BONN, Germany (Reuters) - Agreeing on a U.N. climate treaty in 2010 will be "very difficult" despite a new push to spur negotiations after the Copenhagen summit, the head of the U.N. Climate Change Secretariat said on Tuesday.
Yvo de Boer, a Dutch citizen who announced plans last week to stand down in July after four years, also suggested to Reuters Television that his successor should be from a developing nation.
"I think that's going to be very difficult," he said of prospects for agreeing a new treaty at an annual ministerial meeting in Cancun, Mexico, from November 29-December 10. Rich and poor are divided over sharing out the burden of curbs on emissions.
A U.N. summit in Denmark in December disappointed many nations by failing to agree a new legally binding deal to succeed the existing Kyoto Protocol.
It ended with a non-binding Copenhagen Accord to limit warming to less than 2 degrees Celsius (3.6 F) above pre-industrial times.
De Boer said developing countries would want to know what a treaty would mean "in terms of obligations and what it's going to bring for them in terms of finance and technology, before they're willing to take that step and say: 'yes, we're willing to work toward a legally binding treaty'."
"So I think the first step will be to get the architecture right and I think that can be done in Mexico. The next step would be to decide on a treaty on it," he said.
On Monday, key nations agreed to add an extra negotiating session of senior officials from 194 nations in Bonn from April 9-11, on top of a meeting in Bonn from May 31-June 11. Delegates said it was a sign of willingness to work for a treaty.
De Boer also said he expected that Mexico would host talks among some key negotiators in March.
De Boer said the choice of his successor was up to U.N. Secretary General Ban Ki-moon. But he said "I think it would be quite useful to...have somebody from a developing country."
So far, 100 nations have signed up for the Copenhagen Accord, which promises almost $10 billion a year in aid from 2010-12, rising to $100 billion a year from 2020, as well as setting the 2C temperature ceiling.
De Boer said that the climate debate was shifting into a period when it could carry out decisions already taken to slow droughts, floods, heatwaves, more powerful storms and rising ocean levels.
"We're now moving into a phase that is very much about implementation and about getting developing countries on board and acknowledging cooperation and adaptation," he said.
In Indonesia on Tuesday, a U.N. study said promised cuts in emissions, mainly from burning fossil fuels, so far by 60 countries under the Copenhagen Accord were insufficient to limit temperature rise to 2 degrees.
Achim Steiner, head of the U.N. Environment Programme, urged countries to announce deeper cuts in emissions: "The message is not to sit back and resign and say we will never make it."
De Boer will be joining business consultancy KPMG.
"I've always said that I think the ultimate solution to climate change needs to come from the private sector, within boundaries designed by government, but from the private sector," he said.
(Editing by Jon Boyle)