Quest begins to drill Antarctica’s oldest ice – again

Ice core sample [image credit: Discovering Antarctica]

Previous studies indicated temperature change preceded CO2 change, but the BBC says they occurred ‘in parallel’ or ‘in lockstep’, obscuring the key role of insolation while waffling about supposedly ‘heat trapping’ gases.
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Efforts are about to get under way to drill a core of ice in Antarctica that contains a record of Earth’s climate stretching back 1.5 million years, says BBC News.

A European team will set up its equipment at one of the highest locations on the White Continent, for an operation likely to take four years.

The project aims to recover a near-3km-long cylinder of frozen material.

Scientists hope this ice can help them explain why Earth’s ice ages flipped in frequency in the deep past.

“Beyond EPICA”, as the project is known, is a follow-up to a similar venture at the turn of the millennium called simply EPICA (European Project for Ice Coring in Antarctica).

The new endeavour will base itself a short distance away from the original at Little Dome C, an area located roughly 40km from the Italian-French Concordia Station, on the east Antarctic plateau.
. . .
The deep ice in Antarctica contains tiny bubbles of air. These little gas pockets are a direct snapshot of the historic atmosphere.

Scientists can read off the levels of carbon dioxide and other heat-trapping components, such as methane.

Analysing the atoms in the water-ice molecules encasing the gases also gives an indication of the temperature that persisted at the time of the snowfall that gave rise to the ice.

When researchers drilled the original EPICA core, they uncovered a narrative of past climate temperature and atmospheric carbon dioxide stretching back 800,000 years.

It’s become one of the key climate data-sets of recent decades.

It showed that CO2 and temperature moved in lock-step. Whenever the Earth went into an ice age and temperature fell, the concentration of greenhouse gases in the atmosphere would also decline. And when the climate warmed back up again, the CO2 rose in parallel.

These cycles occurred roughly every 100,000 years every 100,000 years – a phasing that is most likely linked to slight shifts in the eccentricity of Earth’s orbit (a larger or smaller ellipse) around the Sun.

But it is recognised from an alternative record of past climate, which has been deciphered from ocean sediments, that deeper back in time the ice age cycle was much shorter – at about every 41,000 years.

That is a period probably dominated by the way the Earth tilts back and forth on its axis. But why the switch occurred, no-one is really sure. The new Beyond Epica core may contain some clues if its ices can extend the climate narrative back to 1.5 million years ago.

“We believe this ice core will give us information on the climate of the past and on the greenhouse gases that were in the atmosphere during the Mid-Pleistocene Transition (MPT), which happened between 900,000 and 1.2 million years ago,” said team-leader Carlo Barbante, the director of the Institute of Polar Sciences of the National Research Council of Italy.

“During this transition, climate periodicity between ice ages changed from 41,000 to 100,000 years: the reason why this happened is the mystery we hope to solve.”

Full article here.

via Tallbloke’s Talkshop

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December 7, 2021 at 08:42AM

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