China's first review of the problems posed by a hotter planet proposes an even more ambitious goal of an 80 percent cut in "carbon intensity" by 2050, from 2000 levels, but states that emissions per person are likely to top projected developed-nation levels before starting to fall.

If the target was made official, China would be the first major developing country to set long-term goals for braking rising emissions, as urged by the European Union and many other industrialised countries that are part of the Kyoto protocol.

"Before generally accomplishment of modernisation by the middle of the 21st century, China should not undertake absolute and compulsory emission reduction obligations," said a translated summary of the report, seen by Reuters.

The "First National Climate Change Assessment" is not the last word in how China intends to address global warming, but it was drafted over four years in consultation with powerful ministries, suggesting a broad official consensus.

The final version, which gives no figures for total current or future emissions, has not yet been approved for publication. It is separate from a national plan on climate change that Beijing is expected to unveil on April 24.

The concept of cutting emissions for each unit of national income represents a rare convergence of views in the world's top two carbon dioxide producers, China and the United States.

President George W. Bush has repeatedly insisted that carbon emissions be measured in conjunction with US economic growth, and urged industry to voluntarily cut its emissions intensity by 18 percent by 2012. But some states such as California are planning emissions trading schemes without federal backing.

VULNERABLE CHINA

Beijing aims for an initial cut in carbon intensity of 40 percent by 2020 through measures ranging from expanding forests to boosting renewable energy, the report said.

By then, temperatures may be up to 2.1 degrees Celsius above averages for 1961 to 1990, and could start straining food and water supplies. Ground temperatures have already increased 1.1 degrees over the past 50 years, the report adds.

"Due to its highly fragile ecological environment, long coast-lines and low per capita resource... China is extremely vulnerable to the negative impacts of climate change," it said.

With pollution and resource problems an increasing constraint on the economy, Premier Wen Jiabao put green growth at the centre of his address to Parliament this year, while global warming was noticeable largely by its absence from the session's agenda.

But China is set to overtake the United States as top emitter of greenhouse gases before the end of this decade, possibly as early as this year, bringing increasing foreign pressure to act.

The European Union and most other rich nations bound by the Kyoto Protocol want developing countries to start braking the rise in their emissions beyond 2012.

They say emissions-intensity goals are relevant for poorer nations but the speed of China's economic growth, currently hovering at 10 percent a year, means emissions will still surge even as it becomes more efficient.

UNDERPLAYING PROBLEMS?

A recent UN report warned of the dire impacts of global warming, from hunger in Africa to a fast thaw in the Himalayas, but in the negotiations leading up to its approval, Chinese officials and scientists raised doubts about several sections and sought to underplay some findings.

The blueprint indicates that Beijing's scepticism about some scientific claims on global warming is being used to justify resistance to mandatory emissions caps.