In order to better understand glacier melt dynamics, Joan Ramage from Lehigh University, US, and colleagues used satellite data to study two heavily glaciated archipelagoes located between 70 and 83 °N in the Russian high Arctic: Novaya Zemlya and Severnaya Zemlya.

In recent years both the ice caps on these archipelagoes have only shrunk a small amount, despite the rapid rise in surface air temperature. The researchers analysed satellite data for the period 1992–2012 and calculated surface melt onset date and total melt days for each glacier. They then compared these records with local temperature and sea-ice extent data for the same time period.

On both glaciers the team found a strong correlation between the mean number of total melt days and sea-ice extent. The number of melt days increased by 7.7 days per decade on Severnaya Zemlya during the study period, while late summer sea-ice extent in the surrounding waters decreased by more than 13,000 kn2 per year.

“Sea-ice reduction can influence large-scale atmospheric circulation, amplifying Arctic warming, and therefore resulting in stronger glacier snowmelt,” explained Ramage. “In addition, decreasing sea-ice cover can expose increasing areas of open water in summer to evaporation. The additional advection of heat fluxes from warming mixed ocean layers can further accelerate surface melt.”

The findings are published in Environmental Research Letters (ERL).

Sea-ice loss is also influencing the regional weather. “Sea-ice loss might increase snowfall and simultaneously enhance surface melt over Severnaya Zemlya and Novaya Zemlya by additional heat advection from warming mixed ocean layers,” said Ramage. This additional snowfall could explain why glaciers in the Russian high Arctic, and other Arctic regions including Svalbard and Greenland, have not been losing weight as fast as might have been expected.

However, Ramage and her colleagues warn that this situation is unlikely to last. “Once this region is warm enough, liquid rainfall might dominate precipitation, which can further accelerate glacier snowmelt, instead of moderating ablation when in its solid form (snowfall),” she explained.

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