My "Plants and the Human Environment" class has basically just been talking about global warming the entire time, which makes me realize that I don't really care about the long-term impacts of global warming. It's definitely happening, and we definitely caused it, but it would be difficult to reverse the effects without getting the participation of everyone on the planet. And that's basically impossible, so it's more practical to deal with the effects of climate change than try to prevent it.
Thinking that global warming is something you have to try and fight makes the assumption that climate change is inherently bad, that we're all being punished for our lifestyle choices. It's a very scientific martyr complex, the atheist version of "God sent Hurricane Katrina because of the gays." I can't really assign moral value to climate change. To me it's just something that happens, and it doesn't really matter what caused it, because we can't really stop it.
If the climate changes, and sea levels rise, the human population will become less sustainable. But this was going to happen eventually anyway. Ecosystems, in fact, all physical systems balance out in the long run. The choice we're faced with right now is whether to try and save up our potential resources and keep spreading the human race over as much of Earth as possible until everything's completely rationed and everyone lives in tiny little boxes, because that's the way things are going to become sometime in the next thousand years if we don't start going to other planets. A continually expanding population like ours isn't sustainable forever anyway, so why should we worry about making that happen later when it's so much easier to force ourselves to confront the consequences of that fact sooner? Humanity is never, never, ever going to be able to plan long-term. It's just not the way our brains work.
There's an impending extinction event, but it's a kind of extinction event that hasn't happened before. I don't worry about the morality of extinction, because that happens all the time and clinging onto species diversity is something people do because they can't deal with death.