As Canada burns, smoke makes US air unhealthy and skies eerie. Is climate change to blame?

Canada is on fire. On Tuesday there were more than 400 wildfires burning across the country, 238 of them out-of-control. Smoke and unhealthy air quality levels from the conflagration have blanketed multiple Canadian provinces, much of the Great Lakes region and parts of the northeastern United States.

While forest fires are a natural part of the ecosystem of Canada's boreal forests, the size, ferocity and number of fires this year is decidedly abnormal. Most of the country is expected to be under high to extreme risk for much of the wildfire season, which stretches from May to September.

"Climate change is real and having a huge impact on Canadians right now with forest fires burning across the country," tweeted Catherine McKenna, Canada's former climate minister.

On Monday Canada's minister for emergency preparedness, Bill Blair, said the nation is seeing images of fires that "are some of the most severe ever witnessed in Canada."

Here's what to know:

How is smoke from the Canada fires affecting US air quality?

On Tuesday the federal AirNow fire and smoke map listed Albany, NY; Bennington, Vermont; Hartford, Conn.; and parts of New York City as "UNHEALTHY" and advised residents to "reduce activity or consider going indoors."

Due to the smoke in the air, "children and older adults, as well as people with heart or lung disease, should reduce prolonged or heavy exertion," the weather service in Albany, New York, warned. "Exposure to elevated levels of fine particles such as wood smoke can increase the likelihood of respiratory symptoms in sensitive individuals and aggravate heart or lung disease."

Canada wildfire smoke creates eerie glowing sunrises, lower temps in US

The smoky skies have helped reduce temperatures across much of the mid-Atlantic. Due to an area of low pressure that's hovering offshore, along with an area of high pressure over Canada, a northerly flow of air was funneling the smoke south into the U.S. from Canada, AccuWeather said. This was keeping temperatures cooler than average, as the smoke filters out the blazing June sunshine.For example, the weather service in Washington, D.C., said in an online forecast discussion Tuesday that "temperatures this morning have been running 5-8 degrees cooler than forecast due to the smoke in the atmosphere."

The smoke is even giving the sky, sun and moon some unusual colors.  

In addition to the milky, hazy skies, the wildfire smoke has created strange visual appearances of the sun and moon. Tuesday morning, the smoke "transformed the morning sunrise across parts of the East into an orange, photo-worthy haze," AccuWeather reported.

Why are there so many fires in Canada?

Rising temperatures, prolonged droughts and changing rain patterns are making many of North America's forests more prone to fire. Add on top of that the fact that temperatures at higher latitudes are increasing more than at low latitudes and it makes for horrific and historic levels of destruction.

"We're seeing events that are unknown in the historical record," said Robert Scheller, a professor of forestry at North Carolina State University. "It's hard to talk about without painting a grim picture."

Swaths of Canada have been hot and dry recently, said Daniel Swain, a climate scientist at the Institute of the Environment and Sustainability at the University of California, Los Angeles.

Conditions there are “highly anomalous,” Swain said. Typically early to mid-spring would be the peak of seasonal dryness, with late spring and summer rains coming later and causing northern forests to "green up" and become less prone to fire. "So far this year that green up has been attenuated because it's so dry and so warm," he said.

Is climate change to blame for the fires?

While it's impossible to say that any one fire or any one season is specifically linked to an increasingly warm planet, the trends show a strong signal, said Scheller.

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"We have unusually dry conditions and heat pulses in Canada," he said.

That fits with data showing temperatures are rising faster in higher latitudes. In January, Howard Diamond, NOAA's climate science program manager, said the global rise in temperature is unmistakable. "In some parts of the world, particularly at the higher latitudes towards the poles, the warming is much more accelerated."

Wildfire, smoke map for US, CanadaSee more wildfire and smoke information and data here.

How a 'hot drought' is helping fuel the fires

Conditions in Canada are an example of something that has come to be called "hot droughts," Scheller said.

"It's not just lack of precipitation, it's lack of precipitation plus these higher temperatures that really dry the soil and fuels out."

There have always been heat waves and there have always been droughts. What climate change adds is increased variability and increasing extremes. So in Canada, there are not only increased odds of drought but also increased odds of heat waves.

"If you roll the dice and they both come up, then you've got a hot drought," Scheller said.

Does this mean the US fire season will be bad too?

Canada's bad fire season won't necessarily be repeated in the United States, thanks to different weather patterns further south.

There could also be a difference between higher and lower elevations, said Swain. Especially in California, which had seen heavy rain and snow in the previous six months, the legacy of the wet winter should mean a milder-than-average fire season in the mountains.

"This may be a year where there's more fire risk in the valleys than the mountain peaks throughout the West," he said.

Lots of rain has meant plants and chaparral have grown extraordinarily well. "People have reported waist- or shoulder-high grass and brush this year when in some cases it was barely ankle high in the drought," he said.

That means there's a lot more fuel to burn this year than in previous years. Fire danger could emerge in July and August, possibly peaking in August and October depending on when the winter rains arrive.