What the Canada wildfire smoke and Texas heat wave have in common: Climate change

With over 120 million U.S. residents across the Midwest and Northeast under an air quality alert and 60 million residents in the South under heat advisories on Thursday, Americans are contending with two different effects caused by climate change.

“This is part of a growing pattern of extreme weather events that we’re seeing as a result of climate change,” Olivia Dalton, the deputy White House press secretary, told reporters aboard Air Force One on Wednesday. Dalton was accompanying President Biden on a trip to Chicago, which had some of the world’s worst air quality thanks to the smoke from hundreds of Canadian wildfires.

Heat contributes to wildfires

Since the start of the Industrial Revolution, average global temperatures have risen 1.1 degrees Celsius (2 degrees Fahrenheit) due to increasing atmospheric concentrations of heat-trapping gases.

Warmer air, in turn, increases water evaporation, causing more frequent and severe droughts. Drier vegetation combined with warmer weather “has been a key driver in increasing the risk and extent of wildfires,” according to the National Oceanic and Atmospheric Administration.

As of Thursday afternoon, 501 fires were burning in Canada, 251 of which were classified as uncontrolled by the Canadian Interagency Forest Fire Center.

“Scientists say that climate change is making weather conditions like heat and drought that lead to wildfires more likely,” the BBC reported earlier this month. “Spring in Canada has been much warmer and drier than usual, creating a tinder-dry environment for these vast fires.”

In recent decades, the Western U.S. has been frequently smothered in smoke from wildfires.

In Halifax, Nova Scotia, temperatures in early June reached upwards of 94°F, around 18 degrees higher than normal.

"The climate signal is very strong,” Robert Scheller, professor of forestry at North Carolina State University, told the BBC. “We are seeing both a larger area burned, and more severe fires."

“The fire season is getting longer, starting earlier in the spring, going later into the fall,” Chelene C. Hanes, a fire scientist with the Canadian Forest Service, told the New York Times. “We’re getting more of these larger fires.”

Longer, more frequent and more intense heat waves

The rise in global average temperatures has also resulted in more extreme heat waves like the ongoing one in Texas and the southern Plains.

“Heat waves are occurring more often than they used to in major cities across the United States,” the Environmental Protection Agency states on its website. “Their frequency has increased steadily, from an average of two heat waves per year during the 1960s to six per year during the 2010s and 2020s.” The average U.S. heat wave is now four days long, a day longer than in the 1960s.

Texans are feeling the effects of that now: As Yahoo News reported on Wednesday, “more than 100 daily temperature records have fallen over the last two weeks in Texas alone.”

“The severe conditions have caused 13 deaths in Texas and led to a spike in emergency room attendance across the state,” the Independent reported on Thursday.

This summer’s heat has been exacerbated by El Niño, a phenomenon in which a warm band of air and water develops in the Pacific Ocean and moves eastward.

This month was unusually warm even before the current heat dome — a heat-trapping region of high pressure — settled over Texas. “Temperatures around the world this month have been at their highest levels in decades for this time of year,” the New York Times reported in mid-June.

According to an analysis by the research organization Climate Central, climate change made the Texas heat dome’s severity at least five times more likely than it otherwise would have been.

Extreme weather is becoming more common

There is no reason to assume that this summer’s climate-change-related extreme weather will be limited to heat waves and wildfires. Higher ocean surface temperatures and increased evaporation have also been shown to result in more incidence of heavy precipitation.

In one week last summer, the United States saw three 1-in-1,000-year rains: Southern Illinois was drenched by 8 to 12 inches of rain in 12 hours, the St. Louis area got a record-breaking 6 to 10 inches of rain in seven hours and parts of eastern Kentucky were flooded by up to 14 inches of rainfall.