At the climate change summit in Cancun, China has made an proposal that could help to extend the Kyoto Protocol.
Beijing has offered for the first time to add its voluntary carbon emissions target to a binding UN resolution.
The pressure is on leaders to firm up existing promises made at last year’s Copenhagen summit, which ended without a binding deal.
China hopes its offer will encourage developed countries to continue the existing Kyoto deal, which expires in 2012.
From the EU, there was optimism and a warning.
Climate Action Commissioner Connie Hedegaard said: “We are also concerned because the texts are not ready to be used by ministers to finalise their deal. They are still much too long, there are still much too many options and they are still much too complicated. Nonetheless we believe that a robust and balanced outcome that addresses the concerns of all parties is within reach here in Cancun.”
Bolivia accused rich nations of having policies that were tantamount to genocide, pointing to the number of deaths attributed to natural disasters linked to climate change.
Demonstrators in Mexico’s Caribbean beach resort had their own, now familiar, way of urging leaders of the 200 countries at the talks to strike a deal.
Their protests were the most violent of the Cancun summit so far.