Boreal forests in the northernmost latitudes have suffered more tree cover loss to fires in the past decade than any other place on Earth, with Russia losing more trees to fires than any other country, according to the data.
The boreal region is a huge expanse of coniferous forests which circles the northern hemisphere encompassing parts of Scandinavia, Estonia, Lithuania, Russia, Alaska, and Canada, among other countries.
Wildfires in these regions are of particular concern, as they can lead to the release of carbon buried deep in the ground, as well as the loss of the trees themselves. Trees in boreal forests take up to a century to regrow.
According to research published Wednesday by Global Forest Watchan initiative of the World Resources Institute.
Russia has lost around 53 million hectares of forest cover to fires since 2001, an area roughly the size of France. Canada lost approximately 27 million hectares to fires during the same period.
James MacCarthy, an analyst at the World Resources Institute and co-author of the report, told the Guardian: “This is very worrying. These discoveries should be a wake-up call to the world. Forests are our best line of defense against climate change and should be at the top of our list [of priorities].”
He said the carbon released into the atmosphere by wildfires creates a vicious cycle of climate damage. “These forests can change from carbon sinks to carbon sources in the atmosphere,” he said.
The common wildfire picture is in temperate regions, for example in Europe and the United States where fires have increased as hot, dry summer weather has become more prevalent, and in Brazil where fires started for deforestation have caused widespread devastation across the Amazon.
But the boreal forest is rapidly warming and drying out, making it more susceptible to fire. Heat waves have hit northern Canada and Siberia in recent years, and the Arctic has warmed much faster than the rest of the planet.
About a third to 40% of boreal forest fires are thought to be started naturally by lightning, but the other main source of fire is people. Fires started by farmers for agriculture can quickly spread to forests, especially in Russia where controls are sparse and enforcement is lacking.
Fires account for about a quarter of the world’s forest cover loss, with most of the rest absorbed by deforestation for agriculture and logging. But the amount of forest destroyed by fires has increased, accounting for about 30% of tree cover loss in 2021.
Forest cover loss due to fires worldwide is increasing by about 4% per year, or about 230,000 additional hectares each year, about half of which is due to larger fires in boreal regions.
Tree loss to fire is also increasing in the tropics, however, by about 5% per year or an additional 36,000 hectares. Almost all fires in the tropics are started by humans.
Over the 10-year period of the study, the United States lost about 12 million hectares of trees to fires, and Brazil lost about 9.5 million hectares, or about 15 % of all forest cover lost in Brazil during the period. About two-thirds of fire-related losses occurred in primary forests, vital not only for the climate but also for biodiversity.
Around 72% of tree cover loss in Australia between 2001 and 2021 was caused by fires, with extreme weather causing a significant increase in fires in 2019 and 2020.
The amount of tree cover lost to fires worldwide each year has increased by around 3 million hectares since 2001, representing an additional area the size of Belgium lost to fires each year, compared to to ten years ago.
Last year’s fire season was the worst on record. The wildfires were responsible for the loss of an area of trees roughly the size of Thailand, which equates to about 16 football pitches a minute burning.
This year’s fires, with record hot weather in Europe, parts of the United States, South Asia, parts of China and other places around the world, are also likely to be severe. An area one-fifth the size of Belgium has burned in Europe this year.
Separate research has also recently shown that the boreal forest is expanding north into areas that were previously arctic tundra.
Our knowledge of tree cover loss has improved markedly over the past decade, with satellite imagery providing a much more detailed view of what is happening under the tree canopy.