Multiple states in the U.S. were recently in the grip of tornadoes, wildfires, and dust storms. The fires that scorched parts of Texas and Oklahoma burnt through almost 300 homes, reliving the horrors a similar blaze inflicted on Los Angeles in January this year. The fires that raged across Eaton and Palisades in particular claimed at least 28 lives, destroyed more than 14,000 structures, and forced people to evacuate en masse.
The inferno engulfed at least 16,000 hectares of land, destroying various natural ecosystems, per state agency Cal Fire. In fact, Cal Fire said it was among the most destructive fires in California history.
Almost a month later, across the Pacific Ocean, another wildfire swept through the forests near Ofunato city in Japan. According to media reports, the fire had started burning in the mountainous region surrounding the city on February 26. It claimed the life of at least one person, damaged close to 210 buildings, and forced more than 4,200 residents in the area to evacuate. In all, the fire covered nearly 2,900 hectares of land, rendering it one of the largest fires Japan has suffered in the last five decades.
All these fires also released large quantities of carbon into the atmosphere. According to the Copernicus Air Monitoring Service (CAMS) of the European Union, wildfires released 800,000 tonnes of carbon in January 2025 alone and that this was nearly four-times the amount wildfires released in the same period a decade ago. CAMS also examined the fires’ radiative power — i.e. the amount of heat they radiated, measured in watts — as recorded by NASA’s Terra and Aqua satellites (which also track farm fires in India in winter). It found that this power exceeded the long-term average power between 2003 and 2024 by one order of magnitude.
According to the latest India State of Forest Report published on December 21, 2024, Uttarakhand, Odisha and Chhattisgarh recorded the most fires in that year. Uttarakhand alone recorded 5,315 forest fires between November 2022 and June 2023. However, the report also said the number of fire ‘hotspots’ in the country seems to be dropping: from 2.23 lakh in 2021-2022 and 2.12 lakh in 2022-2023 to 2.03 lakh in 2023-2024.
At the same time, India has been experiencing some of its highest land temperatures in recent years. In 2023, researchers at IIT-Kharagpur and the Indian Institute of Tropical Meteorology, Pune, reported that in India’s northwest, northeast, and central regions, land temperature is rising 0.1º-0.3º C per decade in the pre-monsoon season and 0.2º–0.4º C per decade in the post-monsoon season.
Heat waves have also been found to be occurring earlier in the year, moving slower, and lasting longer. Together with prolonged dry spells, they create conditions ripe for wildfires. Suryaprabha Sadasivan, senior vice-president of consulting firm Chase India, wrote in The Hinduon February 12 that forest fires in India emit around 69 million tonnes of carbon dioxide every year.
The intensity and frequency of wildfires raise the question: are the earth’s natural carbon sinks able to absorb all the carbon being emitted?
The planet’s oceans, forests, and soil are well-known carbon sinks. The Arctic Boreal Zone (ABZ) is a particularly important one: for many centuries now, its tundra, coniferous forests, and wetlands around the Arctic Circle have absorbed carbon and sequestered it in the zone’s permafrost. Its coniferous forest is the world’s largest land-based biome.
But according to a new study published in Nature Climate Change, the increasing ferocity of wildfires means that more than 30% of the ABZ has now stopped capturing carbon and is instead releasing it.
In the study, an international team of researchers analysed data from 200 monitoring sites worldwide between 1990 and 2020 and tracked year-round changes in the atmospheric concentration of carbon. Their analysis found that while the ABZ was actively absorbing carbon from the atmosphere from 2001-2020, fully one-third of the region has been releasing carbon dioxide since.
“While we found many northern ecosystems are still acting as carbon dioxide sinks, source regions and fires are now cancelling out much of that net uptake and reversing long-standing trends,” Anna Virkkala, a research scientist at Woodwell Climate Research Center in the US and an author of the study, said in a statement.
The researchers were also able to specify the areas in the ABZ that had become carbon sources: while Alaska accounted for 44% of the ‘new’ emissions, northern Europe and Siberia accounted for 25% and 13%, respectively. The study paper also stated that the carbon emissions from the longer, non-summer months in the ABZ had surpassed the amount of carbon dioxide absorbed during the summer months (June to August).
Finally, the team was able to estimate that the ABZ first began to transform from a carbon sink to a carbon source before 1990 itself and that it was helped along by the Eastern Siberia fires in Russia in 2003 and the Timmins wildfire in Canada in 2012. According to the paper, the carbon dioxide released in these two years far exceeded the amount the ABZ alone was able to absorb.
One important reason for the ABZ releasing more carbon dioxide than what it can absorb is the thawing of tundra permafrost. As global warming — whose effects have been more pronounced in cooler regions — dries out the soil and changes the type of plants that grow, the average temperature of the top soil rises and organic materials in the soil decompose, releasing carbon dioxide into the atmosphere.
The consequences of these changes creates a dangerous feedback loop. According to the study, as wildfires become more common and more intense, they burn through the natural carbon reservoirs that have historically helped regulate the earth’s climate. The carbon released from these fires further fuels global warming, which in turn creates conditions for more frequent and more intense wildfires. And so on.
The study also corroborated the findings of the 2024 Arctic Report Card issued by the US National Oceanic and Atmospheric Administration (NOAA). This document stated that frequent wildfires are turning the Arctic tundra into a source of carbon by forcing it to absorb record levels of pollution due to burning fossil fuels.
Alaska Biological Research senior scientist Gerald Frost, who also co-authored the Arctic Report Card, told the NOAA, “Many of the Arctic’s vital signs that we track are either setting or flirting with record-high or record-low values nearly every year. This is an indication that recent extreme years are the result of long-term, persistent changes, and not the result of variability in the climate system.”
Published – April 10, 2025 05:30 am IST
