Once home to Chairman Mao, Yan’an is now at the centre of China’s green revolution. In the past decade 588,000 hectares of the land around the city have been returned to forest. Trees and lawns cover 57.9 per cent of the city.

In China planting trees is not only encouraged but decreed by the National People’s Congress. Since 1981 every citizen between 11 and 55 has been under orders to plant at least three saplings a year. For students, tree planting is a graduation requirement.

China's reforestation project is designed to arrest desertification and reduce the soil erosion that gives the Yellow River its name. Government officials have promised to spend almost $9 billion (£5.5 billion) on increasing forest coverage each year. Their target? To cover a fifth of the country by 2010.

But while the Chinese plant trees at home, they follow different rules abroad. China recently secured 2.8 million hectares of the Congo Basin to develop a plantation for palm oil, a controversial biofuel that has caused deforestation worldwide.

Every year 32 million acres of trees are chopped down to make way for agricultural land to feed a growing population.

Destroying trees accounts for more greenhouse gas emissions than every train, car, bus and plane on the planet. Around 17 per cent of our emissions can be traced to felled tree stumps where there used to be rainforests.

If everyone planted and looked after two trees a year, we could reverse the deforestation of a decade in the next ten years.

Attempts to counter carbon emissions through offsetting are increasingly popular. BP has just pledged to plant ten million eucalyptus trees in Australia. The UN’s REDD programme is designed to stop deforestation by offering financial incentives to the most at-risk developing countries.

But planting more trees isn’t always the answer. The forests planted to absorb carbon dioxide are often neither ecologically diverse nor a long-term fix. As soon as they start to rot, their carbon stores are released.

Even China’s programme has slowed. The Government stopped reforestation on marginal farmland as it believes the nation no longer has sufficient arable land to feed all of its people.

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