Despite the recent trend towards global warming the earth might be nearing another Ice Age, which will put an end to the 12,000-year temperate spell in which civilisations arose.
Some have said such a transition is overdue, given that each of the three temperate intervals that immediately preceded the current one lasted only about 10,000 years.
But now, in an eagerly awaited study, a group of climate and ice experts say they have new evidence that the earth is not even halfway through the current warm era. The evidence comes from the oldest layers of Antarctic ice ever sampled.
Some scientists earlier proposed similar hypotheses, basing them on the current configuration of the earth's orbit, which seems to set the metronome that ice ages dance to. Temperature patterns deciphered in sea-bottom sediments in recent years supported the theory.
But experts say the new ice data are by far the strongest corroborating evidence, revealing many similarities between today's atmospheric and temperature patterns and those of a prolonged warm interval lasting 28,000 years, that reached its peak 430,000 years ago, reports straitstimes.asia1.com
According to sciam.com the core also reveals that not all ice ages are created equal. From the Vostok core, scientists deduced that those that occurred in the last 400,000 years were very intense, lasting around 80,000 to 100,000 years each. The new data suggest that earlier ice ages were shorter and the longer-lasting interglacial periods had lower temperatures, a finding that agrees with lower-resolution marine sediment cores. Because they have not yet reached the bottom of the ice sheet, the researchers hope that they will be able to extend the climate record even further back in time through continued drilling at the same site. Notes White: "The possibility of a million-year ice core is out there and a million years ago is a really significant period in the earth’s climate history."
Climate experts not associated with the project agreed, saying the longer record provided by this ice core provided more chances to test a computer simulation's ability to recreate past conditions.
Outside experts and the European team also agreed that the discoveries had only just begun.
In the next 6 to 12 months, the team is to decipher changes in the atmosphere over the full 740,000-year span. And more ice is still being extracted from the hole, potentially taking the record back another 100,000 years or more.
Dr. Richard B. Alley, an ice-core expert at Penn State not affiliated with the project, called it "a triumph of brilliant persistence" in the face of broken drills and temperatures of 60 below zero at the drilling site, which is hundreds of miles from the nearest permanent research hub.
"The current publication is something akin to the first run on a new accelerator or the first look at a galaxy through the latest mega-telescope," he wrote in an e-mail message. "The results are clearly of value in and of themselves, but are even more exciting for what they promise in the future," informs nytimes.com
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