What events contribute to reductions in the Antarctic sea-ice extent?
How do biogeochemistries and ecosystems link to atmosphere and cryosphere?
Are critical feedbacks from altered sea-ice buoyancy, heat fluxes, albedo, particle nucleation, momentum, biologically mediating climate-active gases?
What level of model coupling better predicts sea-ice change?
In recent decades the polar oceans have undergone significant change, as exemplified by the dramatic loss of sea ice in the Arctic. In an apparent paradox, the Antarctic sea-ice extent increased over the observational record despite global warming reaching an all-time maximum during austral winter 2014. Yet soon after getting maximum extent, the extent of Antarctic winter sea-ice shrunk to a record low in 2016 (Fig3.1) and remained low in subsequent years (Fig3.2). Reductions in sea ice have been shown to have significant ramifications for Antarctic marine ecosystems and Southern Ocean biogeochemical cycles (e.g., Henley et al. 2020).
State-of-the-art numerical models did not mirror the persistent increase in Antarctic sea-ice extent nor its collapse. We are left to question our understanding of the polar (and hence global) system. What will be the future of critical Earth System processes such as the radiation balance and carbon uptake? The carbon cycle is sensitive to changes in sea ice because ice cover modulates the uptake of carbon dioxide. Defining processes in Southern Ocean biogeochemistry (BGC) will improve predictions of the changes in the oceanic carbon cycle in response to sea-ice change. This fit-for-purpose observational program will lay the groundwork for long-term monitoring of the BCG system. The MIZ study will also probe the role of sea ice in modifying ecosystem functions.
Such a multi-disciplinary measurement campaign with novel numerical models and deep-learning data analysis will step-up our knowledge of the Antarctic sea-ice system. However, the marginal ice zone presents severe challenges to observe, measure, sample, and monitor. The setting is highly dynamic. Ice floes, often heaving, sometimes aggregate in bands interspersed with swaths of open water. Passing atmospheric systems (cyclones) generate waves and swell action, rapidly changing sea-ice location and weather conditions. The new Australian icebreaker RSV Nuyina enables such a challenging program, and an exciting component of this endeavour is equipping the vessel with scientific and data management capability.
AAPP objectives for the MIZ Study are:
- Acquire gap-filling baseline information and understanding of the East Antarctic MIZ physical-biological-biogeochemical environment, primary interactions and feedbacks therein, and the processes controlling its seasonal evolution.
- Identify environmental drivers of primary production (ice algae, under-ice blooms, and ice-edge blooms), food-web dynamics, and carbon export.
- Evaluate the skill of Earth System Models (including biogeochemical and ecosystem components) to reproduce seasonal evolution and improve model parameterization of key processes to enhance sea-ice prediction and forecasting as well as aerosol and cloud modeling.
- Validate a range of remote-sensing products, including sea-ice thickness, ice dynamics, sea-ice concentration, sea-surface temperature, chlorophyll, and width of the marginal ice zone
- Pinpoint vulnerabilities of the marginal ice zone to climate change.
ACEAS objectives for the MIZ Study are:
- Assess how Southern Ocean wind changes affect the regional oceanic circulation and sea ice (e.g. sea ice transport, creation of polynyas) on timescales ranging from decadal (e.g. over the last few centuries to millennia) to centennial (e.g. past abrupt climate change), to multi-millennial (e.g. glacial-interglacial timescales) using ocean/sea-ice models
- Assess how the regional changes in wind, oceanic circulation and sea-ice impact ocean temperature, salinity, biogeochemical properties (e.g. O2, DIC, PO4, chlorophyll), and atmospheric CO2 combining ocean/sea-ice/carbon cycle models and palaeo-proxy records
- Use palaeo-proxy records to identify past Antarctic meltwater events in East Antarctica, and assess their influence on oceanic circulation and sea-ice using proxy records and coupled modelling
- Evaluate the consequent effects on open water and under ice biogeochemistry and ecology for both contemporary and past climate
- Use palaeo-proxy records to assess past changes in ecosystem structure and function and export production near the Marginal Ice Zone (MIZ), and their potential link to changes in iron supply from the cryosphere and atmosphere.
