Abstract
Since the first estimates of Svalbard-wide glacier mass balance were made in the early 2000s, there has been great progress in remote sensing and modelling of mass balance, existing field records have been extended, field records at new locations have been added, and there has been considerable environmental change. There is a wide spread in the available estimates of both total mass balance and climatic mass balance, but there is overall agreement that the glaciers on Svalbard have been losing mass since the 1960s, with a tendency towards more negative mass balance since 2000. We define criteria to select data that are representative and of high credibility; this subset shows a more coherent evolution and reduced spread. In addition, we combine individual field mass balance records collected by different groups into a single dataset that samples glaciers across Svalbard and a range of different size classes. We find a close relationship between measured glacier mass balance and size of the glacier, in such a way that smaller glaciers experience more negative climatic mass balances. A qualitatively similar relationship between the accumulation area ratio and glacier area is found for all glaciers in the Svalbard, suggesting that the relation derived from glaciological records is not only an artefact caused by the limited number of samples (n=12). We apply this relation to upscale measured climatic mass balance for a new estimate for all glaciers of Svalbard. Our reconciled estimates are for the climatic mass balance -7 ± 2 Gt a-1 (2000-2019) and a total mass balance of -8 ± 6 Gt a-1. From the difference and the related uncertainty, we derive an estimate of frontal ablation amounting to ca. 5-10 Gt a-1. While this is similar to a previous estimate of Svalbard-wide frontal ablation, the uncertainties are large. Furthermore, several large and long-lasting surges have had considerable and multi-year impact on the total mass balance, and in particular on calving rates, emphasizing the need for better-resolved and more frequently updated estimates of frontal ablation.
Highlights
Ongoing climate change alters the energy and mass balances of glaciers, which in turn have hydrological and ecological implications at the regional scale and which drive global sea-level changes
The steeper slope of the cumulative mass balances shows that glaciers in southern and central Spitsbergen (Werenskioldbreen, Svenbreen, and Austre Grønfjordbreen) have more negative surface mass balance (SMB) than those located in NW Svalbard (Austre Brøggerbreen and Midtre Lovénbreen)
A qualitatively similar relationship between the accumulation area ratio and glacier area is found for all glaciers in the Svalbard, suggesting that the area-SMB relation is an artifact caused by the limited number of samples (n = 12)
Summary
Ongoing climate change alters the energy and mass balances of glaciers, which in turn have hydrological and ecological implications at the regional scale and which drive global sea-level changes. We discuss new technologies that have become available in the past 20 years These include improved capability of satellite remote sensing for mass balance monitoring and meteorologically forced models to simulate climatic mass balance. Both techniques enable issues with temporal gaps and spatial representativeness of glaciological measurements to be overcome and to be linked optimally with adjacent disciplines in an Earth System perspective. Of Svalbard, ranging from milder and more humid conditions in the south and west, to the colder and drier conditions in the northeast These gradients are reflected in the spatial pattern of climatic mass balance, and in the distribution of glacier-covered area.
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