Massive fires are burning throughout Indonesia, casting a noxious pall across Southeast Asia and exploding what some are calling a “carbon bomb” that has global implications. The fires are the result of poor land use practices, deforestation and a delayed rainy season thanks to the strongest El Niño in at least 20 years.

The fires, most of which are burning in peatlands that tend to produce long-lasting, smoky, underground blazes, are having widespread public health impacts, contributing to respiratory ailments and premature deaths in the region. Peat is soil comprised of partly decayed plant material formed in wetlands.

Studies have estimated that forest and peat fires that burn each year across Southeast Asia are responsible for about 110,000 premature deaths per year across the region. This year, the toll may be higher than that.

Satellite image from September 24, 2015, showing smoke from wildfires burning across Indonesia.

There have been nearly 100,000 active fire detections in Indonesia so far in 2015, according to the World Resources Institute. This is higher than 2006, which was one of the highest fire years on record, but lower than 1997-98, which was the worst fire year.

Image: World Resources Institute

The situation in Indonesia, which has culminated in a huge spike of fires this week, according to Global Forest Watch, are reverberating throughout the global climate system.

Peat fires can belch huge amounts of carbon dioxide — the most important long-lived global warming pollutant — into the atmosphere.

According to data from Guido Van der Werf of Vrije Universiteit Amsterdam, the fires so far this year have emitted an estimated 1 billion tons of carbon dioxide equivalents, which is higher than the average annual emissions of Germany. (Such fires also emit soot and other pollutants that also affect the climate but in different ways and on different timescales than carbon dioxide.)

By the time the fires are put out, and no one knows precisely when this will be, the emissions may even come close to meeting or beating India’s, Van der Werf says. This is astounding, considering that India ranks high on the list of largest emitters worldwide.

"Since September, daily emissions from Indonesia’s fires exceeded daily emissions from the entire U.S. economy on 26 days,” WRI found. The U.S. is the number two country, behind China, on the list of top annual emitters of carbon dioxide.

The Indonesian government has stated that peatland fires and deforestation account for 63% of the country’s greenhouse gas emissions.

Indonesia's President Joko Widodo inspects a peatland clearing that was engulfed by fire on Borneo island on Sept. 23.

“As governments prepare to meet in Paris to save the world from catastrophic warming, the earth in Indonesia is already on fire. Companies destroying forests and draining peatland have made Indonesia’s landscape into a huge carbon bomb, and the drought has given it a thousand fuses. The Indonesian government can no longer turn a blind eye to this destruction when half of Asia is living with the consequences,” said Bustar Maitar, Indonesian Forest Project Leader for Greenpeace Southeast Asia, in a statement on Sept. 17.

Peatlands around the world are a critical storage area for carbon dioxide, with most of it sequestered into the saturated soil. When peatlands are dried and burned, which can be cheaper than clearing land with heavy equipment, they release the carbon that took centuries to accumulate, emitting in a geological instant the global warming gases that nature had painstakingly deposited.

Such "slash and burn agriculture" is a major cause of carbon emissions and habitat destruction for rare species like orangutans, gibbons and leopards.

El Niño’s role

The unusually active fire season in Indonesia is largely the result of two colliding factors: the agricultural practices in the country, with large and small farmers setting blazes to clear previously forested land or to clear cut land for further planting; and one of the strongest El Niño events on record.

Indonesia fire count (high confidence fires) so far in 2015 compared to data going back to 2013. Image: Global Forest Watch

El Niño, which is characterized by unusually mild ocean conditions across the equatorial tropical Pacific Ocean along with weakened or reversed trade winds, tends to shift rains away from Indonesia during August through October. This is the time of year when Indonesia tends to be dry anyway, but El Niño accentuates this dryness and can lengthen it straight into November, according to Tony Barnston of the International Research Institute for Climate and Society (IRI) at Columbia University.

When there is a strong El Niño, the return to more rainfall is delayed, as we’re seeing now; “It’s not getting wetter at all so far, and the rest of October will probably be bone dry,” he wrote in an email to Mashable. Barnston is the chief forecaster at IRI.

According to Susan Minnemeyer, who works on the Global Forest Watch database for the World Resources Institute in Washington, analysis of satellite-detected fires shows a sharp spike on Oct. 14, which was “significantly higher than peaks for either June 2013 or November 2014, which were the two previous largest peaks,” she told Mashable in an interview.

Map showing typical effects of El Nino events, showing below average rainfall across Indonesia. Image: IRI

The peak in “high confidence” fires, which are hotter fires more likely to be associated with land clearing, was 1,729 on Oct. 14. However, the total number of fires detected through the Global Forest Watch database was a whopping 4,719 on that day. Minnemeyer says there is a low likelihood, about 6%, of false positive fire counts.

Satellite-based fire detections for Indonesia in 2015 compared to other years when this data was available. Image: Guido van der Werf

Minnemeyer says there has been a recent decrease in the number of fires in South Sumatra, but an uptick in fire activity in Kalimantan.

“Emissions from the fires from the beginning of September were nowhere near the number where they are now,” she said.

Land use

The Global Forest Watch tool shows that 50 to 60% of the fires in Indonesia are happening outside of land devoted to agriculture, indicating that small landholders and medium-sized developments that have not been mapped are involved as well.

Some fire is also burning in land set aside for producing paper, wood and palm oil, particularly in Kalimantan, also known as Borneo.

On peat lands, the land is drained of water and dried after clearing it of vegetation. Such drying makes it particularly flammable, Minnemeyer says. Peat fires often start above ground but sizzle their way underneath the surface, where they can smolder for weeks to months on end.

Peat is difficult for farmers to grow crops on because of its acidic soil, and fire is actually a tool used to make the land more suitable. Burning peat improves the soils’ fertility, Minnemeyer says, “bringing it into a zone where it’s possible to grow crops on it.”

What’s happening this year, though, is that the fires that have been set or started naturally by lightning or other causes have quickly grown so large that they are “virtually impossible to put them out,” Minnemeyer said.

The fires are even occurring in land supposedly protected from agricultural development, she said.

2015 fires in Indonesia based on land concessions and land use. Image: Global Forest Watch/WRI

“We’ve been seeing huge numbers of fires in large protected areas this year,” she said. “... It doesn’t seem that they’re actually converting land inside the park but there must be people getting in there or some other means of starting the fires.”

Indonesia has long struggled with destruction of its lush rainforests for the purposes of harvesting wood and palm oil, which is used in food products as well as personal care brands. In recent years, the government of the country has promised to crack down on clearing forested land, though the evidence is mixed on how successful this has been.

Regarding the greenhouse gas emissions from these fires, Van der Werf told Mashable in an email that “It is easy to point the finger to Indonesia but they will (rightfully so) point their finger back at us for emitting much more (in a cleaner way, that is true).”

“One key issue is that these fires can be prevented with better land management,” Van der Werf wrote. He said that two aspects of the way land concessions are distributed in Indonesia are complicating the situation. First, many of the land concessions, which is where agricultural production is permitted, happen to be located on peatlands. The second is that many of the concessions are also in areas where small landholders were already living.

“Keep in mind that the larger companies exclude fires often better than the smallholders simply to protect their assets, but because of tensions they both suffer,” he wrote.