UN Secretary General Ban Ki-moon said today that countries must "accelerate the rhythm of negotiations" on capping global warming ahead of an international climate conference in Paris in December.
"We don't have much time. There remain less than 100 days before the final negotiations," he said, following a meeting with Foreign Minister Laurent Fabius in the French capital.
Both men expressed their "prudent optimism" that the climate conference in Paris would achieve its goal of an agreement capping warming at 2 degrees over the pre-industrial average.
"The countries have been negotiating for more than 20 years. The Paris conference is the final step during which they have promised to agree on an ambitious climate accord. There is no time to lose," said Ban.
Fabius said the talks were "different to the others".
"It's a race against the clock. Last year was the hottest on record. It seems that this year will be even hotter. There is no plan B, there is no planet B."
The UN's COP21 conference runs from November 30 to December 11 in Paris, bringing together leaders from around the world as they try to improve on failed negotiations at the last UN climate conference in Copenhagen in 2009.