The role of the Southern Ocean in sea level change
Climate Risk and Earth Observation
Research Themes Project
Overview
This project will address the following key issues related to the role of the Southern Ocean in global and regional sea level changes:
- Can we quantify the amount of heat entering the Southern Ocean?
- Can we, through perturbation experiments (with some forcing turned on or off), separate the impact of wind-induced from Antarctic fresh water-induced ocean responses, and natural versus anthropogenic forcing in sea level and ocean dynamics in the Southern Ocean?
- Is the dipole structure of sea level change derived from coarse resolution models robust? Will eddy-resolving model give a similar dipolar structure? Are there distinct responses to strengthening vs shifting of westerlies, and if yes, are they dependent on model resolution?
- Can we use updates of observations and projections of the Antarctic Ice Sheet contribution, together with other contributions, to better understand the regional sea-level change distribution and thus to refine sea level projections?
Our project component focuses on issue 4 above through a combination of data analysis and ice sheet modelling.
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Impact and Engagement
Sea level rise is an important climate change research topic. Global mean sea level (GMSL) has been rising according to tide gauge and satellite altimetry observations, and is projected to continue to rise, with a likely range between 0.28 m and 0.98 m by 2100. A larger rise could occur if there is a significantly larger contribution from changes in Antarctic dynamics. Over 100 million people live within a metre of current high tide mark, thus are highly possible to be affected by sea level rise. Several processes can affect GMSL, including ocean thermal expansion, mass loss of glaciers and ice caps, the Antarctic Ice Sheet and the Greenland Ice Sheet, and changes in the land water storage.
The Southern Ocean is a key area for improving projections of ocean heat content and sea level change because 1) it is one of the key areas where heat enters the ocean, resulting in heat storage in the upper ocean and in the abyssal layers, and contributing to ocean thermal expansion. 2) A warming ocean is critical to the dynamic response of the Antarctic ice sheet.
Over the lifetime of the project, we will contribute toward the following goals
- Analysis of technique-specific uncertainties of Antarctic Ice Sheet mass flux time series
- Compilation of state-of-the-art of Antarctic Ice Sheet mass flux rates from early 1990s to 2019, with robust error range
- Updated fingerprint of Antarctica Ice Sheet mass change in the Southern Ocean based on latest mass flux information.
- Refined projection of regional and global sea level associated with Antarctic Ice Sheet mass loss, based on stand-alone ice-sheet modelling or coupled ocean-atmosphere-land ice modelling.
The output of this project will mainly be scientific papers published in peer-reviewed journals.
Partner
The project is funded by CSIRO-Commonwealth Scientific & Industrial Research Organisation as part of Centre for Southern Hemisphere Oceans Research (CSHOR). CSHOR is a collaborative research partnership between the Qingdao National Laboratory for Marine Science and Technology (QNLM) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO). The University of New South Wales and the University of Tasmania are also partners in CSHOR.
