Global sea levels rising more rapidly: Report
By Himaya Quasem, The Straits Times, 2 Dec 2012
More grim news has emerged for low-lying, coastal nations such as Singapore.
A report, hailed as the most accurate to date, says that the ice sheets in Greenland and Antarctica are shrinking three times faster than they did in the 1990s, adding 11mm to global sea levels over the past two decades.
Melting polar ice can cause rises in sea levels, and the latest data underscores the risks faced by coastal cities and nations such as Singapore.
"Higher sea levels will likely displace coastal populations by exposing them to higher tidal and storm impacts," Dr Paul Berkman, an expert in Arctic Ocean geopolitics at the University of Cambridge, told The Sunday Times.
"(This) will have environmental, economic and social impacts within and between nations."
The latest findings, published in the journal Science, are in line with the broad range of forecasts in the 2007 assessment by the United Nations' Intergovernmental Panel on Climate Change (IPCC).
He said the changes in regional ice balance detected by his team were consistent with those expected as a result of climate change, adding that the results, published last Thursday, could help to improve models for predicting sea level changes.
"We hope that our dataset will be adopted as the benchmark for all other climate scientists to use," Prof Shepherd told The Sunday Times.
"And of course, we encourage people in government to pay attention to both the recent acceleration in ice sheet losses and the potential implications this may have for future sea levels."
Late last year, Singapore's Government raised the minimum level for new land reclamations by at least a metre above current standards, to protect against the perils of rising sea levels.
The national water agency PUB also announced a raft of flood protection measures.
This included raising the level of platforms in buildings with basements by at least 60cm above the adjacent ground level or 60cm above the highest recorded flood level.
More than 20 polar research teams and 10 satellite missions contributed to the landmark study on sea levels and receding polar ice.
According to the findings, nearly five trillion tonnes of ice from Greenland and Antarctica has melted and flowed into the oceans in the past two decades. This accounts for a fifth of the total rise in sea levels.
The results also help to quell a longstanding debate over whether the ice sheet covering on the Antarctic is losing or gaining mass, Prof Shepherd said.
"We can now say for sure that Antarctica is losing ice and we can see how the rate of loss from Greenland is going up over the same period as well," he added.
In the past, research on ice sheet activity has relied on different measurement means, resulting in a wide range of estimates and large uncertainties.
The scientists involved in the latest study say they were able to reconcile differences between dozens of earlier studies by the careful use of matching time periods and survey areas.
They also combined data from satellites recording the surface altitude, flow of the glaciers and gravitational effect of the ice mass.
In 2007, the IPCC projected that sea levels could rise by between 18cm and 59cm by the end of this century.
Although the ice sheet losses recorded in the latest study fall within the range documented in 2007, the spread of the IPCC estimate was so broad that it was not clear whether Antarctica was growing or shrinking.
The new satellite data shows that East Antarctica has gained some ice. However, other parts of Antarctica have shed twice that amount. This means that overall, the region has lost ice.
In fact, it was following the release of the 2007 IPCC report that scientists decided to undertake a comprehensive study to clear up disagreements on estimates based on differing satellite measuring techniques.
About 47 experts from around the world were involved in the study.
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