Wildfires are a natural phenomenon in many ecosystems, including forests along the U.S. Pacific West Coast, as natural fires serve to rejuvenate ecological communities. However, from mid-August through mid-September 2020, forests in California, Oregon, and Washington State suffered through unprecedented wildfires caused by extreme weather events that can be attributed to climate change. By September 15, 2020, in Washington state, 700,000 acres (280,000 hectares) had burned; in Oregon, about 1 million acres (405,000 hectares) had burned; and in California, the worst-hit state, more than 7700 fires had burned 3 million acres (1.2 million hectares), damaged or destroyed more than 5000 structures, and killed at least 35 people. The single largest fire to date was the California Complex fire in Northern California, which was still raging on September 15 after it had already burned about 800,000 acres (320,000 hectares). These epic blazes have created some of the worst air pollution in the world from Seattle, Washington, to Southern California, with haze reaching as far east as New York City. See also: Air pollution; Extreme weather events; Forest fire; Global climate change; Wildfire impact on air quality
Recent extreme weather is the main factor behind these unprecedented wildfires. Normally, wildfires do not occur all at once, but are staggered among different biomes, such as chapparal and coniferous forests. But climate change has caused the Pacific West Coast summer season to extend such that weather is much hotter and drier than normal. Anytime there is an abundance of dry vegetation and an ignition source, be it a spark, lightning bolt, or a downed powerline, a wildfire can occur. As the climate warms, so does surface evaporation, particularly in drought-prone regions, which speeds the drying of vegetation. In 2020, the Pacific West Coast also experienced other extreme weather events, including dangerous heat waves, intense thunder and lightning storms, and strong winds. Strong winds not only dry vegetation, but they also increase the oxygen supply, which makes fires burn more intensely and transports flames and embers away from the source. In addition to extreme weather, 110 years of fire suppression in the affected region has caused abnormally dense vegetation growth, resulting in an overgrowth of "fuel" for destructive wildfires. According to NASA, by September 11, 2020, carbon dioxide emissions from burning forests in California already exceeded annual totals for all other years. See also: Biome; Drought; Fire; Forest; Global warming; Lightning; Thunderstorm
The COVID-19 pandemic has also played a role in the ability of firefighters to control the Pacific West Coast wildfires. The pandemic has made it more difficult to recruit fire crews, and there is limited access to fire camps. With so many fires blazing simultaneously, personnel are stretched thin, and responders must take additional precautions to protect themselves and others from getting the disease. See also: Novel coronavirus is declared a global pandemic
