Stabilizing atmospheric carbon dioxide concentrations at 450 ppm, according to broad scientific consensus, will give the world a 50% probability of limiting warming to 2°C above pre-industrial levels. The 2°C target was formally agreed at COP-15 at Copenhagen 2009. Governments have since agreed to
launch a review in 2013 to consider strengthening the long-term goal to 1.5°C.

We published the first Low Carbon Economy Index (LCEI) ahead of COP-15, to look at the progress of the G20 economies against a global carbon budget1 necessary to stabilise atmospheric carbon dioxide concentrations at 450 ppm. We estimated a low carbon pathway for the 21st century for the global economy, which required the world to decarbonise at 3.7% a year
to 2050.