The Antarctic ice sheet is capable of losing up to one-third of its mass during warm interglacials. An international team of scientists, led by NIOZ Royal Netherlands Institute for Sea Research found evidence for a sea-level highstand 1.2 million years ago which is three times higher than calculated in the current ice sheet models. Bas de Boer, researcher at Utrecht University, designed the new ice-sheet model that was used in the study. The results were published in the journal ‘Quaternary Science Review’ on 28 August.
The findings of this research point at the Antarctic Ice Sheet instability during interglacial periods. It provides a further strong case in the on-going discussions about the degree of Antarctic Ice Sheet contribution to global sea-level change in response to a warmer climate that we should prepare for. “This new finding shows once more that Antarctica is unstable and definitely prone to release huge amounts of water during warm interglacials”, says NIOZ scientist Dr. Paolo Stocchi. “Reconstructing events in the geological past help us to understand the physical processes that regulate the response of ice sheets to climate change and, most importantly, all the uncertainties. We can therefore improve to forecast the future.”
It was a stalactite that led to new information about the sea-level stand in the Middle Pleistocene Transition, a geological time 1.2 million years ago where very little is known about. The Custonaci stalactite, found in a karst cave in North West Sicily in Italy, provided the scientists with evidence of four marine inundations that correspond to this time. The measured age of the corals on the Custonaci stalactite was 1.123 million years (based on Uranium/Thorium ratios and Strontium 87/86 isotopic ratios), which makes it the oldest known speleothem containing marine hiatuses.