First, we do not live separate from our environment, we have a symbiotic relationship with it. So trying to untangle that to evade blame or responsibility seems a little daft. If I breathe, I am effecting the environment. If a meteor hits the earth, it is effecting the environment. Your need to eat to survive impacts the environment. Beaver dams impact the environment. I think the more logical debate should be between how much of our environmental impact is necessary and how much is gratuitous. Unlike trees and beavers and meteors, humans have quite a bit of free will and the ability to comprehend the long term impact of their actions. And with our unique powers come unique responsibilities.
Moreover, regardless how much of climate change is attributed to causes besides human behavior, I don't see how that absolves us of our need to use and impact our environment in a sustainable manner. Pollution and deforestation have very measurable negative impacts on life on earth aside from their relation to global climate change. And surely access to clean air and drinkable water are basic human rights, even if you don't think polar bears have basic rights.
I believe climate change is an observable reality, and that it can be catastrophic for at least some species, species who don't have a say in what we do, and I feel a personal obligation to prevent animal and plant species from unnecessary suffering and permanent extinction when possible.
Whether it is for precautionary or reactionary reasons, maintaining a healthy planet is important. I might die as a result of being hit by a bus, but I should still probably stop smoking. You know. Just in case. Come, my friends, 'Tis not too late to seek a newer world.
Not to mention the well worn but nonetheless true argument that given the huge percentage of medicines, not to mention other useful compounds, that come from botanical sources, it is simple insanity to burn down the rainforest without even cataloging its contents. It is burning a library unread.
