Accelerating Ice Mass Loss Across Arctic Russia in Response to Atmospheric Warming, Sea Ice Decline, and Atlantification of the Eurasian Arctic Shelf Seas
Paul Tepes,Peter Nienow,Noel Gourmelen
First published: 30 June 2021
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2021JF006068"We used eight years of high-resolution CryoSat-2 interferometric altimetry to generate maps of surface elevation change dh and derive mass balance from 2010 to 2018 over the glaciers and ice caps of Novaya Zemlya and Severnaya Zemlya in the Russian Arctic. The high-density swath elevation fields were used further to generate, for the first time, robust time series of dh at 90-days time steps over single tidewater glacier basins at regional scale. We analyzed the time series in conjunction with climate data reanalyzes to establish links between the Russian Arctic's glaciers and ice caps mass imbalance and environmental forcings.
We find that Novaya Zemlya continues to dominate sea level input in the BKS region, with total ice loss of 9.7 ± 0.5 Gt a−1 driven by similar area-specific rates of loss from both land- (441 ± 31 kg m−2 a−1) and marine-terminating glaciers (425 ± 30 kg m−2 a−1). Along Novaya Zemlya's Barents coast, both surface melt and ice dynamics form a strong coupled mechanism leading to enhanced tidewater glacier mass imbalance, due to dramatic thinning in the lower tidewater terminus regions. Ice loss in Severnaya Zemlya is predominantly driven by six marine-terminating ice streams, whereas elsewhere in the archipelago, the ice at the basin scale is slightly thickening. Of the six ice streams, the acceleration of basin V on Vavilov ice cap in spring 2015 has led to the most significant shift in mass balance in the BKS region since 2010.
Our results reveal a clear and significant link between amplified, coupled atmosphere-ocean forcing and ice thinning over Novaya Zemlya, with a 1.5-years delay in the response of the ice masses to the onset of forcing. This linear response is particularly strong along the Barents Sea coast, where ongoing Atlantification is driving the climate dynamics and the subsequent ice mass response. Calving rates in Severnaya Zemlya are also controlled by Atlantic Ocean heat transfer, in this instance along the Eurasian continental slope, and assisted by Ekman vertical transport enabling warmer waters to reach tidewater glacier termini. However, over Severnaya Zemlya, oceanic and atmospheric forcing are decoupled, the former sustaining or activating ice dynamics at individual marine-terminating basins, and the latter sustaining a positive surface mass balance over the entire archipelago.
A linear relationship between ice loss and oceanic and atmospheric forcing has been demonstrated previously over parts of Greenland (Cowton et al., 2018; Khazendar et al., 2019; Slater et al., 2019, 2020). In the Eurasian High Arctic, a coupled atmosphere-ocean warming feedback is currently expanding eastwards in response to the northward shift of Atlantic climate (Polyakov et al., 2017), sea ice decline (Stroeve et al., 2018), and positive climate feedbacks (Goosse et al., 2018). Our detailed temporal and spatial observations of patterns of glacier thinning suggest that this progression is already significantly impacting glacier and ice cap stability in the eastern Russian Arctic, with the potential for future dynamic regime changes and enhanced mechanisms of ice loss.
Despite the complexities of climate variability in the BKS sector and a range of dynamic responses specific to the Russian High Arctic, our study confirms that relatively simple, linear relationships are sufficient to describe regional ice-climate interactions and may be used to predict future ice loss in regions where coupled ocean-atmosphere forcing prevails. These relationships provide considerable potential for improving global sea level predictions through the incorporation of parametrizations in coupled ice-atmosphere-ocean modeling work (Slater et al., 2020)."