BEIJING - China is preparing its first plan to battle wrenching climate change, a senior policy adviser said, stressing rising alarm about global warming in a nation where economic growth has gone untethered.

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Zou Ji, a climate policy expert at the People's University of China in Beijing, told Reuters the national programme will probably set broad goals for emissions and coping with changing weather patterns.

It is likely to be released this year after at least two years of preparation, he said.

The plan showed that China was joining deepening global alarm that greenhouse gases from factories, power plants and vehicles are lifting average temperatures and will seriously, perhaps calamitously, alter the world's climate, said Zou.

"All this shows that the Chinese government is paying more and more attention to this issue," he said. "When it's approved and issued it will be China's first official, comprehensive document on climate change."

Last week a UN panel of scientists warned that human activity is almost certainly behind global warming.

The expert group gave a "best estimate" that temperatures would rise by between 1.8 and 4.0 Celsius (3.2 and 7.8 Fahrenheit) in the 21st century, bringing more droughts, heatwaves and a rise in sea levels that could continue for over 1,000 years even if greenhouse gas emissions are capped.

China is galloping to become possibly the world's third-biggest economy by 2008, overtaking Germany and lagging only Japan and the United States.

DYING RIVERS, RISING SEAS

In late January, the former chief of energy research in China's powerful National Development and Reform Commission, Zhou Dadi, warned in a speech that pollution and climate change have become a "major constraint" on national economic development.

Zou and other experts have spelled out other worries in a series of recent assessments, warning that global warming may trip up China's sprint for middle-class prosperity.

Increasingly frequent droughts and floods will threaten crops, Zou said. Hotter weather could speed the spread of deadly infectious diseases. Rising sea levels will slam rising waves against China's densely populated coast, driving sea water high upstream in shrinking rivers, ruining surrounding farmland.

Floods, droughts, hurricanes and other climate disasters now sap at least 2 percent away from China's potential GDP every year, and the absolute value of that damage is likely to grow with deepening climate change, Zou said.

China will likely also have to spend huge sums raising protective walls along its vulnerable coast, Zou said. "I liken it to building a new Great Wall," he said.