They are born all over the planet, some 3.5 million of them a year, beginning life as tiny flickers in the grass. They grow fast; feeding on forests, devouring ground, turning landscapes into ash.
As these fires burn, Brian Magi is watching, scanning maps to see the places the flames have touched, and charting the changes in the way humans are using fire to both form and destroy the land.
Magi, assistant professor of atmospheric sciences in the Department of Geography & Earth Sciences, researches the connections between fire, land, atmosphere and climate – and the role humans play in that mix. This is research that has gained new urgency as the world’s changing climate is believed to have sparked an increase in wildfires – an increase that could hold significant consequences for Earth’s largest remaining forests.
The smell of smoke, the crackle of flames – even in the most urban of people, these can raise a primal prickle of fear. Yet, fire is both a creative force and a key component in the carbon cycle, Magi says.
“When fire burns, it converts carbon stored in trees and grasses into carbon that largely gets into the atmosphere,” he says. “In the global view, fire is a natural part of our ecosystem.”
When California’s wildfires ignited during the worst drought in the state’s recorded history, they left behind a wake of devastation. With shrinking snowpack and drier summers, “the perception that the West is burning more each year is pretty much correct,” Magi says. “But elsewhere in the world, humans use fire to manage landscape on a vastly different scale. Satellites can count fires from space. When you look at those maps, you could see clearly that even with the American West burning as it was, the fires contributed a very small fraction of the total number of fires each year.”
Magi’s research highlights the hotspots where most of the Earth’s fires occur: sub-Saharan Africa, southern Africa, and South America. “Africa is the king of fire in the world,” he says. “Those two continents account for roughly 70-75% of all fires every year. The fires mostly occur outside of the rain forests. Rain forests only burn when very intentional human deforestation is unleashed.”
Fire is the easiest way to manage a cultivated landscape, he says. “When you burn residue from the present year’s crops, that releases the nutrients from the biomass back into the soil,” he says. “You are taking phosphorus and nitrogen back into the soil, faster than through decomposition. It’s very effective. Within days, you’ll have new growth of fresh grass over the savanna.”
Meanwhile, the boreal forest is susceptible to lightning-triggered wildfires. This vast stretch of dense, wilderness forest in the northern reaches of the planet have almost zero human settlement, yet research suggests a connection between the fires and people.
“Wildfires in the boreal forests of Canada and Alaska are on the rise as a result of human-driven climate change,” Magi says. “Russia has boreal forests too, and likely these are burning more too, but data is not as solid as it is for North America.”
Part of what Magi seeks to gain by looking back at fire’s behavior over time is an understanding of future fires, including ones in those forested areas. If, for instance, a changing climate forces farmers to seek more productive pasturelands, lands that they’ll manage through fire, they will inch ever closer to wild areas, Magi says. That means instead of burning savanna as they have in the past, they will burn trees.
“People might move…more deeply into this biomass-heavy region, burning all along the way,” he says. “That’s already happening in the Amazon.”
A National Science Foundation Geography and Spatial Sciences program grant has helped to fund Magi’s research into the ways environment and human activity have influenced fires over time. Magi has been working with colleagues from Yale University and the University of Oregon on the project, which uses satellite-based reconstructions of fire activity, modern-day simulations and a treasure trove of data collected from around the world on the incidence of fire.
“The research we’re trying to do will inform how fire will behave in Earth’s system in the future,” Magi says. “The climate will be changing. If climate and the land are changing, will humans change in a way that changes how fire behaves?”
Magi is using the diverse fire data to advance methods used in global fire simulations, which themselves are a part of the international effort to model future climate. He and a doctoral student funded by the grant will use climate model output and fire data to simulate past fire activity.
He and his colleagues also organized a workshop to bring together dozens of experts on fire, fire data, and fire modeling to learn from each other’s research, and he joined other researchers in Germany for an intensive fire modeling workshop. As he and other researchers delve into the impact of the spread of fire into heavily forested regions, Magi remains optimistic about the answers science could provide.
“All of the solutions are there,” he says. “We just have to figure out how to better balance ourselves with the environment. The fact that we know these things gives me great hope.”
Words: Amber Veverka | Images: Lynn Roberson
