We have converted most of the land to agriculture and released maybe trillions of tons of greenhouse gas in the atmosphere, there are 8 billions of us working on it. And what did we do? Increased the global temperature 2 degrees? Made the sea level rise a couple of meters?
It may be bad for us, but compared to terraforming a planet like Mars, that's nothing, and we have the entire humanity industrial complex to do it while on mars, we need to build everything, starting from a hostile environment.
The advancements required to arrive at modern LLMs and the tech needed to get humans safely to Mars or live safely on the Moon are orders of magnitude in difference.
Keeping humans alive is hard.
Of course you’ll probably have lots of side-effects.