The Italian Almanac
Italian Science - November 22
Italian scientists working in Antarctica have dug up the first ever sample of underwater permafrost, something not normally seen as possible.
Permafrost, or permanently frozen ground, forms when the air temperature is consistently well under the freezing point of water - zero degrees centigrade. Even though the sea regularly freezes in Antarctica, the ice never reaches the seabed so there is always some water above it. In theory, this should mean that permafrost cannot form. But Italian geologists working out of the Mario Zucchelli research base in Antarctica have found permafrost under three metres of water in the Tethys Bay area.
One of the team, glacier expert Mauro Guglielmin, from Varese's Insubria University, said a 3.2 metre hole had been drilled in the seabed to retrieve soil samples. "The samples appear to contain ice, which shouldn't normally be possible in underwater conditions," he said, adding that the temperature in the ground at that point was -2.5 degrees. What this means, he explained, is that the permafrost formed thousands of years ago, when the region was even colder than it is now.
The area of land now underwater must once have been dry land, which was later covered as global temperatures rose, melting ice caps and raising the sea level. Exactly when this happened is still unclear, but Guglielmin said tests on the sample from the seabed should be able to gauge the period fairly accurately.
The tests will be carried out in Varese, once the samples have been shipped back. Although it was once colder, Antarctica is still the coldest place on earth. Temperatures reach a minimum of between -85 and -90 degrees centigrade in the winter and about 30 degrees higher in the summer.