Jonathan Watts is not well. For a minute I fear the worst. Having just completed When a Billion Chinese Jump, his extraordinary book examining China's relationship with the environment, has Watts' central nervous system finally been overwhelmed by Beijing's infamous smog or polluted water supply? As it turns out, Watts has simply picked up an unidentified bug. 'As long as I don't come across as delirious,' he says. Watts, who also reports for The Guardian newspaper, wouldn't be the first environmental commentator to be accused of delirium. There are bound to be those who accuse him of exaggerating problems and minimising solutions. Watts admits that his work is both a warning and a polemic, but adds that he strives to be fair. He sympathises with diplomats who accuse the West of hypocrisy - for outsourcing its dirtiest industries and filthiest pollution and then berating China for over-consumption and a lack of recycling. The problem that must be grasped now, Watts says, is scale. 'Economic development has always been unsustainable. But when it was little Britain 200 years ago, it was one tiny, unsustainable country pillaging the resources of the world ... When the country is the size of China, you really do reach a tipping point.' Watts' conviction that we are hitting an ecological wall explains why China is crucial to the future of humanity as a whole. 'China is really the culmination of 200 years of carbon-fuelled, capital-driven economic development. In Britain, you read about the smoke stacks in history books and Charles Dickens. In China, you see 200 years of history right in front of your eyes being played at fast forward.' When a Billion Chinese Jump traces a journey across space and time to examine whether China's development will ultimately be a force for good or ill. Part travelogue, part history lesson and part first-hand reportage, the book begins in the southwest, in the semi-mythical mountain idyll of Shangri-La. Watts then snakes across the country to the northeast and Xanadu (Shangdu) in Inner Mongolia. 'In between there are a lot of places you wouldn't want to go,' he says grimly. Watts' personal journey began decades before. As a child growing up in London, he recalls praying for China - and in particular, that everyone in that country wouldn't decide to jump all at once, knock the world off its axis and destroy the planet. But his first experience of Asia came in Japan. He taught English in Kobe and Osaka and returned later as a journalist. Japan inspired his interest in China. 'Japan is obsessed with China. There were far more stories about China in the Japanese media than in the British media. I gradually realised China was the big story of the early 21st century.' Watts moved to Beijing in 2003 as a reporter for The Guardian and found himself writing an environmental story on an almost weekly basis. 'It was clearly a factor in so many other issues - water shortages, melting glaciers, protests about chemical plants, smog above Beijing. You just couldn't ignore it.' Watts began taking the lengthy road trips - to Tibet and the mountainous forests of Yunnan and Sichuan - that formed the basis of his book. He began the story in Yunnan to show the planet as it used to look. 'Yunnan is exceptional, but an awful lot of the world used to be like this.' From the forests, Watts traced the path of 'our ecological wealth' through mountains, water and animals. One chapter reports memorably on the futile search to find the baiji, the Yangtze River dolphin. Once worshipped as a river goddess, the baiji became extinct after industrialisation encroached on its habitat. Watts develops the theme of human impact on the environment in the next four chapters. 'There is globalisation in Guangdong, urbanisation in Shanghai, pollution in Jiangsu and Zhejiang and industrialisation in Chongqing.' Watts knows the same processes that are doing so much to destroy the environment have also had some positive effects. 'I hope I also show the benefits humanity has had - for example, fighting poverty.' He points to villages such as Huaxi in Jiangsu which has been transformed from its communist past by modern enterprise initiatives. Watts' journey then reaches Henan, Shaanxi, Gansu and Xinjiang. 'The northwest is probably suffering more than anywhere. Some people describe it as the Africa of China. It has always been dry, but the water shortages and the blasted earth are really felt. There is a relation to climate change and carbon emissions.' The book's final section examines responses to the problem - through technology, culture and political will. For instance, Professor Li Can at the Dalian National Laboratory for Clean Energy, who is trying to use solar energy to convert carbon dioxide into hydrogen. Asked whether China's political leaders are ready to take the environment seriously, Watts says there are encouraging signs: the government has financed research into renewable energy. But he isn't holding his breath. 'Copenhagen showed that the world's leaders are not ready to come to a big accommodation - to find a fair balance between what's been done in the past and what can happen in the future.'