Study Shows Extreme Scale of Arctic Sea-Ice Melt

Open water above northern Greenland. Photo taken from Polar 6 research aircraft of Alfred Wegener Institute during ASIMBO 2018 research campaign. (Photo courtesy Alfred Wegener Institute)

(CN) – Marine scientists offered more sobering news Tuesday that climate change is pummeling the Arctic the hardest: 80% of young ice melts before it has a chance to leave its “nursery” in the shallow Russian marginal seas of the Arctic Ocean.

Researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research published their findings in the journal Scientific Reports showing how the dramatic loss of Arctic ice is influencing sea-ice transport across the Arctic Ocean. They say an ice-free summer in the Arctic is one step closer to happening, and the Arctic Ocean will lose an important means of transporting nutrients, algae and sediments.

In the winter, air temperatures of minus 40 degrees Fahrenheit in the marginal seas of the Barents, Kara, Laptev and East Siberian Seas – the ‘nursery’ of Arctic sea ice – help to produce new sea ice while a strong offshore wind drives the young ice out to the open sea. Once driven out, the young ice eventually catches up with the Transpolar Drift, one of the two main currents in the Arctic Ocean.

Over the course of two to three years, the ice floes from the Siberian part of the Arctic Ocean move across the Central Arctic and into the Fram Strait where it finally melts.

Marine research experts monitoring and analyzing sea ice movements using satellite date from 1998 to 2017 determined that just two decades ago, roughly half the ice from Russia’s shelf seas made this transarctic journey. Today only 20% does; the rest of the young ice melts before it turns a year old.

“Our study shows extreme changes in the Arctic: the melting of sea ice in the Kara Sea, Laptev Sea and East Siberian Sea is now so rapid and widespread that we’re seeing a lasting reduction in the amount of new ice for the Transpolar Drift. Now most of the ice that still reaches the Fram Strait isn’t formed in the marginal seas, but comes from the Central Arctic,” lead study author and Alfred Wegener Institute sea-ice physicist Thomas Krumpen said in a statement.

“What we’re witnessing is a major transport current faltering, which is bringing the world one major step closer to a sea-ice-free summer in the Arctic,” he said.

Sea-ice physicists taking regular measurements of ice thickness in Fram Strait confirmed this trend.

“The ice now leaving the Arctic through the Fram Strait is, on average, 30% thinner than it was 15 years ago. The reasons: On the one hand, rising winter temperatures in the Arctic and a melting season that now begins much earlier; on the other, this ice is no longer formed in the shelf seas, but much farther north. As a result, it has far less time to drift through the Arctic and grow into thicker pack ice,” Krumpen explained.

The ice floes still carried by the Transpolar Drift to the Fram Strait are for the most part formed in the open-sea regions of the Arctic Ocean, far from the coasts. As a result, they contain significantly fewer particles like algae, sediments and nutrients compared to ice from the shallow shelf seas where waves, wind and tides stir up particles from the seafloor. In addition, rivers like the Lena and the Yenisei carry major quantities of minerals and sediments to coastal areas that become trapped in the ice as the water freezes.

For the past 20 years, biologists have been analyzing samples obtained with sediment traps in the Fram Strait. This analysis revealed in the past, mineral load was transported to the Fram Strait locked in the sea ice. The earlier melting floes now release the material on their way to the Central Arctic and what little material does reach the Fram Strait shows a different composition.

“Instead of Siberian minerals, we’re now finding more remains of dead algae and microorganisms in our sediment traps,” study co-author Eva-Maria Nöthig said. She and her colleagues believe in the long term this altered sea-ice-based particle transport is likely to produce lasting changes in the biogeochemical cycles and ecological processes of the central Arctic Ocean. What types of lasting changes are yet to be fully understood and will feed into new research projects to help provide the answers.

The Alfred Wegener Institute will spearhead what it bills as the greatest Arctic research expedition in history this September. The “MOSAiC expedition” will address key research questions related to the evolution of sea ice and the ecological processes in the Arctic Ocean.

The German research icebreaker Polarstern will journey with 600 people from 17 countries to drift with the Transpolar Drift through the Arctic Ocean for an entire year, intentionally trapped in the ice. Aircraft and other icebreakers will be used to regularly resupply the expedition that is expected to help inform the research of many times that number of experts.

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