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Ice cores: 800,000 years of climate change

CARDIFF U. (UK) — Drill cores taken from Greenland’s vast ice sheets offer the first clue that Earth’s climate is capable of very rapid transitions.

The ice cores, which cover the last 800,000 years, have led to vigorous scientific investigation into the possible causes of abrupt climate change.

Such evidence comes from the accumulation of layers of ancient snow, which compact to form the ice sheets we see today. Each layer of ice can reveal past temperatures and even evidence for the timing and magnitude of distant storms or volcanic eruptions.


Planktonic foraminifera from a Marine core. (Credit: Stephen Barker)

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By drilling cores in the ice an international team of scientists have reconstructed an incredible record of past climates. Until now such temperature records from Greenland have covered only the last 100,000 years or so.

The team’s reconstruction is based on the much longer ice core temperature record retrieved from Antarctica and uses a mathematical formulation to extend the Greenland record beyond its current limit.

“Our approach is based on an earlier suggestion that the record of Antarctic temperature variability could be derived from the Greenland record,” says study leader Stephen Barker of Cardiff University. “However, we turned this idea on its head to derive a much longer record for Greenland using the available records from Antarctica.”

The research published in the journal Science demonstrates abrupt climate change has been a systemic feature of Earth’s climate for hundreds of thousands of years and may play an active role in longer term climate variability through its influence on ice age terminations.

“It is intriguing to get an insight into what abrupt climate variability may have looked like before the Greenland records begin. We now have to wait until longer Greenland records are produced so that we can see how successful our prediction is,” says Barker.

The new predictions provide an extended testing bed for the climate models that are used to predict future climate variability.

The collaborative research was funded in part by a Leverhulme Trust Philip Leverhulme Prize awarded to Barker, the Natural Environment Research Council, and National Science Foundation.

Co-authors of the study include researchers from the Alfred Wegener Institute, University of Minnesota, Laboratoire de Glaciologie, CNRS and Joseph Fourier University, University of Maine, Laboratoire Chrono-Environnement, University of Cambridge, and the British Antarctic Survey.

More news from Cardiff University: www.cardiff.ac.uk/news

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