As the planet has warmed in recent years, studies have shown that wildfires have become larger across the western United States, making skies hazy with smoke. This year, as smoke from Canadian wildfires has enveloped cities from New York City to Detroit, the eastern portion of the country is also getting a taste of that particular consequence of climate change.
On Wednesday, New York City Mayor Eric Adams called the smoke "something that has never impacted us on this scale before." But while it may be the first time, it probably won't be the last, because rising temperatures are making wildfires more intense.
What’s happening in Canada
"There are currently 414 active wildfires across Canada, according to the Canadian Interagency Forest Fire Center, with more than half (239) considered to be 'out of control,'" Yahoo News reported Wednesday. It is unusual for wildfires to start so early in the season in Canada, but the East Coast province of Nova Scotia, from which much of the smoke blanketing the eastern U.S. is coming, had below average snow this past winter and less than half of its average rainfall in April.
“Climate change is clearly fueling longer and stronger wildfire seasons, and as we've seen vividly this week, smoke can travel far downwind and afflict areas far larger than the burned regions,” Dr. Vijay Limaye, a climate and health scientist at the Natural Resources Defense Council, told Yahoo News. “Because this problem is expected to worsen in the years to come, it's crucial that we recognize climate change as the underlying driver of the problem here and work to address it by moving swiftly away from fossil fuels and towards renewable energy sources, while also taking precautions to stay safer.”
What causes wildfires
Two big risk factors for wildfires are excessive heat and drought, both of which are becoming more common due to climate change.
Average global temperatures have risen 1.1 degree Celsius (2 degrees Fahrenheit) since the Industrial Revolution. That has caused more frequent and severe heat waves, such as the Pacific Heat Dome of 2021, in which normally mild cities such as Portland, Ore. and Seattle saw temperatures soar into the triple digits.
Since warmer air causes more water to evaporate, droughts are becoming more frequent and severe, making conditions more favorable for wildfires.
Throughout the West, the combination of more heat and drought has led to consistently larger wildfires in this century than in the last one. California has experienced 18 of the 20 largest wildfires in its history since 2000, causing insurance giants State Farm and AllState to announce last month that they will no longer issue new homeowners insurance policies in the state.
"We're seeing increases in the intensity and the severity, the overall burned area of wildfires and the duration of fire across the fire season," NASA wildfire expert Liz Hoy said in a December 2022 video. "And while fire is a natural part of ecosystems, what's really driving this change is we're seeing a lot of changes in our climate. We're seeing increases in global temperature as well as more extreme weather events, so longer droughts. And so we have these hot and dry conditions, which makes vegetation, forests and grasses more available to burn because they're drier. And so with these drier conditions and these drier fuels, we're likely to see more fires."
Climate change and drought
Large swaths of the Mountain West are currently experiencing drought conditions, and parts of the Great Plains are suffering from extreme drought, according to the U.S. Drought Monitor. Drought conditions also extend to typically wet portions of the Upper Midwest and Northeast.
It's not just the U.S. that is experiencing climatic changes. In February, an unusually warm, dry winter forced ski resorts in the French Alps to close for lack of snow, and left canals running dry in Venice, Italy.
That followed a summer of record-breaking heat waves and droughts that left thousands dead across Europe and caused the continent's worst wildfire season on record. Last summer also featured droughts from Asia to New York City. Those droughts were made 20 times more likely by climate change, according to an October 2022 study by World Weather Attribution, a group of international scientists.
With reporting from Marquise Francis.