Carbon greenhouse gas. Picture: THINKSTOCK

DOHA — US deputy envoy on climate change Jonathan Pershing said on Wednesday morning the US was more likely to ratify the new legally binding global agreement on climate change that the world is negotiating than its predecessor, which it signed but never ratified.

The US is the world’s second-largest emitter of greenhouse gases, linked to climate change, accounting for 18.27% of total global emissions.

Only 15% of total global emissions are accounted for by those who have ratified, and stuck to, the 1997 Kyoto Protocol.

Nearly 200 countries have gathered in Doha, Qatar, for this year’s round of United Nations talks on how to keep emissions at a level that will limit the average increase in global temperatures to less than 2°C from preindustrial levels.

"That’s the million-dollar question," Oxfam International’s Tim Gore said of the likelihood of the US actually ratifying any new deal.

The parties to the UN Framework Convention on Climate Change agreed at last year’s Durban-hosted talks that a new legally binding deal would be secured by 2015, to be implemented in 2020.

Mr Pershing said he did not have access to a "crystal ball", but the way the talks were going — with agreement that a new deal would include emissions reduction obligations for all countries, not just industrialised ones — meant it was more likely the US would be able to ratify it.

That, however, was up to the US Congress, which has always stood in the way of ratification.

"It is a different world (from 1997, when the protocol was agreed). The new agreement has to involve everyone," Mr Pershing said.

• Blaine is attending the talks on a scholarship from the UN Framework Convention on Climate Change.