The summer of 2024 was the warmest on record in Svalbard – with temperatures no longer meeting the definition of a “polar climate”.
“The magnitude of the 2024 summer warming in Svalbard is of such significance that it no longer fits the climatological definition of a ‘polar climate’ […].”
This is the alarming conclusion of a recent study by the Finnish Meteorological Institute, published on April 15 in Geophysical Research Letters.
Longyearbyen, the capital of Svalbard, is located at 78° north latitude, 1,200 kilometers from the North Pole and is no longer considered Arctic from a climatological perspective? At least not last year: according to the study, the average monthly temperature in August 2024, measured at the nearby airport, reached a new record high of 11°C. According to the definition, a polar climate prevails when the average temperature of each month does not exceed 10°C.
The summer of 2024 was a record-breaking season in Svalbard in several respects. August temperatures not only exceeded the 10°C threshold by 1°C, but were also 2.6°C higher than the previous August record set in 2023. Moreover, the new August record even surpassed the typical maximum for July — usually the warmest month in Svalbard — by 1°C.
This made August 2024 the warmest month since records began in 1899. The entire summer from June to August was also the warmest since records began – with a record that was broken with an unprecedented jump in temperature.
Dr. Heïdi Sevestre, glaciologist:
“There was no wind up Trollsteinen. At 10PM the midnight sun was still just below the horizon, the sky was golden and red. And as I walked, I found myself wondering what this place, my favorite place on Earth, might look like in 5, 10 years. I thought about the insane temperature increase this place is facing… That perhaps one day we would only talk about sea ice in the past tense. That perhaps one day Svalbard would become too warm to still be called Arctic. “
Impressions and reflections from the renowned glaciologist, shared in a LinkedIn post and gathered during a hike on Svalbard two weeks ago, shortly before she came across the current study.
So far, record temperatures in the High Arctic have mainly occurred in winter – sometimes with unusual rainfall and fatal consequences for wildlife, especially reindeer.
Warmth from the south
To investigate the causes of this massive warming, which has also become more pronounced during summer in recent years, the research team led by Daan van den Broek, a meteorologist at the Finnish Meteorological Institute and lead author of the study, analyzed atmospheric and oceanic reanalysis data.
The key factor behind the record temperatures in August was the persistence of southerly winds over Svalbard and the Barents Sea, which also caused exceptional sea surface warming. In the Barents Sea in particular, surface water temperatures in August were 4 to 5°C above the long-term average.
The unusually high sea surface temperatures persisted beyond the summer but declined significantly over the course of fall and winter. Compared to the long-term average (1991–2020), however, sea surface temperatures remain slightly elevated. Daan van den Broek sees a connection between this and the unusually low sea ice cover in the Barents Sea and around Svalbard, as he explained in an email to polarjournal.net.
The researchers attribute the persistently high temperatures to a strongly meandering jet stream — a phenomenon that is increasingly causing stable weather patterns in temperate latitudes, sometimes lasting for weeks.
Summer temperatures have a decisive impact on the Arctic ecosystem. When they rise unusually sharply, they accelerate not only the melting of glaciers but also the thawing of permafrost. These changes affect the entire ecology of the region — from vegetation to the animal species adapted to the harsh climate.
No heavier precipitation
Higher sea temperatures often result in heavier precipitation – as was recently observed in various regions of Europe. However, this effect did not occur around Svalbard in the summer of 2024, according to van den Broek.
Despite the exceptionally high sea surface temperatures, precipitation levels in the region did not increase. August, when sea temperature anomalies peaked, brought average to below-average precipitation. Autumn and winter were also drier than in previous years. According to the researcher, this was due to stable high-pressure systems over Svalbard, which suppressed the influence of the warm ocean on precipitation.
Warmer summers on Svalbard in the future
What van den Broek finds particularly worrying is that warm extremes in the Arctic do not simply increase linearly with climate change, but increase disproportionately. “This means that – granted that the conditions are favourable – warm extremes have much more ‘potential’ than during previous climatological periods,” explains van den Broek. This is mainly due to the interaction with high sea surface temperatures.
Overall, the research team expects summers on Svalbard to continue warming. In addition, extreme outlier months with unusually high temperatures could become more frequent — especially when atmospheric circulation patterns already favor warm conditions.
However, this forecast depends on the absence of sudden, large-scale changes in oceanic or atmospheric circulation — such as a potential collapse of the Atlantic Meridional Overturning Circulation (AMOC).
According to van den Broek, it remains unclear whether stable, anomalous weather patterns will be intensified by climate change itself — and, in his view, this is difficult to predict.