This scenario is pretty similar to the Azolla event:

https://en.wikipedia.org/wiki/Azolla_event

Where "event" in this case is something that happened over an 800 000 years interval.

> the resulting draw-down of carbon dioxide has been speculated to have helped reverse the planet from the "greenhouse Earth" state of the Paleocene-Eocene Thermal Maximum, when the planet was hot enough for turtles and palm trees to prosper at the poles, to the current icehouse Earth known as the Late Cenozoic Ice Age.

Time to buy a condo in the Greater McMurdo area?