The United Nations top official on climate change has urged governments to make further commitments to reduce emissions.
Another climate summit opens on Monday, this time in Durban, South Africa.
Climate secretariat head Christiana Figueres says the representatives need to commit to what she says is the world's most compelling industrial revolution.
But some of the developing world's biggest greenhouse gas emitters are bidding to delay talks on a new climate agreement.
India and Brazil are joining the United States, Russia and Japan in wanting to start talks on a legal deal no earlier than 2015. They want a longer timeframe.
The European Union and various climate blocs want to start as soon as possible and have the deal finalised by 2015.