In 2019, Arctic suffered its worst wildfire season with massive blazes in Alaska, Greenland, and Siberia producing plumes of smoke that can be seen from space. The Guardian reported that the Arctic region had recorded its hottest June ever with more than 100 wildfires recorded in the Arctic circle.

The intensity of last year's wildfires is unparalleled in the 16 years that the European Union's Copernicus Atmosphere Monitoring Service (CAMS) has been tracking global wildfire data. Usually, wildfires occur in the Arctic in July and August because of lightning strikes, but due to the unusually hot and dry season in June 2019, the fire season had started earlier.

Almost a year later, the remnants of the record blazes last year or "zombie fires" seen across the Arctic region may be coming back to life, scientists warned on Wednesday.

What Causes the Zombie Fires in the Arctic?

European Union's Copernicus Atmospheric Monitoring Service senior scientist and wildfire expert, Mark Parrington said that satellite observation of active fires has hinted that 'zombie fires' might have reignited in the Arctic circle, Yahoo! News reported.

Though it is yet to be confirmed by ground measurements, they saw that the hotspots are mainly concentrated in regions where the blaze occurred last year. Siberia and Alaska were among the areas where fires unprecedented in scale happened.

The blazes in June 2019 were the hottest on record going back 150 years, which estimated to have released 50 million tons of carbon dioxide into the atmosphere. That is equivalent to the annual carbon emissions of Sweden.

According to Parrington, the Arctic region might see a cumulative effect of last year's fire season, which will feed into the upcoming season and may lead to large-scale and long-term fires across the same region once again.

Hot weather and low humidity increase the risk of wildfires, and Europe, in particular, has recorded record-breaking temperatures for March and April this year. Similarly, Mike Waddington, an expert on watershed ecosystems at McMaster University in Canada, said that there had been tremendous warmth in the Arctic this year, which led to drying and making the peat soils ripe for burning.

"A zombie fire is a fire that continues to burn underground and then reignites on the surface after a period of time," according to Waddington.

Read Also: Wildfire Smoke Still Affects Us After Flames Are Extinguished

Dormant and undetected fires

Holdover fires are dormant and undetected deep in organic soil that can spark into flames weeks, months, and even years later. Scientists have seen a similar phenomenon in Alaska while monitoring the area.

According to the Alaska Fire Science Consortium, as reported in their Spring 2020 newsletter, fire managers have noted an increase in occurrences where fires survive the cold and wet boreal winter months and re-emerge in the spring.

Scientists in on the ground in Alaska have identified 39 holdover fires since 2005. Subsequently, using observations with satellite data, experts have found that most of the fires were too small, ranging from less than 1 hectare to 11 hectares, while seven of them are visible from space.

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