In the strictest sense, no. But one difference, which might matter to some people, is that "ending it now" seems to imply actively killing people. Most people, I believe, would see that as inherently different from simply dying due to whatever interaction(s) happen with the natural environment around us.

All of that said, I'm not arguing against pursuing actions to protect the environment. Just pointing out that "preventing the extermination of the human race" really isn't a terribly good justification for doing so when you look at the big picture.

If you accept that premise, the question then becomes: "what are the good arguments for pursuing actions to protect the environment / reverse climate change?" That is, what arguments will persuade people to care about protecting the environment for future generations that don't exist yet, in a time beyond their own limited lifespan?