Forest fires destroyed nearly 23 million acres of land in 2021, and it's expected to get worse, experts say

The planet continues to experience a massive loss in forest land as the world warms and allows severe wildfires to run rampant in regions spanning the globe.

Overall, forest fires are getting worse worldwide, according to a new report released Wednesday by Global Forest Watch, a forest monitoring platform led by the World Resources Institute. The data captures stand-replacing fires, which kill all or most of the living overstory trees in a forest, and includes wildfires, escaped fires from human activities such as agriculture and hunting and intentionally set fires that result in tree cover loss.

Tree cover loss due to fires is now twice as high as it was in 2001, with forest fires destroying about 7.4 million more acres of land -- an area roughly the size of Belgium -- last year compared to the turn of the century, according to the researchers, who analyzed two decades of fire data from the Global Land Analysis and Discovery Lab at the University of Maryland.

Forest fires also accounted for more than 25% of all tree cover loss in that past 20 years, with 2021 ranking as the second-worst fire season on record due to unprecedented damage to boreal forests in the Northern Hemisphere, according to the report.

About 70% of all fire-related tree cover loss over the past 20 years has occurred in those boreal forests, likely due to warming temperatures in northern, high-latitude regions, the researchers said.

Nearly 23 million acres of land -- an area the size of Thailand or roughly 16 soccer pitches per minute -- were scorched globally last year, according to the report. The rate of tree cover loss due to fire is increasing by about 568,000 acres -- roughly 4% -- every year.

In tropical forests, which are moist and wet environments, stand-replacing fires were historically rare events. However, fire loss in the tropics is increasing about 5% per year, which is an annual increase of about 89,000 acres, the experts said. Almost all fires that occur in the tropics are started by people, such as escaped fires from agriculture and land cleaning.

The top five countries that experienced tree cover loss over the past 20 years were Russia, at 131 million acres; Canada, at 66.7 million acres; the U.S., at 29.7 million acres; Brazil, at 23.5 million acres; and Australia, at 15.6 million acres. Extreme weather caused a significant spike in bush fire activity in Australia from 2019 to 2020.

Climate change is likely the major driver of increasing fire activity, the researchers said. A "climate feedback loop" has occurred in which rising temperatures create drier conditions, causing more forest area to burn, which then release even more carbon into the atmosphere.

The obliteration of forests could further hinder efforts to reduce greenhouse gas emissions and mitigate global warming.

Forests are critical to Earth's ecology for their ability to capture and store carbon out of the atmosphere, alter the air quality and quantity of drinking water and provide habitat for the world's land species.

But longer fire seasons and an increase in fire frequency could turn some forests into a net source of carbon emissions, releasing more carbon than they are absorbing, which poses a long-term threat to countries' ability to uphold commitments under the Paris Agreement, which aims to limit global temperature rise to less than 2 degrees Celsius since the Industrial Revolution.

The cause of increasing forest fires are complex and vary significantly by geography, the researchers said, adding that there is no "silver bullet" to reversing the trend of increasing tree cover loss due to fires.

In addition, there is no solution to bring fire activity back down from historic levels without drastically reducing greenhouse gas emissions and breaking the fire-climate feedback loop, according to the analysis. Human activity in and around forests is also making them more susceptible to wildfires, especially in the tropics.

ABC News' Tracy Wholf contributed to this report.