The December Copenhagen climate summit – foolishly sold as the last-chance saloon for solving global warming – looms ever larger. Estimates of the money needed to help countries (particularly developing ones) mitigate and adapt to climate change are piling up faster than negotiators’ airmiles.

Earlier this year, China, India and South Africa demanded rich countries spend 0.5-1 per cent of GDP to help them fight climate change. On Thursday a British report argued UN adaptation estimates of $49bn-$171bn a year (by 2030) were two to three times too low. Next week, African leaders will consider plans to ask rich countries for $67bn a year from 2020.