Abstract
AbstractProjected climate warming and wettening will have a major impact on the state of glaciers and seasonal snow in High Arctic regions. Following up on a historical simulation (1957–2018) for Svalbard, we make future projections of glacier climatic mass balance (CMB), snow conditions on glaciers and land, and runoff, under Representative Concentration Pathways (RCP) 4.5 and 8.5 emission scenarios for 2019–60. We find that the average CMB for Svalbard glaciers, which was weakly positive during 1957–2018, becomes negative at an accelerating rate during 2019–60 for both RCP scenarios. Modelled mass loss is most pronounced in southern Svalbard, where the equilibrium line altitude is predicted to rise well above the hypsometry peak, leading to the first occurrences of zero accumulation-area ratio already by the 2030s. In parallel with firn line retreat, the total pore volume in snow and firn drops by as much as 70–80% in 2060, compared to 2018. Total refreezing remains largely unchanged, despite a marked change in the seasonal pattern towards increased refreezing in winter. Finally, we find pronounced shortening of the snow season, while combined runoff from glaciers and land more than doubles from 1957–2018 to 2019–60, for both scenarios.
Highlights
Due to sea-ice related feedbacks, the climate on the archipelago of Svalbard, situated at the southwestern boundary of wintertime Arctic sea-ice, experiences amplified climate change compared to the global mean (AMAP, 2017; IPCC, 2019)
Time series of climatic mass balance (CMB) for 1957– 2060 (Fig. 5a) reveal an acceleration of mass loss despite linear temperature and precipitation trends, illustrating the impact of a feedback resulting from ablation zone expansion on the CMB (Van Pelt and others, 2012; Van Pelt and Kohler, 2015)
We presented projections of future CMB, snow conditions and runoff for Svalbard
Summary
Due to sea-ice related feedbacks, the climate on the archipelago of Svalbard, situated at the southwestern boundary of wintertime Arctic sea-ice, experiences amplified climate change compared to the global mean (AMAP, 2017; IPCC, 2019). A number of recent modelling studies have quantified the past SMB/CMB of all glaciers in Svalbard (Lang and others, 2015b; Aas and others, 2016; Østby and others, 2017; Möller and Kohler, 2018; Van Pelt and others, 2019; Noël and others, 2020), which cover an approximate area of 33 775 km or 57% of the total land area (Fig. 1). These studies consistently show a close to zero or weakly negative SMB/CMB in recent decades, but with a clear negative trend (Schuler and others, 2020). Schuler and others (2020) combined observational records from various regions in Svalbard to estimate a total CMB of −7 ± 4 Gt a−1 during 2000–2019, and a total glacier mass balance, i.e. including frontal ablation, of −8 ± 6 Gt a−1
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