Guest comment by Malte Meinshausen, Reto Knutti and Dave Frame
Yesterday’s BBC article on the “Avoiding Dangerous Climate Change” report of the Exeter meeting last year, carried two messages that have left some a little confused. On the one hand, it said that a stabilization of greenhouse gases at 400-450 ppm CO2-equivalent concentrations is required to keep global mean warming below 2°C, which in turn is assumed to be necessary to avoid ‘dangerous’ climate change. On the other hand, people are cited saying that “We’re going to be at 400 ppm in 10 years’ time”.
So given that we will exceed 400 ppm CO2 in the near future, is a target of 2°C feasible? To make a long story short: the answer is yes.