The latest data on forest fires confirms what we’ve long feared: Forest fires are becoming more widespread, burning at least twice as much tree cover today as they did two decades ago.

Using data from researchers at the University of Maryland, recently updated to cover the years 2001 to 2023, we calculated that the area burned by forest fires increased by about 5.4% per year over that time period. Forest fires now result in nearly 6 million more hectares of tree cover loss per year than they did in 2001 — an area roughly the size of Croatia.

Fire is also making up a larger share of global tree cover loss compared to other drivers like mining and forestry. While fires only accounted for about 20% of all tree cover loss in 2001, they now account for roughly 33%.

This increase in fire activity has been starkly visible in recent years. Record-setting forest fires are becoming the norm, with 2020, 2021 and 2023 marking the fourth, third and first worst years for global forest fires, respectively.

Nearly 12 million hectares — an area roughly the size of Nicaragua — burned in 2023, topping the previous record by about 24%. Extreme wildfires in Canada accounted for about two thirds (65%) of the fire-driven tree cover loss last year and more than one-quarter (27%) of all tree cover loss globally.

Climate Change Is Making Fires Worse

Climate change is one of the major drivers behind increasing fire activity. Extreme heat waves are already 5 times more likely today than they were 150 years ago and are expected to become even more frequent as the planet continues to warm. Hotter temperatures dry out the landscape and help create the perfect environment for larger, more frequent forest fires.

When forests burn, they release carbon that is stored in the trunks, branches and leaves of trees, as well as carbon stored underground in the soil. As forest fires become larger and happen more often, they emit more carbon, further exacerbating climate change and contributing to more fires as part of a “fire-climate feedback loop.”

This feedback loop, combined with the expansion of human activities into forested areas, is driving much of the increase in fire activity we see today. As climate-fueled forest fires burn larger areas, they will affect more people and impact the global economy.

Here’s a look at some of the places most impacted by increasing forest fires, based on the latest data:

Mounting Temperatures Are Fueling More Severe Fires in Boreal Forests

The large majority — roughly 70% — of all fire-related tree cover loss between 2001 and 2023 occurred in boreal regions. Though fire is a natural part of how boreal forests function ecologically, fire-related tree cover loss in these areas increased by a rate of about 138,000 hectares (around 3.6%) per year over the last 23 years. That’s about half the total global increase between 2001 and 2023.

Climate change is the main cause of increasing fire activity in boreal forests. Northern high-latitude regions are warming at a faster rate than the rest of the planet, which contributes to longer fire seasons, greater fire frequency and severity and larger burned areas.

In 2021, for example, Russia saw 5.4 million hectares of fire-related tree cover loss, the most recorded for that country in the last 23 years. This was due in part to prolonged heatwaves that would have been practically impossible without human-induced climate change.

In 2023, record-breaking wildfires in Canada burned almost 7.8 million hectares of tree cover, or about 6 times the country’s annual average for 2001-2022. As forests burned, they released nearly 3 billion tons of carbon dioxide into the atmosphere — roughly equivalent to the amount of carbon that India (the world’s third largest emitter) generated from fossil fuel use in 2022. These extreme wildfires caused billions of dollars in property damage, displaced thousands of people from their homes, and spewed air pollution that traveled as far as Europe and China. They were largely fueled by warmer-than-average temperatures and drought conditions, with some parts of the country experiencing temperatures up to 10 degrees C (18 degrees F) above normal.

This trend is worrying for several reasons. Boreal forests store 30%-40% of all terrestrial carbon globally, making them one of the largest carbon storehouses on the planet. Most carbon in boreal forests is stored underground in the soil, including in permafrost, and has historically been protected from the infrequent and lower severity fires that occur naturally. But changes in climate and fire activity are melting permafrost and making soil carbon more vulnerable to burning.

In addition, fires that are more frequent and more severe than normal can drastically alter the structure of forests in boreal regions. Boreal forests have long been dominated by coniferous tree species like black spruce, but frequent fires can reduce the resilience of black spruce and other conifers and effectively eliminate them from the landscape, allowing deciduous trees to take their place. Such changes could have wide-ranging impacts on biodiversity, soil dynamics, fire behavior, carbon sequestration and cultural traditions. In some extreme cases, when fires are especially severe or frequent, trees may fail to regrow at all.

These shifting forest dynamics could eventually turn boreal forests from a carbon sink (an area that absorbs more carbon than it emits) into a source of carbon emissions. In fact, recent research shows that boreal forests are already losing their ability to store carbon.

Agricultural Expansion and Forest Degradation Are Stoking Fires in Tropical Forests

In contrast to boreal forests, stand-replacing fires are not a usual part of the ecological cycle in tropical forests. Yet fires are increasing in this region as well. Over the last 23 years, fire-related tree cover loss in the tropics increased at a rate of about 41,500 hectares (around 9%) per year and accounted for roughly 15% of the total global increase in tree cover loss from fires between 2001 and 2023.

