<P dir=ltr align=left>Ice cores unlock climate secrets</P>

14 June 2004 | 14:30 Code : 3782 Geoscience events
<P dir=ltr align=left>Analysis of the ice proves our planet has had eight ice ages during that period, punctuated by rather brief warm spells - one of which we enjoy today...</P>

If past patterns are followed in the future, we can expect our "mild snap" to last another 15,000 years.

The data may also help predict how greenhouse gases will affect climate.

Initial tests on gas trapped in the ice core show that current carbon dioxide (CO2) levels are higher than they have been in 440,000 years.

Nobody quite knows how this will alter our climate, but researchers hope a detailed picture of past fluctuations will give them a better idea.

Distant worlds

A large team of scientists, from 10 different countries, has spent most of the last decade extracting the mammoth column of ice from a location called Dome C, on east Antarctica's plateau.

The European Project for Ice Coring in Antarctica (Epica) aims to unlock the climatic secrets of our past - and in doing so gain a better understanding of what we can expect in the future.

This is not the first ice core project - but it ventures much further back in time.

Dome C contains 800,000 years worth of snowfall, allowing Epica to obtain a climate record two times longer than its nearest ice core rival.

"We think this project will really change the way we look at climate," said co-author Eric W. Wolff, of the British Antarctic Survey, Cambridge, UK.

Each slice of the ice core tells tales about the distant world it came from.

For instance, scientists can work out climate by looking at the ratio of different types, or isotopes, of hydrogen atoms.

Different colds

Deuterium is a heavy isotope of hydrogen. If a sample of ice has a lot of it, that means the temperature was warmer - and vice versa.

"At very cold temperatures a great deal of the heavy isotopes have rained out," explained Jerry F. McManus, of Woods Hole Oceanographic Institution, US. "So all that is left is what we would call isotopically depleted or lighter. That is how we know how cold it was."


tags: QAZVIN

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