First in an occasional series

GUANGZHOU, China—The Pearl River Delta was the incubator of China's economic transformation, where special economic zones gave free markets a fighting chance against central government control.

With the rise of industrial development came some of the world's worst air pollution. Now, for the first time, the smog stretching from the city of Guangzhou south to Hong Kong threatens the vigor of China's fastest-growing economic region. Merrill Lynch's Hong Kong investment advisers are so worried that smoggy air is chasing jobs from downtown Hong Kong that they recently advised clients to snap up real estate in Singapore, where the air is clean.

Alarmed at the perception and the reality of a growing environmental nightmare they acknowledge is tied to global warming, government officials from Beijing to this port city formerly known as Canton are trying something altogether new: the beginnings of an organized attempt by China to confront the problem while it still might be controlled.

The mayor of Shenzhen, a high-tech mecca of 9 million people that was a fishing village just 20 years ago, this summer asked citizens to stop buying cars.

In an unprecedented crackdown, Guangdong province has begun sending out human "sniffers" to track down noxious emissions. "The police use dogs to sniff drugs -- we use our people to sniff pollution," said Chen Jian, director of the Guangdong Energy Conservation & Monitoring Center, a government agency. "It's like for wine or perfume. You use your nose."

In Beijing, the capital some 1,200 miles to the north, the central government is moving ahead with an unprecedented, aggressive plan to target specific companies all across China for mandatory curbs on energy use and emissions.

For years, Chinese leaders argued that they did not have the luxury of tackling climate change. As a developing economy, China needed to focus on growth. Besides, leaders said, Western nations did nothing to protect the environment during their industrial revolutions.

But this year China is expected to surpass the U.S. as the world's largest emitter of greenhouse gases: carbon dioxide, methane and others that contribute to global warming. The concerns about climate change are jeopardizing China's economic growth, and a surge of environmental protests has put China's security apparatus on high alert. And with the Summer Olympics a year away in Beijing, the government is scrambling to scour a persistent cloud of smog out of the skies.

China's response is emblematic of a massive, worldwide shift in the climate-change debate. There is little argument anymore that human activity is contributing to rising global temperatures. The questions now focus on how much damage it is causing, what to do about it, how fast the work must be done, what it will cost and how much time is left to attack the greenhouse gas emissions that scientists say contribute to the warming.

From China to Africa, South America to the United States, governments and private agencies are working to find practical solutions to what they say is the overheating of our planet. On Monday, the United Nations will convene a one-day international meeting of top officials for what the UN says will be the largest gathering of world leaders on climate change, in advance of a UN Climate Change Conference in Bali in December.

The challenge of fighting climate change is perhaps best seen in China, where the need to keep the economy humming supersedes all other political and social considerations, even the need for clean air. And like other countries, China is finding that it is far easier to set ambitious national goals than it is to achieve them.

Still, China hopes to cut emissions of carbon dioxide and other greenhouse gases 10 percent by 2010, a mammoth undertaking that, if successful, would have a real impact on the global environment.

To reach that goal, Chinese leaders are targeting their country's voracious appetite for electric power. The economy is growing so quickly that a cut in overall consumption has been deemed impossible. That would short-circuit the economy and potentially put the government at risk. But a still-consequential half measure aims at the "intensity" of energy consumption: a 20 percent cut in energy use per unit of national economic output by 2010.

There is no guarantee China will succeed, or even remain committed to its green rhetoric. Indeed, despite the push from the central government, the targets are proving tough to hit. Emissions are down, but not as much as the government wanted. Energy consumption per unit of gross domestic product dropped 1.23 percent in 2006 -- less than a third of the goal.

Meanwhile the economy grew by 11 percent, a surge that continues so far this year.

An emerging domestic concern

China's noxious emissions also are an issue for other countries and trading partners. And they are an emerging domestic problem: Citizens have demonstrated recently about toxic water and soil, and Chinese officials do not want air quality to become the next flash point. When a joint research project conducted by the Chinese government and the World Bank found that air pollution contributes to as many as 400,000 deaths a year in Chinese cities, the government resisted releasing the data for fear of arousing political turmoil.

Yet China is pushing ahead. The cornerstone of its effort is an aggressive new program focused on the 1,000 largest consumers of power. The central government has required those companies, which consume one-third of the nation's energy supply, to sign agreements to slash energy use and emissions.