The planet will be fine. It's a rock. It's the inhabitants who will have a problem.
Which is completely true! Antarctica was even covered by rainforest at one point! It's just the rate of change that's the issue (by many many orders of magnitude).
I always refer those people to this XKCD: https://xkcd.com/1732/. It visualizes things very powerfully. Yet, I never get a response anymore after sending this to them.