A worker rides past towers of a coal-fired power plant in Guangan, China. Photograph: Frederic J Brown

China is ready to abandon its resistance to limits on its carbon emissions and wants to reach an international deal to fight global warming, the Guardian has learned.

According to Britain’s climate change secretary, Ed Miliband, who met senior officials in Beijing this week, China is ready to “do business” with developed countries to reach an agreement to replace the Kyoto treaty.

Miliband said he was encouraged by the change in tone since late last year in the country that emits more greenhouse gases than any other. “I think they’re up for a deal. I get the strong impression that they want an agreement,” he told the Guardian.

“They see the impact of climate change on China and they know the world is moving towards a low-carbon economy and see the business opportunities that will come with that.”

The shift in the Chinese position significantly improves the chances of an agreement being reached when world leaders meet in Copenhagen in December to negotiate a deal that scientists say is critical if dangerous warming is to be avoided.

While Britain and the European Union – which have a large historical responsibility for greenhouse gas emissions – are pushing for ambitious reduction targets at home, no global climate deal will be possible in Copenhagen without the agreement of China and the US, which together are responsible for more than 40% of the world’s annual carbon emissions.

China’s official negotiating position is unchanged, but the government is understood to be preparing a set of targets up to and beyond 2020 to lower the country’s “carbon intensity”. This translates to cutting the emissions needed to produce each unit of economic growth.

Miliband said Barack Obama’s pledge to reduce US emissions to 1990 levels by 2020 has unblocked the international negotiating process.

“China used to think the developed world is not serious. That’s what they were saying [at UN talks] in December,” he said. “But now they know the US is on the pitch and ready to engage with them. It has made a real difference to what China is saying.”

His comments echoed the message from Chinese officials. Su Wei, a senior negotiator, told the Guardian last month that the US had made a “substantive change” under the Obama administration.

“The message we have got is that the current US administration takes climate change seriously, that it recognises its historical responsibility and that it has the capacity to help developing countries address climate change,” Su said.

But while the tone may have changed, there is still a long way to go before agreement can be reached on specifics.

China wants developed nations to commit to more ambitious reduction targets, to share low-carbon technology and to set up a UN fund that would buy related intellectual property rights for use across the world. Beijing’s position is complicated by the fact that it already owns a large share of the patents for wind and solar energy in developed nations.

Europe and the US accept the Chinese economy should be allowed to grow further, improving the living standards of its millions of poor, before it makes overall emissions reductions. Instead, the western nations are pushing for strong measures to improve efficiency and establish caps for certain industries. One possibility being considered by Chinese officials is to set a carbon intensity goal up to 2040 that would include energy efficiency, renewable energy, transport and afforestation.

“It would be very welcome for China to set a commitment for carbon intensity,” said Miliband. “It would send a signal around the world.”

He was visiting Minqin county, a remote area in north-western China threatened by desertification and drought. Along with the melting of the Himalayan glaciers, the spread of deserts and the shortage of water have highlighted the destructive impact of unsustainable development and climate change.

“We’re very concerned about climate change,” said Xu Wenshan, the deputy mayor of Wuwei, at a welcome banquet. “Living in such an ecologically fragile area, we will feel the impact directly if there is a further rise in the temperature.”

Jim Watson, of the UK’s Tyndall Centre for Climate Change Research, said it had become the mainstream view in China that global warming was caused by human activity, which was not the view five years ago.

“We see significant policy shifts and encouraging developments in technology, for example phenomenal development of wind power and plug-in cars. That could be a sign of things to come,” he said. “My impression is that although the negotiators haven’t moved ground officially, there are a hell of a lot of new ideas. They are very interested in low-carbon economy.”

Last month, the Tyndale centre published research showing that it was possible for China to begin reducing its total emissions from 2020.

Government officials say that is unrealistic and China has so far resisted announcing a target for when emissions might peak. But the authorities tend towards the later end of the various academic forecasts of between 2020 and 2040.

Watson noted that if emissions are measured on a historical per-capita basis, China is 78th in the world rather than first.