Climate

For Peat’s Sake: Drying And Burning Wetlands Amplify Global Warming

CREDIT: AP Photo/Rony Muharrman

A firemen sprays water to try to put out peatland fire in Indonesia, Sept 16, 2014.

“Smouldering peat fires already are the largest fires on Earth in terms of their carbon footprint,” explained mega-fire expert Prof. Guillermo Rein last week. He is coauthor of a new study called “Global vulnerability of peatlands to fire and carbon loss,” which warns that massive, difficult-to-stop peatland fires are likely to become even larger in the future, as human activity keeps drying out the formerly wet peatlands.

Since a key reason many peatlands will become drier is global warming, and since peatland fires can release staggering amounts of carbon dioxide, this process is a vicious circle, a dangerous amplifying carbon cycle feedback.

Most of the world’s wetlands are peat, which are better known as bogs, moors, mires, and swamp forests. Wikipedia notes, ”Under the proper conditions, peat is the earliest stage in the formation of coal.”

The study explains why the loss of peatlands is of such great concern to scientists: “Globally, the amount of carbon stored in peats exceeds that stored in vegetation and is similar in size to the current atmospheric carbon pool.”

Massive Indonesia peatland fires of 1997 and 1998, when it was especially dry from El Niño, burned almost 25 million acres, among the largest set of forest fires in the past two hundred years. A 2002 Nature analysis estimated the CO2 released by those fires was “equivalent to 13–40% of the mean annual global carbon emissions from fossil fuels, and contributed greatly to the largest annual increase in atmospheric CO2 concentration detected since records began in 1957.”

Why do such fires release so much carbon? As one soil scientist explained in November, it is typical in Indonesia that “even after the forest fires end, the peat continues to smolder underground until all organic matter has completely burned into ashes.”

A 2008 Nature Geoscience study — “High sensitivity of peat decomposition to climate change through water-table feedback” — projected that “a warming of 4°C causes a 40% loss of soil organic carbon from the shallow peat and 86% from the deep peat” of Northern peatlands. On our current emissions path, the world is set to warm well beyond 4°C (7°F). According to the 2008 study, “We conclude that peatlands will quickly respond to the expected warming in this century by losing labile soil organic carbon during dry periods.”

20100225-rehabA 2011 study led by University of Guelph professor Merritt Turetsky found that “drying of northern wetlands has led to much more severe peatland wildfires and nine times as much carbon released into the atmosphere.” Turetsky noted at the time, “Our study shows that when disturbance lowers the water table, that resistance disappears and peat becomes very flammable and vulnerable to deep burning.” And that’s when peatlands turn from a CO2 sink to a CO2 source.

The latest peatlands study was also led by Turetsky. It explains that “drying as a result of climate change and human activity lowers the water table in peatlands and increases the frequency and extent of peat fires.” Tragically, Indonesia has drained a great deal of its peatlands (and even burned forested areas) to create palm oil plantations, a key reason there are so many forest fires and smoldering peat fires — fires that often ruin the air quality in the region.

“The scary thing is future climate change may actually do the same thing: dry out peatlands,” explained another co-author, climatologist Guido van der Werf. “If peatlands become more vulnerable to fire worldwide, this will exacerbate climate change in an unending loop.” As several 2014 studies made clear, climate change will dry out and Dust-Bowlify large parts of the planet’s arable landmass.

The new study concludes that “almost all peat-rich regions will become more susceptible to drying and burning with a changing climate.” It’s time for humanity to try harder to slash carbon pollution and avoid triggering yet another amplifying carbon cycle feedback.