Since President Xi Jinping took power in China 18 months ago, the world has sometimes fretted about the ways in which the Asian country seems determined to use its newfound political and economic heft.
Beijing can seem to take an uncompromising and zero-sum view of the world. In the western Pacific, China has unsettled its neighbours by making territorial claims. Relations with the US have been overshadowed by concerns over Chinese cyber espionage.
But in one area of critical importance to the world — the need to combat climate change — China has taken a much more co-operative stance.
The past year has seen several examples of Beijing's brand of climate detente. The first came in 2014 when China set itself the target of stemming any rise in carbon emissions beyond 2030. Last week, on a visit to the US, President Xi went further, committing $3.1bn in finance to help low-income countries least able to help themselves. He also committed China to launch a national carbon market by 2017.
True, these are modest steps in the business of actually reducing greenhouse gases. Beijing has yet to accept any internationally binding legal commitments on emissions. The fund could cynically be described as little more than guilt money. Nonetheless, these are still very welcome steps.
China is demonstrating leadership at a time when the climate agenda has lacked champions willing to take political risks. Beijing's initiative adds momentum to the discussions ahead of the international climate conference in Paris at the end of the year. Its engagement should help to avoid a re-run of the fiasco that overtook the last climate meeting in Copenhagen in 2009.
China's climate initiatives are a concrete expression of an unavoidable truth; that in any future deal Beijing will have to play its part. Until now China has been able to shelter behind the concordat struck in the 1990s. Then, along with other developing countries, it was absolved from the need to put right a problem it was deemed not to have caused.
A quarter of a century on, Beijing can no longer credibly claim to be a blameless bystander. It is by some measures the world's largest economy. While western emissions have been on a downward trajectory, its own have shot up. Indeed, China is now by some distance the world's biggest polluter.
With the developing world responsible for ever more emissions, no realistic solution can depend upon western nations installing more solar and wind alone. It requires responses across the developing as well as the developed worlds, including a shift within fossil fuels away from coal towards gas.
There are signs that other large emerging markets may respond to China's example. Dilma Rousseff, Brazil's president, said on Sunday that her country would reduce emissions by 37 per cent by 2025 from 2005 levels, and aim for a 43 per cent cut by 2030.
Of course China's willingness to take action on the climate is not altogether altruistic. It is bound up strongly in self interest. Left to run unchecked, the degradation of China's environment is a serious danger to the wellbeing of the country's citizens. Ultimately this could pose a threat to the ruling elite.
Global climate politics since the stalemate in Copenhagen has been remorselessly gloomy. China's willingness to play a part is a rare bright spot in an otherwise dim picture. It comes not a moment too soon, given expectations that the year 2015 may be the hottest on record. A solution to global warming may remain a distant prospect. But at last the emerging world led by China is starting to pull its weight.