Yes, it is increasingly unlikely that we will stabilize at 450 ppm atmospheric concentrations of carbon dioxide, and then quickly come back to 350. But when reporters ask me if it’s “too late,” — or, as one did last week, “have we crossed a tipping point?” — I have to explain that the question doesn’t have a purely scientific answer.
For if humanity gets truly serious about emissions reduction — and by serious I mean “World War II serious” in both scale and urgency — we could go to near zero global emissions in, say, 2 decades and then quickly go carbon negative. It wouldn’t be easy, far from it (see “How the world can stabilize at 350 to 450 ppm: The full global warming solution“).
Well, kudos to the reporter that knew to ask about a tipping point. The response this cynical blog would have preferred Professor Joe give is to ask, “To which tipping point do you refer?”