A pedestrian walks along Honoapiilani Highway near properties destroyed by the West Maui Fire in Lahaina on the island of Maui, Hawaii on Aug. 17.Stephen Lam/The Associated Press
Twenty years ago, Jack Minassian stared out of a helicopter at something he expected never to see. Beneath him was the Hawaiian rain forest, and it was on fire. Flames towered 45 metres into the sky.
“This was in an area that wasn’t supposed to burn,” said Mr. Minassian, who at the time was the fire management officer for the National Parks Service throughout the Pacific islands. A nearby weather station registered a relative humidity reading of just two per cent. That’s “an oven reading,” he said.
Mr. Minassian had moved to Hawaii in 1988 and recalls people telling him, “You don’t have to worry about the rain forest, it won’t burn.” Parts of Hawaii’s Big Island, after all, rank among the wettest areas of the United States, with annual rainfall in excess of five metres.
And yet, fire has come here, as it has to tropical forests in Brazil and Indonesia, to the redwoods in California and the lush, temperate rainforests of the Pacific Northwest. Earlier this summer, a fast-moving wildfire destroyed a home near Forks, Wash., a place typically so damp and gloomy it became a fictional homeland for vampires.
In Hawaii, meanwhile, fire is now consuming three times the number of forest hectares it did in the 1980s – even before the devastating wildfire this month that destroyed homes and killed dozens of people in the Maui community of Lahaina.
A changing climate is an obvious culprit, with elevated temperatures generating more severe weather, drying out landscapes and then whipping them into an inferno with strong winds. Not even Earth’s soggiest places, it seems, can promise succour from the flames any longer.
But the Maui blaze, the deadliest wildfire in the U.S. in more than a century, also comes as those studying wildfires find growing evidence of the sometimes disastrous consequences when landscapes are transformed by human action.
In Hawaii, “these fires weren’t happening 30 years ago, during the plantation era,” said J.B. Friday, a forester at the University of Hawaii.
“The underlying driver is the abandonment of agricultural lands.”
Forests once covered dry areas of the Hawaiian Islands. When they were cleared to grow pineapple and sugarcane, plantation managers ensured the land was irrigated and tended. But the shuttering of the state’s plantations – the last sugar mill closed in 2016 – has left large tracts of neglected land.
“The native forest doesn’t come back by itself,” Dr. Friday said.
Instead, non-native grasses have taken over. Early ranchers brought Kikuyu from East Africa to support grazing. Homeowners planted ornamental fountain grass. Buffalo grass and molasses grass, too, have spread widely.
Those grasses “are very flammable,” said Dr. Friday, a condition exacerbated by weather oscillations associated with climate change. Wetter winters yield greater volumes of grasses, which then dry out in the summer, providing additional fuel for fires. Sixty per cent of significant wildfires in Hawaii in 2019 were on former agricultural land, with most of the remainder in areas with non-native plants. Less than two per cent were on native shrub land or forest.
This isn’t true everywhere, of course. The immense fires across Northern Canada this year have swept through stands of boreal forest, some little touched by humans. Many had natural origins, like lightning.
But in Hawaii and other parts of the world where wildfires have swept through tropical areas, humans have played a far more active role.
This year marks the return of El Niño, a weather pattern that has in the past yielded severe wildfires in Asia and South America. In Brazil, researchers are bracing for another year of flames, recalling what happened seven years ago, when more than 9,000 square kilometres of Amazon forest burned.
“When we have severe droughts like the one we had in 2015, 2016 – and the one we’re going to have this year – the number of fires increases a lot. And the frequency of such drought is increasing,” said David Lapola, a research scientist at the Center for Meteorological and Climatic Research Applied to Agriculture of the University of Campinas in São Paulo.
“Climate change doesn’t allow proper time for the forest to recover, because recovery from such a dry spell for the forest should take at least a few decades.”
But in Brazil, too, human intervention has played a role. Wetter forests in southern parts of Roraima state “were considered immune to fire,” Brazilian scholars wrote in research published in 2021. However, they found logged tracts were several times more vulnerable to ignition and nearly 90 per cent more likely to be engulfed by a fire considered “very strong.” (The Forks fire similarly ignited in a clear-cut; it slowed when it hit the timberline.)
In Indonesia, it’s much the same.
“Fires in Indonesia are anthropogenic,” said Gusti Anshari, a tropical peatland researcher at Indonesia’s Tanjungpura University. “Most fires occur on degraded forests and unmanaged lands, which are barren.” Dry weather creates the conditions, and “drained peatlands and degraded vegetation become flammable.”
In tall grasses, particularly when stoked by high wind, “the fire travels faster than you can run,” said Dan Gavin, a biogeographer at the University of Oregon who studies climate change. “It’s a wicked problem.”
Worse, the first vegetation to grow back after a wildfire can be especially flammable. In Oregon’s wet forests, some areas have begun to experience reburns.
It all begs questions about how to respond. Prof. Gavin says technological change is needed in the transmission of electricity, because power lines can spark fires. There is cause for reviving old forestry practices, too, said Don Hankins, a pyrogeographer at California State University, Chico, who is of Indigenous descent. Indigenous groups in many parts of the world historically used fire to tend forests, reducing the fuel that could otherwise yield runaway blazes.
“If we look to reapply those practices, then it’s really our best hope at making a difference,” he said.
Urban design could help, too. One Lahaina house that notably survived the recent fire was equipped with a metal roof. Building a golf course on the perimeter of a neighbourhood rather than at its centre would provide “an effective firebreak,” Mr. Minassian said.
It may also be time to consider holding responsible those whose lands – be they vacant plantations or otherwise – have become fire hazards, Dr. Friday said. Perhaps, he said, they could be obligated to maintain firebreaks. Or ranchers could be incentivized to have livestock graze. Reforestation could help, too.
“Bottom line is we need to manage these lands,” he said. “If you don’t manage the land, bad things happen.”