That number reveals humanity’s steady billion-tonne by billion-tonne march to the edge of the carbon cliff, beyond which scientists warn lies a fateful fall to catastrophic climate change.

 

With the global total of climate-disrupting emissions likely to come in at around 52 gigatonnes (billion metric tonnes) this year, we’re already at the edge, according to new research.

To have a good chance of staying below two degrees C of warming, global emissions should be between 41 and 47 gigatonnes (Gt) by 2020, said Joeri Rogelj, a climate scientist at Switzerland’s Institute for Atmospheric and Climate Science in Zurich.