By Charly SHELTON

Lightning strikes in the boreal forest of Canada are a common occurrence as are the forest fires caused by them. But they are becoming more commonplace and frequent as the years go by and it is starting to change the landscape itself, a new study shows.

A NASA-funded study released at the end of last month shows a rapid rise in lightning strike-induced fires farther north than before. The study, led by Vrije Universiteit Amsterdam and the University of California, Irvine, examined the causes of recent massive forest fires in Northern Canada and Alaska, which have been increasing in frequency and severity year-to-year. There was a record number of lightning-ignited fires in the Canadian Northwest Territories in 2014 and in Alaska in 2015. After examining the data from NASA’s Terra and Aqua satellites and ground-based lightning tracking networks, the team found increases since 1975 between 2% and 5% per year in the number of lightning-ignited fires.

Lead author Sander Veraverbeke of Vrije Universiteit Amsterdam, who conducted the work while at UC Irvine, said in a statement there are many factors that contribute to high fire years in the far north and many of their connections are still poorly understood, but the observable trends are consistent with climate change.

“We found that it is not just a matter of more burning with higher temperatures. The reality is more complex: Higher temperatures also spur more thunderstorms. Lightning from these thunderstorms is what has been igniting many more fires in these recent extreme events,” Veraverbeke said in a released statement.

Thunderstorms need warm air and moisture to develop. This is why they are so common in the summer, particularly over the southeastern United States. As the warm, moist air rises up into clouds, the water molecules knock into one another and lose an electron in the process. The now positively charged moisture continues its journey to the top of the cloud, eventually to cool, condense and become rain, and the orphan electrons gather at the bottom of the cloud, giving it a negative charge. The electrons build up so much that they repel the other negative electrons on the ground to retreat deeper into the earth, giving the ground a positive charge. Lightning is a surge of those negatively charged electrons seeking a balanced home in the now positively charged earth. Without warm air to make the moisture rise, thunderstorms don’t form. As such, they are relatively rare over the frozen forests of Northern Canada and Alaska but are, as the study finds, increasing rapidly.

This is not only a problem for Smokey Bears and trees; it is actually changing the biomes of the region. As the fires creep north, they are blurring the line between the boreal forests and the Arctic tundra landscapes.

 “In these high-latitude ecosystems, permafrost soils store large amounts of carbon that become vulnerable after fires pass through,” said co-author James Randerson of the University of California, Irvine, in a released statement. “Exposed mineral soils after tundra fires also provide favorable seedbeds for trees migrating north under a warmer climate.”

 “Taken together, we discovered a complex feedback loop between climate, lightning, fires, carbon and forests that may quickly alter northern landscapes,” Veraverbeke added. “A better understanding of these relationships is critical to better predict future influences from climate on fires, and from fires on climate.”

Closer to home, the Angeles National Forest is no stranger to lightning strike-induced fires. Within the last three years, 10 forest fires have been attributed to lightning strikes, with no lightning fires reported as yet this year. As the summer heat continues for the next three months or so, there is still a likelihood of thunderstorms causing fires. For those who find themselves caught in the forest during a thunderstorm, U.S. Forest Service Fire Information Officer Nathan Judy suggests there are a few safety precautions to be aware of.

“Avoid natural lightning rods such as a tall, isolated tree in an open area,” Judy said. “Avoid hilltops, open fields, lakes or streams or a boat on the water.”

 More helpful information can be found at https://www.ready.gov/thunderstorms-lightning.

  Charly Shelton