Melting away: Antarctica ice loss increases six-fold since 1979

Alarming new study shows 252 billion tonnes of ice per year is disappearing in areas once considered stable.

    Pace of melting is expected to lead to a disastrous sea level rise in the years to come [File: Alexandre Meneghini/Reuters]
    Pace of melting is expected to lead to a disastrous sea level rise in the years to come [File: Alexandre Meneghini/Reuters]

    Climate change is melting ice in Antarctica faster than ever before - about six times more a year now than 40 years ago - leading to increasingly high sea levels worldwide, scientists warned.

    Antarctic melting has raised global sea levels more than 1.4 centimetres between 1979 and 2017, said the report in the Proceedings of the National Academy of Sciences (PNAS), a peer-reviewed US journal, on Monday.

    The pace of melting is expected to lead to a disastrous sea level rise in the years to come, according to lead author Eric Rignot, chair of Earth system science at the University of California, Irvine.

    "As the Antarctic ice sheet continues to melt away, we expect multi-metre sea level rise from Antarctica in the coming centuries," Rignot said.

    A rise of 1.8 metres by 2100 - as some scientists forecast in worst-case scenarios - would flood many coastal cities home to millions of people around the world.

    40 billion tonnes

    For the current study, researchers embarked on the longest-ever assessment of ice mass in the Antarctic, across 18 geographic regions.

    Data came from high-resolution aerial photographs taken by NASA planes, along with satellite radar from multiple space agencies.

    Richard Alley, a Pennsylvania State University scientist not involved in Rignot's study, called it "really good science".

    Researchers discovered from 1979 to 1990, Antarctica shed an average of 40 billion tonnes of ice mass annually.

    By the years 2009 to 2017, the ice loss had increased more than six-fold, to 252 billion tonnes a year.

    Even more worrying, researchers found areas once considered "stable and immune to change" in East Antarctica, are shedding a lot of ice, too, said the study.

    "The Wilkes Land sector of East Antarctica has, overall, always been an important participant in the mass loss, even as far back as the 1980s, as our research has shown," Rignot said.

    "This region is probably more sensitive to climate than has traditionally been assumed, and that's important to know, because it holds even more ice than West Antarctica and the Antarctic Peninsula together."

    180528044155165

    Massive ice loss

    The total amount of ice in the Antarctic, if it all melted, would be enough to raise sea levels 57 metres.

    By far, the most ice in Antarctica is concentrated in the east. The East Antarctic Ice Sheet is the world's largest, containing roughly half of Earth's freshwater.

    Until now, most research has shown the majority of melting is happening in the West. The latest research shows East Antarctic melting deserves "closer attention," according to the PNAS report.

    Warming ocean water will only speed up ice loss in the future, and experts say sea levels will continue to mount for centuries, no matter what humans do now to rein in climate change.

    Recent research has shown oceans are heating up more quickly than previously thought, setting new heat records in the last few years.

    Antarctica on the edge

    Earthrise

    Antarctica on the edge

    SOURCE: News agencies