U.N. climate chief Yvo de Boer said on Thursday he will step down in July to join a consultancy group, two months after a Copenhagen summit failed to support a legally binding climate pact.

His departure is unlikely to dent further U.N.-led climate talks meant to agree a successor to the Kyoto Protocol, stalled over sharing the cost of cutting carbon emissions.

The Dutch former environment official will join KPMG, the Secretariat for the U.N. framework convention on climate change (UNFCCC) said. De Boer has led the agency since 2006 and his contract was expected to be renewed in September.

"It was a difficult decision to make, but I believe the time is ripe for me to take on a new challenge, working on climate and sustainability with the private sector and academia," de Boer said in a statement.

"Copenhagen did not provide us with a clear agreement in legal terms, but the political commitment and sense of direction towards a low-emissions world are overwhelming," he added.

U.N. Secretary-General Ban Ki-moon would consult and decide on a replacement, a U.N. spokesman said.

The Copenhagen meeting missed de Boer's own benchmarks for success, neither specifying exact emissions limits for developed nations nor a time frame to agree a new pact, but was applauded for harnessing pledges from both rich and poor countries.

"It wasn't that surprising ... I would like to see someone from a developing country who can negotiate with those countries," said Seb Walhain, head of environmental markets at Fortis Netherlands, of de Boer's departure.

Carbon markets de

pend on the U.N. talks to find a Kyoto successor from 2013, to continue a global trade in offsets. "It won't have any effect on the carbon market," said Walhain.

BIG EARS

U.N. rules require consensus among all 194 countries, partly hampering climate talks and leading some analysts to call for a new approach, for example through G20 world leaders.

"We must quickly find a suitable successor who can oversee the negotiations and reform the UNFCCC to ensure it is up to the massive task of dealing with what are some of the most complex negotiations ever," said British energy and climate minister Ed Miliband.

"He's been a really important guardian and leader on climate change," said Kim Carstensen, head of the WWF environmental group's global climate initiative.

De Boer, born in 1954, has been far more outspoken than previous heads of the Bonn-based Secretariat. He had often criticised developed nations for what he called a lack of ambition in setting out cuts in greenhouse gases by 2020.

But he also told developing nations not to get their hopes up too high. In the run-up to Copenhagen, he told African nations and small island states that their calls for deep emissions cuts by the developed world was "too heavy a lift."

At a marathon U.N. meeting in Bali in 2007, de Boer left the room in tears after a Chinese delegate criticised the Secretariat for starting a meeting before all delegates were present.

De Boer was known for his quips -- he compared his own large ears to those of Dr. Spock in the television series "Star Trek." And he compared the drawn-out process at the Copenhagen summit to cooking a Christmas turkey or baking a cake.

(Additional reporting by Alister Doyle in Oslo and Nina Chestney in London; editing by Janet Lawrence)