Posted with permission from China Daily

Chinese scientists, first to directly observe it, also note the dangers

Ice sheets in East Antarctica are melting faster than anticipated, and Chinese scientists are warning that the phenomenon could raise sea levels worldwide by up to four meters by 2100.

The scientists are the first in the world to directly observe the melting.

The melting is a "danger sign", as changes in average sea level threaten coastal cities and regions, the global fishing industry and ship safety if the trend continues, said Shen Qiang, lead scientist at the Chinese Academy of Sciences' Institute of Geodesy and Geophysics, whose team made the discovery.

By compiling hundreds of thousands of precision satellite images, Shen and his team created the world's most accurate map to illuminate the rate at which Antarctica's glaciers are sliding into the sea. The study was published in Scientific Reports, an online science journal.

"For the first time, we can directly observe and prove how fast the ice sheets in East Antarctica are melting without relying on models from climate and marine sciences," he said.

"Understanding this speed helps us pinpoint which fragile ice sheet may crack and break off, thus allowing more accurate evaluation of its effect on global climate and better disaster prediction."

Shen's team discovered that East Antarctica is melting faster than anticipated, with an annual rate increase of around 7.7 billion metric tons of ice from 2008 to 2015.

"This speed boost is alarming," he said. "But we have not passed a tipping point simply because East Antarctica is so huge."

East Antarctica represents two-thirds of the continent, and is about 10 times the size of West Antarctica. The entire continent holds more than 24.5 million cubic kilometers of ice, or 70 percent of the planet's fresh water.

For decades, scientists described East Antarctica as a "sleeping ice giant" due to its massive size and thick ice sheets, which average 2 kilometers deep with some areas going beyond 4 km, Shen said.

"Therefore, scientists thought East Antarctica was more stable and less affected by climate change compared with the much smaller West Antarctica," Shen said. "But now we are not so sure."

In 2016, scientists discovered that warm waters from East Antarctica's surrounding ocean were sneaking underneath its floating glaciers and eating the ice away from below, according to Nature, an international science journal.

In 2017, scientists from the United States discovered that East Antarctica ice sheets have a history of instability dating back 20 million years, indicating its ice sheets may contribute substantially to the global sea level rise as Earth's climate warms.

"Data regarding East Antarctica is very hard to come by because it is huge and surrounded by giant glaciers, making it hard to access by icebreaker ships or survey drones," Shen said.

However, the difficulties did not stop scientists from a dozen countries to venture into this icy desert to set up research stations, observatories and signal receivers during the past decades.

"Antarctica, especially its eastern region, is very old, remote, cold and dry," Shen said. "Hence it is an ideal place to study the history of our planet, observe outer space without interference or examine ancient microbes that have been trapped under ice for millions of years."

If East Antarctica melts away, scientists will lose irreplaceable data. The rising sea level will also wreak havoc in coastal regions, submerging New York City, Tokyo, Mumbai, Amsterdam and other port cities, Shen said.

Meanwhile, adding a large amount of fresh water into the ocean will damage the salinity balance of the sea, leading to changes in ocean currents and weather patterns. "This will be catastrophic for the global fishing industries and sea voyages," he added.

Mariners from Chile are already troubled by a growing number of rogue icebergs, Shen said, adding that when East Antarctica's ice sheets melt, it can create bigger and more dangerous icebergs.

"People like to think changes in Antarctica are still far away and do not affect our daily lives," Shen said. "But when we do feel it, it might be too late."

zhangzhihao@chinadaily.com.cn

(China Daily 03/23/2018 page5)