Exploding arctic thunderstorms a sign of “accelerating global warming”

Published on : 01/10/2022 – 5:39 PMModified : 01/10/2022 – 5:41 PM

Love at first sight in the Arctic. And not just a little. There were 7,278 lightning flashes recorded beyond the 80^e parallel – even further north than the northern tip of Greenland – noted Vaisala, a Finnish environmental event measurement company, in its annual report published on Friday January 7.

This is twice the number of lightning strikes that have struck this region in the past eight years combined, say the authors of this document. A spectacular increase that should still be put into perspective because “we started from almost nothing in recent years as far north, and it suffices that there have been a few stormy events with several hundred lightning to obtain such a result. “, underlines Sander Veraverbeke, a climatologist at the Free University of Amsterdam who was one of the first to take an interest from 2014-2015 in lightning in the arctic region.

A taste of the upheavals to come

Nevertheless, the simple fact that lightning always ventures further north is considered extraordinary and worrying at the same time by a growing number of scientists who are interested in it. The multiplication of these lightning in the Arctic, north of 65^e parallel, “indeed constitutes an important indicator of the acceleration of global warming”, notes Declan Finney, climatologist at the Ronin Research Institute (New Jersey), contacted by France 24.

“We are still talking about what we consider above all to be tropical events that occur more and more often in the Arctic”, underlines this specialist. In 2002, scientists interviewed local people in the Arctic region of northern Canada and “no one had seen more than a handful of lightning bolts in their life. One of the older ones had only attended. a single thunderstorm, seventy years earlier “, note the website of the National Geographic channel.

In fact, a very precise cocktail is needed for a thunderstorm and lightning to be possible. A mixture that was not common in the Arctic: high humidity, some heat on the surface of the ground, a colder temperature at altitude and unstable weather.

Humidity “has never been a problem in this ocean region,” says Sander Veraverbeke. But the temperatures have long been too low. In this regard, “there is no doubt that the increase in the number of lightning in the Arctic is a phenomenon attributable to global warming”, adds this specialist.

It is also “a warning of what lies ahead [c’est-à-dire davantage d’orages qui seront plus virulents, NDLR] elsewhere, “said Declan Finney. The rise in temperatures in the Arctic is indeed much faster than in the rest of the world and, as such, it is a foretaste of the upheavals to come due to global warming.

When permafrost burns

While waiting for ever more frequent and violent thunderstorms to strike the shores of more temperate regions, this multiplication of lightning in the far North is causing another risk for this ecosystem: fires. Because in this very sparsely populated part of the world, it is not man who ignites forest fires, but almost always lightning.

“When it comes to Alaska or Siberia, or even further north, fires are not what comes first to mind, yet there were record numbers in the Arctic region in 2019 and 2020 “, emphasizes Sander Veraverbeke, who works specifically on the interactions between climate and fires.

And that’s a problem for the climate. There are, in fact, large quantities of carbon that are stored under the tundra of these areas far to the north. “The fires which break out in these regions are very dangerous for the climate because the organic earth which burns there emits much more carbon per square meter than the soils of the temperate zones”, affirms Sander Veraverbeke.

These fires also gradually transform the nature of the soil and “pave the way for an ever further northern expansion of the forests, then more prompt to burn and release even more CO.₂“, adds Declan Finney.

It is a true climatic vicious circle which sets in. The climate crisis “is pushing up temperatures in the Arctic, resulting in more thunderstorms and lightning, which are causing more fires, which have the effect of worsening global warming”, summarizes Sander Veraverbeke.

Not to mention the time bomb that represents permafrost. For the specialist from the Free University of Amsterdam, this gigantic “carbon and methane refrigerator” – which retains nearly 1,600 billion tonnes of carbon – also risk, because of fires, of releasing into the atmosphere the greenhouse gases which it kept well in the cold under a layer of perpetually frozen earth.

The problem is that we do not know precisely to what extent fires and global warming will accelerate the releases into the atmosphere of carbon that was previously trapped in permafrost. “This is one of the big questions that scientists are asking themselves more and more on this problem”, recognizes Declan Finney. For him, the more lightning strikes the Arctic, the more it becomes “urgent to better understand the effect of fires on permafrost”.