After a record-shattering August, Longyearbyen (Svalbard) measures its warmest summer on record for the 3rd (!) consequecutive year. Moreover, with an average summer temperature of 8.6°C, last year’s record (7.8°C) is broken by a large margin. On top of this, August 2024 was the warmest month on record. This fact is particularly astonishing given that, climatologically, July is the warmest month on Svalbard.
The registered average summer temperature of 2024 is no less than 3.1°C above the climatological norm over the 1991-2020 period (5.5°C). With this record warm summer, the top-5 warmest summers on record in Longyearbyen now contains four years from 2020 or after. The complete top-10 ranking consists solely of years in the current century, of which 8 years after 2010 – despite a temperature record dating back to the late 1800s.
August 2024 warmest month on record at Svalbard Airport
Although the summer as a whole was remarkable in terms of weather statistics in Longyearbyen, August stood out in particular. First and foremost, the monthly temperature: August ended with an average temperature of 11.0°C. This is not only a mind-boggling 2.6°C above the previous record, but also no less than 5.0°C above the climatological norm for August (6°C based on 1991-2020 reference period).
Strikingly, this is only the second time ever Longyearbyen has recorded a monthly mean temperature over 10°C. Before last year’s record-warm July (mean temperature 10.1°C), Longyearbyen never measured a monthly mean temperature of 10°C or higher. Even more, before 2020, Longyearbyen never measured a monthly mean over 9°C. Meanwhile, August 2024 may breach the limit of 11°C.
What’s more, the month saw some incredibly warm days. On the 11th of August, the temperature rose to 20.3°C; the first time ever August measured over 20°C in Longyearbyen. The very next day, the mercury hit 20.0°C once again. Before these days, Longyearbyen never saw a temperature higher than 18.1°C in August (1997). Moreover, these days were only the 6th and 7th day ever with 20.0°C or higher in Longyearbyen – 6 of these occurrences happening since 2020.
Warmest June on record
In terms of temperature, the other summer months were extreme too, though less so than August. July ‘only’ ranked 6th warmest, with an average temperature of 8.3°C—still 1.3°C above the already substantially warmed climatological mean, though clearly below last year’s record. June, however, was record warm, though with a small margin. With an average temperature of 6.1°C, June 2024 just overtook the previous record of 6°C, set a mere 2 years ago.
A wet summer
Besides extremely warm, the summer of 2024 has been unusually wet in Longyearbyen. All months saw more precipitation than usual, and July specifically stood out with almost 50 mm, more than twice as much as usual (49 mm vs. a climatological norm of 20 mm). On July 8th, 23 mm of rain fell, more than what normally falls in the whole month of July. June saw 19 mm of precipitation, 10 mm above the climatological norm.
As the rain fell during very mild conditions, even in the mountainous areas most precipitation fell as rain rather than snow, enhancing the melt of snow and ice even at high elevations.
Exposed glaciers without accumulation zone
The extraordinary temperatures are not without consequences. Already halfway through summer, most of the snow fields around the Longyearbyen area were gone. It is normal that most snow fields melt over summer, however, some generally survive. Also, the upper part of the glaciers, known as the accumulation zone – the zone in which snow survives year around and provides new mass for the glaciers – are almost completely snow free in most glaciers around Longyearbyen, specifically the glaciers at lower elevation.
A glacier mass balans consists out of accumulation (snow that survives year around and turns into glacier-ice through compression) and melt. When there is more melt than accumulation, the mass balance is negative. The mass balance has been (strongly) negative in most recent years, leading to rapidly shrinking glaciers. However, this summer, many glaciers are experiencing the unique situation that they do not just experience strong melt in summer, but the absence of snow in the accumulation zone means there is also no new mass to even partially offset these losses.
Record melt
On the 23rd of July – another extremely warm day at the Archipelago (max temp at Svalbard Airport: 17.1°C) – Svalbard’s ice caps broke their record for daily surface melt. According to Xavier Fettweis, Professor in Climatology at the University of Liège, daily surface melt was 5 times higher than usual. The accumulated surface melt from the 1st of September 2023 was 3-5 times larger than average.
Southerly winds
Besides global warming and its impacts (diminishing sea ice, warming oceans and atmosphere, etc.), the extremely warm Augst was caused by anomalously persistent southerly winds, advecting extremely mild air from lower latitudes to the region. This flow pattern was due to persistent high pressure systems towards Svalbard’s east, with low pressure systems coming up from the southwest, pushing mild (and often humid) air towards the Archipelago.
Fastest warming place on earth
Svalbard is one of the fastest warming places on Earth. The reason for the faster-than-average warming is due to several feedbacks, such as the ice-albedo feedback. Even more, Svalbard is strongly affected by changes in ocean currents and shifts in wind patterns. Specifically, Svalbard ends up on the ‘warmer side’ of cyclones more frequently, and relatively warm Atlantic water penetrates further into the Svalbard region and its fjords, a process known as Atlantification.
read more about Longyearbyen’s climate here
Most of Svalbard’s warming has been concentrated in the winter months. Nevertheless, the last few summers have been astounding, with the summer of 2024 defying every statistical norm.
