Environment

Antarctica Ice shelf the size of France threatened by effects of climate change

Antarctica Ice shelf the size ...
The wall of the Ross Ice Shelf stretches for a staggering 600 km (373 miles) in length
The wall of the Ross Ice Shelf stretches for a staggering 600 km (373 miles) in length
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The wall of the Ross Ice Shelf stretches for a staggering 600 km (373 miles) in length
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The wall of the Ross Ice Shelf stretches for a staggering 600 km (373 miles) in length

According to a new study, a vital section of the world's largest ice shelf is losing ice 10 times faster than the overall melt rate for the structure, posing a potential risk to its future stability. The Ross Ice Shelf stretches out over 500,809 km2 (193,363 miles2), and accounts for 32 percent of Antarctica's total ice shelf area.

Antarctica's ice shelves are known to play a vital role in mitigating rising sea levels, however they do not do so directly. Whilst ice shelves are always connected to a landmass, their vast frozen bulk is actually afloat in the ocean. Because of this, even when a significantly-sized chunk of a shelf breaks off, drops into the ocean and melts, it does not contribute to the rise in sea level, as the mass that formed the fragment was already displacing the water.

Their ability to slow the rise in global sea-level stems from their ability to slow the flow rate of the ice streams and glaciers that feed them. Think of an ice shelf as a stopper. If one were to fully break apart and disappear, the material flowing from the glaciers behind it would flow directly into the ocean.

"Previous studies have shown that when ice shelves collapse, the feeding glaciers can speed up by a factor of two or three," warns Dr. Poul Christoffersen of the University of Cambridge's Scott Polar Research Institute, who co-authored a new study detailing an important threat to the world's largest ice shelf.

It is very unlikely that the Ross Ice Shelf is going to collapse any time soon. However, the newly-published research has highlighted a potential threat to the long-term stability of the frozen leviathan.

The goal of the study was to shed light on the amount of ice that was melting at the base of the shelf, in a region surrounding a landmass called Ross Island. Secondly, the scientists behind the research sought to discover the extent to which ocean water warmed by the Sun's radiation drove the melting process.

The shelf environment surrounding Ross Island is of particular importance, as the landmass is responsible for partially pinning the icy structure back against the shore, and slowing the outward flow of the shelf.

Data used in the study was collected over the course of four years using a range of instruments. A custom-made radar system took measurements from 78 sites surrounding Ross Island in order to keep track of the changing thickness of the shelf.

The team was also able to draw on data collected by instruments placed along a wire anchored to the ocean floor below the shelf, known as a mooring. These sensors measured ocean currents, temperature and salinity on an hourly basis. Upwards Looking Sonar (ULS) was also employed to track how much ice was melted.

The instruments revealed that relatively warm water was flowing into a cavity located beneath the shelf, causing it to lose ice at roughly three times the normal rate for the region during summer months. For context, the region is losing ice 10 times faster than the average melt rate expected for the entire shelf.

It was determined that the water invading the cavity was heated by the Sun in a stretch of open ocean near to the shelf known as the Ross Sea Polyna, which is kept largely free of sea ice thanks to powerful offshore winds. Once warmed, the water was driven into the cavity by a combination of strong winds and tidal forcing.

The Ross Ice Shelf is currently relatively stable in terms of mass, as ice lost to melting is largely replaced by material flowing in from tributary glaciers and the long-term accumulation of snow. However, the balance is dependent on Ross Island's ability to pin the shelf back, slowing its outward progress, and further warming in the future could weaken this mechanism.

In the coming decades, the waters surrounding the shelf are predicted to become increasingly free of sea ice. Without these enormous floating ice cubes acting as heatsinks, the surface water temperature is likely to rise significantly.

According to the authors of the study, this temperature increase could intensify the rate of melting, and thus undermine the stabilizing pinning points that allow Ross Island to exert its influence.

A paper detailing the findings has been published in the journal Nature Geoscience.

