Retreat of Southern Hemisphere Sea Ice, 130 000 to 116 000 years BP

Sea ice is of huge importance to global climate, the Antarctic ice sheet, and to all life in the Southern Ocean. However the area covered by sea ice in the Southern Hemisphere is predicted to drastically decrease over the next century; the decrease by 2200 could be as much as 58%.

The models, on which predictions of sea ice loss are based, have never been tested against a documented retreat of Southern Hemisphere sea ice. A major retreat in Northern Hemisphere sea ice since 1978 has enabled climate and sea ice models to be evaluated for their ability to replicate retreat data. This has helped ensure that we have high confidence in Arctic sea ice predictions. In the Southern Hemisphere, there has been no similar sea retreat since 1978, which has meant that models cannot be tested against retreat data. This lack of sea ice retreat data has thus been a major contributor to the current lack of confidence in Southern Hemisphere sea ice forecasts.

Here we propose to address this lack of data which covers a retreat of the Southern Hemisphere sea ice. We have found a period during the Last Interglacial (LIG) between 130,000 and 116,000 years Before Present (BP), when there was a substantial retreat in Southern Hemisphere sea ice. By reconstructing and modelling a retreat during this LIG period, under a climate which was similar to that of today, this proposal aims to transform understanding of the structure and causes of a major Southern Hemisphere retreat event. The project will be the first ever quantitative investigation of a large Southern Hemisphere sea ice retreat, and will be be of considerable importance to both the sea ice and palaeoclimate science communities.

We will generate a new LIG sea ice dataset, using a robust new statistical approach. This will draw from, and build upon, the core expertise of our science team members. Our new Southern Hemisphere sea ice data data will then be used to help establish the cause of the LIG retreat and to test current climate and sea ice models. In addition to identifying the most likely cause of the decrease in sea ice during the LIG, this project will establish for the first time the degree of confidence that the sea ice community can have in our UK model-based predictions of a future retreat in Southern Hemisphere sea ice.

WHO WILL BENEFIT FROM THIS RESEARCH?
Target audiences who will benefit from this research are: palaeoclimate and sea ice scientists (the main beneficiaries of the research as detailed in the above `Academic beneficiaries' section) as well as stakeholders (with a focus on policy-makers) and the general public (with a strong emphasis on schoolchildren at key stage 1 and 2).

The main users of the research outcomes who are outside of the immediate research community will be policy-makers and their science advisors. In particular, the Scientific Committee on Antarctic Research (SCAR) and the International Panel on Climate Change (IPCC) use evidence on polar and climate change to gauge the severity of anthropogenically enhanced global warming to help policy-makers develop an appropriate level of response.

HOW WILL THEY BENEFIT FROM THIS RESEARCH?
POLICY-MAKERS. Submission of our previous publications to the appropriate IPCC AR5 Chapter editors ensured that our work forms part of past IPCC reports, thereby influencing UK and global policy. As an example of this influence, if this proposed research were to demonstrate that the UK Coupled Model Inter-comparison Project (CMIP6) Climate Model predictions of Southern Hemisphere sea ice changes are likely to be underestimated, it would increase the urgency for action proposed by SCAR and the IPCC. Similarly, if Southern Hemisphere sea ice changes are overestimated, this may allow attention to be focussed elsewhere.

CHILDREN AND TEACHERS. We hope to engage and inspire children with the spirit of Antarctic scientific endeavour - these young people will go on to become the future scientists and decision makers for NERC and for Antarctica. We propose to partner with the charity UK Antarctic Heritage Trust to produce inspirational resources for schools. The Antarctic Heritage Trust are dedicated to caring for, and promoting, Antarctic scientific heritage. Together, we will create a variety of learning resources based jointly on Trust archival material and our contemporary research outcomes. This approach will build on previous Trust successes in producing and distributing school resources. The learning resources will be aimed at teachers and pupils in schools to use in the classroom. A combination of digital and print resources will be written with the aid of a freelance educational specialist. The digital resources will be made freely available through existing child and teacher friendly sites, including show.me.uk and mylearning.org along with the tried and tested discoveringantarctica.org.uk website. Printed resources will be particularly targeted at less privileged schools.

PRESSURE GROUPS / CLIMATE SCEPTICS. We will write at least one project RealClimate (www.realclimate.org) project blog post to reach the 'climate sceptic' pressure groups. The post will be co-written with the sea ice modellers Prof. D. Feltham and Dr. D. Schroeder. Post(s) will directly address a major line of attack on climate science: "Increases in Southern Hemisphere sea ice, particularly since 2012, undermine evidence for global warming". By talking with these users, using their own preferred means of communication, we will work to minimise the potential for any misunderstanding of Southern Hemisphere sea ice science.

LOCAL SCHOOLS, WI, AND U3A AUDIENCES. We will build on our record of public lectures by providing three public lectures per year of the project.

MEDIA AND THE GENERAL PUBLIC. Press releases, twitter, and a project web page will be used to both encourage and satisfy public interest in the work.