The call came as the latest round of talks closed in Bonn today, June 14th, with incremental progress on the shape of a comprehensive climate deal to be agreed in 2015. Greenpeace UK political advisor Ruth Davis said a deadline for pledges was vital for the negotiations to remain on track.

"This deadline is needed partly to give enough time to assess the pledges against the latest climate science, and partly so that countries can compare their efforts," Davis said. "Having enough time to negotiate these targets is vital to avoiding the kind of last minute scramble that made the 2009 Copenhagen summit such a disaster."

These negotiations were held against a backdrop of the worst recorded flooding in Eastern Europe and extreme weather in the US. German and New York officials stated this week that they would spend billions fortifying their cities against future extreme weather, showing that the costs of climate change are already being tallied in rich countries as well as poor.