This week is just the beginning of what could be a long, smoke-filled summer in North America — and the start of a new seasonal pattern made possible by climate change.
The flames that have scorched Canada for weeks, driving thousands from their homes in regions along both coasts, have pumped plumes of caustic smoke south across some of the most densely populated areas of the US. Many of the 436 wildfires raging right now, according to the latest numbers from Canada’s Wildland Fire Information Systems, ignited either before or in the very earliest days of what’s normally a busy season for Canadian fires.
June is often the worst month, said Brendan Rogers, a scientist at the Woodwell Climate Research Center in Massachusetts who studies boreal forest fires. Canada is seeing snow that melts out faster in the spring, he said, allowing for an earlier start to the burning season.
But an early start doesn’t mean a swifter end. Natural Resources Canada’s outlook that calls for “well above average” risk of outbreaks from British Columbia to the Ontario-Quebec border throughout this month, and an above-average risk in most of the Northwest Territories, the remainder of Quebec, a large part of Labrador and the Maritime Provinces. Most of the country remains at above-average risk through August. If the forecast bears out, Canada won’t begin to see much relief until September and even then large parts of British Columbia, Alberta, Saskatchewan and Manitoba will have a well above-average risk.
“Why is this happening? May was a record warm month across Canada,” said Daniel Swain, a climate scientist at the University of California Los Angeles. “There are links between record warmth and climate change.”
In all 2,305 fires have consumed about four million hectares across the country making it the worst fire season in the country’s history, according to Prime Minister Justin Trudeau. The resulting thick plumes of smoke pouring south into the US Northeast has created some of the worst concentrations of air pollution in the region since 1999, according to AccuWeather Inc. Air quality alerts in the US stretched as far west as Indiana and Michigan and as far south as South Carolina. Parts of at least 15 US states have been affected so far. Tuesday was the third-worst day of wildfire pollution in US history, according to Stanford University’s Environmental Change and Human Outcomes Lab. (At publication time, Wednesday’s data was not available yet.)
New York City on Wednesday afternoon suffered under the worst air quality of any major city on Earth. Mayor Eric Adams urged residents to limit outdoor activities and schools declared they were keeping children inside as more Canadian smoke swirled south through the day. Across the Hudson in New Jersey, Governor Phil Murphy called the sooty skies “evidence of the intensifying climate crisis.”
Wildfire smoke is mix of gases and particles from burned trees, buildings and whatever else the flames consume, according to the US Centers for Disease Control and Prevention. It can “make anyone sick,” the agency warned, but people with asthma, pulmonary or heart disease, or who are pregnant, young or elderly are especially vulnerable. Among the symptoms are an elevated heart rate, headaches, wheezing, coughing and fatigue. Paper masks that became a staple during the Covid-19 pandemic won’t filter out wildfire smoke, according to the CDC. N95 and P100 respirators are needed, and the best method is avoiding smoke.
New York could be spared in coming days as the winds shift. What should give the densely populated US Northeast pause is that fires across Quebec have been burning for weeks — only a change in wind direction earlier this week that sent smoke billowing through Manhattan streets. With little to stop Canada's raging fires, this could just be the first of many episodes that plague the region this summer whenever the wind shifts back.
Climate change has spurred on hotter, drier conditions around the world that have lengthened fire seasons in many regions, including California, Europe and Siberia. Changes to the climate have put more energy into the atmosphere, which means severe lightning storms are happening much further north.
When Rogers first began exploring the tundra he didn't need safety training for lightning. Now such knowledge is crucial. “The unfortunate part is we are locked in, for some extended time, to continued warming with worsening fire seasons,” he said.
Rogers has found fires increasing across the boreal forests and tundra of Canada and Alaska as snow melts earlier. The blazes cause the permafrost to melt, releasing more greenhouse gases into the atmosphere in a dangerous feedback loop. Black carbon from the fires themselves ends up landing on ice sheets in Greenland, spurring faster melting there.
Climate change has without a doubt added to Canada’s fires this year, Rogers said.
Canada has been burning across almost the entire length of the country, which Swain and other experts described as unusual. Canada is such a big place that wildfire season normally peaks at different times. The flames started in May as large fires moved across Alberta, a western province, shutting down oil sands production and crimping the nation’s energy output. That was followed by an outbreak around Halifax, Nova Scotia on the Atlantic coast.While Canada is having a record year, the US the fire season is off to a slow start. There have been 18,403 fires that have burned 518,698 acres since January 1, according to the US National Interagency Fire Center. That total lags behind the 10-year average of 21,908 fires burning just over 1 million acres at this point. The divergence between North American neighbors is a tale of two winters. A series of Pacific storms brought rain and snow to the Western US, squelching a years long drought throughout the region and leading to widespread flooding. The result was a slow start to fire season, said Zach Tolby, manager and lead scientist at the US National Oceanic and Atmospheric Administration’s Fire Weather Testbed.
Canada, by contrast, missed out on the winter rains and rolled through spring with little additional precipitation. Several pre-summer heat waves have already visited Canada, and large parts of its west in particular is mired in drought. That left the region susceptible to bigger, stronger fires, with a lot of smoke to fill the skies far beyond the country.
“You don’t think of New York City as a place to have wildfire-related impacts,” said Swain. “Even people who don’t live in the actual wildfire zones are very much at risk from these severe smoke-pollution episodes. It is just an illustration of how wildfire impacts are not just located in places where your house burns down.”
