A team of U.K. researchers are planning to melt some of the oldest ice on Earth in an ambitious bid to reconstruct up to 1.5 million years of our planet’s climate history. In doing so, they could also help solve a mystery that has puzzled scientists for over two decades.
Over the course of seven weeks, scientists at the British Antarctic Survey plan to gradually melt 1.5-million-year-old Antarctic ice cores at their lab in Cambridge, England, unlocking whatever dust, volcanic ash, and even single-celled algae that might be preserved inside. These materials hold clues about Earth’s ancient climate and atmospheric composition, and could provide new insights into how greenhouse gases influenced global temperatures more than a million years ago. They could also help scientists understand how human-generated emissions will shape Earth’s future.
“Our climate system has been through so many different changes that we really need to be able to go back in time to understand these different processes and different tipping points,” Liz Thomas, head of ice core research at the BAS, told the BBC.
One crucial mystery the scientists hope to solve is why Earth’s glacial cycles appeared to suddenly switch at a point between 800,000 and 1.2 million years ago, a shift known as the Mid-Pleistocene Transition. Antarctic ice core analysis done in 2004 found a close link between Earth’s climate and atmospheric gases over the past 800,000 years, suggesting that the planet experienced ice ages interspersed with warmer periods on a 100,000-year cycle. But marine sediment records dating back at least 1 million years have indicated that, before then, glacial periods occurred more frequently, about once every 41,000 years.
Thomas and her colleagues hope the new cores will reveal the composition of greenhouse gases in Earth’s atmosphere during this mysterious transition, and that could explain why it happened at all.
“The project is driven by a central scientific question: why did the planet’s climate cycle shift roughly one million years ago from a 41,000-year to a 100,000-year phasing of glacial-interglacial cycles?” Thomas said in a statement.
“By extending the ice core record beyond this turning point, researchers hope to improve predictions of how Earth’s climate may respond to future greenhouse gas increases.”
Her team will use a technique called continuous flow analysis, which involves slowly melting ice core sections and simultaneously measuring any chemical elements, particles, and isotopic data to extrapolate Earth’s past climate conditions. Air bubbles trapped inside the cores can reveal our planet’s ancient atmospheric conditions, changes in greenhouse gas concentrations, and Earth’s temperature at the time.
“This unprecedented ice core dataset will provide vital insights into the link between atmospheric [carbon dioxide] levels and climate during a previously uncharted period in Earth’s history, offering valuable context for predicting future climate change,” Thomas said.
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