In February and March 2015, scientists studying the highly dynamic, thinning Arctic drift ice north of Svalbard were forced to evacuate their ice camp several times as ice floes broke up under their feet. Although they never knew exactly when it would happen, they had come to expect and prepare for ice breakups, which have become more common in recent years. During their work as part of the Norwegian-led research project Norwegian Young Sea Ice Cruise (N-ICE2015), an expedition launched to observe Arctic sea ice conditions, they were accustomed to watching for danger signs and moving quickly to salvage their gear and instruments when the ice broke up.
The Arctic Ocean is shifting to a new regime: A younger and thinner ice pack is replacing older, thicker sea ice [Meier et al., 2014]. Large areas of the ocean that were previously covered by sea ice year round are now ice free for parts of the summer. This will have consequences locally and in a much wider area around the Arctic. Much of our current knowledge of Arctic sea ice stems from the former old-ice regime, and we need new knowledge to understand the system in its current thinner state and to improve our capacity to predict its future.
From the midst of the polar night to early summer (January to June 2015), the N-ICE2015 crew allowed the Arctic waters to freeze around the Norwegian Polar Institute’s research vessel Lance to help provide this new knowledge. The concept of N-ICE2015 followed the precedent of many previous expeditions, including the Fram expedition by Fridtjof Nansen, Russian drifting stations, the Surface Heat Budget of the Arctic Ocean campaign in 1998–1999 [Perovich et al., 1999], and the Tara drift during International Polar Year 2007–2008 [Gascard et al., 2008]. However, all of these expeditions were conducted in a thicker ice regime.
Lance, adrift in the ice, provided a base for 100 scientists and engineers who spent 3 to 6 weeks on board the vessel studying air-snow-ice-ocean interactions in a region with thinner sea ice. The scientists also investigated how the marine ecosystem responds to these new conditions. Interdisciplinary work was an integral part of N-ICE2015, as physical oceanographers, sea ice physicists, atmospheric scientists, and marine biogeochemists worked successfully side by side.
What Provides the Heat to Melt the Ice?
What causes the sea ice in this region to melt? This was one of the key questions during the field campaign. Is it caused by the 1°C warming since the 1980s of the Atlantic water (currently, a relatively warm +3.0°C) that flows into the Arctic Ocean west of Svalbard [Onarheim et al., 2014]? Is the heat in the warm water mixed toward the surface to melt the ice in the deep basin? Or is the ice melt solely triggered by the return of the Sun and solar heating of the ice and ocean? How do storms affect the ice pack and the mixing of ocean heat to the surface? How does the freezing during the previous winter affect the conditions during spring?
To answer these questions, the team was primarily interested in observing the ocean heat content, vertical mixing of the ocean heat toward the sea ice, and how sunlight penetrated the ice and snow and contributed to melting of the thinner ice pack. Dozens of autonomous buoys deployed on the sea ice as far as 20 kilometers away from the vessel measured the growth and melting of sea ice to give indications of ocean heat flux on a larger scale.
Is the Thinner Ice Pack More Susceptible to Atmospheric Forcing?
Signs that the movement (dynamics) of the ice pack has changed have appeared as the ice pack has grown thinner. The ice is moving faster [Spreen et al., 2011], and the thinner ice may be more sensitive to breakup due to storms and waves.
Understanding the dynamics of the ice pack is one of the key challenges for climate models. To this aim, the N-ICE2015 campaign and partners deployed two arrays of autonomous buoys on the sea ice several tens of kilometers away from Lance. Ski patrols using snow machines deployed the buoys during the cold of the polar night. Later in spring, buoys were deployed by helicopter. These buoys sent their positions and measurements via satellite in near-real time to track the movement and deformation of the ice pack, providing valuable data on ice dynamics for use in improving climate models and satellite products.
Because the thinner ice pack might be more vulnerable to storms than the thicker ice decades ago [Parkinson and Comiso, 2013], the role of Arctic storms in sea ice loss has received attention recently. N-ICE2015 scientists monitored interactions of the thinner ice pack with storms using a combination of buoys that measured wave action in the ice pack and satellite observations.
How Does the Ecosystem Respond to Thinner Ice?
The biologists involved were interested in finding out how organisms living in the sea ice and the underlying water column adapt to the thinner ice cover. Will under-ice phytoplankton blooms become more widespread in the new ice regime, as has been suggested by observations in other parts of the Arctic [Arrigo et al., 2012]? Or are ice algal blooms likely to experience negative effects from later freeze-up, earlier melt-out, and possibly detrimentally high light levels transmitted through thinner ice?
Scientists were keen to find out how ice algae cope under the new ice regime. Changes in the timing and magnitude of the ice algal and phytoplankton blooms would have downstream effects on the organisms that eat algae and phytoplankton and, eventually, the entire ice-associated ecosystem.
Collaboration, Coverage, and Outreach
Research during N-ICE2015 was truly international and reflected the current interest in the Arctic. Scientists from institutions in more than 10 countries, including Canada, Denmark, Finland, France, Germany, Japan, Korea, Norway, Russia, the United Kingdom, and the United States, participated, and the crew came from many more nations. This unique opportunity brought together many experts in their respective fields to contribute to a better understanding of the Arctic.
The N-ICE2015 research campaign also benefited from social media. Accounts on Instagram, Facebook, and Twitter showcased the research to a wide general audience on a regular basis (search for hashtag #NICE2015Arctic on Twitter and Instagram).
Traditional media outlets, including news teams from National Geographic and BBC, were invited on board the research vessel, which brought wider attention to the research and the ongoing changes in the Arctic. The Norwegian national broadcaster (NRK) used the opportunity to educate the audience about climate change in the Arctic through Oppdrag Nansen, a television program that documented how four 13-year-olds followed the footsteps of Nansen by staying on board Lance for a week to study the ice and snow with the scientists on board.
Work for Years to Come
Although the field campaign from January to June 2015 was a key component of the project, work is far from over. In the months and years to come, the scientists will analyze the various observations to make sense of it all. New understanding of the thinner ice regime in the Arctic will help reduce the uncertainty in predictions of how the ice conditions evolve. Core data sets will be made available to the broader scientific community, which can make use of them in developing and evaluating process and regional and global climate models.
This work was supported by the Centre of Ice, Climate and Ecosystems at the Norwegian Polar Institute and the Ministry of Climate and Environment and the Ministry of Foreign Affairs of Norway. This work was also supported, in part, by funding from the Ice, Climate, Economics-Arctic Research on Change (ICE-ARC) project from the European Union 7th Framework Programme, grant 603887, the Norwegian Research Council, and the European Space Agency. Many participating institutions also provided support.