern human dispersals outside Africa, such as a firmer estimate of when the Bering land bridge between Asia and North America closed, and when Indonesia was broken into an island chain after being, up to the point of the Wallace line, a mere pennisular extension of the mainland.

Since we know just how rapidly this happened, we can also get some sense of how traumatic or non-traumatic those events would have seen to people experiencing them (Tahiti, of course, where the data were collected, would have been uninhabited by any kind of hominin at the time).

We know that the sea level was lowest at around the Last Glacial Maximum (ca. 20,000 years ago), but it turns out that most of the post-LGM rise in sea levels was deferred for more than 5,000 years.

The sea level surge date should roughly correspond to Epipaleolithic events, i.e. those prior to the Neolithic Revolution but after the glaciers of the Last Glacial Maximum had retreated, such as the repopulation of Europe from Southern European refugia.

This data also allows for a better pin pointing of when in time (we already knew where geographically and at what ocean depth to look) we should see mass abandonment of coastal settlements from the LGM era of low sea levels, whose remains it should be possible to locate with marine archaeology. Since these ruins would be pre-Neolithic, however, their traces could be quite subtle after tens of thousands of years of being encased beneath the waves.