Source: University of Cambridge

14 comments
Dagere76
My only take is there are also scientist that claim that our earth tilt has be changing year to year faster than ever from the earth wobble. Their conclusion also leads to increased temperature to Antarctica. https://climate.nasa.gov/news/2805/scientists-id-three-causes-of-earths-spin-axis-drift/ But really who know because I am not a scientist I have to go by what I read...which on the internet could be 5 thousand different things from different scientist. Sadly no matter the cause we probably will not fix it :(
betoodourke
CCH is absurd. What temperature is Earth supposed to be?
Johannes
That's an interesting article, Dagere76, and one of the causes suggested for the spin axis drift is the reducing mass of Greenland... Quote: In general, the redistribution of mass on and within Earth -- like changes to land, ice sheets, oceans and mantle flow -- affects the planet's rotation. As temperatures increased throughout the 20th century, Greenland's ice mass decreased. In fact, a total of about 7,500 gigatons -- the weight of more than 20 million Empire State Buildings -- of Greenland's ice melted into the ocean during this time period. This makes Greenland one of the top contributors of mass being transferred to the oceans, causing sea level to rise and, consequently, a drift in Earth's spin axis
GaryMccollom
Why is nobody talking about this and better yet why don't scientists research other fields besides their own as this is rather significant. "Scottish scientists have detected 91 volcanoes under a massive ice sheet in west Antarctica, potentially revealing one of the largest volcanic regions on Earth. The volcanoes are located in the West Antarctic Rift System, a 2,200-mile valley created by separating tectonic plates. The discovery brings the total number of volcanoes in the area to 138. The heights of the volcanoes range from 300 feet to 12,600 feet, with the tallest as high as Mount Fuji in Japan." https://www.pbs.org/newshour/science/scientists-found-91-volcanoes-under-antarctica
GaryMccollom
Then there are the massive issue with the moving magnetic pole. "Conclusions We have applied for the first time a recent statistical tool, transfer entropy, to shed light on the question of a possible link between the Earth’s magnetic field and climate and provide new perspectives in its future analysis. In this work, we have analyzed two real time series with an analogous evolution for the last 300 years, the South Atlantic Anomaly area extent on the Earth’s surface and the Global Sea Level rise. We have analyzed the anomalies of both time series, after removing the long term trend. The results seem to support the existence of an information flow between SAA and GSL anomalies, with larger information transferred from SAA to GSL and a confidence level about 90%. The found connection does not mean that the geomagnetic field is fully responsible of the climate changes, rather that it is an important driving component to the variations of the climate. This result is especially relevant because could help to find a physical mechanism able to explain this connection by discarding those in which the climate controls the geomagnetic field and supporting the mechanisms associated to the geomagnetic field. Although this work seems to provide a favorable argument to this link, future investigations are needed to completely exploit this issue, for example to check other time series at longer timescales." https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0207270
GaryMccollom
"Something strange is going on at the top of the world. Earth’s north magnetic pole has been skittering away from Canada and towards Siberia, driven by liquid iron sloshing within the planet’s core. The magnetic pole is moving so quickly that it has forced the world’s geomagnetism experts into a rare move." Mankind is maybe contributing 20% to climate change and thats at the high end, so little we even know about the depths of our oceans nvm the moving poles. https://www.nature.com/articles/d41586-019-00007-1
Paulinator
Reading the comments section one thing becomes apparent...the climate change scare tactics used to justify a tax on everything are failing spectacularly. Bring on more creepy Scandinavian 12-year-olds to convince us otherwise.
MartinVoelker
"Reading the comments section" I keep seeing people dismissing scientific research by insinuating devious deception or "scare tactics used to justify a tax on everything". If you don't have substantive remarks, do not come here to spread paranoid innuendo.
Nobody
MartinVoelker: Most people are not denying some degree of global warming but question how much is really man made and even solvable. What many question are the carbon tax solutions or socialist programs presented to cure the problem. Destroying the world economy and forcing everyone into socialist government control sounds like a false cure that will be far worse than the problem. When even the carbon tax advocates admit that most of the money will be spend for reparations to poor countries caused by the rich countries burning fossil fuels, then you know this about wealth redistribution and political power rather than a real solution. This is not paranoia but simply recognizing deception. As a retired scientist I can guarantee you that many scientists say what they are paid to and it is a lot more political than you could ever imagine. Everyone is entitled to their opinion. What gives you the right to tell anyone not to come here?
Douglas Bennett Rogers
Using the T**4 law, we see that dessert humidity has the overwhelming effect on global mean temperature. The highly variable six micron water band cuts a big chunk out of the 140 F blackbody curve of the dessert.