China has for the first time given a timeframe for reducing its carbon emissions.
The world's largest emitter of greenhouse gases says it will begin dropping emissions in 2050.
The comments by top policy-maker Su Wei have been carried in the Financial Times newspaper, but they did not indicate at what level emissions would top out.
At a G8 meeting in July, China and India resisted calls to agree to a 50% cut in global emissions by 2050.
Mr Su has restated Beijing's view that because China still needs to expand its economy to pull people out of poverty, it is too soon to discuss caps on emissions.
His comments come at the end of a week of talks on climate change in the German city of Bonn. The talks, intended to help the world agree on the amount to cut greenhouse gas emissions by, by the year 2020, appear to have made slow progress.
NZ ambassador says differences persist
New Zealand has put forward an offer of cuts of between 10% and 20% of 1990 levels.
Senior foreign affairs official Adrian Macey is New Zealand's chief negotiator at the talks. He says big differences persist between developing and developed countries.
The major developing economies are reluctant to commit themselves, he says, and consider the commitments made by developed countries to be inadequate.
"Developing countries are wanting lots of assurances about financing, so there's quite a lot of things that have to happen before we can get a breakthrough."
Mr Macey says another problem is creating a negotiable document from an unmanageable raft of conflicting and overlapping proposals from different countries.
Mr Macey says the talks have tried to simplify the proposals.
The process will be resumed at talks in Bangkok in September-October and Barcelona in November, ahead of a major conference on climate change in Copenhagen in December.
The head of the UN Climate Change Secretariat, Yvo de Boer, said after the Bonn meeting, that "selective progress" has been made towards trimming the huge 200-page draft treaty text.
He warned participants that just 15 days of negotiations remain before the new United Nations pact to be agreed upon in Copenhagen, and talks need to accelerate or they risk failure.
