A new study by geoscientists led by the University of Leicester reveals that 20 million years ago, rapid Antarctic ice melt was driven by Earth’s eccentric orbit, offering key insights into the ice sheet’s future instability amid ongoing climate change.
Researchers from the University of Leicester and the University of Southampton have uncovered periods of sudden melting in the Antarctic ice sheet from over 20 million years ago . The study, published in Nature Communications, suggests the Antarctic ice sheet is more unstable than previously believed, triggered by Earth’s changing orbit around the Sun.
The findings offer a critical glimpse into how the Antarctic may react in the absence of the Greenland Ice Sheet as modern emissions continue unchecked. Historically, the size of the Antarctic ice sheet has fluctuated regularly, akin to a heartbeat. Existing climate records have shown varying “rhythms” in the heartbeat of early Antarctic ice ages.
According to the study, these inconsistencies are due to the Earth’s eccentric orbit, which affects its distance from the Sun and thus the climate. When Earth’s orbit is more elliptical, the planet experiences greater variations in solar heat, causing the ice sheet to melt more rapidly. However, when the orbit is more circular, the ice sheet is generally more stable.
The study examines the period between 28 and 20 million years ago when Earth was considerably warmer. Utilizing geological cores from the Integrated Ocean Drilling Program (IODP), a publicly funded international marine research initiative supported by 21 countries, the research established a benchmark climate record, allowing scientists to refine their climate models.
“From our research, we can see that the Antarctic ice sheet is more unstable than previously thought. We demonstrate how sensitive the geologically early Antarctic ice sheet was to changes in Earth’s orbit and axis,” lead author Tim van Peer, a research fellow in the School of Geography, Geology and the Environment at the University of Leicester, said in a news release.
Paul Wilson, a professor of ocean and Earth science at the University of Southampton, emphasized the significance of analyzing fossil shells from deep-sea cores.
“It may be a surprising thing to learn that we take the pulse of the Antarctic ice sheet by doing some simple chemistry on pinhead-sized fossil shells from the deep sea floor on the other side of the world,” Wilson said in the news release. “But the really beautiful thing is that we can do it back through the geological record over tens of millions of years. Earth science is about time travel into the past and we are always learning lessons to help us understand our future.”
The research offers a somber warning about the modern Antarctic ice sheet’s stability.
“We cannot assume that the modern-day Antarctic ice sheet is stable,” van Peer added. “If climate emissions continue unabated, we are on course to melt a large amount of the Antarctic ice sheet. We need to mitigate climate change by reducing our emissions. This is the only way to not cross tipping points in the stability of the Antarctic ice sheet.”
The insights from the study underscore the interconnectedness of Earth’s climate systems, both past and present, and stress the importance of proactive measures to combat climate change.