Ridges - Safe HAVens for ice-associated Flora and Fauna in a Seasonally ice-covered Arctic OCean (HAVOC)

The HAVOC project aims to understand the role of sea-ice ridges, that is sea ice that has been pushed together and formed deep keels and high sails from blocks of ice, as a habitat for the sea-ice associated ecosystem in the central Arctic Ocean. With younger and thinner sea ice, a larger fraction of sea ice will melt every summer, and the last remnants of the ice that can survive summer melt, will be composed of thicker parts of the ice cover, often ridges. Ridges may thus be the last remnant of the sea ice pack that
can be used by species that are dependent on sea ice for survival. Ridges often remain the least studied component of the sea ice cover, in part due to difficulties in the field. The international MOSAiC experiment in 2019-2020, will replicate the drift of the Fram by Nansen in 1893-1896, provides a unique opportunity to study the life cycle of sea-ice ridges, their physical impact on the surroundings, and how they function as a habitat. New understanding is used to evaluate how important ridges are, and if processes related to
ridges need to be taken into account in climate models to reduce uncertainty in projections of the future Arctic marine ecosystem.

This project will fill critical knowledge gaps on the functioning of the sea-ice
associated ecosystem in the central Arctic Ocean. Our understanding of
the key processes is simply outdated for us to fully understand the current
conditions and to predict the future. A better process understanding is
required to improve climate models and thus our ability to forecast the
future. To date, essential information on the impact of ocean warming on ice
ecosystems especially with regard to seasonal variations is lacking, which is
largely related to the difficulties of conducting such observations over time
periods relevant for understanding all the interactions in the Polar climate
system. For improved process understanding annual time series are pivotal
to understand these interactions and feedbacks. MOSAiC, an extensive
international ice drift experiment, will study the central Arctic over full year
cycle in 2019/2020, giving an unprecedented opportunity to understand
the processes in a thinner ice pack. MOSAiC will provide unique insights
on the atmosphere-ice-ocean system and add important knowledge on
the processes in the Arctic ecosystem especially during seasons that are
under-sampled so far (late autumn, winter, and early spring). Our work will
examine the role of sea-ice ridges, one of the least studied features of the
ice pack, to better understand their role in sea-ice cover that has become
seasonal and melts in summer. Ridges may provide the last habitat and
optimal refuge for organisms that are dependent on sea ice, while the ice
otherwise would melt in summer. Thus ridges become a key component for
ice-associated organisms to survive and a hot spot for diversity. Data we
collect throughout a full-year cycle is used to improve representation of these
processes in coupled-ice ocean and ecosystem models that contribute to
an improved capacity to predict future conditions. This will be an essential
contribution for the management of the Norwegian Arctic.