1170913627

1170913627

Green and orange smoke swirls

Photo by: Jonathan Knowles

Jonathan Knowles

Rise of the Zombie Fire: Wildfires that Refuse to Die

By: Robin Fearon

Holdover or 'zombie' fires are wildfires that lay dormant beneath the soil and undergrowth, through wet and cold winters. They smolder and retain their heat until warmer temperatures and dry conditions reignite the flames.

October 29, 2020

Tackling this phenomenon is a real problem for firefighters, especially in areas like the North American boreal forests of Alaska and Canada, but the problem is bigger than that.

The Undead Burnings

following record wildfires in Siberia in 2019, zombie fires buried in the peat-rich soil of the Arctic Circle are causing the most concern right now. As warmer weather further thaws the frozen ground layer and dryer vegetation burns, it releases carbon trapped in the earth, triggering a climate change feedback loop where increased heating and thawing releases millions of tons of greenhouse gases like carbon dioxide or methane.

Authorities worry that zombie fires are becoming more frequent in the once permanently frozen tundra regions. Permafrost is a layer of ground that is continuously frozen for two years or more, and while fires in the tundra are not unknown, they are not normally seen above the Arctic Circle. Vegetation that does not typically burn, such as dwarf shrubs, moss, grass, and surface peat, are now providing fuel for fires in terrain that was thought to be fire resistant.

Mega Emisions

534970676

534970676

Canada, Manitoba, Melting sea ice and smoking forest fires near Cape Tatnum on Hudson Bay on warm summer morning

Photo by: Paul Souders

Paul Souders

Researchers estimate that between January and August 2020 there were 270 million tons (244 megatonnes) of carbon dioxide emitted by Arctic fires. This is one third more than the 200 million ton record set in 2019. Grigory Kuksin, head of the Russian wildfire unit at Greenpeace, calls the fires and their impact a “climate bomb”.

Satellite imagery and data from the Copernicus Atmosphere Monitoring Service (CAMS) provides scientists with daily estimates of wildfire and burning biomass emissions. Copernicus uses Europe's Sentinel satellite network and NASA's Terra and Landsat satellites to identify forest fires, burn areas, and underground hotspots that could reignite. By pinpointing the remote areas where fires have reignited, CAMS scientists are showing where holdover fires persist over the long Arctic winter.

A Fire By Any Other Name

Like the deadly, relentless undead creatures they are named after, zombie fires present a major headache for authorities and firefighters. In the US, fires are regularly recorded burning after overwintering, from Alaska in the far north to states that frequently suffer wildfire outbreaks like Colorado. One underground fire in the Stanislaus Forest near Yosemite burned for more than five years and may have been a holdover from the Rim Fire in 2013.

Online maps show active and recent US wildfire activity. NASA's Fire Information for Resource Management System is a near real-time map of fires across the planet. Satellites routinely provide the big picture and are a vital tool in predicting where overwintering fires could re-emerge. Drone and aircraft-mounted video as well as thermal and infrared cameras add another layer of early detection systems.

Right now, zombie fires currently account for less than one percent of burned areas in Alaska. There is no question that deep burning caused by previous intense wildfires can increase their risk. By monitoring the edges of fire perimeters from blazes in the preceding year, firefighters can act quickly to extinguish any flare-ups.

Next Up

DNA's Building Blocks May Have Their Origins in Outer Space

One of life's building blocks could have originated in outer space. But if this experiment shows how these building blocks actually formed, how exactly did they get to Earth?

When Was There Life on Venus?

What we have is a cosmic whodunit. Venus, the second planet from the sun and considered by the more romantic types as "Earth's twin" and the avatar of love, is dead.

Last Call for the King of Planets

This month Jupiter is entering conjunction which means it's the last chance this year to catch a glimpse of the largest planet in our solar system.

July in the Sky: Celestial Events Happening This Month

With eclipses, meteor showers, and more, it's a busy month in the night sky this July. Take some time this summer to look up and enjoy these cosmic wonders.

Following Blue Origin’s NS-12 Rocket Launch

Blue Origin, Billionaire Jeff Bezos’ spaceflight company, is rescheduled to launch its NS-12 reusable spacecraft on Wednesday, December 11. Watch it LIVE.

Why Does Pluto Have Such a Weird Orbit?

Pluto is the black sheep of the planets in our solar system and it looks like astronomers aren’t sure how long Pluto will remain in its present orbit.

Stuck at Home? What to See in the Night Sky this Month

In times of darkness and incertainty, opt for exploration of wonder in the skies.

How Did the Solar System Form?

How did our solar system form? It's a pretty simple and straightforward question, but as with most things in science, simple and straightforward doesn't necessarily mean easy.

The Kuiper Belt: When Solar Systems Dance

Pluto isn't alone after all. Besides being the home of Pluto, the Kuiper belt hosts dwarf planets, and smaller bits of rock and ice.

Check out the Earth’s 800,000 Year Old Battle Wound

Scientists may have discovered the location of an ancient buried crater, a result of a meteorite that barreled into the Earth some 800,000 years ago.