There was one place where China's assumption of the title of the world's largest emitter of greenhouse gases came as no surprise: Beijing has anticipated and planned for this moment. Until earlier this year climate change was hardly mentioned in the Chinese media. Now the government is encouraging newspapers, radio and television to report on the subject, beginning the long process of educating the population - which increasingly defines itself by what it owns - to understand the long-term consequences of a level of consumption they have only recently been able to enjoy. At government level, a series of briefings by climate-change experts for the leadership, and a policy effort that involved 17 ministries, produced China's first national climate-change plan this month. It falls well short of what will eventually be required, but it is a beginning.
There are two reasons for this flurry of media attention and political activity: Beijing has understood how severe the impacts of climate change could be for China. They include severe long-term water shortages, potential inundation of east coast cities, and falling agricultural yields. And, diplomatically, China's pole position as leading emitter will have a negative impact on its unthreatening international image of a "peacefully rising" power, an image it has devoted considerable effort to promote.
China has been able to avoid taking a forward diplomatic position on climate change as long as George Bush's US, by far the biggest per capita emitter and, until now, the biggest overall, was acting as the spoiler for global mitigation efforts. Why should a developing country, even one aiming to be the next global power, volunteer for the frontline of the fight when the world's richest and most technologically advanced country would not even join the army?
But as the world's biggest emitter, the spotlight is now on China: as one government adviser put it recently, "the tall tree attracts the wind". China's hitherto benign image in the global south is now at risk as the impacts of climate change become more severe: a policy had to be agreed and China had to be seen to act.
More starkly, given the potential impact of climate change on China's development, mitigation is as much in its interest as it is in the interests of all. The circle that remains to be squared is how the burden of mitigation is to be shared between the developed and the developing world - who is to pay, and what action is possible that will not slow the growth the Chinese government needs to keep its people content.
In the era of militant ideology, the Chinese people lived a politics of sacrifice and struggle. Today, they live a government promise of prosperity and power. In the scramble to deliver the past two decades of rapid growth, sustainability has been sacrificed to short-term goals. The economy is carbon heavy, inefficient and environmentally disastrous. Unlike the old industrialised countries, China does not have a hundred years in which to clean up, nor is there a developing world to which it can export its polluting industries, as the world did to China. Finally, the developed world put so much carbon into the atmosphere through its own industrialisation that there is now no margin for China to repeat the pattern of rapid dirty growth followed by leisurely clean-up. It is an unenviable position for China, and one for which the rest of the world must take a large share of responsibility.
For those who live in the developed world, there are two possible responses to China's passing this milestone: to blame it for the reckless pursuit of its own short-term interests, regardless of the cost to the planet; or to acknowledge that, historically, we created most of the problem, that most of the goods made in China are consumed in the industrialised world, that the aspirations of people in China to live more prosperous lives are legitimate, and that it is incumbent on us, morally and practically, to put our money where our mouth is. This means drastically reducing our own emissions and helping China with the finance and technology required to move to a sustainable, low-carbon economic system.
The fight against climate change will be won or lost in China and India. China's government has a fragile hold on the affections of its people, who have high material expectations. A creaking system of government makes effective policy implementation a hit-and-miss affair. Like the west, China has powerful constituencies, many with vested interests in outdated, inefficient and deeply damaging models. If democratic governments have failed, so far, to demonstrate the leadership on climate change that the urgency of the situation demands, it is no easier for Beijing to formulate and implement a policy that encompasses historic justice, sustainable development and technological innovation sufficiently radical to safeguard the future. China will act, but only if we act first.
Isabel Hilton