Concerning uptick in high Arctic lightning

Lightning is a dramatic and visually impressive weather phenomenon, but it is also a key component and indicator of climate regimes and the trajectory they are taking in the face of anthropogenic forcing. Indeed, the World Meteorological Organisation has designated lightning as an ‘Essential Climate Variable’, meaning that the frequency and pattern of lightning activity should be monitored and analysed to help us understand how the climate is changing at a global and regional scale.

The Finnish company Vaisala compiles annual reports on global lightning data, and its recently published report for 2021 confirmed a trend that has generated significant concern among scientists. The year 2021 saw the highest ever lightning count in the high Arctic region above 80 degrees North, where lightning had historically been rare. Whilst this represents the continuation of a steady increase that has been apparent across the last five years, last year saw a particularly significant hike in activity: 91% more lightning was recorded in this region in 2021 than in 2012-2020 combined. In August 2019, lightning was detected little more than 50 km from the geographic North Pole itself.

The increase in lightning activity in the remote high Arctic is thought to be a consequence of more regular intrusions of the warm, moist air masses that are conducive to electrical storms. These conditions will of course also tend to reduce ice integrity and accelerate melting, releasing more liquid water which can in turn evaporate and promote further lightning activity. The spectacular rise in lightning activity in the Arctic is therefore being interpreted as a clear indication of the extent to which the polar climate is changing, as the region experiences disproportionately faster warming relative to the global average. Beyond their immediate effects on the polar environment and implications for sea-level rise, such drastic changes in the Arctic climate could also have knock-on effects on atmospheric conditions elsewhere, potentially driving extreme weather events across the Northern Hemisphere.