Author: Laurel Hamers / Source: Science News
In 2015, massive wildfires burned through Indonesia, sending thick smoke and haze as far as Thailand.
These fires were “the worst environmental disaster in modern history,” says Thomas Smith, a wildfire expert at King’s College London. Smith estimates that the fires and smoke killed 100,000 people in Indonesia and neighboring countries and caused billions of dollars in damage. The fires were costly for the rest of the planet, too: At their peak, the blazes belched more climate-warming carbon dioxide into the atmosphere each day than did all U.S. economic activity.
Two years later and 13,000 kilometers away, a fire smoldered on the fringes of a barren, northern landscape. The remote blaze could have gone unnoticed. But Jessica McCarty and other fire researchers actively monitor satellite imagery of Earth the way some people check Facebook. One Sunday in August, McCarty, of Miami University in Ohio, was surprised to see massive plumes of what appeared to be white smoke over a swath of Greenland. The giant landmass had not been on her fire radar. It’s mostly ice, and the parts that aren’t have sparse vegetation.
The settings of these two blazes couldn’t have been more different, but scientists suspect the two had something important in common: plenty of decaying organic matter known as peat.
Peatlands — which include bogs, other swampy wetlands and, yes, Greenland’s icy soil — are ecosystems rich in decayed organic matter.
In their healthy, soggy state, peatlands are quite fire resistant. So when it comes to fire risk, peat-heavy landscapes haven’t historically gotten the same attention as, say, the dry pine forests of the western United States. But with those devastating peat fires in Indonesia, the spotlight has turned to the planet’s other peatlands, too.
Worldwide, peatlands store massive amounts of carbon in thick blankets of wet organic matter accumulated in the ground over centuries. And though they cover just 3 to 5 percent of Earth’s land surface, peatlands store a quarter of all soil carbon. That adds up to more carbon than all of the world’s forests combined.
But changes in land use — draining the water to plant acres of crops that demand drier soil, a common practice in tropical regions, or building a road through an area — can dry out the peat. And then, a single carelessly tossed cigarette or an errant lightning strike can ignite a fire that will smoke and smolder for months, releasing thousands of years of stored carbon as carbon dioxide into the atmosphere.
Or fires set to clear land for agriculture can get out of hand, like they’ve done in Indonesia: Over the last few decades, the country has drained many of its peatlands to grow oil palms and other crops. Now, the country is seeing the worst-case scenario of what can happen when peatlands are disrupted and desiccated. In northern latitudes, meanwhile, thawing permafrost exposes peat that has been buried for years, which can fuel fires like those seen in Greenland last summer.
In the short term, peat fires clog the air with deadly smoke and smog. In densely populated areas such as Indonesia, blazes can devour homes and businesses and claim lives. But the fires’ impact lingers long after the flames die down. Peat fires reshape entire ecosystems. Once the peat burns away, it can take thousands of years to build up again. And all of the carbon that was once neatly stored away is instead floating around in the atmosphere, contributing to climate change much like burning coal does.
Now, scientists are trying to get a better handle on peatlands and the effects of agriculture, development and a climate that’s shifting toward warmer and drier. Recent discoveries of hidden peatlands in Africa and South America expand the extent of peat around the world, and up the stakes for protecting those carbon stores. New research is making it increasingly clear that, without a shift in approach, humans might strip away healthy peatlands and get, in return, a lot of climate-warming carbon dioxide.
Bogs don’t conjure warm, fuzzy feelings for most people. The landscapes are often associated in popular culture with witches, Europe’s mummified “bog bodies” and dreary weather. It’s perhaps telling that “quagmire” — another word for a bog — is also used to refer to a sticky predicament. But to the scientists who study them, bogs are far from bleak.
“Most people walk far, far out of their way to avoid walking through these things, but I love them,” says Merritt Turetsky, a peat researcher at the University of Guelph in Canada. The bogs that she studies in Canada and Alaska look like “hobbit ecosystems,” she says, with all of the action happening low to the ground: stunted trees studding a colorful carpet of mosses and lichens. And, she points out, bogs play a crucial role in keeping our planet healthy.
Carbon is constantly being recycled throughout the world: It’s taken in by plants as carbon dioxide, for example, and is dissolved in the oceans. But excess circulating carbon can throw ecosystems out of whack. Too much carbon dioxide in the atmosphere makes the planet heat up; too much dissolved in the ocean makes the water more acidic. Long-term carbon stores in ocean sediments and rocks such as limestone pull carbon out of the short-term cycle, cloistering it where it can’t do harm. The same goes for peatlands; dig down many meters into a bog, and you’ll find carbon that’s been buried for thousands of years.
And while the untrained eye might look at a bog and see nothing but a soggy morass that calls for waterproof waders, peatlands can be surprisingly diverse. In the tropics, where swamp forests are filled with large, leafy trees, blankets of peat are typically built up by decayed woody plants. Temperate peatlands, like those in the northern United States and Canada, sport scrubbier vegetation and are made mostly from decayed sphagnum moss.
Peat is “not exactly nonrenewable, but it accumulates so slowly,” Turetsky says. “A fire can burn through a dry bog and literally release thousands of years of carbon in a couple minutes of combustion.” She learned that firsthand as a graduate student.
Almost 20 years ago, she buried small bags of peat in a Canadian bog to study their decomposition. When she returned two years later to dig up the samples, her entire field site had gone up in smoke. Her precious data were gone.
“I was devastated for about a day,” Turetsky says. “But then I started thinking about it: We were shocked that this system had burned.”
The very next day, she started collecting new data, this time observing how the bog recovered from the fire. Back then, she says, people assumed…
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