22 March 2017 10:20

A Lancaster University environmental scientist is taking part in an Antarctic expedition which aims to look back in time to understand rising global sea levels.

Dr Yani Najman from Lancaster Environment Centre is one of 50 researchers on board the Alfred Wegener Institute’s research vessel Polarstern which departed from Punta Arenas (Chile) on 6 February 2017, bound for the Amundsen Sea – the region of the Antarctic currently characterised by rapid loss of ice.

The international team will use a seafloor drill rig in the Antarctic in an attempt to unlock the historical information stored in the sediment beneath the sea. The drill can extract sediment cores of up to 70 metres in length. Subsequent analyses of the cores – such as determining the species and ages of the fossil algae – will yield essential information on past water temperatures and the history of ice cover in the West Antarctic.

The results are expected to improve forecasts for rising global sea levels.

Dr Yani Najman said: “The purpose of the expedition is to ask how the West Antarctic Ice Sheet has changed in response to alternating warm and cold time periods? How has the ice sheet has advanced and retreated in the past and at what speed. The answers will help us work out what that could mean for the sea levels both today and in the future.”

Between 1901 and 2010, the global sea level rose by 19 centimetres. Projections for the future suggest a rise of anywhere between 26 and 82 centimetres by the end of the century. The latest models show that the sea level might even rise by an additional metre. Prognoses for sea-level rises are important, because they provide the basis for potentially adapting to and minimising the impacts of climate change.

Although today’s computer models are now capable of depicting the relationship between ice and the ocean, there is still a lack of data on the behaviour of the West Antarctic Ice Sheet.

Dr Karsten Gohl from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) is the chief-scientist of the Polarstern expedition.

Dr Gohl said: “Particularly in the Amundsen Sea region, we’ve observed an unusually rapid retreat over the past few decades, which many believe to be the first step in a complete collapse of the West Antarctic Ice Sheet… We plan to collect samples from epochs of the Earth’s history with similar climatic conditions to those we expect to see in the next 100 to 200 years.”

The information Geoscientists need is found in the remains of single-celled algae (foraminifera and diatoms), which sink to the seafloor as sediments when they die.

They hope to look back as far as the Pliocene: three to five million years ago, when the temperature was two to three degrees higher than it was just before the industrial revolution, and the carbon dioxide concentration in the atmosphere, 400 parts per million, was roughly the same as it is today.

During the expedition, the drill will be used to drill sediment cores from as many as nine different sites to map historical changes in the ice cover of the Amundsen Sea

Dr Karsten Gohl said: “We hope the drilling technique and measurements will work smoothly despite the harsh conditions in the Antarctic, so that when we return to Punta Arenas on 19 March, it won’t be empty-handed, but with several hundred metres of sediment cores.”

Once the ship has returned, the samples and data will be analysed in the laboratories. Geoscientists and climate modellers at the AWI as well as researchers from partner institutes MARUM, the British Antarctic Survey, German and British universities can’t wait to get their hands on the new data.