You decide. Personally, I think finding ways to expand our resources in a shrinking would should be encouraged as much as possible. Until we invent warp drive, we've only got one planet and, assuming we don't burn or dig it all up first, we might as well learn to make the most of it.
Here's another, less frightening way to do exactly that. Personally, this gives me more hope for the future than I've had for a while.