Feb 22, 2026 02:02 AM
https://www.eurekalert.org/news-releases/1116826
INTRO: Researchers have identified a ‘tipping point’ about 2.7 million years ago when global climate conditions switched from being relatively warm and stable to cold and chaotic, as continental ice sheets expanded in the northern hemisphere.
Following this transition, Earth’s climate began swinging back and forth between warm interglacial periods and frigid ice ages, linked to slow, cyclic changes in Earth’s orbit. However, glacial periods after this tipping point became far more variable, with large swings in temperature over relatively short timescales of roughly a thousand years.
An international team of researchers, led by the University of Cambridge, analysed the chemical fingerprints in deep-sea cores, from beneath the seafloor off the coast of Portugal. They looked at the chemical makeup of the sediments – in particular the ratios of elements such as calcium, titanium, zirconium and strontium –to reconstruct how fast the climate was changing.
“Things were relatively quiet until 2.7 million years ago, when we began to see the first evidence of severe ‘cold snaps’,” said Professor David Hodell from Cambridge’s Department of Earth Sciences, who led the research. “These events may have been harbingers of things to come because at 2.5 million years ago, we start to see a distinct pattern of multiple rapid swings in the Earth’s climate, on thousand-year timescales. From then on, variability was a persistent feature of the glacial climate, which is consistent with what we see in Greenland ice cores during the most recent Ice Age.”
Growth of ice sheets and rapid millennial climate change seem to have gone together. This pattern of variability was consistent across different cores taken from different sites, providing strong confirmation that the signals reflect widespread climate events, not just local variation.
“This is the time when the glacial-interglacial cycle really got going,” said Hodell. “Glacial periods weren’t just cold, they were also highly variable with large swings in temperature over relatively short timescales.”
This climate tipping point coincided with the emergence of the genus Homo, the group to which modern humans belong, suggesting that climate swings may have played a role in shaping early human evolution. The results are reported in the journal Science...... (MORE - details, no ads)
INTRO: Researchers have identified a ‘tipping point’ about 2.7 million years ago when global climate conditions switched from being relatively warm and stable to cold and chaotic, as continental ice sheets expanded in the northern hemisphere.
Following this transition, Earth’s climate began swinging back and forth between warm interglacial periods and frigid ice ages, linked to slow, cyclic changes in Earth’s orbit. However, glacial periods after this tipping point became far more variable, with large swings in temperature over relatively short timescales of roughly a thousand years.
An international team of researchers, led by the University of Cambridge, analysed the chemical fingerprints in deep-sea cores, from beneath the seafloor off the coast of Portugal. They looked at the chemical makeup of the sediments – in particular the ratios of elements such as calcium, titanium, zirconium and strontium –to reconstruct how fast the climate was changing.
“Things were relatively quiet until 2.7 million years ago, when we began to see the first evidence of severe ‘cold snaps’,” said Professor David Hodell from Cambridge’s Department of Earth Sciences, who led the research. “These events may have been harbingers of things to come because at 2.5 million years ago, we start to see a distinct pattern of multiple rapid swings in the Earth’s climate, on thousand-year timescales. From then on, variability was a persistent feature of the glacial climate, which is consistent with what we see in Greenland ice cores during the most recent Ice Age.”
Growth of ice sheets and rapid millennial climate change seem to have gone together. This pattern of variability was consistent across different cores taken from different sites, providing strong confirmation that the signals reflect widespread climate events, not just local variation.
“This is the time when the glacial-interglacial cycle really got going,” said Hodell. “Glacial periods weren’t just cold, they were also highly variable with large swings in temperature over relatively short timescales.”
This climate tipping point coincided with the emergence of the genus Homo, the group to which modern humans belong, suggesting that climate swings may have played a role in shaping early human evolution. The results are reported in the journal Science...... (MORE - details, no ads)