Nothing lasts forever, so it's absurd to think the climate will stay the same, also. We just happen to be existing in the time when it's changing noticeably. Luck (or not) of the draw.
Obviously, as Scrbblchick noted, we should take care of what we've got, but it's a lock-cinch that nothing lasts forever. You can take great care of something and have it last far beyond its expected expiration date, but eventually, everything expires, dies or whatever.
So one of these days, the earth is going to change irrevocably and we will just have to deal with it -- or die trying. Climate change is a given because change in general is a given.