A novel proxy for Arctic sea-ice

It is widely acknowledged that polar sea-ice plays a critical role in global climate change. As such, sea-ice reconstruction should be of paramount importance in establishing climatic evolution of the geological past. Although direct records of sea-ice are considered to be reasonably accurate over the last 200 years (with satellite imaging for the past 30 years), it is only through the use of 'proxy' measures (chemical, physical or biological indicators of sea-ice) that a more extended record is achievable. The main aim of the current project proposes to evaluate the use of some well characterised organic chemicals to serve as a proxy for the past presence of sea-ice. These chemicals, so-called highly branched isoprenoids (HBIs), possess a number of characteristics that make them attractive as sea-ice proxies. Firstly, HBIs of the type proposed are unique to sea-ice diatoms, so their presence in polar sediments can be directly correlated with the previous occurrence of sea-ice. Secondly, they are relatively resistant to degradation, which extends their usefulness in the geological record. Thirdly, their relative abundance should make them straightforward to measure (A Standard Operating Procedure has been identified as an output from the project) with, additionally, a high degree of geological resolution. The results of this investigation will be evaluated against previous proxies used in Arctic sediments. This project fits well with other aspects of the Council's programme and clearly has a 100% relevance to both the 'Polar North' classification and the 'Global Change' ENRI. The project represents excellent value for money, as access to existing cores has already been established, and all of the necessary chemical and analytical requirements are held in-house within the Petroleum and Environmental Geochemistry Group at the University of Plymouth. The project will also benefit from additional staff expertise available both locally and internationally