pdf SCAR XXVIII 22: Proposal for a SCAR Scientific Research Programme on Antarctic Climate Evolution (ACE)

SCAR XXVIII 22: Proposal for a SCAR Scientific Research Programme on Antarctic Climate Evolution (ACE)

Executive Summary

ACE is a new international initiative that promotes the exchange of data and ideas between research groups focussing on the evolution of Antarctica’s climate system and ice sheet. ACE will exist to facilitate scientific exchange between the modelling and data acquisition communities for the purposes of project development and hypothesis testing. The broad outcomes of the programme will be: (1) quantitative assessment of the climate and glacial history of Antarctica; (2) identification of the processes which govern Antarctic change, and those which feed back this change around the globe; (3) improvements in our technical ability to model past changes in Antarctica; and (4) precisely documented case studies of past changes, which models of future change in Antarctica can be tested against.

The Southern Ocean plays a lead role in the development and maintenance of the Earth’s climate system. Equator-to-pole heat transport through the ocean and atmosphere is largely controlled by the latitudinal thermal gradient, which in turn is mostly a function of polar temperatures. Past variability in Antarctic temperatures and the extent of glacial and sea ice thereby impacts climate systems throughout the globe. The Antarctic ice sheet is the largest reservoir of fresh water on Earth and exerts an influence on global sea levels and hydrology, as well as ocean chemistry. The seas surrounding Antarctica contain the world’s only zonal circum-global current system wherein mixing occurs between water masses from all the ocean basins. Circumpolar flow maintains the thermal isolation of Antarctica from warmer surface waters to the north and has been linked to the development of continental glaciers and a dynamic sea ice regime. The Southern Ocean impacts the global thermohaline circulation as a major site of bottom and intermediate water formation. The southern seas are also important for ventilation of CO2 between the atmosphere and the ocean, by virtue of large-scale processes of upwelling, downwelling, and isopycnal mixing in a region of cold surface waters and strong winds. Antarctica, thus, has a key position in global climate processes now and in the past. To understand these processes it is necessary to examine their role in documented past climate change. The ACE programme aims to do this by formulating geological-based hypotheses on past changes in Antarctica and testing them using coupled climate/ice-sheet models.