DURBAN, South Africa — China, the world’s biggest carbon emitter, has emerged as an unlikely darling of the United Nations climate talks, the first excitement at what has so a far been a sluggish conference.

It hasn’t taken much to spark the excitement. Chinese delegation head Xie Zhenhua created a stir Monday by saying China might be willing to sign a legally binding agreement for reducing emissions, post-2020 — if other countries keep their commitments, and depending on China’s state of development, and a laundry list of other pre-conditions.

“China is open,” Xie told reporters, sounding a world apart from the positions of fellow major polluters including the United States and Canada.

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The impression of a shift in China’s position has stuck among delegates at the conference. But the big question about China’s policies remains: Is it all just hot air?

“Working hard to tackle climate change, China always has been and always will be,” said an upbeat booklet at the country’s official pavilion — the first time China has opened a stand at a UN climate summit.

Brochures distributed to visitors at the pavilion make grandiose boasts about Chinese policy, claiming that China has been concerned about climate change issues for thousands of years of its history. It cites as evidence the Yi Jing (Book of Changes), Taoism and the philosopher Laozi.

More recently, beset by devastating climate and pollution crises and facing mounting domestic pressure, China has proposed a smorgasbord of policies and projects at home, backed by a new five-year government plan that highlights green growth and low-carbon initiatives.

Changhua Wu, greater China director with The Climate Group, a non-profit organization, said China hasn’t changed its policies at Durban — it is just managing to communicate better about its work on climate change, and reversing the international impression that it isn't doing enough.

“From a public-relations perspective, China is definitely getting more savvy,” Wu said.

“The confidence comes from actually doing something,” she added, pointing to the work China has done at home. “But people always want China to be doing more.”

China has repeatedly stated that as a developing nation, with no historical responsibility for carbon emissions, it cannot be held to the same standards as industrialized countries.

“China will shoulder the responsibility that is appropriate to its development,” Xie reiterated Monday.

But the United States, the world's second-largest polluter after China, emphasized again Monday that major developing country emitters like China and India must be part of any legally binding agreement, as a condition for negotiations.

Todd Stern, the US chief envoy in Durban, said at a press briefing that any future global deal would have to be equally binding on all countries, including China, with “no trap doors, no Swiss cheese.”

“In order for there to be a legally binding agreement that makes sense, all the major players are going to have to be in,” Stern said.

South African international relations minister Maite Nkoana-Mashabane, who is the official host of the conference, was among the optimists praising China’s apparent shift in stance.

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"China is laying its cards on the table. Other negotiators will be laying the cards on the table and work then gets escalated. And that is what makes us hopeful we are moving in the right direction,” she said.

Wu said China won’t likely even consider signing an internationally binding deal until after 2015, when a scientific assessment ends, and it wouldn’t take effect until 2020 at the earliest.

“That’s not new, but somehow people just pick up on the language,” she said.

Until then China will focus on its domestic policies related to climate change, and the particularly tough task of implementing emissions controls in a country with runaway growth and the world’s biggest population.

Wu concluded: “In history no country has been put in the same situation as China is today.”