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World’s largest ice sheet is more susceptible to global warming than scientists once thought

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The eastern two-thirds of Antarctica is covered by a very large ice sheet that, if melted, would raise sea levels by 52 meters. Most scientists once thought this ice sheet would be largely immune to climate change, but that is no longer the case. And our new research Naturerevealing the dire consequences of awakening the sleeping giants of Antarctica.


Nearly 70% of the Earth’s freshwater is frozen in the vast continental ice sheets that cover Greenland and Antarctica. Together, we will save an amount equivalent to about 65 meters of sea level rise. Therefore, even relatively small changes in the volume of these remote polar ice sheets would have global implications.Ann Estimate One billion people live within 10 meters above sea level, including 230 million within 1 meter.

Scientists measure changes in the volume of these ice sheets by estimating mass input and mass output, primarily due to snowfall. The mass output is mostly melting snow and ice and icebergs breaking off and rising to the surface. The difference between input and output is known as the “mass balance” of the ice sheet. climate change.

The latest efforts to measure the mass balance of ice sheets paint a very disturbing picture.Lost Greenland ice sheet, including sea level rise of about 7.4 meters 3.9 trillion tons of ice Global sea level rose by 11 mm between 1992 and 2018. A similar story comes out of western Antarctica, known as the West Antarctic Ice Sheet.It held about 5.3 meters of sea level and lost more 2 trillion tons of ice Between 1992 and 2017, sea level rose by about 6 mm.

World's largest ice sheet is more susceptible to global warming than scientists once thought

A camp on the surface of the East Antarctic Ice Sheet.Credit: Nerilie Abram, provided by the author

more sensitive than you think

Perhaps surprisingly, little research has focused on the East Antarctic Ice Sheet. Global warmingThis is because much of the ice sheet has persisted through “natural” climate change. millions of yearsand recent measurements show that it is either in equilibrium or possibly has gained mass (meaning more snow, since the warmer atmosphere can hold more moisture). In fact, even a few ice sheets Decrease in sea level rise Over the past century.

However, over the past two decades or so, observations have suggested that the East Antarctic Ice Sheet may be much more sensitive to climate warming than previously thought.Selection subject outlet glacier Like Totten and Vanderford leaning back. And in the ice sheet “Wilkes Land” there are clear signs of mass loss.weak lower abdomenbecause it lies on “land” well below sea level, the so-called particularly unstable.

World's largest ice sheet is more susceptible to global warming than scientists once thought

Antarctic ice thickness (UK and Ireland shown to scale).Credits: Data: Morlighem et al. (2020; Nature Geoscience) Images: Guy Paxman, authors provided

lessons from the past

there is also evidence Parts of East Antarctica retreated very dramatically during past warm periods when carbon dioxide concentrations and atmospheric temperatures were slightly higher than today.

East Antarctica may have had several meters of impact on global sea level, with ice loss concentrated in Wilkes Land during the warm period of the mid-Pliocene about 3 million years ago. Recent works It also suggests that the Wilkes Land ice retreated 700 km inland from its current position about 400,000 years ago, when global temperatures were only 1-2°C warmer than today. An important lesson from the past is therefore that the East Antarctic Ice Sheet, although currently stable, is highly sensitive to relatively moderate warming.

World's largest ice sheet is more susceptible to global warming than scientists once thought

An iceberg tower breaking off from the East Antarctic ice sheet.Credit: Nerilie Abram, provided by the author

don’t wake the sleeping giant

So what will really happen in the coming decades and centuries? We recently analyzed predictions from various computer simulations to answer this question. Our results were surprising, but also somewhat encouraging.

We find that the ice sheet is probably broadly balanced in the short term, as mass loss due to global warming is offset by increased snowfall. Although there are great uncertainties, he concluded that ice sheets would only raise sea levels by about 2 cm by 2100. This is much smaller than the contribution expected from the melting of Greenland or West Antarctic ice.

Over the next few centuries, however, the impacts on sea levels from East Antarctica will be highly dependent on our ability to curb emissions. In that case, East Antarctica could have an impact of about 1 to 3 meters by 2300 and about 2 to 5 meters by 2500, plus substantial impacts from Greenland and West Antarctica, plus coastal impacts. It could threaten the millions of people who live there. area.

  • World's largest ice sheet is more susceptible to global warming than scientists once thought

    The edge of the Vanderford Glacier, one of the major outlet glaciers appearing to be thinning and retreating in Wilkes Land, East Antarctica.Credit: Richard Jones, author provided

  • World's largest ice sheet is more susceptible to global warming than scientists once thought

    How much sea level would rise thanks to meltwater from each Antarctic ice sheet if warming were kept below 2C (left column for each year) and under extreme warming scenarios (right column).Credit: Richard Jones, Monash University, provided by the author

Importantly, however, if the Paris Agreement to limit global warming to well below 2°C is passed, the contribution of East Antarctic sea-level rise will remain less than half a meter five centuries from now.

world’s greatest destiny ice sheet remains in our hands.


The fate of the world’s largest ice sheet is in our hands, scientists say


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Quote: World’s Largest Ice Sheet More Vulnerable to Global Warming Than Scientists Previously Thought (11 Aug 2022) https://phys.org/news/2022-08-world-biggest- Get 08/11/2022 from ice-sheet-vulnerable.html

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World’s largest ice sheet is more susceptible to global warming than scientists once thought

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