![]() Smoke reaches the stratosphere when heat from a powerful wildfire creates an updraft that combines with moisture in the atmosphere to generate towering thunderclouds. There, it can have additional effects on the climate. While Fasullo’s research highlights the cooling effects of smoke in the lower atmosphere, on occasion, wildfire smoke punches through the troposphere and into the stratosphere, the atmospheric layer that starts about 10 miles up. Fasullo says that this shift might have contributed to the emergence of La Niña conditions last year, which cooled ocean surface temperatures in the eastern equatorial Pacific, although more research is needed to confirm that hypothesis.īut according to Fasullo, there’s no longer any question that “wildfires can create their own climate, or instigate a climate response.” Fire-fueled weather The researchers’ models showed that smoke-induced cooling in the Southern Hemisphere shifted a critical belt of tropical thunderstorms, the Intertropical Convergence Zone, further north. Indeed, the impact seems to have rippled across the climate system. “It’s not a big effect, but when you integrate over the entire Southern Ocean, it adds up,” Fasullo says. But new research on Australia’s 2019-2020 bushfire season points to another, potentially far more significant, way that wildfire smoke can cool Earth’s surface. But when wildfire smoke is thick enough, Field says, “you could get a brief 5 degree Celsius cooling effect.”įield describes these cooling effects as “episodic” and “almost an academic curiosity” compared with the public health impacts of wildfire smoke. “The effect ranges, depending how far you are from the source, how big the fire was and how much smoke it injected,” says Robert Field, a research scientist at NASA’s Goddard Institute for Space Studies. As far back as 1950, scientists have measured this effect by comparing temperatures on heavy smoke days with temperatures forecast to have occurred in its absence. In addition to creating a health hazard, dense wildfire smoke near the ground sometimes blocks enough light to reduce surface temperatures. The Dixie Fire is currently California's largest blaze, destroying over 100 homes and leveling a historic town. This week, Athens is choking on smoke as wildfires rage across nearby forests. In late July, smoke from Canadian wildfires spread across Minnesota, leading to “ unprecedented” levels of air pollution. experienced this firsthand in mid-July, when a pulse of smoke from a wildfire outbreak in southern Canada wafted over New York City, Philadelphia, and Washington D.C., reddening sunsets and triggering air quality alerts. Swept around by winds, this wildfire smoke can pollute the air hundreds to thousands of miles away. “It’s absolutely clear that research related to the effect of wildfires on climate is very topical,” says Sergey Khaykin, a fire weather expert at Sorbonne University in France.Īs wildfires burn across the land, they emit a cocktail of tiny particles, water vapor, and gases into the air. The effect is far too small to counteract human-caused global warming, but beyond that, researchers say it’s too early to predict what it means for the broader climate system.īut with fire seasons growing more intense around the world and this summer triggering a spate of extreme fire weather in North America and elsewhere, the search for answers is growing increasingly urgent. ![]() Scientists have only recently begun studying these effects, with Australia’s record 2019-2020 bushfire season marking the first time researchers detected wildfire smoke-induced global cooling. Wildfire smoke can also have global cooling effects by making clouds in the lower atmosphere more reflective or blocking sunlight in the upper atmosphere, similar to what a volcanic eruption does. But paradoxically, the most intense wildfires can have the opposite effect on temperatures, cooling Earth’s surface both regionally and globally.ĭense wildfire smoke can temporarily block sunlight near the ground, causing regional temperatures to drop by several degrees. ![]() Extreme heat often brings extreme wildfires, and this year is no exception, with unprecedented heat waves fueling enormous outbreaks of fires in the western United States and Canada, as well as across the Mediterranean and in Siberia. ![]()
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