Smoke and haze stunned the East Coast this week. Get used to it, experts warn.

When New York City's mayor stepped outside this week, he was shaken and confused by what he saw: "What the hell is this?"

"This" was a thick, glowing haze of smoke from fires hundreds of miles away in Canada. It made the air unhealthy to breathe, snarled air traffic and cast a surreal shadow over millions of residents.

Fire has always been a natural part of the ecosystem of Canada’s forests and smoke from Canadian fires has at times been strong enough to drift down into the United States. But fire experts say what’s happening this year is historic and unprecedented.

"There's no analog to what we're seeing now," said Mike Flannigan, a professor of wildland fire at Thompson Rivers University in Kamloops, Canada. "I've been watching fires since the 1970s and it's never been like thi

A large upper-level area of low pressure that's centered off the coast of Maine and Nova Scotia is causing winds to blow from the north and northwest, transporting the smoke into the region, meteorologist Zack Taylor of the National Weather Service told USA TODAY Thursday. The low has been very persistent and stubborn to move over the past several days, he said.

"This can happen at any time of year," he said, adding that these upper-level lows tend to be slow to break down and can get stuck there until another system comes along.

That's bad news for this current bout of smoke. "Not a whole lot is going to change" over the next couple of days, he said, adding that the northerly winds will continue to bring smoke into the East. However, by early next week, there will be a little change in the weather pattern, with westerly winds bringing some relief from the worst of the smoke.

But as long as the Canadian fires remain active and large, "the smoke will be there," Taylor said, and any time there's a northerly wind, there will be a chance of smoke across the eastern U.S.

Not every year is going to be a bad year for smoke, but it's going to be the overall reality going forward. "We’re going to have to learn to live with fire," said Flannigan. "Your life is going to be impacted from smoke for weeks on end.

Is this the first time smoke from Canada has so broadly affected large swathes of US?

Both 2013 and 2001 saw smoke from Canadian fires drifting southward into the United States. What is different this year is the amount of smoke.

Why are forest fires increasing in Canada?

Three things are required for forest fires to happen:

• Fuel: Dry grass, brush and trees that can burn.
• Ignition: Something to light the fire. In Canada, usually 50% of fires are started by lightning, 50% by humans. In the United States it’s 90% by humans.
• Weather: Hot, windy weather conditions are the worst.

As climate change warms the planet and makes weather patterns increasingly unstable, hotter, drier periods are increasing in Canada’s forests, making it more likely fires will start and grow into catastrophic blazes.

Canada’s summers are becoming hotter and it is also experiencing more “heat pulse” events where there are extreme spikes in temperature.

In 2021, the town of Lytton on Canada’s west coast recorded the highest temperature ever observed in the country: 121.3 degrees. On July 2, 2021, the town was destroyed by a wildfire.

Heat makes forests more tinder dry and more fire-prone.

“As the temperature warms, the atmosphere’s ability to suck moisture out of fuels increases almost exponentially,” said Flannigan.

Warmer weather also leads to more lightning strikes, which causes more fires.

Could Canada have done anything to prevent the fires?

Not really, say experts. Canada is covered in a massive boreal forest, a mix of deciduous trees and conifers, 90% of which are owned by federal and provincial governments.

"The boreal forest is largely unmanaged except where clear-cuts have occurred," said Robert Scheller, a professor of forestry at North Carolina State University. "Due to their crown shape and fuels profile, boreal forests can readily burn if the weather conditions are conducive. In addition, these areas are often very remote, limiting widespread fire suppression."

Canada has actually been relatively proactive about forest health, said Hugh Safford, a professor who researches fire ecology at the University of California, Davis.

"Since the early 2000s the Boreal Forest Conservation Framework and the subsequent 2010 Canadian Boreal Forest Agreement have driven more ecologically sensitive logging practices and encouraged the use of fire as a management tool," he said.

While Canada's forests aren't heavily managed, they are logged. The country has a robust and sustainable timber industry that produces lumber and paper worth more than $475 billion a year. Canada’s wood product exports are the second largest in the world after Brazil.

What can be done to stop the fires?

The only real answer is to lower the amount of carbon dioxide in the atmosphere, which will eventually reduce temperatures overall.

Going forward, life will be a cascading series of such events, said Scheller. The consequences of climate change are becoming clear "everywhere – and sooner than people expect."

It's a bleak outlook for those who study – and love – forests.

"We are going to burn up a lot of the world’s forests over the next half-century," said Safford. "Wildfire smoke is even more unhealthy than vehicle emissions and it kills, directly and indirectly, thousands to millions of people every year. I don’t see any sign of humans changing their practices at a rate that is going to avoid these outcomes."