Since early June, Canadian wildfire smoke has been drifting down through wide swaths of the United States, creating serious public health impacts on both sides of the border. More than 100 million Americans have woken up to air quality alerts, forcing many to reconsider how much time they spend outside. While those conditions have varied in recent weeks, the threat from the Canadian wildfire season remains unprecedented. NRDC's senior scientist Vijay Limaye—an expert on the intersection of climate change and public health—offers some answers to key questions on the root of the crisis and what we need to do now.

First, the basics. What’s the climate-wildfire link?

No single fire is directly caused by climate change. Warming temperatures, extended droughts, and other consequences of climate change can, however, turn a forest into a tinderbox, making for longer and more active wildfire seasons and creating the conditions for forests to burn—and fires to spread—faster than they would otherwise. “Climate change is loading the dice,” reports the National Oceanic and Atmospheric Administration, “transforming what was once a natural, cyclical, and seasonal visitor on the landscape into an omnipresent threat.”

How is climate change driving these Canadian fires specifically?

Warmer temperatures and less precipitation than normal turned much of Canada’s native forestland into a tinderbox this spring, creating the conditions for these calamitous fires. Large swaths of Canada, specifically Alberta and Saskatchewan, have experienced abnormally dry conditions and even drought for much of the year. Western Canada received less winter snowfall than usual. And much of the country experienced its warmest May on record, with temperatures soaring up to 12 degrees Fahrenheit above average in places.

All of that has put Canada on track to have its worst wildfire season on record, with hundreds of large fires continuing to blaze out of control across the country. There’s no recorded precedent for so much of the United States to be enveloped in this much smoke from Canadian wildfires.

What are the health risks?

Wildfire smoke contains particles tiny enough to travel deep into human lungs and then into the bloodstream. With enough exposure, these particles can irritate the eyes and throat, aggravate asthma, decrease lung function, inflame airways, trigger nonfatal heart attacks, and even cause premature death in those with existing lung or heart disease.

How long will this last?

While the skies have largely cleared over much of the country, future conditions will vary with winds and weather so long as the massive fires continue to burn. Currently, more than 850 wildfires remain active across Canada. The smoke-forecasting website BlueSky Canada can let you know if hazy skies are headed your way.

What can we do about any of it?

We need to embrace solutions on every scale. Here are three big ones.

• Educate yourself on the causes of the climate crisis: Remember that carbon pollution, along with other greenhouse gas pollution from human activity, is trapping 49 percent more heat in the earth’s atmosphere than those same gases did some 30 years ago.
• Champion the solutions: We’ve got to cut the carbon pollution from burning coal, gas, and oil nearly in half compared to 2010 levels, by 2030, and stop adding it to the atmosphere altogether, on balance, by 2050, to avert a climate catastrophe. That means phasing out fossil fuels and shifting toward cleaner ways to power our future by, for example, getting more clean electricity from the wind and sun; making our homes and workplaces more energy efficient; switching to electric vehicles; and building a modern and reliable power and storage grid.
• Breathe easier: If the wildfire smoke returns to your area, check out our guide with reminders on how to stay safe.

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