RUJIGOU, China — The barren hillsides give a hint of the inferno underfoot. White smoke billows from cracks in the earth, venting a sulfurous rotten smell into the air. The rocky ground is hot to the touch, and heat penetrates the soles of shoes.
Beneath some rocks, an eerie red glow betrays an unseen hell: the epicenter of a severe underground coal fire.
"Don't stay too long," warned Ma Ping, a retired coal miner. "The gases are poisonous."
Another miner tugs on the sleeve of a visitor.
"You can cook a potato here," said Zhou Ningsheng, his face still black from a just-finished shift, as he pointed to a vent in the earth. "You can see with your own eyes."
China has the worst underground coal fires of any country on Earth. The fires destroy as much as 20 million tons of coal annually, nearly the equivalent of Germany's entire annual production. The costs go beyond the waste of a valuable fuel, however.
Scientists blame uncontrolled coal fires as a significant source of greenhouse gases, which lead to global warming. Unnoticed by most people, the coal fires can burn for years — even decades and longer — seeping carbon dioxide, methane and other gases that warm the atmosphere.
"Coal fires are a disaster for all of humanity. And it's only due to global warming that people are finally beginning to pay attention," said Guan Haiyan, a coal fire expert at Shenhua Remote Sensing and Geo-engineering Co.
This article is part of an occasional series by McClatchy on how human activities affect global warming. The rising demand for coal worldwide to satisfy a hunger for energy has given way to greater mining, and a proliferation of fires in coal seams and abandoned mines. China, which has tripled coal production in the past three decades, has mobilized thousands of firefighters to combat the 62 known coal fires that are scattered across its north.
Major fires have been extinguished. However, Dutch scientists scribbling back-of-the-envelope calculations say that coal fires in China may still be the cause of 2 to 3 percent of the world's annual emissions of carbon dioxide from burning fossil fuels. They call for greatly increasing efforts to extinguish China's coal fires — and those in places such as India, Russia and Indonesia — as a practical step to fighting global warming.
"It's a relatively cheap way to stop greenhouse gas emissions," said Horst Rueter, a German geophysicist who's the scientific coordinator for a Sino-German initiative to combat China's coal fires.
Rueter said he thought that China's coal fires accounted for at least half the global emissions from coal fires around the world, making them a steady source of pollutants.
Others said that such runaway fires, while significant, paled beside overall emissions from the United States, a fossil fuel glutton that may give off a quarter of the world's greenhouse gases.
Coal fires can occur naturally and are not a new phenomenon. Australia's Burning Mountain has smoldered for thousands of years. An underground coal fire in Centralia, Pa., began in 1962, eventually opening sinkholes that threatened to gobble and incinerate pets and children. Centralia became a ghost town, and experts say that the fire there may burn for a century or more.
At the Rujigou coalfield in the Ningxia Autonomous Region of western China, fires have burned since the late Qing Dynasty (1644-1911). Legend has it that coal miners who were angry over not being paid started a coal fire more than a century ago.
"It was industrial revenge," Guan said.
Many coal fires begin spontaneously when underground seams come in contact with the air — either through fault lines from earthquakes or mining activity — generating a chemical reaction that can slowly heat and ignite the coal. Human activity is an intensifier of the fires, however, especially when workers abandon dust-filled mines without sealing the airshafts, allowing temperatures to build.
China's coal fires stretch across a northern belt that runs nearly 3,000 miles from east to west. A cluster of them are in Ningxia and a little to the north in Inner Mongolia at the edge of the Gobi Desert. The concentration of coal fires in the region puts it in the running for one of the world's worst ecological disasters, and only humans can extinguish the problem.
"These fires just don't go out," said Anupma Prakash, an expert on mapping coal fires at the University of Alaska at Fairbanks.
Coal fires pollute the air with putrid smoke and wreak havoc on water supplies and aboveground ecology, creating "heat islands" where little vegetation can grow, not even hardy grasses. Wildlife flees.
"There used to be rabbits and pheasants around here, but not anymore," said Liang Guobao, who oversees a generator facility at the San Kuang coal mine in the sprawling Wuda coalfields in Inner Mongolia. His generator powers fans to clear the air in underground shafts.
Liang walked with a visitor around the barren landscape, pointing out places where the ground had collapsed after subterranean coal fires ate away seams and left empty caverns.
"The mine started here in 1958, and almost immediately the fires began," Liang said.
Coal fuels China's roaring economy, powering its factories but also taking a human, social and environmental toll. China uses coal for 70 percent of its primary energy needs, far higher than the world average of 40 percent. China's coal production topped 2.3 billion tons last year, equaling the output of the United States, Russia, Australia and India combined, said Yang Fuqiang of the Beijing office of The Energy Foundation, a San Francisco group that promotes energy efficiency.
Even as it provides power, coal exploitation leaves a trail of deaths.
Last year, 3,786 Chinese miners died in accidents, a rate 70 times higher than for miners in the United States.
Coal burning is a principal cause of air pollution in China, where 400,000 people die each year from illnesses related to that pollution, the World Bank estimates, mainly heart and lung diseases.
For those who grew up in the region, the scarring of the hilly environment from unseen coal fires is part of the landscape. Ma recalled walking in the hills as a youth and discovering long, deep fissures in the earth.
"We wouldn't know how deep they were. If we dropped a stone in, we could hear it bounce off the walls . . . but we couldn't hear it hit bottom," Ma said.
As much as 40 percent of China's coal comes from small local mines rather than big state-owned enterprises. Small operators follow a pattern when their mines catch fire.
"When they have a fire, they just leave and go to another place," said Li Jing, the director of the Institute of Resource Technology at Beijing Normal University.
Over the past decade, China has put far greater emphasis on attacking coal fires. The work is labor intensive, costly and dangerous in its initial stages. The blazes can reach underground temperatures of 1,300 to 1,500 degrees Fahrenheit, imperiling firefighters.
"First, they shape the terrain and cool down the surface so the heavy machinery can work," Rueter said. Teams drill holes down through the burning coal in 50 to 60 spots and inject water for several months "to cool down the entire rock volume."
Later, they may make up a slurry of sand, water, cement and some chemicals, and pour it into the holes. Once the fire is out, the entire rock area must fall below 158 degrees Fahrenheit to ensure that the coal doesn't reignite. A layer of clay is put on top and trees planted to gauge whether the fire has begun anew.
Prakash, the coal fire expert in Alaska, said she thought that worldwide efforts to combat coal fires had fallen short.
"The coal exploration is more intense than the coal firefighting efforts," she said. "In the areas I have seen — China, India, Indonesia, South Africa — they haven't gotten any better."
China is sensitive to charges that it may not be doing enough to put out the fires.
Fourteen months ago, it announced with fanfare that it finally had put out the Rujigou coal fires that had burned for decades. A story from Xinhua, the official news agency, said the state had spent $53 million over a decade to douse the fires.
A visit to the site, however, showed that the fires weren't completely extinguished.
"The leaders said they'd put out all the fires," said one miner, declining to give his name for fear that he'd be fired for exposing a falsehood.
"There are many reasons" that the work never was completed, he said. "One reason is that the investment to put out the fires was not enough. And the leaders changed too frequently."
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