In the Arctic, the number of thunderstorms is increasing at an alarming rate

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New work shows that in the Arctic, the frequency of thunderstorms has increased over the past decade. In this regard, the number of lightning strikes recorded in 2020 was 800% higher than that observed in the early 2010s. The results were published in the journal Geophysical research letters this March 22.

When we are interested in stormy phenomena, the last regions of the globe that we would come to think of are the north and south polar zones. Indeed, the cold climate and the great stability of the atmosphere at these latitudes very strongly inhibit the convection processes at the origin of thunderstorms.

A galloping increase in thunderstorms in the Arctic

However, scientists have recently studied the issue of thunderstorms that occur from time to time in the Arctic – mainly between June and August. More precisely, it was aboutassess the frequency and distribution of lightning strikes beyond the 65th parallel north. To do this, they used the observational data acquired by the Lightning Global Location Network (WWLLN). It is a lightning strike measurement system based on the detection of the radio signal emitted by the lightning channel. The stations which constitute it – distributed to the four corners of the globe – allow an almost global coverage of the planet.

The period worked by the researchers extends from 2010 to 2020. However, over this time interval, they found that the number of lightning strikes had tripled. While arctic discharges represented 0.2% of the world total in 2010, this figure rose to 0.6% in 2020. In terms of lightning strikes, these percentages materialize a drop from around 18,000 impacts in 2010 to more than 150,000 in 2020. Or in other words, an increase of more than 800%.

Number of lightning strikes in June-July-August north of 65 ° N. Above, the geographical distribution for the year 2020. Below, the number per year. Finally, the dark gray curve marks the 3-year moving average. Note the clear increase between 2010 and 2020. Credits: Washington University.

Global warming questioned

In their paper, the researchers link this increase to climate change that would make the atmosphere more unstable. Indeed, with the retreat of sea ice and the accelerated warming of adjacent continents, the vertical profile of temperature and humidity is strongly modified. Thus, the arctic world would become an area increasingly favorable to the deployment of stormy convection. In August 2019, there was significant electrical activity in this regard only a few hundred kilometers from the North Pole.

This development has very concrete implications for the safety of people and property. “With long periods of ice-free ocean and increased shipping in the Arctic, you’re going to have the same concern you have at low latitudes: when there are a lot of people and they don’t know about the threat of lightning it becomes a problem“, explains Bob Holzworth, lead author of the study. To sum up, if the growing risk associated with lightning is not taken into account, northern populations and shipping may become particularly vulnerable to this hazard. Also, the need for preparation and adaptation was clearly formulated by the researchers.

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