Ice is melting in Antarctica at a faster rate than ever before and speeding up sea level rise, scientists have warned. Unless urgent action is taken, coastal areas around the world are likely to be threatened by rising sea level sooner than thought.
The warning is the result of a major new climate assessment conducted by an international team of 84 scientists. Led by the University of Leeds in England and NASA’s Jet Propulsion Laboratory in California, the team reviewed 24 satellite surveys measuring ice loss to create the most complete review of changes in Antarctic ice to date.
Their findings, published on Wednesday in Nature, show that the rate of ice loss in Antarctica has tripled in the past decade. Prior to 2012, Antarctica lost 76 billion tonnes of ice each year, which contributed 0.2mm to sea level rise annually. From 2012 to 2017, the study found that annual ice loss increased to 219 billion tonnes, resulting in 0.6mm of sea level rise per year.
“We have long suspected that changes in Earth’s climate will affect the polar ice sheets,” University of Leeds Professor Andrew Shepherd, who led the assessment, said in a statement.
“According to our analysis, there has been a steep increase in ice losses from Antarctica during the past decade, and the continent is causing sea levels to rise faster today than at any time in the past 25 years,” he added. “This has to be a concern for the governments we trust to protect our coastal cities and communities.”
Shepherd told Reuters that the figures suggest Antarctica could raise global sea level by around 15cm by 2100. Although the numbers may seem small, the change would worsen coastal flooding due to storms and high tides. The team said that coastal cities in the United States would be particularly impacted by sea level rise due to Antarctic ice loss.
“For the Northern Hemisphere, for North America, the fact that the location in West Antarctica is where the action is amplifies that rate of sea-level rise by up to about an additional 25% in a city like Boston or New York,” Rob DeConto, an Antarctic expert at the University of Massachusetts at Amherst who was not involved in the new study, told The Washington Post.
The gravitational pull that Antarctica’s ice sheet exerts on the ocean decreases as it shrinks. As a result, the water would move more freely towards the Northern Hemisphere and could pile up around the U.S. coastline.
In a separate paper, also published on Wednesday in Nature, scientists assessed how two different scenarios would affect Antarctica in 2070. If the world continues to emit large amounts of greenhouse gases, the paper estimates Antarctic ice loss would continue to accelerate, leading to half a metre of sea level rise by 2070. The authors say this would cause economic losses of over $1 trillion per year due to coastal flooding.
However, if widespread action is taken over the next ten years to reduce emissions and slow anthropogenic effects on the environment, it would keep global temperature rise at or below the 2 degrees Celsius limit set by the Paris Agreement and limit Antarctic ice loss and subsequent sea level rise.
“Decisions made in the next decade will determine what trajectory is realized,” the authors write.
“Some of the changes Antarctica will face are already irreversible, such as the loss of some ice shelves, but there is a lot we can prevent or reverse,” Study co-author Prof Martin Siegert, from the Grantham Institute at the London School of Economics, said in a statement.
“To avoid the worst impacts, we will need strong international cooperation and effective regulation backed by rigorous science. This will rely on governments recognising that Antarctica is intimately coupled to the rest of the Earth system, and damage there will cause problems everywhere.”