[otherme123]

There are some positive feedbacks that once triggered could not be reverted for millenia. For example a potential stop of the AMOC https://en.wikipedia.org/wiki/Atlantic_meridional_overturnin...

[holowoodman]

Melting glaciers and ice caps is another such thing. As soon as the polar albedo changes because there is no more snow and ice, temperatures will stay elevated for a far longer time than it took to melt those caps.