- Assess the impact of changes in oceanic circulation, sea-ice and iron inputs on ecosystems and the carbon cycle in the MIZ using Earth system models
- Perform contemporary measurements in the MIZ on under ice and open water food webs, coupled biogeochemistry, downward carbon export, water column and sea ice chemistry, and isotopes of oxygen, carbon and neodymium to calibrate paleo proxy records.
The MIZ Study will provide:
- a suite of calibrated observational and derived data sets of crucial climate and ecosystems variables (promptly and publicly available as agreed in the data-management plan)
- a set of numerical modelling modules, ranging from stand-alone to highly coupled models
- a synthesis of the climatology for the (East) Antarctic marginal ice zone
- state-of-the-art sampling protocols following international Best Practices
- a recommendation about requirements for long-term monitoring in the Southern Ocean and near-coastal Antarctic
- Early Carrier Researchers and students' skill sets complementary to their academic training
- a commentary on the science capability of RSV Nuyina
- a well-connected Australian research capability targeting Southern Ocean science
- peer-reviewed scientific publications
- initiation of a health tracker for the East Antarctic sea-ice zone (WP2)
- outreach activities, and
- information collated in different formats to inform stakeholders, including policy, non-science end users, and the general public.
Outcomes of the Miz Study
During its four-year lifetime, the MIZ Study will:
- Add (or update previous) knowledge about the highly variable role of MIZ to better understand the governing interactions and processes.
- Investigate the skill of numerical model components, parameterizations, configurations, and modelling systems by testing them against our data (validate model formulations).
- Undertake fieldwork centered around the inaugural marine-science voyage on RSV Nuyina over 60 days during late winter/early spring 2023, supplemented by various smaller missions carried out through the AAP or international partner providers (organized through COMNAP).
- Develop a cross-disciplinary observing strategy and deployed varied autonomous scientific sensor packages to enable long-term and broad-field measurements.
- Devise observing protocols following international Best Practices and standards for sample and data sharing.
- Derive effective and fast data handling and processing strategies to recover samples and data, conduct state-of-the-art sample and data analysis, and synergistic elongation of the combined dataset.
- Extend existing climatologies, produce improved data products (derived variables), and revise data-only approaches.
- Advance the approach and methods the research community uses globally, across disciplines of climate science, sea level, ecosystems, geology, and biogeochemistry, including those outside polar regions.
- provide a shared platform to develop sampling strategies, analysis methods, and code development.
- provide a vibrant example for integrating research questions from one discipline to the next, increasing the information and scientific return from asset investments.
- proactively educate and train students and Early-/Mid-career scientists.
The big-picture outcome is to derive new information on processes and interactions within the physical and ecological MIZ environment and, by synergistic analysis, better understand the role of (East) Antarctic marginal ice zone in Earth systems.
For team and science-community networking, we will convene a third MIZ Study workshop to:
- merge the AAPP- and ACEAS-led components of the MIZ Study,
- round out with external national and international collaborators, and
- decide on numerical, analytical and observational approaches.
In addition, MIZ Study Work Packages are encouraged to network regularly (i.e., every 2 or 3 months), and hold annual MIZ Study workshops.
The SCAR 2022 Open Science Conference (01 - 10 Aug) theme was "Sea ice in the atmosphere-ice-ocean-biosphere system: How, where, and why is it changing, and what are the effects?". The online conference is expected to be posted on Youtube soon.
For outreach to Antarctic & Southern Ocean stakeholders, we will initiate a Policy and Research Forum focusing on the relevance of the region to policy and government stakeholders as well as the wider community.
There will be other opportunities to increase skills, for example, the Arctic Processes in CMIP6 Bootcamp (Germany, 05-14 Oct 2022).
Less experienced team members are encouraged to join international organisations such as the Association of Polar Early Career Scientists [APECS] and the APECS Ozeania National Committee. Senior scientists can make themselves available as mentors.