Half of Greenland and vast areas of Antarctica are destined to melt if global warming continues at the same pace until the end of the century, scientists warned on Thursday.
Their research shows that the loss of so much ice will trigger dramatic rises in sea levels, ultimately swamping low-lying islands and coastal regions and threatening the flood defenses of cities such as London.
The last time so much ice was lost from the poles -- in a period between ice ages 129,000 years ago -- global sea levels rose between 4m and 6m.
Experts believe many coastal regions would suffer long before sea levels rose significantly, because even a minor rise will make storm surges more devastating and increase the risk of flooding.
The warning comes from climate scientists who combined historical records of Arctic and Antarctic ice melting with advanced computer models capable of predicting future environmental conditions.
They found that if nothing is done to put the brakes on climate change, Greenland, the west Antarctic ice sheet and other expanses of polar ice will be warmed beyond a "tipping point" after which their melting is inevitable.
Jonathan Overpeck, director of the Institute for the Study of Planet Earth at the University of Arizona, and Bette Otto-Bliesner, at the US National Center for Atmospheric Research in Colorado, looked back in history to find a time when sea levels were higher than they are today.
They identified a period when glacial melting increased sea levels by several meters.
They used a computer model of the environment to work out how warm the world must have been to trigger the mass melting and concluded that the Earth was between 3oC and 5oC warmer than it is today.
Using the same model, the scientists spun the clock forward to see when climate change is likely to make the world as warm again.
"We showed that that level of warming will come later in this century unless we act on carbon emissions," Overpeck said.
"An Arctic warming of 3oC to 5oC is enough to cause 4m to 6m of sea level rise," he said.
If temperatures do rise as the scientists predict, the ice at the poles will not be lost immediately. Enough ice is likely to melt within the next 100 years to raise sea levels by a meter, but ultimately the fresh water pouring into the North Atlantic would slow down the Gulf stream by a quarter.
"These ice sheets have melted before and sea levels rose. The warmth needed isn't that much above present conditions," said Otto-Bliesner.
The major concern is that unless climate change slows down significantly, the eventual loss of polar ice and subsequent 6m rise in sea levels will become unavoidable.
"There has been an increasing number of observations from the ice sheets suggesting they are responding faster to climate change than anticipated," Overpeck said.
"Now along come our results showing these kinds of changes occurred in the past and lead to large ice sheet retreat and sea level rise," he said.
A 1m rise in the sea level would see the Maldives disappear, make most of Bangladesh uninhabitable and put cities such as New Orleans "out of business," according to Overpeck.
The research was published in two papers in the US journal Science on Thursday.
FIRST STEP: Business groups in Taiwan welcomed the deal, which does not include tariff reductions at this stage, as they called for the elimination of double taxation Taiwan and the US yesterday signed an initial agreement under the US-Taiwan Initiative on 21st-Century Trade. The agreement was signed yesterday morning by Representative to the US Hsiao Bi-khim (蕭美琴) and American Institute in Taiwan (AIT) Managing Director Ingrid Larson in Washington, the Office of Trade Negotiations in Taipei said. The ceremony was witnessed by Minister Without Portfolio John Deng (鄧振中) and Deputy US Trade Representative Sarah Bianchi. Taiwan and the US started talks under the initiative in August last year, after Taipei was left out of the Washington-led Indo-Pacific Economic Framework. “The deal that will be signed tonight is not only very historic,
Beijing yesterday blamed US “provocation” for an incident last week in which a Chinese plane crossed in front of a US surveillance aircraft over the South China Sea. The incident came at a time of frayed ties between Washington and Beijing over issues including Taiwan and the shooting down of an alleged Chinese spy balloon that flew over the US this year. “The United States’ long-term and frequent sending of ships and planes to conduct close surveillance on China seriously harms China’s national sovereignty and security,” Chinese Ministry of Foreign Affairs spokesperson Mao Ning (毛寧) said when asked about the latest incident. “This
‘GLOBAL NETWORK’: The only way to deter a Chinese invasion is for the international community to unite in its resolve, Deputy Minister of Foreign Affairs Roy Lee said Deputy Minister of Foreign Affairs Roy Lee (李淳) yesterday urged democratic nations around the world to not let Beijing dictate the definition of their “one China” policies, saying that they should increase cooperation with Taiwan to build a resilient democratic network. Lee made the remarks during his speech, titled “Ukraine and Taiwan: Why Global Unity Matters,” at the annual Bratislava Forum in Slovakia. “People in Taiwan have been paying close attention to the situation in Ukraine and admire Ukrainians for defending their homeland. They are [also] fighting for Taiwan and democratic countries around the world,” Lee told forum participants. “The international
HARD-WON FREEDOM: Beijing’s 1989 crackdown on protesters has not been and should not be forgotten, as China tightens its grip on Hong Kong, Lai said Taiwanese enjoy democracy and freedom and have multiple ways to express their creativity, and hopefully young people in China would also one day have the freedom to sing and express themselves, President Tsai Ing-wen (蔡英文) said yesterday, commemorating the Tiananmen Square Massacre. Yesterday was the 34th anniversary of the Chinese People’s Liberation Army’s bloody crackdown on student-led protests in Beijing in 1989, also known as the June Fourth Incident. Tsai posted a photograph taken in March in a subway station in Guizhou, China, where hundreds of young people gathered to sing People With No Ideals Don’t Get Hurt (沒有理想的人不傷心), saying that they
RSS