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Wildfires are spreading to fuel-rich regions of the world that used to be less prone to burning, according to a new analysis of 20 years of data by The Guardian.
While the overall annual burning area in the world has remained relatively static in this period, research indicates a changing regional fire pattern that is affecting more forests and fewer grasslands.
In recent years, fires have devastated areas of California, Australia, Siberia and the Pantanal that used to be relatively unaffected. In Africa, by contrast, there has been a reduction in savanna fires.
Experts believe that changing fire patterns are driven by human factors: global warming, which is creating more dusty conditions in forests, and land conversion, which is turning grasslands into agricultural fields, conurbations and roads.
The causes and consequences are still being studied, but scientists worry that this change will put more carbon dioxide from forests into the atmosphere, while eroding the unique biovitality of grasslands, which are better adapted to fire.
“Since the early 2000s, we are seeing a decline in grassland fires, which dominate the global numbers. At the same time, there is an increase in some fuel-intensive systems, such as the western United States, that various studies have linked to climate change, ”said Niels Andela, an expert in remote sensing at Cardiff University. “This trend is not yet visible everywhere, but it is likely to become more apparent in other parts of the world.”
Drying has made Australian forests more vulnerable
In Australia last year, the fire season was exceptional due to the location of the fires rather than the number of square kilometers burned.
The affected area actually decreased in 2019, but the smoke cloud was three times larger than any other sight before. The scientists described it as “a new benchmark for the magnitude of stratospheric disturbances.”
Most years, large fires are allowed to spread through the sparsely populated northern and western regions. But in the 2019-20 fire season, fires raged across the southeast, consuming forests that weren’t used to fires of this scale.
Dr Pep Canadell, chief research scientist at the Commonwealth Scientific and Industrial Research Organization’s Climate Science Center in Australia, blamed the highest temperatures in more than 100 years, a two-year drought in many parts of the world. southeastern Australia that dried up the forest and provided fuel for the fire. He cautioned that those trends are likely to continue.
“There is no question that climate change was a very significant factor in the extreme fire activity of the last season. We’ve always had droughts and heat waves leading to extreme fire weather conditions, but our long-term background temperature trend is now 1 ° C above pre-industrial level, with heat waves much hotter and longer than before. , and consistent with the rise in temperature, our droughts. now they are hotter, which makes the drier fuels burn faster. “
Map of australia
California fires are spreading north
Like Australia, California fires are spreading to new places as their size and frequency hit record highs.
John Abatzoglou, associate professor at the University of California, Merced, said: “In forested systems, including those that sustain firefighting responses like those in the US and Canada, we have seen an increase in burned area and a series of very large fires in recent decades. “
He said part of the blame can be attributed to a hot and dry climate that makes potential fuels vulnerable to fire.
“The confluence of increased fuel consumption in a warmer, drier climate has certainly contributed to the large increase in burned forest area in parts of the western United States.”
Dr. Matthew W Jones, Senior Research Associate at the Tyndall Center for Climate Change Research at the University of East Anglia, said: “There has been a staggering eight-fold increase in the area burned by wildfires in California over the past 20 years. Changes on this scale are not only seen in California, but in the forests of the western United States generally.
“Water is increasingly scarce and forests dry out more regularly during spring, summer and fall. Forests are essentially becoming tinderboxes for rich fuels, set to burn more frequently as a result of climate change. “
California map
Repeated drying pattern in southern Europe
Climate change-related drying has also contributed to increased fire activity in southern European countries such as Portugal.
According to Dr. Jacquelyn Chase, professor of geography and planning at California State University: “There is consensus among fire researchers that climate change is extending the dry season and contributing to mega fires, although vegetation and changes Demographics in rural areas are also important factors in fire severity and location there.
“The Mediterranean climate has always produced fires in the dry season, but the size of these has been clearly associated with recent changes.”
Map of portugal
Rainforests like the Amazon hit too, for different reasons
The Brazilian Amazon has faced more fires recently, and while these are almost entirely human-caused, experts say climate change still plays a role in their severity.
Dr Erika Berenguer, Senior Research Associate at Oxford and Lancaster Universities, said that all types of fires in the Amazon are man-made and related to agriculture, which fall into three categories: deforestation ( with fires used to clear felled trees), pastures (with fires to keep livestock pastures clean and fertile) and subsistence (with fires to refresh the fields).
In each case, fires escape into the forest understory with increasing frequency, and the forest itself has become drier and more vulnerable due to climate change.
He said that “climate change has made the Amazon rainforest become drier in some places and much hotter. This makes it more difficult for the forest to act as a fire damper, rather than making it more vulnerable. “
Amazon map
Maps based on annual accumulations of burned area data from the Global Fire Emissions Database. Our thanks to Michael Humber, research assistant professor in the department of geographic sciences at the University of Maryland, who facilitated The Guardian’s analysis of the fire data. NASA and the Cardiff University School of Earth and Environmental Sciences also contributed to The Guardian’s analysis of the data from the burned area.
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