"I do not need to remind you that we simply cannot afford not to deliver implementation results urgently," Chief of the UN Framework Convention on Climate Change (UNFCCC) Christiana Figueres told delegates.

Greenpeace chief Kumi Naidoo warned not to put too much faith in the UN on climate, adding that he had "no reason to have even any sense of optimism" that anything has changed since the last UNFCCC meeting failed in Doha, Qatar last December.

"The UN negotiating system is cumbersome, it is problematic, it is tedious. However, the UN, warts and all, is the best and only vehicle we have to ensure we can move forward as a united global family to address climate change."