The skies over Northeastern U.S. states were smoky and eerie for most of last week, endangering residents with a blanket of toxic smog blown in from dozens of wildfires across Canada. As more than 100 forest blazes in Quebec were classified as "out of control," a weather pattern carried the thick smoke south. "Code Red" air quality alerts were issued as far south as the Carolinas, and the yellow-orange-gray haze reached Chicago, Detroit and other parts of the Upper Midwest. Events were cancelled, flight takeoffs were delayed due to low visibility, many people sheltered inside and Covid-era face masks reappeared. Schools canceled field trips, moved recess indoors and postponed athletic matches. At one point, New York City registered the worst air quality in the world among major urban centers.

At the same time, 75 wildfires burned in Alberta, a western Canada province. A "heat dome" weather system pushed temperatures to new records over the weekend and worsened blazes that displaced tens of thousands of residents. President Biden ordered the deployment of all available federal firefighting assets to help Canada.

Scientists have long warned that global warming raises the chance of severe wildfires. The world needs to urgently reduce wildfire risk and make peace with nature, United Nations Secretary General António Guterres said last week, citing Canada’s widespread fires as a reminder. "Wildfires are no longer a problem just for people who live in fire-prone forested areas," says Alexandra Paige Fischer, a University of Michigan professor. Coincidentally, the situation gained added attention the same week as publication of "Fire Weather: A True Story From a Hotter World." He warns that "over the coming decades, wildfire pollution is poised to become the country’s main source of particulate pollution."

Author says: "Fire isn't going away. We're going to be burning for this entire century. . . . This is a global shift. It's an epochal shift, and we happen to be alive for it." -- John Vaillant, author of "Fire Weather: A True Story From a Hotter World," published last week

Resident says: "It looks like Mars outside." -- Dennis Scannell of Syracuse, N.Y.

National Weather Service tweets: "Sun is no longer visible, everything’s orange, the parking lot lights have come on." – Alert in Binghamton, N.Y., last Wednesday