The Marine Working Group (MWG) is composed of 32 members from 21 countries. Additionally, four early-career IASC Fellows have participated in our efforts since 2015, and we also receive support from a Secretary located at the Swedish Polar Research Secretariat. We strongly encourage more involvement (e.g., funding proposals) from non-working group members. Through appointments by each nation’s Arctic research coordinating bodies, our members’ interests span most aspects of the marine environment in the Arctic, including biogeochemistry, physics, land-ocean and ocean-ice linkages, remote sensing, marine ecology, sedimentation, and carbon and nitrogen cycling.
The MWG facilitates international coordination of research in the Arctic marine environment and supports cross-cutting objectives through face-to-face annual meetings. Frequent electronic communication is used throughout the remainder of the year, including exchange and collaboration with terrestrial, cryospheric, atmospheric and social scientists where appropriate. Another important goal is to provide support for early career scientists and include their involvement in international research coordinated by IASC member countries, including expanding roles for IASC Fellows in MWG tasks.

Scientific Themes
Broadly speaking, MWG activities are focused around five scientific foci:

· Predicting and understanding raid changes to the Arctic Ocean system
· Understanding biological and ecosystem processes in the Arctic Ocean and sub-arctic seas
· Understanding sea ice structure dynamics and its relationship to the Arctic system
· Understanding geochemical processes in the Arctic Ocean and sub-Arctic seas
· Enhancing and improving access to the paleo record of the Arctic Ocean through scientific drilling

In addition, the following four general themes were identified by the Marine WG as important cross-cutting issues which should be addressed by most, if not all, the IASC Working Groups:

· How will the diminishing ice cover affect the carbon cycle in the Arctic and what are the impacts?
· How does the variability of different components of the Arctic system impact the heat and momentum exchanges between ocean, ice, atmosphere and space in a changing climate?
· How will changes in the hydrological cycle impact various components of the Arctic system?
· How will biological productivity change under changing sea ice regimes?

Specifically, these foci and cross-cutting themes have led to recent efforts that include renewal of the Arctic in Rapid Transition network that has provided a mechanism for the early career science community to become engaged in international arctic research; implementation of the Multidisciplinary drifting Observatory for the study of Arctic Climate (MOSAiC); contributing to the Workshop on Arctic Glaciology and Proglacial Marine Ecosystems, and expansion of the Distributed Biological Observatory on a pan-Arctic basis. A special session that includes examination of the changes in the productivity of ice associated marine ecosystems was also developed by the MWG as part of POLAR 2018 in Davos, Switzerland. Finally, strengthening international cooperation with Russian scientists remains a key goal, including support for IASC’s Russian Arctic (ISIRA) activities that are seeking to improve conditions for marine research within Russia’s Exclusive Economic Zone.

Near-term goals that have been incorporated into a formal work plan for the MWG include:

1. Improve the engagement of working group members in actions of the MWG between face-to-face meetings
2. Encourage and facilitate two-way communication between working group members and their national science constituencies that MWG members represent.
3. Improve lines of communication and cooperation with terrestrial, cryospheric, atmospheric and social scientists where appropriate, as with researchers focused on parallel southern hemisphere scientific questions.
4. Promote transparency in MWG decisions that support international cooperation in Arctic marine research.
5. Support of early career scientists for involvement in international research coordinated by IASC member countries, including expanding roles for IASC Fellows in MWG tasks.

The MWG seeks to encourage and facilitate two-way communication between working group members from each member state of IASC and their national science constituencies. If you have any questions about the Marine Working Group, please get in touch with any of our working group members. Our annual meetings, held during the Arctic Science Summit Week, are open to the public and provide a forum for advancing proposals to initiate and improve cooperative arctic research in marine systems. We welcome involvement of the interested scientific community in helping to guide future initiatives and sustain on-going projects.