“The record we’ve produced offers a much more robust overview of fluctuating Antarctic temperatures and how these relate to changes in the amount of ice, and the topography of Antarctica, over this period and paves the way for improved estimates of future events,” explains the Birmingham lead author Dr James Bendle.
The link between CO2, sea-surface temperatures and the amount of ice on Antarctica is clear through the last 45 million years. But one surprising finding was that ocean cooling did not always correspond to increases in Antarctic ice. Specifically for a 1 million year long period of ocean cooling from 25 to 24 million years ago. “We show that this is likely related to tectonic subsidence and the influx of relatively warm ocean water in the Ross Sea region,” says Dr Bendle.
“We can see that ice in Antarctica is currently changing – not least with the loss of some ice-shelves and cracks appearing recently in the Thwaites Glacier, one of the largest glaciers in the region. This new study of Earth’s past is one of the clearest indications yet that humans continue to produce CO2 levels for which we can expect major ice loss at the Antarctic margins and global sea-level rise over the coming decades and centuries.”
The team plan to continue to apply biomarker and machine learning approaches to reconstruct the climatic evolution of Antarctica and implications for future warming and sea-level rise.
The work was funded and facilitated by the International Ocean Drilling Programme, Antarctica New Zealand, The Royal Society Te Apārangi Marsden Fund (NZ), The Natural Environment Research Council (part of UK Research and Innovation), the Scientific Committee of Antarctic Research and the US National Science Foundation award. Plus support in kind from the University of Birmingham, Yale University and the Royal Netherlands Institute for Sea Research (NIOZ).
