Gisteren is er een paper uitgekomen over de gletsjers op Spitsbergen: "Svalbard’s 2024 record summer: An early view of Arctic glacier meltdown?" In de zomer van 2024 ging er zo'n 62 gigaton verloren, 1% van de totale massa.
Het grootste deel hiervan smolt in een periode van zes weken met ongekend hoge temperaturen. Gezien dit soort hoge temperaturen vaker voor gaan komen geeft dit een kijkje in de toekomst van smeltende arctische gletsjers.
Paar begrippen voor context:
The total mass balance (TMB) of a glacierized region responds to the exchange of mass and energy between the atmosphere and the glacier, as well as between the ocean and the submarine glacier fronts. The former is termed the climatic mass balance (CMB), and the latter is known as frontal ablation (FA), the sum of frontal melting and ice calving (16).
Het massaverlies bestaat uit twee delen CMB, smelten en verdampen door de warme lucht, en FA, smelten door contact met de oceaan en het verlies van ijs doordat het in de oceaan valt. Het was vooral de CMB die uitzonderlijk hoog was:
To assess the total mass loss, the CMB (−42.1 ± 10.7 Gt) needs to be complemented with estimates of FA of marine-terminating glaciers. Using remote sensing data (22) and a model of ice thickness (10), we estimate a FA of 19.6 ± 3.1 Gt for 2024, of which 3.2 ± 0.5 Gt relates to front area retreat. While this marine ice loss is high, it is not extreme compared to the average for 2010-2020 (16.8 ± 2.5 Gt y−1) (23). Together, the total ice loss for the mass balance year 2023/24 amounted to 61.7 ± 11.1 Gt (SI Appendix, Table S1), equivalent to about 1% of the total ice volume of all Svalbard glaciers (10).
Een overzicht voor de hele regio:
Een afbeelding zegt meer dan woorden:
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Svalbard glacier mass balance 2024 vs 1991-2020 climatology. (A) Cumulative daily CMB for the season 2023/24 (blue) compared to the range of values of previous years 1991–2023 (gray shading) and the average value for the 1991–2023 period (black). Light and dark red shading indicate days where daily CMB was below the 5 and 1% percentile of the 1991–2023 period. (B) Seasonal mass balances of Kongsvegen as measured by the glaciological method, for winter (blue) and summer seasons (red) as well as the annual value (black). Values are per unit area and presented in water equivalents (w.e.). (C) Comparison of measured and simulated, glacier-wide mass balances of Kongsvegen for the period 1991–2024, again the colors refer to different seasons: winter (blue), summer (red), and annual (black). The values for the extreme year 2024 are shown as filled circles, using the same color code. (D) Map of Svalbard in the high Arctic showing color-coded the CMB anomaly for August 2024, relative to the period 1991–2020 and expressed in terms of the climatology SD. The red line shows the boundaries of Kongsvegen glacier. Marine termini are marked with thick, black lines. Labels show estimates of CMB and FA for five subregions (division indicated by lines). Blue and black dots denote locations of the GNSS observatories NYA1 and LYRS, respectively. (E) Location of Svalbard (red circle) within the Arctic.
Voor de goede orde ook nog de temperatuurafwijking t.o.v. 1991-2020:
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Record air temperature in August 2024. The 2024 anomaly of August air temperature, according to CARRA, with respect to the 1991–2020 climatology. Inserts compare measured temperatures at several long-term, operational weather stations during August 2024 (red dot) with those of the 1991–2020 climatology (boxplot).
Abstract
A record-breaking melt season affected the Arctic glaciers of Svalbard in summer 2024 by a substantial margin. Across the entire archipelago, glacier melting corresponded to an anomaly of up to four SD and exceeded any previous observation. The pan-Svalbard mass loss in summer 2024 amounts to ~61.7 ± 11.1 Gt and corresponds to 1% of the total ice volume on Svalbard and is comparable to that of the Greenland ice sheet (55 ± 35 Gt), which occupies an area about 50 times larger. Altogether, Svalbard and other glacier regions surrounding the Barents Sea lost 102.1 ± 22.9 Gt of ice in a single year and contributed 0.27 ± 0.06 mm (of which 0.16 mm alone is due to Svalbard) to global sea-level, putting the circum-Barents region among the strongest contributors to global sea-level rise in 2024. Most of the 2024 glacier melt occurred during a 6-wk period of persistent atmospheric circulation pattern causing record-high air temperatures, an event with an extremely low recurrence interval under current climate conditions. However, future climate projections suggest that such temperature levels will become increasingly commonplace by the end of the 21st century, potentially even surpassing those of 2024. Svalbard’s summer of 2024 serves as a forecast for future glacier meltdown in the Arctic, offering a glimpse into conditions 70 y ahead.
T.V. Schuler, R.E. Benestad, K. Isaksen, H.P. Kierulf, J. Kohler, G. Moholdt, & L.S. Schmidt, Svalbard’s 2024 record summer: An early view of Arctic glacier meltdown?, Proc. Natl. Acad. Sci. U.S.A. 122 (34) e2503806122,
https://doi.org/10.1073/pnas.2503806122 (2025).