New York, April 19 :
There was a green and forested landscape prior to the time that the ice sheet began to form in Greenland and scientists have now discovered that the three-million-year-old landscape still exists beneath the Greenland ice sheet.
“Pre-glacial landscapes can remain preserved for long periods under continental ice sheets, said the study.
“Rather than scraping and sculpting the landscape, the ice sheet has been frozen to the ground, like a giant freezer that has preserved an antique landscape,” said Paul R. Bierman from the University of Vermont in the US.
The researchers made the discovery on the basis of an analysis of the chemical composition of silts recovered from the bottom of an ice core more than 3,000 metres long.
In the time since the ice sheet formed “the soil has been preserved and only slowly eroded, implying that an ancient landscape underlies 3,000 metres of ice at Summit, Greenland”, the researchers concluded.
Summit is situated at an elevation of 3,216 metres (10,551 feet) above sea level.
The new discovery indicates that even during the warmest periods since the ice sheet formed, the centre of Greenland remained stable, allowing the landscape to be locked away, unmodified, under ice through millions of years of cyclical warming and cooling.
Understanding how Greenland’s ice sheet behaved in the past, and in particular, how much of the ice sheet melted during previous warm periods as well as how it re-grew is important to developing a scientific understanding of how the ice sheet might behave in the future.
As global average temperatures rise, scientists are concerned about how the ice sheets in Greenland and Antarctica will respond.
Vast amounts of freshwater are stored in the ice and may be released by melting, which would raise sea levels, perhaps by many meters.
The magnitude and rate of sea level rise are unknown factors in climate models.
The study will appear in the forthcoming issue of the journal Science.