Destructive Wildfires At Least Three Times More Likely Due to Climate Change, Report Finds

Wildfires affecting Canada, Greece, and Amazonia last year were made between three and 20 times more likely to occur by anthropogenic climate change, according to the inaugural State of Wildfires report.

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Climate change is making wildfires more frequent and intense globally, a first-of-its-kind report investigating the causes, predictability, and anthropogenic influences of fire events has found.

Published Wednesday in the journal Earth System Science Data (ESSD), the inaugural State of Wildfires report looked at large-scale wildfire events during the 2023-24 season. Despite being “slightly below average” in terms of area burnt compared to previous seasons, the total amount of carbon emissions generated from all fire events combined last year was 16% above average, totalling 8.6 billion tonnes of carbon dioxide (CO2), the analysis revealed.

Almost a quarter of this increase can be attributed to Canada’s record-breaking fire season. Last year, nearly 6,600 blazes burnt across 45 million acres, 5% of the entire forest area of Canada and roughly seven times the annual average, affecting 230,000 people. According to the EU-funded Copernicus Atmosphere Monitoring Service (CAMS), fire carbon emissions totalled 480 megatonnes, over nine times the historical average, with toxic smoke reaching as far as the US East Coast.

Other large-scale fire events included wildfires in Greece, which were the largest ever recorded in the European Union, as well as fires in western Amazonia and northern parts of South America. The latter were driven by severe and prolonged drought conditions, the report said. Among the deadliest events figured the Maui wildfires, which killed 100 people as they engulfed the historic city of Lahaina, destroying much of its homes, businesses, and the harbour, and fires in Chile, which claimed 131 lives.

The Role of Climate Change

According to the report, which is set to be published every year, climate change increased the probability of high fire weather conditions, long-term average burned area, and extreme burned area during the 2023/24 season.

The risk of a fire developing is driven by three main factors (also referred to as “fire weather”): dry fuel such as leaves, grass, branches, and other organic materials; oxygen in the air; and heat to ignite and burn.

The report found that anthropogenic influence on the climate system made the fires in Canada at least three times more likely as it increased the risk of high fire weather, while the fires in drought-stricken Amazonia were made at least 20 times more likely to occur by climate change.

A similar dynamic played out in Greece, where human influence on the climate increased the probability of high fire weather by up to a factor of four.

The report also touched on more recent events, such as the ongoing wildfires affecting Greece. An attribution analysis revealed that the destructive blazes, which began spreading into Athens’ suburbs on Monday after first igniting on Sunday, were made at least twice as likely to occur by climate change.

Both the frequency and intensity of wildfires have more than doubled in the last two decades, as more frequent hot, dry, and windy conditions create the perfect fuel. And when the ecological, social and economic consequences of wildfires were accounted for, six of the last seven years were the most “energetically intense.”

Climate change has increased the wildfire season by roughly two weeks on average globally, mostly by enhancing the availability of fuel through heat and dry conditions. The average wildfire season in Western US is now 105 days longer, burns six times as many acres, and sees three times as many large fires – fires that burn more than 1,000 acres compared to the 1970s, according to Climate Central.

Despite an increase in the frequency and severity of wildfires globally, however, the amount of area burned by wildfires each year has gone down over the last few decades.

A 2017 paper published in Science found that global burned area declined by approximately 25% over the past 18 years, despite the influence of climate. The phenomenon can be explained by a decline in burn rates in grasslands and savannas as a result of the expansion and intensification of agriculture.

Wednesday’s report confirmed these findings. In the case of Canada, for example, it found that the alteration of landscapes for agriculture and forestry purposes reduced the density of vegetation, ultimately contributing to decreased fire extent in the affected areas.

“In Canada and Greece, 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,” explained Dr Francesca Di Giuseppe, Senior Scientist at the European Centre for Medium-Range Weather Forecasts (ECMWF). “But our analysis also shows that factors such as suppression and landscape fragmentation related to human activities likely played important roles in limiting the final extent of the burned areas,” she added.

The past nine years have been the hottest on record. 2023 was the hottest year globally, with global average temperatures at 1.46C above pre-industrial levels. 2024 is now on track to break that record.

Featured image: Wikimedia Commons.