TOKYO - Japanese scientists have gone back in time to study the earth's climate by drilling more than 3 kilometres into Antarctica's ice sheet, a researcher said on Tuesday.
Yoshiyuki Fujii said the cores are among the oldest samples yet extracted by scientists and hoped bubbles of gas, such as carbon dioxide, trapped in the core samples will offer clues to past patterns of global climate change.
They might also further highlight the threat from global warming by giving a million-year-old record of carbon dioxide and methane levels in the atmosphere. Both are powerful greenhouse gases.
"By analysing the ice we would like to decipher climate and temperature conditions that stretch back to ages that have not been clarified before," said Fujii, director-general of the National Institute of Polar Research.
In particular, he hoped the samples would explain changes to the earth's climate from an inversion of the earth's magnetic field that occurred around 790,000 years ago. During such an event, the earth's magnetic poles switch entirely.
Fujii told Reuters the team in Antarctica drilled near their base located at an altitude of 3,810 metres (12,600 feet). The samples would be brought to Japan for analysis.
This is believed to be the oldest sample allowing such analysis, although isolated ice samples believed to be about six million years old have previously been found, Fujii said.
Last year, several European studies of Antarctic ice core samples released findings that showed current levels of methane and carbon dioxide in the atmosphere are higher than at any time in the past 650,000 years.
Scientists in those studies also drilled down to about three kilometres (two miles)
Many scientists believe rising levels of carbon dioxide released from burning fossil fuels and methane from agriculture are warming the atmosphere, threatening to cause greater extremes of weather, melting ice caps and rising sea levels.
Scientists said last year was the second warmest year on record since 1860 and that eight of the 10 warmest years since records began have occurred in the past decade.
REUTERS NEWS SERVICE
