Changing climate isn't an issue in itself, the problems occur when it goes too fast. Both humans and nature need time to adapt. If sea level rises as much as in the worst case scenarios it will be a big deal for a lot of our major cities along the coast lines. Poor countries will have problem to cope with increasing temperatures and the risk is that it sparks conflicts and increase migrant streams.
And there are other issues as well, what would for ex happen if everyone used as much oil as the average American? global population is going to peak at somewhere around 11 billion and if all of them is going to live a first World Life then we need 6-10 times more oil than today...