Nations are currently negotiating the $100bn a year to 2020 they promised in the Copenhagen accord from COP15, and the high-level groups financing source solutions have been provided to them as a roadmap.

“This goal to mobilize the money by 2020 is a challenge, but feasible and doable even in context of ongoing economic crisis,” says UN Secretary-General Ban Ki-moon, speaking at a meeting of the group in Cancún.