It's not to prevent it, or to mitigate its damages, it's for the people who disproportionately caused it, and have already benefitted from it, to finalize their control over the resources they want. Some of those resources are some of us.
Humans are not that good at planning longer than 6 months to 5 years out. The brain is legacy hardware, optimized for the Pleistocene epoch. Reward circuitry (Striatum) often overpowers logical simulation (Cortex).
A lot of Trump's seemingly odd obsessions like taking over Greenland and Canada are less odd (but still very unsettling) when you accept that the global power elite have already accepted that run-away climate change is inevitable and the only open questions are who is going to profit from it and how.
The US has Alaska, but if it wants more newly arable land in the future, the only options seem to be Greenland and Canada, the two places which Trump just so happens to be obsessed with annexing.