Sea ice and snow cover, together with clouds, regulate Earth’s climate by reflecting and absorbing solar radiation. Sea ice and its snow cover play an active role in controlling the OIA exchange of heat, momentum, nutrients, organic/inorganic matter, aerosols and gases (including CO 2 ). Transitioning to a warmer world with sea ice-free conditions for portions of the year represents a fundamental change in the functioning of the polar ocean-atmosphere system. Further, sea ice influences global deep ocean circulation, constitutes an active component of the polar ocean ecosystem, provides key resources for people within the Arctic (including Indigenous peoples), and affects human activities (e.g. shipping, resource extraction). It is therefore essential to fill key gaps in knowledge of how the coupled OIA system functions within the polar regions and the Earth system.

The overarching objective of CRiceS is to deliver improved understanding of the physical, chemical, and biogeochemical interactions within the OIA system, new knowledge of polar and global climate, and enhanced ability of society to respond to climate change. The unique and broad interdisciplinary expertise within CRiceS allows us to quantify the characteristics and functioning of the OIA system in the past, present and future (across diverse timescales) and its role from regional to global spatial scales. Knowledge at these scales is essential for developing improved understanding of how OIA physical and chemical processes control polar and global climate.

O1) Translate knowledge across scales from observed OIA processes (e.g. microscopic properties of sea ice, aerosols/clouds, etc.) to controlling climate scale processes within models that describe the coupled ocean-ice/snow-atmosphere system (WP1-2). Despite expanding in-situ observation infrastructures, an increasing number of measurement campaigns and emerging satellite datasets, data availability and accuracy in the polar regions remains a challenge. A critical obstacle in advancing breakthroughs in polar science is the inclusion of process understanding from observations into predictive models including ESMs. CRiceS will achieve effective fusion of model and observation realms, by including multi-disciplinary research communities over multiple work packages to tackle existing challenges, fill gaps, exploit opportunities and work jointly towards utilization and synthesis (e.g. advanced data products) based on existing datasets/infrastructures that span a range of spatial and temporal scales of the coupled system.

O3) Deliver open data and models that service the scientific community, stakeholders, and beyond (WP5). CRiceS will apply and monitor practices of Open Science and Responsible Research at all steps of project workflow, to ensure optimal visibility, prolonged legacy and expanded impact of CRiceS output. The interdisciplinary nature of CRiceS will create new mechanisms and protocols for successful integration of several Earth System research communities via open models, data and toolsets. Co-design of hazard and impact indicators will introduce new pathways in translating and communicating research results to societally relevant metrics.