Chemical to help assess past changes to Antarctic sea ice

London: A chemical, the source of which has been traced to a widespread and commonly occurring constituent of microalgae inhabiting Antarctic sea ice, can help scientists assess historical changes to the frozen continent, says a study.

It could also potentially be used to demonstrate past alterations to glaciers and ice shelves caused by climatic changes, the study published in the journal Nature Communications suggests.

"In addition to allowing us to unlock historical changes to Antarctic sea ice, our new method also has the potential to provide further insights into other critical climatic features that may have changed in the past," said the study's lead author Simon Belt, Professor of Chemistry at Plymouth University in Britain.

"Indeed, sea ice around the Antarctic coastline is strongly influenced by nearby glaciers and ice shelves, both of which contribute to increased global sea level when they melt. Therefore, our new approach may also permit a much broader spectrum of climatic changes to be unravelled in the future," Belt noted.

The new method builds on an existing technique, also developed by Plymouth University over the last 10 years, which identified a means by which scientists could measure changes to sea ice in the Arctic.

The previous technique is based on the presence of IP25, 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 the scientists reported discovery of a related chemical in the Southern Ocean.

Analysis of surface sediments covering different regions of Antarctica showed the presence of IPSO25 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.

"The identification of IPSO25 in the Antarctic sea ice diatom Berkeleya adeliensis likely ensures that future interpretations of the sedimentary occurrence of this sea ice proxy can be made with greater confidence and in more detail," the study said.