Degradation of the climate signal preserved in Svalbard ice. Have the high Svalbard ice fields reached a tipping point?

The whole Arctic regions are undergoing faster warming than the global average. The Svalbard archipelago is particularly sensitive to temperature increase due to the moderate altitude of the main ice fields. Though the greater temperature increase has been observed during the winter periods, enhanced summer temperatures are extending in time and altitude the areas affected by melting. The Spitsbergen region of the Svalbard archipelago has three main ice fields: Lomonosovfonna, Åsgardfonna, and Holtedahlfonna. The summit of these ice fields ranges between 1250 of Lomonosovfonna and Åsgardfonna to the 1100 m a.s.l. of Holtedahlfonna. From 2012 to 2017 three shallow cores, covering the periods 2003-2016 have been collected at Holtedahlfonna summit. The oxygen stable isotope ratio signal obtained have been compared with the longer ice core record (124 m deep) collected in 2005 at the same location extending back to the 17th century. In the three shallow cores we have measured an unexpected more negative isotopic ratio signal compared to the long Holtedahlfonna ice core record although the Svalbard annual atmospheric temperature are increasing. Meteorological and ocean measurements as well as model re-analysis conducted at the drilling site, show a clear increase of the number of days with average temperatures above zero, and strong decrease of summer snow accumulation. The combination of ice core data, meteorological and oceanic re-analysis and mass balance calculation suggests that the Svalbard higher ice cap might have reached a tipping point where the summer accumulation is almost fully removed causing a bias on the isotopic signal.