Though fires are responsible for less than 10% of all tree cover loss in the tropics, more common drivers like commodity-driven deforestation and shifting agriculture make tropical forests less resilient and more susceptible to fires. Deforestation and forest degradation associated with agricultural expansion lead to higher temperatures and dried out vegetation, creating more fuel and allowing fires to spread faster.

In addition, it is relatively common in tropical regions to use fires to clear land for new pasture or agricultural fields after trees have been felled and left to dry. This tree cover loss is not attributed to fires in our analysis because the trees have already been cut down. However, during periods of drought, intentional fires can accidentally escape newly cleared fields and spread into surrounding forests. As a result, almost all fires that occur in the tropics are started by people, rather than sparked by natural ignition sources like lightning strikes. And they are exacerbated by warmer and drier conditions, which can cause fires to rage out of control.

In Bolivia, for example, agricultural expansion and droughts have led to a significant increase in the amount of fire-related tree cover loss over the last two decades. This increase in fire activity is threatening some of the world’s most iconic and protected places, such as Noel Kempff Mercado National Park, a UNESCO World Heritage Site that is home to thousands of species and is one of the largest intact parks in the Amazon.

Similar to boreal forests, increasing tree cover loss due to fires in the tropics is causing higher carbon emissions. Previous studies found that in some years, forest fires accounted for more than half of all carbon emissions in the Brazilian Amazon. This suggests the Amazon basin may be nearing or already at a tipping point for turning into a net carbon source.

Heatwaves and Shifting Population Patterns Are Increasing Fire Risk in Temperate and Subtropical Forests

Historically, fires in temperate and subtropical forests have burned less area than boreal and tropical forests: Combined, they accounted for 15% of all fire-related tree cover loss between 2001 and 2023. But the data shows that fires are increasing in these regions as well, by about 34,300 hectares (roughly 5.3%) per year. While temperate and subtropical areas tend to contain a larger proportion of managed forests — which can house fewer species and store less carbon than natural ones — fires in these regions still pose significant risks for people and nature.

As with boreal forests, climate change is the primary driver behind the increasing fire activity in temperate and subtropical forests. For example, heatwaves and summer droughts play a dominant role in driving fire activity across the Mediterranean basin. In 2022, record-breaking heat and drought in Spain resulted in more than 70,000 hectares of tree cover burned, the largest amount since 2001.

Land-use changes and shifting populations are also compounding the impacts of climate change in these regions. In Greece, a combination of heatwaves, drought, and large plantations of highly flammable non-native species (like Eucalyptus) created ideal conditions for extreme wildfires in 2021 and 2023. In Europe more broadly, the abandonment of agricultural land in recent years has been followed by excessive vegetation growth that has increased fire risk.

In the United States, natural lands are rapidly being converted into “wildland-urban interfaces,” or places where homes and other manmade structures intermingle with trees and vegetation. This increases the risk of fire ignitions, damage and loss of life. In 2022, wildfires in the U.S. burned nearly 1 million hectares of tree cover and caused roughly $3.3 billion in damages. One of the largest fires that year, California’s Mosquito Fire, burned thousands of hectares of forest in and near areas classified as wildland-urban interfaces, destroying 78 structures in nearby communities.

Both the annual cost and number of deaths from wildfires in the United States have increased over the past four decades. As human activities continue to warm the planet and reshape the landscape, deadly, multi-billion-dollar disasters like these will likely become more common in the U.S., Europe and elsewhere.

How Do We Reduce Forest Fires?

The causes of increasing forest fires are complex and vary by geography. Much has been written about how to manage wildfires and mitigate fire risk, but there is no silver bullet solution.

Climate change clearly plays an important role in driving more frequent and intense fires, especially in boreal forests. As such, there is no solution for bringing fire activity back down to historical levels without drastically reducing greenhouse gas emissions and breaking the fire-climate feedback loop. Mitigating the worst impacts of climate change is still possible, but it will require rapid and significant transformations across all systems.

In addition to climate change, human activity in and around forests makes them more susceptible to wildfires and plays a role in driving higher levels of fire-related tree cover loss in the tropics and elsewhere. Improving forest resilience by ending deforestation and forest degradation is key to preventing future fires. So is limiting nearby burning that can easily escape into forests, particularly during periods of drought. Incorporating wildfire risk mitigation into forest management strategies in fire-prone regions would help protect forest carbon and create jobs and support rural communities at the same time.

While data alone cannot solve this issue, the recent data on fire-driven tree cover loss on Global Forest Watch, along with other fire monitoring data, can help us track fire activity in both the long term and in near-real-time to identify trends and develop targeted responses.