Because apparently today I feel like a deontologist

The hardest thing about climate change is this: your lifestyle doesn't matter. Even if you personally eliminate animal products from your diet, use public transport exclusively, and use only electricity from renewable power plants (which you can't because of how the nationwide electric grid is set up), you wouldn't make even a fraction of a dent in greenhouse gas emissions. Your personal culpability for climate change is arbitrarily close to zero. And yes, if you convince a bunch of other people (and we're talking millions here, not dozens) to follow your lifestyle you'd begin to make a difference, but realistically speaking you're not going to do that. In fact, realistically speaking you're not even going to be able to make the lifestyle changes yourself, because you live in a system that requires you to participate in climate change in order to subsist. And so do the people you'd be trying to convince. And while we can hope, vote, and fight for the restructuring of the global economy required to slow climate change, it's hard to go about that, and that sort of agitation isn't really a lifestyle; you can continue to live more or less the same kind of life you did before while fighting for change. From a utilitarian standpoint, your lifestyle is irrelevant and your focus should be exclusively on political and direct action.

But, even so, you should alter your lifestyle. You should reduce the amount of animal products in your diet, or even eliminate them; you should use public transportation whenever possible; you should recycle and seek to reduce your waste as much as possible. Not because these things will make any tangible difference (they won't), but because our lives should reflect our values and ideals. Because doing those things remind you of the greater goal. Because you seek to live in the sort of world where everyone does acts as you do. It won't make a difference. It won't accomplish anything. But that's no reason not to do it.