‘…500 gigatons is a lot, but we’re producing more than 30 gigatons a year as a planet, and that number has been growing about 3 percent a year. Which gives us, oh, about 15 years before we go soaring past the two-degree threshold. If we are to avoid doing that, computer modeling shows that the world’s carbon emissions have to peak in 2015 and then come hurtling down.’
via Global warming maths – we’re down to our last 500 gigatonnes : Renew Economy.