A new scientific study has shown a thawing Antarctic glacier that is the biggest contributor to rising sea levels is likely to continue shrinking for decades, even without an extra spur from global warming.
The melting of ice in the Antarctic is considered a top threat to global sea level rise, and scientists now say the trend could continue for decades or even centuries to come.
AAP Newsagency reports researchers focused on the Pine Island Glacier in Antarctica, which has been thinning at an increasingly rapid pace for about the past 20 years, as the waters beneath get warmer along with the rest of the ocean.
Based on new geological surveys and advanced dating techniques on rocks that have been exposed by the retreating ice, experts said in the journal Science that a similar phenomenon occurred thousands of years ago.
Some 8000 years ago, the glacier thinned as fast as it has in recent decades, suggesting it may follow a similar pattern in the future, they reported.
“This thinning was sustained for decades to centuries at an average rate of more than 100 centimetres per year, comparable to contemporary thinning rates,” said the article.
“Our findings reveal that Pine Island Glacier has experienced rapid thinning at least once in the past, and that, once set in motion, rapid ice sheet changes in this region can persist for centuries.”
“It seems to be a similar mechanism now it could easily continue for decades,” Professor Mike Bentley of Durham University in England, a co-leader of the project that included experts in the United States and Germany, told Reuters Newsagency.
Other studies indicate that a build-up of man-made greenhouse gases, rather than natural shifts, is behind the warmer waters blamed for an accelerating thinning and retreat of the glacier in the past two decades, he said.
Regardless of the cause, the glacier’s history suggests that nations may have to factor several centimetres of rising sea level from Pine Island alone into their planning for coastal defences. Experts are studying the history of other glaciers for clues to their future.
The research team came from Britain, Germany and the US.
Last month, scientists reported in the journal Nature Climate Change that the glacier was melting irreversibly and could add as much as a centimetre to ocean levels in 20 years.
A massive river of ice, the glacier by itself is responsible for 20 per cent of total ice loss from the West Antarctic Ice Sheet today.
On average, it shed 20 billion tons of ice annually from 1992-2011, a loss that is likely to increase up to and above 100 billion tons each year, said the Nature study.
