Centralia, Pa., coal fire is one of hundreds that burn in the U.S.
The underground coal fire that has slowly consumed Centralia, Pa., isn't unusual. Many such fires burn around the world.
The fire burning deep below Centralia, Pa., is just one of numerous coal fires burning in at least 20 states today, with thousands more worldwide. They gobble up resources, spew dangerous emissions, and scar the land. Yet little is known about their impact on climate change or human health due to carbon dioxide and mercury emissions, say experts.Skip to next paragraph
In Pictures The last days of Centralia
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Approximately 200 underground coal fires burn in about 20 states, according to Glenn Stracher, a researcher at East Georgia College in Swainsboro, Ga., A separate tally shows 112 fire sites in 21 states, according to Office of Surface Mining data analyzed by Dr. Stracher and fellow researcher Ann Kim.
Causes of such coal fires range from spontaneous combustion to lightning to wildfires that ignite coal seams that then move underground to smolder and burn at temperatures that can reach 500 degrees F. or more.
Analysis of heat-fused rock "clinkers" shows that coal fires are an ancient phenomenon. "We've been dating clinkers, showing coal fires have occurred for at least couple of million years, so they're not new," says Mark Engle, a researcher at the US Geological Survey, "but undoubtedly human activity has exacerbated it."
Fires emit toxic emissions
In 2002, the US Environmental Protection Agency estimated that underground coal fires around the world emitted about 48 tons of mercury annually.
Worldwide, thousands of underground coal fires burn, with perhaps 1,300 in Indonesia alone, says Dr. Stracher, who is editing a four-volume scientific compilation of coal and peat fires around the world. He estimates that fires are burning in at least 20 nations, but notes that researchers have little understanding of their environmental damage and the scope of their impact on human health.
"The truth is, we don't really have a good regional or global estimate of emissions from these fires," Stracher says. "It's quite possible the emissions from these fires should be a significant part of the climate change models. We just don't know."
The coal fires also spew a lot of toxins into the atmosphere, causing water and soil pollution, he notes. Mercury is among the hazardous emissions – along with millions of tons of CO2. One estimate by French researchers in a 2007 study put carbon dioxide emissions from coal fires at .3 percent of global emissions.