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Wildfires are a naturally occurring phenomenon and the causes of wildfires can include non-human activity. For example, naturally occurring wildfires can be caused by lightning striking dry wooded areas. Controlled burning, sometimes referred to as prescribed burning, is also used by humans as a method of land management. Ecosystems have adapted to withstand wildfires, especially in areas where they have occurred frequently in the past.
Recent years have seen an increase in the size and duration of unprescribed wildfires around the world. For example, in 2017, there were an unusually large number of forest fires around the world including in the Mediterranean, Russia and North America. So far in 2023, wildfires, including in Europe, North America and the Pacific Islands, have led to widespread damage to ecosystems and the environment. Wildfires occurring in populated areas have also led to people being evacuated from their homes and the loss of human life.
2. Causes of uncontrolled wildfires
The increase in the frequency, severity and duration of wildfires has been attributed to warmer and drier conditions arising from climate change. Fire needs the following three elements to occur: fuel, oxygen and a source of ignition. This is referred to as the fire triangle. The New England Journal of Medicine noted that climate change can increase the chance of each of the three essential conditions for fire occurring. The same article found wildfire seasons in different parts of the world were starting earlier and continuing for longer. It concluded that wildfires might also hasten climate change by reducing the size of forests and their ability to absorb carbon dioxide in the atmosphere. Changing land use, including growing urbanisation, has also been identified as a factor leading to the increase in wildfires. For example, the Insurance Information Institute has estimated 85% of wildfires in North America were started by humans.
In a report published in 2022, the UN Environment Programme concluded climate change and changing land use were projected to make wildfires more frequent and intense. It forecasted extreme fires could increase by 30% by the end of 2050 and by 50% by the end of the century. The Intergovernmental Panel on Climate Change has argued the impact of climate change on wildfires is increasing. It noted the risk of wildfires had become more frequent in North America, South America, central Asia, southern Europe, southern Africa and Australia.
Wildfires have a long-term impact on ecosystems. A study published by the journal Environmental Research in January 2023 found that wildfires in Europe in 2017 led to an increase in soil loss in those burnt areas. It concluded that this reduced the chances of nature recovery in the areas affected, increasing the risk of more fires occurring in the future.
Large wildfires have occurred this year in countries in southern Europe, including Greece and Italy, as well as other Mediterranean countries, including Algeria and Tunisia. In July 2023, wildfires on the Greek islands of Rhodes and Corfu led to tens of thousands of people being evacuated, including residents and tourists. The Greek government described the evacuation from Rhodes as the largest caused by a wildfire in the country’s history. In August 2023, wildfires in Tenerife in Spain also led to the evacuation of part of the island.
According to the European Environment Agency (EEA), the size of the land area burnt in European countries around the Mediterranean (southern France, Greece, Italy, Portugal and Spain) has decreased overall since the 1980s, with the exception of Portugal. The EEA has argued this can be attributed to more effective fire control measures being introduced in these countries. However, it noted this trend has been subject to a large degree of variability. For example, it notes the burnt area in 2017 was the second largest on record. The EEA has also said record droughts and heat waves are now affecting regions of central and northern Europe not typically prone to forest fires.
According to NASA, during the first half of August 2023 the number of hectares burnt throughout Canada has been roughly double the size that would have burnt normally during the entire season. These fires have been widespread in the country’s eastern provinces, including Nova Scotia, Ontario and Quebec, as well as in British Columbia on Canada’s Pacific coast. Smoke from wildfires in Quebec in June 2023 spread south through Canada into the US, affecting the air quality in New York City, Philadelphia and Washington DC. In August 2023, wildfires in Canada’s Northwest Territories led to the evacuation of the city of Yellowknife and other areas, resulting in roughly half of the population of the territory becoming displaced. Similar evacuations took place in British Columbia.
Andrew Weaver, professor at the School of Earth and Ocean Sciences at the University of Victoria, has argued that extreme, high temperatures in June and July 2023 was one of the key reasons for the scale of the fires experienced in Canada. He also argued the severity of these fires had been increased by the way forests had been managed. For example, he criticised reforestation practices which have created monocultures that were more susceptible to fire. He also criticised the use of the herbicide glyphosate, which has killed off broadleaf plant species.
In August 2023, wildfires spread across the island of Maui in Hawaii. These fires were fanned by strong winds caused by an area of high pressure north of Hawaii and Hurricane Dora in the south. This led to large-scale damage in towns including Lahaina in the west of Maui.
Kevin Hamilton, emeritus professor of atmospheric sciences at the University of Hawaii, has said the state has seen a rising trend in the amount of land burnt. He described the Hawaiian islands as consisting of both wet and dry areas. He argued the dry areas of Hawaii were becoming drier as global temperatures rose, leading to an increased risk of uncontrolled fires. The journal Nature notes that, while wildfires do occur naturally in the Pacific archipelago, fires in Hawaii are getting worse and more frequent. It argued that one of the trends causing these more frequent fires is the increase in dry grass on former agricultural land. This has occurred as the economy of Hawaii has moved from ranching and sugar and pineapple cultivation to tourism, providing fuel to fires when they occur. Nature also noted that rising temperatures have resulted in vegetation becoming drier and more flammable.