Isoprime stable isotope application specialists, Dr Kyle Taylor and Dr Rob Berstan have recently assisted scientists at the University of Plymouth with a study published in Nature Communications, developing a new technique to reconstruct historic changes to Antarctic sea ice with a view to better understanding Earth’s climatic history, and the impact of climate change on ice sheet extent. The new method builds on an existing technique, also developed by Plymouth University over the last ten years, which identified a means by which scientists could measure changes to sea ice in the Arctic. That technique already led scientists to reveal periods in Earth’s history when the Arctic was ice free during summers, and also the timing of expansion of Arctic sea ice to its modern extent, as well as being used as a means of tracing food webs for modern Arctic ecological studies.
The previous technique is based on the presence of IP25 (ice proxy with 25 carbon atoms), a lipid chemical made solely by microalgae that live in the bottom of Arctic sea ice. When the ice melts, the algae and its lipids fall into the sediments which can be recovered, dated and analysed. IP25 does not exist in the Antarctic, but analysis of surface sediments covering different regions of Antarctica have shown the presence of IPSO25 (ice proxy for the Southern Ocean with 25 carbon atoms) in nearly all cases. Its source, Berkeleya adeliensis, is a widespread and commonly occurring constituent of microalgae inhabiting Antarctic sea ice, which explains why IPSO25 is so common in the sediments. Isoprime Limited contributed the carbon isotope analysis of the IPSO25 lipids, the results of which assisted in providing additional evidence with respect to the source of the lipids and the biosynthetic environment they are produced in. The full research paper – Source identification and distribution reveals the potential of the geochemical Antarctic sea ice proxy IPSO25 by Belt, Smik, Brown, Kim, Rowland, Allen, Gal, Shin, Lee and Taylor – is published (open access) in Nature Communications, doi: 10.1038/NCOMMS12655.
Find out more about stable isotope analysis in climate change applications and IRMS instruments here