Group: China Tops World in CO2 Emissions

Cyclists rides through the polluted air beside Beijing's Tiananmen Square in China in this Feb. 21, 2001 file photo. China has overtaken the United States as the world's top emitter of carbon dioxide, an environmental research group said Wednesday, June 20, 2007, driving home dire warnings of the country's hefty contributions to global warming. (AP Photo/Greg Baker) (Greg Baker - AP)

"China's growth will saturate at some point," he said. But "for now, we don't see a trend (toward) this saturation yet."

Olivier said the research was based on data on fossil fuel consumption from BP PLC's Review of Energy 2007, compiled by the British oil company, and cement production data through 2006 published by the U.S. Geological Survey.

John Christensen, head of the U.N. Environment Program's Center on Energy, Climate and Sustainable Development in Denmark, said the figures did not come as a surprise.

"The Dutch agency referred to BP statistics, which is the standard reference tool. We have no reason to doubt that the numbers are right. We have no reason to doubt the methodology," Christensen said. "It's been stated many times that China will overtake the U.S. in emissions."

Other sources of carbon dioxide, such as deforestation and the flaring of gas in oil and gas production, are not included in the data. They also do not include methane from fuel production and agriculture and nitrous oxide from industry.

Fatih Birol, chief economist of the Paris-based International Energy Agency also said the findings were not surprising, given China's economic growth of more than 9 percent annually over the past 25 years.

His agency had estimated China would overtake the U.S. before 2010; in November it sharpened the forecast to 2007 or 2008.

But the issue isn't just current emissions, but carbon dioxide stuck in the atmosphere, where it lingers for about a century trapping heat below, said Jay Apt, a professor of engineering, business and public policy at Carnegie Mellon University in Pittsburgh.

Apt and a colleague calculated the share of carbon dioxide now in the atmosphere that can be attributed to each country and determined that the United States is responsible for 27 percent, European nations contributed 20 percent and China only 8 percent.

"The planet does not respond to emissions, the planet responds to the amount of carbon dioxide in the atmosphere," said Apt. "It means the U.S. will have the lion's share of carbon dioxide in the atmosphere for the foreseeable future. In fact, even if China's exponential growth continues, China will not surpass the U.S. in the numbers of carbon dioxide atoms in the atmosphere, that is concentration, until at least 2050, which is too late to start anything."

The International Energy Agency's Birol said the key message from the emission figures isn't who is No. 1, but the need to slow growth in CO2 emissions. "The rest of the world with the help of China needs to find ways for China to reduce CO2 emissions," Birol said.

China has come under growing international pressure to take more forceful measures to curb releases of greenhouse gases.