Indonesia Peat Fires May Fuel Global Warming, Experts Say

As they have every dry season for the last 20 years, once lush tropical peatlands in Indonesia smoldered for weeks this year, leaving the region cloaked in a thick, carbon-rich haze.

The rainy season arrived at the end of October, squelching the flames. Even so, Jack Rieley, a peatland ecologist at the University of Nottingham in the United Kingdom, had no time to sigh in relief. With the rains come the floods.

"Another downside is the peatlands are losing their water-retention potential," he said. "Surrounding areas, especially those downstream, tend to flood quicker now."

The downsides, according to Rieley, result from the vast chunks of Indonesia's peatlands that have been burned, logged, drained, and left vulnerable to fire. It's all part of an effort to feed a burgeoning population of more than 210 million people and jump-start an ailing economy.

Tropical peatlands consist of layer upon layer of forest debris too wet to decompose. They cover approximately 50 million acres (20 million hectares) in Indonesia, or nearly 11 percent of the country's total land area. Key areas of peatland burning include Borneo, Sumatra, and West Papua.

Rieley is the co-leader of an international project that has studied the ecology of the peatland in the province of Central Kalimantan in Borneo since 1993.

Scientists know that these peatlands serve as gigantic stores of carbon. They have accumulated woody debris for millennia, locking it up in soggy piles that in places reach 66 feet (20 meters) deep.

Now that the peatlands regularly burn, Rieley and his colleagues say these carbon stores have become carbon sources. They're rapidly increasing atmospheric concentrations of the greenhouse gas carbon dioxide (CO2), potentially spurring global warming.

"I am a peatland expert, not a climate one," Rieley said. "What I do know, however, is that tropical peatlands are releasing a very large amount of carbon from [storage] that is likely to be contributing to the accelerating increase in CO2 in the atmosphere."

"If other experts believe that this higher level of CO2 is propelling global warming, then of course tropical peatlands are part of that," he added.

Larry Smith is an associate professor of geography at the University of California, Los Angeles, who studies the vast peatlands in Siberia. He said scientists are just now beginning to understand the role peatlands play in the regulation of greenhouse gases. Healthy peatlands absorb carbon dioxide as new vegetation grows, serving as a carbon sink. But microbes that thrive in these oxygen-poor, soggy environments slowly and incompletely decompose the plant material, causing peat to accumulate over time.

"A primary product of anaerobic [oxygen-poor] decomposition by microbes is methane," Smith said. "As [the peat] is decomposed, some carbon is released as methane rather than carbon dioxide."

Calculations on how much carbon peatlands store show that most of the world's peatlands are "slight sinks to neutral in terms of their net carbon balance," Smith said.

He and his colleagues are now trying to tease out the details of where the balance for Siberian peatlands teeters—from being a slight carbon sink or neutral to a source of carbon. Preliminary calculations suggest peatland could become carbon generators if global temperatures continue to rise, drying out the peatlands.

According to Rieley and his colleagues, the balance has already swung in Indonesia. Historically, tropical peat bogs have absorbed carbon at much faster rates than the peatlands in more northern latitudes.

"They are obviously of great importance in the global carbon cycle," Rieley said. "This role is now being destroyed by inappropriate land use and fire that has changed tropical peat bogs from sinks into sources of carbon."

Mega Rice Project

For decades Indonesia's peatlands have been burned and drained to make room for agriculture and settlements, but in 1995 the pace of destruction quickened with former dictator Suharto's Mega Rice Project.

The project was intended to turn Central Kalimantan into the country's rice bowl by logging and draining approximately 2.5 million acres (1 million hectares) of peatland and planting it with rice.

For two years workers cleared the forests and dug some 2,900 miles (4,600 kilometers) of canals, some as wide as 100 feet (30 meters). The canals were to keep the soil drained in the rainy season and crops irrigated in the dry season.

But the plan backfired. The peatlands are raised above the adjacent rivers, so the constructed canals only sucked the peatlands dry. Then in 1997 the El Niño weather phenomenon brought a severe, eight-month drought to the region. The high and dry peatlands went up in flames.

Rieley set out to measure the carbon released by the fires. He was joined by colleagues Florian Siegert of the Ludwig-Maximilians-University in Munich, Germany, and Susan Page of the University of Leicester in the United Kingdom. The team used a combination of satellite imagery and ground measurements to estimate that the 1997 peat and forest fires released between 0.87 and 2.57 billion tons of carbon into the atmosphere.

"Undoubtedly these fires and associated carbon loss from degrading peat converted to agriculture and settlement are contributors to the accelerating increase in atmospheric CO2 concentrations," Rieley said.

The team's original report appeared in the science journal Nature in 2002. In today's issue (November 11, 2004) of the journal, a news feature investigates the current crisis and the conservation community's attempts to bring the peatlands back to life.

At a press conference on Wednesday, Rieley and colleagues called on political leaders and international aid organizations for support in their efforts to save the Indonesian peatlands.