Core Themes

The CRiceS overall concept is organized around four scientific Core Themes (CTs) which will interact strongly using an iterative workflow to address key uncertainties in how OIA processes control polar and global climate. Please read more below.

CT1. Heat, mass and momentum exchanges - The convergence and conversion of heat, mass and momentum at high latitudes is a fundamental component of the global energy budget. In order to reduce uncertainties in sea ice predictions and projections on seasonal to centennial timescales in both the Arctic and Antarctic, we need to better represent the crucial interactions and feedbacks between the OIA and the biological system. One of the key uncertainties is knowledge of the role of snow on sea ice within the OIA system. Snow and sea ice control the surface albedo and energy exchanges between atmosphere and ocean and are thus a critical component of the Earth’s climate system. Especially for snow on sea ice, there is a lack of representative observations, large uncertainties in existing observations, and challenges to represent snow-on-sea-ice processes in models. There are uncertainties in sea-ice related processes, for example the radiative transfer through snow and ice and the turbulent heat and momentum exchanges at the ice-atmosphere and ice-ocean interfaces. Current climate models fail to resolve many known small scale/non-homogeneous sea-ice and snow processes. These processes affect aerosols and clouds (CT2) and biogeochemistry/greenhouse gas exchanges (CT3) which influence coupled system behavior (CT4).

CT2. Aerosols & clouds - Aerosol-cloud interactions are the single largest source of uncertainty in quantifying anthropogenic radiative forcing, and are especially difficult to constrain in the polar regions where climate models struggle to reproduce available aerosol and cloud observations. Specifically, over the Southern Ocean, there is a well-known persistent overestimation of absorbed solar radiation in current ESMs linked to the poor representation of aerosols and/or clouds. Aerosols and their precursors (e.g. biological emissions CT3) emitted from the polar oceans (CT1) are important, yet uncertain, sources of cloud condensation nuclei and ice nuclei for large portions of the year at both poles. Knowledge gaps remain in the exact nature of aerosol sources (including transported aerosols), aerosol processing (including removal processes), and the role of aerosols in forming clouds and determining cloud phase. These uncertainties significantly limit model capabilities of representing aerosol-cloud-radiation feedback mechanisms within and outside of the polar regions. Polar aerosol-cloud processes have direct coupling with biogeochemical processes (CT3) and the state of atmosphere and ocean/ice (CT1), which requires a holistic approach using integrative observations and fully coupled models (CT4).

CT3. Biogeochemical cycles/greenhouse gas exchange - Changes in snow and sea ice, and ocean dynamics (CT1) are crucial for biological production and thus marine uptake of anthropogenic carbon at high latitudes and transport of biogeochemical properties into the ocean interior. However, ESMs still have considerable difficulties in reproducing these processes. Further, sea ice and snow are still treated as biogeochemically inert in most large-scale models, while they are now known to play an active role in biogeochemical processes, such as gas exchange. New descriptions of how sea ice/snow affect gas, aerosol (CT2), nutrient and carbon exchange between atmosphere and ocean are needed to make reliable future predictions. Uncertainties in gas transport across polar air-sea interfaces and related processes limit our ability to predict carbon storage, ocean acidification and ocean oxygen content in models. Biogeochemical cycling and greenhouse gas exchanges are interlinked with the physical state of the atmosphere, ice, and ocean (CT1) and are linked to aerosol processes, such as aerosol formation and nutrients delivered through aerosol deposition (CT2). These interlinkages are fully addressed within CT4.

CT4. Integrated system understanding - This theme develops interdisciplinary research approaches to improve OIA system understanding using knowledge from CT1-3 within integrated case studies and fully coupled models. The intrinsically interconnected chemical, physical, and biological processes within the OIA system represent a complex multi-scale, multi-compartment system that is currently not well understood. Most importantly, we lack the knowledge to extrapolate our knowledge of how the fully coupled OIA system operates to make short and long-term projections. This is in part due to the fact that targeted observations and models focus on one compartment or one set of processes, rather than focusing on the fully coupled system and also due to the influence of natural variability within the OIA system. We focus on how these chemical and physical systems act together across CT1-CT3 and identify essential couplings needed within models to represent past, present, and future OIA systems and their role within the dynamically evolving Earth system.