system
Given the following post, respond as if you're commenting on Reddit:
human
What would happen if sea levels DROPPED?

We always hear about the social/economic/environmental problems and side effects of worldwide rising sea levels, but out of curiosity, what would one expect if the opposite was true? How would things change if sea level dropped, say, 10-20 metres. More, if that's more interesting.

Thanks in advance!

Edit: thanks everyone for the thought out and informative comments, dnd setting inbound ;)
gpt
Well ... it happened before, of course, and within the previous few hundred thousand years no less ... litterally within human memory, during the last ice age. The Lascaux paintings are documentary evidence from that time period.

Just as global warming leads to rising sea levels as the ice caps melt, global cooling is the mechanism linked to sea level decrease and growing icesheets.

When the last glaciation was at its height the area between Alaska and Kamtchatska was above sea level, and formed a landmass known as Beringia. Sea level went down 100 meters relative to the present. The ancestors of American Indians and Inuit crossed that land bridge on foot, as did a lot of wildlife that went either East or West. The shores of southern Spain and France were covered by subarctic tundra-like vegetation, and the icesheet reached all the way down to Central Park and Wisconsin.

And the effects of a climatic regime where such a sea level decrease would occur would be those of going back to a global ice age ... much of currently inhabited Europe, Asia and North America would become uninhabitable, as 2-3 kilometer thick icesheets came thundering towards the equator (geologically speaking). Areas amenable to agriculture would shrink due to a shortened growing season. Inhabitable areas would migrate closer to the equator, and shrink. Economies would collapse, massive socio-economic disruptions, extinctions, possibly our own, would occur ... yadda yadda yadda, as they say... it would be apocalyptic.