New Delhi: Human-caused climate change made wildfires in South America's Amazon rainforests at least 20 times more likely, according to a new review that took stock of fire activity globally, identifying extreme events from March 2023 to February 2024.
Notable events included record-breaking wildfires in Canada, the largest recorded wildfire in Greece (July 2023) and drought-driven fires in Amazon ( September-November, 2023, and January-February 2024), researchers said.
The research team also looked at deadly fires that occurred in Hawaii in August 2023 and those in Chile in February 2024.
The State of Wildfires report, published in the journal Earth System Science Data, also found that forest fires in Canada and those in Greece were made at least thrice and twice more likely by climate change, respectively.
The international team of researchers, including those from the UK and Brazil, said carbon emissions from wildfires around the world were 16 per cent above average, amounting to 8.6 billion tonnes of carbon dioxide.
The air quality in the Amazon region was among the worst on the planet, according to the authors.
Emissions due to forest fires in Canada were over nine times the average of the past two decades and contributed to almost a quarter of the global emissions, they said.
The researchers explained that loss of carbon from the tropical rainforests of Amazon and the far-northern forests of Canada have lasting implications for the Earth's climate, given that forests take decades to centuries to recover from any fire disturbance.
Extreme fire years such as 2023-24 could, therefore, result in a lasting deficit in carbon storage for many years to come, they said.
"Wildfires are becoming more frequent and intense as the climate warms, and both society and the environment are suffering from the consequences," said one of the corresponding authors Matthew Jones, a research fellow at the University of East Anglia, UK.
Focusing on the extreme wildfires of Canada, Amazon and Greece, the researchers said that hot and dry conditions promoting fire have shifted significantly across these regions, when compared to a world with no climate change.
"The probability of extreme fire seasons of these magnitudes has increased significantly due to climate change, with a 2.9 to 3.6-fold increase in the likelihood of high fire weather in Canada and a 20.0 to 28.5-fold increase in Amazonia," they wrote.
In Canada and Greece, area burned by fires could have been larger had the landscape not been changed by people, even as multiple factors were at play, including weather and moisture.
"A mix of severe fire weather and plenty of dry vegetation reinforced one another to drive a major uptick in the number and extent of fires last year," said another corresponding author Francesca Di Giuseppe, a senior scientist at the European Centre for Medium-Range Weather Forecasts, UK.
Fire weather refers to a combination of meteorological conditions that significantly influence the likelihood and behaviour of wildfires. Key factors include high temperatures, low humidity, strong winds, and lack of precipitation.
Agricultural activities also were found to have increased the extent of the 2023 wildfires in the Amazon. This has left forests more vulnerable to fire during periods of drought and fire weather, amplifying the effect of climate change, the authors said.