A new global climate agreement to be signed next year in Paris should cover all key elements and be effective for 10 years, the deputy head of China's delegation at the United Nations climate talks in Lima, Peru, said on Thursday.

Su Wei, the country's chief climate negotiator, said China has an open mind on the final term for referring to the Paris agreement: It will be either be a "protocol" or some other form that carries legal force, he said.

"First we need to determine the substance, and then let the substance determine the form," Su said.

The agreement should address all key elements, including mitigation, adaptation, financing, technology transfer and transparency, he said.

The talks started on Monday and will run through Dec 12.

China favors a 10-year commitment, rather than five years, because it provides more accountability in the market, Su said, whereas a five-year commitment could result in too much time spent on negotiations.

"Those actions will be very much facilitated by market mechanisms," said Su, who is also director general of the climate change department of the National Development and Reform Commission.

The Lima conference agenda calls for countries to contribute to the 2015 agreement in the form of "intended nationally determined contributions", known as INDCs, early next year.

China is preparing its INDC and plans to unveil a package of post-2020 actions in the first half of 2015, although it will try to put it forward at "an earlier date," Su said.

Last month, in a joint announcement with the United States, Beijing said it would aim for emissions to peak around 2030. It was the first time it has set a deadline. The US said it would seek to reduce emissions by 26 to 28 percent below 2005 levels by 2025.

Beyond those announced goals, Su said, other goals to markedly reduce carbon intensity and boost forest conservation will be included in the package.

The announcement made by the two countries does not necessarily blur the distinction between developed and developing countries, he said.

"It's not an announcement of joint action, not an announcement of joint objectives. It's a joint announcement of independent actions to be taken in the period after 2020," Su said. He said one effect of the announcement has been an injection of new momentum into climate talks.

Another key decision to be made at the Lima talks relates to finance. A total of $9.7 billion has been put on the table for the UN Green Climate Fund; however, that's "far from adequate", Su said. Developed countries pledged to mobilize $100 billion per year in support of developing countries by 2020.

"Ten billion dollars is only one-tenth of that objective, and we don't have a clear road map or picture of how the target will be met," Su said.

He said "it is not good news" if Australia refuses to provide any money to the GCF. Australia has said it will continue to support small island nations from its own internal resources rather than by donating to the UN's fund.

Adaptation is another agenda item in Lima.

"We want to put adaptation on the same footing as mitigation. The impact of climate change is not in the future, it's happening now," Su said.

This year is on track to be the warmest on record, a UN weather agency said on Wednesday.

Su called for delegates in Lima to speed up the process and start real negotiations. He said it's a general consensus among developing countries "to put text on the screens", for example.

Screen or no screen has become an issue hindering the Lima talks, observers said. In the past three days, many developing countries demanded that the text of draft decisions, including matters regarding the 2015 Paris agreement, be put on a screen. Countries would then change the text as they made proposals.

But two co-chairs of the working group appeared intent on continuing what they had done last year - listen to comments and proposals made by the parties and then produce new versions of the draft-decision text.