France's top climate negotiator said Tuesday there has been a "breakthrough" in 46-nation talks in Paris to pave the way for a world pact to beat back global warming.

"This is a breakthrough," said Laurence Tubiana, at the close of the two-day ministerial meeting, pointing to a hard-won consensus on key points that have stymied negotiations ahead of a crucial UN conference at year's end.

Top diplomats representing all regional blocs agreed to a review every five years of collective carbon-cutting impacts once the agreement kicks in, Tubiana said.

The United Nations has embraced a goal of capping global warming to two degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels, the threshold for dangerous climate impacts.

But because national pledges being made ahead of the November 30-December 11 conference are voluntary, there is no guarantee that they will add up.
The new consensus on a review process "means the accord will be durable," Tubiana said. "We went into this meeting asking if we would have to renegotiate the accord in 2030. We left knowing this will not be the case."

Tubiana also said that all countries present in Paris favoured the principle of external verification of national measures taken to honour their CO2 reduction pledges.

"There are still a lot of details to be worked out, but the idea of everyone accepting to be verified within a common framework is very significant," Tubiana said.