NewsBytesExplainer: Why do US and Canada see wildfires every year?
Parts of western United States and Canada in the North American continent are gearing up for the annual wildfire season as several fires have already started ripping through southwest US. After witnessing the worst heatwave this year, the countries recorded several deaths and are now anticipating a highly destructive fire season. What is the reason behind this tragedy and is climate change exacerbating it?
According to the US drought monitor, nearly half the country is facing some form of a drought, which is the most severe in the western states. The western states are also experiencing high temperatures. Similarly, parts of western Canada experienced some of the highest-ever temperatures, with Lytton village in British Columbia recording an all-time high of 49.6°C on June 29.
Dr. Mike Flannigan, a professor of wildland fires at the University of Alberta, told BBC that wildfires need three things: vegetation/fuel, ignition, and weather (hot, dry, and windy). "It really depends on the day-to-day weather, but the potential is sky-high for parts of Canada and the American west as they are in a multi-year drought," he said.
Usually, the fire season starts in the southwest region of the US, mainly in Arizona, where several fires are currently burning. The fires later spread to the north in California, before moving to Oregon and Washington. Experts suggest the US fire season has advanced.
Another reason that adds to the tragedy is said to be the lack of compressed and hardened snow due to higher temperatures. Snow cover usually acts as a physical barrier against burning and it also helps ease droughts. Notably, the snow cover at the Sierra Nevada mountain range was particularly low in July 2020, when California had witnessed record-breaking wildfires.
Already, the total average area burned this year in Arizona has surpassed 2019 and 2018. Reportedly, 42,400 more acres have burned in California this year compared to the same period last year. A record four million acres had burned in California last year. While the total area burned in Canada so far this year is under the 10-year average, British Columbia exceeded its average.
Dr. Susan Prichard of the School of Environmental and Forest Sciences at the University of Washington said currently it is very early in what appears to be an "exceptionally dry and long fire season." The year-on-year amount of land burned has seen an upwards trend since the 1980s in the US, while the 10-year rolling average has doubled for Canada compared to the 1970s.
Mostly, lightning and not human activity has been the immediate cause of wildfires in the US and Canada. According to scientists, climate change may be making wildfire seasons more intense and prolonged due to warmer, drier conditions. A study by climate researchers had found that the heatwave prevailing over the US and Canada was "virtually impossible" without climate change.
Further, Dr. Flannigan said, "Warm temperatures mean more lightning, longer fire seasons, and drier fuel, so on average we are going to see a lot more fire, and we are going to have to learn to live with fire."