To what extent will our future on Earth be shaped by fire? As the world gets hotter, the risk of more and bigger fires increases.

2010 was the hottest year on record, with global temperatures 0.53 degree Celsius above the 1961-1990 average. This year is not as hot so far. But serious drought has still gripped parts of the Americas and Africa.

Blair Trewin, an Australian climatologist, says that warm extremes are increasingly outnumbering cold extremes as the influence of the background warming trend strengthens.

David Bowman, Ph.D., professor of environmental change biology at the University of Tasmania and lead author of a recent study on the global effects of fire, says this “could lead to a dangerous feedback as more burning releases more carbon into the atmosphere, further driving climate change.”

He and his international team of researchers are concerned about the total impact of four kinds of fires, and the way they are combining to intensify climate impacts. The four are natural fires that occur regardless of humans, for example by a lightning strike; tame fire used by hunter-gatherers to manage landscapes for game and wild food production; agricultural fire to clear land cheaply and grow food and plantation crops — a widespread practice in Indonesia and other parts of Southeast Asia; and industrial fire to power modern societies that have switched from using living to fossilized plants in the form of coal, oil and natural gas as the primary fuel.

Bowman warns that the excessive combustion of fossil fuels to generate electricity, power heavy industry and run modern transport is driving climate change and may completely overwhelm human capacities to control fire.

Fire has been around since shortly after plants colonized the surface of the Earth over 400 million years ago. Humans learned how to use and control it. But a group of specialists commissioned by the U.N. Food and Agriculture Organization (FAO) reported in May that in many parts of the world, the number of large wildfires has been increasing at an “alarming” rate, causing ever-higher suppression costs, property losses and environmental damage.

The biggest and most damaging, which the report calls “megafires”, overwhelm efforts to extinguish them, even in developed countries that have made major investments in firefighting capacity, better predictive systems, improved technology and cooperation, and larger fleets of aircraft to drop water and fire-retardent chemicals from the air.

Megafires exceed all efforts at control until firefighters get a favorable change in weather or the fire runs out of combustible fuel to burn.

China’s 1987 Great Black Dragon Fire may mark the start of the megafire phenomenon in the modern era. It killed over 200 people and burned about 1.2 million hectares of virgin pine forest.

The specialists commissioned by the FAO focused on eight megafires since 1997, in Indonesia, Brazil, the United States, Greece, Botswana, Australia, Russia and Israel. They found that nearly all had human causes. They were either lit intentionally or by negligence.

The Indonesian fires in 1997-1998, raged out of control for months, burning over 9.7 million hectares and releasing approximately 700 million tons of greenhouse gases into the atmosphere, making them one of the world’s largest pollution sources. The smoke engulfed Singapore, Malaysia and other parts of Southeast Asia, disrupting transport and acting as blanket that trapped other pollutants harmful to human health.

Wildfires release a range of chemicals into the atmosphere, similar to those from fossil fuel burning. They include the greenhouse gases carbon dioxide and methane, but also other air pollutants such as carbon monoxide, nitrogen oxides, volatile organic compounds, aerosols and fine particles of soot.

The gaseous pollutants also influence tropospheric ozone formation, a pollutant as well as a potent greenhouse gas.

Gabriele Pfister, a scientist at the National Centre for Atmospheric Research in Boulder, Colorado, has investigated how smoke from forest fires travels and its impact on air quality far from the fires.

She says that about half the world’s air pollution comes from wildfires and that a bad fire year can result in pollution from the fires circling the globe.

Bowman says that managing flammable landscapes is one of the big climate change adaption challenges, equal to the challenge of sea level rise in densely populated, low-lying coastal zones in Asia and elsewhere.

This is a warning that Asian countries should heed. They should work more closely together to improve land management and fire prevention.

Michael Richardson is a visiting senior research fellow at the Institute of South East Asian Studies in Singapore.

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