Forest Fire

BURN NOTICE: New technology can tell us where forest fires are, and how they behave

How do you study a forest on fire? When the heat has reached nearly 1500˚F, and there is no breathable oxygen, and the trees begin to explode, the center of the flames is an unsurvivable environment; it might as well be the surface of the sun.

And that means science has been essentially blind to the behavior of forest fires for most of modern history. We simply haven’t known whether flames leap from tree to tree, or if they creep along the earth’s surface, and to what extent trees burn at their base, or high into their canopies.

The truth is that firefighters often don’t know about forest fires for hours after they begin burning. The cutting edge of forest-fire detection in the United States is currently the Active Fire Mapping program, run by the forest service. Its satellite flies once each day over a scattered network of ground stations across 180 national forests across the United States, looking for thermal infrared radiation high enough to suggest a fire.

But forest fires can cost more than $1.5 million per square mile burned, and so a once-a-day detection system allows the flames to grow for hours unnoticed.

Small sensors scattered through a forest could help. In a test in Southern California, 14 small sensors were placed in a 1.5-acre area, which researchers then burned. The sensors—small cylinders hardened against the weather with a thick wax coating—detected the fire right away. “It took four minutes after the fire was set,” says Brent Chapel, CEO of ProximaRF, the company that built the technology. His company estimates that if firefighters can reach a blaze within half an hour, they can hold it to seven acres or less, on average. (Recent burns in Northern California reached tens of thousands of acres within two days of detection.)

The difficulty is keeping these sensors functional through years of rugged weather. “My concern is that it can be several years before a fire occurs in a particular area, so if we put the sensors in that area, will they still work?” says Ralph Gonzales, the fire program leader at San Dimas Technology Development Center, the forest service’s research group that led the test. But if the sensors can be hardened for years of operation, and the onboard RFID or wi-fi technology can be made cheap enough, we might learn, once and for all, how fires move through the wilderness.

In the meantime, the best way to detect fires early may be to watch for them from above. One country is already using a whole satellite network to monitor its burns. Canada’s Natural Resources ministry has rented the eyes of 178 tiny satellites, operated by a San Francisco-based startup, Planet, to watch its 857 million acres of forest. The rate of detection is still no better than once a day, but whereas the US system can see only down to a single kilometer, and has patchy coverage, the Canadian program uses machine learning to detect fires anywhere in the entire country, using smoke and flame imagery to calculate the size and speed of the fire, and where it’s likely to go.

The trouble, of course, is that containing these fires may not be the ultimate solution. Scott Stephens, professor of wild land resource science at UC Berkeley, uses historical evidence, like 19th-century paintings of Yosemite and other national parks, to estimate the size of past fires, and the degree to which we’ve let our forests grow more dense than they used to be. He conducts experiments in controlled burns at a special research forest in California, and he estimates that the natural cycle of fires here used to consume at least 10{9bb277a29d88ac2b3c3629eae3e23f14252dcf4b29f05cc003facefab6673bd7} of the state each year. That’s the way nature does it. And yet “if 10{9bb277a29d88ac2b3c3629eae3e23f14252dcf4b29f05cc003facefab6673bd7} of California burned, it would be the single greatest natural disaster in modern US history,” he says. The technology can help us detect forest fires early, and sensors can help us model how those fires behave, but at some point we’ll have to reckon with the fact that stifling the natural cycle of fire and regrowth may simply fuel the problem.

Photo by Luke Flynt on Unsplash

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