Antarctica’s Thwaites glacier at risk of collapse and may lead to sea levels rising by two feet

Antarctica’s Thwaites glacier has warm water from three directions well under it threatening to destroy the ice sheet and raise global sea levels by up to two feet.

A team of scientists from Oregon State University made the most of ice free waters in West Antarctica to look under the glacier – which is about the size of Great Britain.

Warm water from the deep ocean is welling up under the glacier from three different directions and mixing under the ice, the researchers discovered.

If it collapses it could take other parts of the ice shelf with it and lead to the single largest driver of sea-level rise this century, lead researcher Erin Pettit told Nature.

Researchers sent a robotic submersible called Rán – named after the Norse god of the sea – under the ice at Thwaites Glacier and discovered streams of warm water

Researchers are studying Thwaites in detail, with various ongoing studies. One piece of research is looking at the grounding line – the region – where the glacier rests on the ocean bed and where it floats over water. It is a crucial site for glacial melt and warm water is coming from three different directions, a new study has found

The £39million study involving UK and US scientists was launched after concerns the increasingly unstable glacier may have already started to collapse.

They are working to gather data from a range of different experiments and tests to better predict if an when Thwaites it will happen.

The latest findings from a study into the wider ice shelf the glacier sits on come two years into the five year project.

Glaciologist Erin Pettit and her team worked directly on the ice shelf conducting seismic tests to study the sea floor and deploy sensor 980ft into the ice.

They are studying the wider shelf, which extends across more than 65miles of open ocean and acts as a cork holding back ice on land, Pettit said.

‘Thwaites has got these three guns pointed right at it,’ Pettit, a glaciologist at Oregon State University, ‘water is coming from all direction’.

Melting of Thwaites is cause for global concern as its sheer enormity means that it contains enough ice that, if it was to melt, there would be worldwide implications.

Thwaites Glacier is in West Antarctica and is sometimes called the Doomsday Glacier due to its potential impact on global sea levels

Other groups will look at the glacier’s flow on land and the ocean circulation – with all of the research feeding into models of the glacier and its future.

‘We’ve never seen an ice sheet disintegrate in a warming climate, so we’re struggling to project how it could happen,’ glaciologist Ted Scambos told Nature.

Sometimes called the Doomsday Glacier due to the potential impact its collapse could have on sea levels, Thwaites is unusually broad and fast.

Already, Thwaites accounts for about four per cent of global sea-level rise as warming waters cause it to melt from the underside.

Researchers have long held concerns that a tipping point in the stability at its foundations could result in a run-away collapse of the glacier.

WHAT WOULD SEA LEVEL RISES MEAN FOR COASTAL CITIES?

Global sea levels could rise as much as 10ft (3 metres) if the Thwaites Glacier in West Antarctica collapses.

Sea level rises threaten cities from Shanghai to London, to low-lying swathes of Florida or Bangladesh, and to entire nations such as the Maldives.

In the UK, for instance, a rise of 6.7ft (2 metres) or more may cause areas such as Hull, Peterborough, Portsmouth and parts of east London and the Thames Estuary at risk of becoming submerged.

The collapse of the glacier, which could begin with decades, could also submerge major cities such as New York and Sydney.

Parts of New Orleans, Houston and Miami in the south on the US would also be particularly hard hit.

A 2014 study looked by the union of concerned scientists looked at 52 sea level indicators in communities across the US.

It found tidal flooding will dramatically increase in many East and Gulf Coast locations, based on a conservative estimate of predicted sea level increases based on current data.

The results showed that most of these communities will experience a steep increase in the number and severity of tidal flooding events over the coming decades.

By 2030, more than half of the 52 communities studied are projected to experience, on average, at least 24 tidal floods per year in exposed areas, assuming moderate sea level rise projections. Twenty of these communities could see a tripling or more in tidal flooding events.

The mid-Atlantic coast is expected to see some of the greatest increases in flood frequency. Places such as Annapolis, Maryland and Washington, DC can expect more than 150 tidal floods a year, and several locations in New Jersey could see 80 tidal floods or more.

In the UK, a two metre (6.5 ft) rise by 2040 would see large parts of Kent almost completely submerged, according to the results of a paper published in Proceedings of the National Academy of Science in November 2016.

Areas on the south coast like Portsmouth, as well as Cambridge and Peterborough would also be heavily affected.

Cities and towns around the Humber estuary, such as Hull, Scunthorpe and Grimsby would also experience intense flooding.

A map showing what the land is like underneath the ice on Antarctica created as part of the wider project is helping scientists predict the impact of global warming on the frozen continent – they used data from seismology and air surveys

As part of the wider project a number of robotic vehicles have been sent under the ice to gather data including one called Rán – named after the Norse god of the sea.

That information was used to add to a detailed map of the sea floor and information on the conditions of the ocean and currents.

‘The conditions were perfect: calm seas, open water,’ Anna Wåhlin, an oceanographer with the University of Gothenburg in Sweden told Nature.

An earlier robotic submarine was able to confirm the presence of warm water under the ice, which Pettit and her team expanded on to find there were three sources of the warm water all ‘attacking’ the glacier from different sides.

Thwaites is split into two sections – a stable eastern side with a rocky outcrop and flows of about 1,900ft per year and a western side with flows of 1.2 miles per year.

‘It’s not just a flat sheet of ice that is melting uniformly. It’s more complex than we thought,’ Pettit told Nature.

As part of the wider project a number of robotic vehicles have been sent under the ice to gather data including one called Rán – named after the Norse god of the sea

The team were able to use data gathered by the robot to create a detailed map of the sea floor underneath the glacier

Using radar to study the inside of the shelf they found it was full of channels, ridges and cliffs created by warm currents.

The likelihood of it collapsing – or when it might happen – won’t be known for at least another three years – until the end of the full study, researchers say.

Next year the little robot submarine will create a large map of the area all the way to where the main body of the glacier sits on bedrock.

They will also use a combination of gliders, drilling and other sensors to gather as much data as they can about the seafloor and ocean currents.

Wåhlin says if they don’t have answers on Thwaite’s future by the end of the study in three years time ‘it would be shameful’.

She said by then we should know much more about the risks the ice shelf poses.

THE RETREAT OF THE THWAITES GLACIER

The Thwaites glacier is slightly smaller than the total size of the UK, approximately the same size as the state of Washington, and is located in the Amundsen Sea.

It is up to 4,000 metres (13,100 feet thick) and is considered a key in making projections of global sea level rise.

The glacier is retreating in the face of the warming ocean and is thought to be unstable because its interior lies more than two kilometres (1.2 miles) below sea level while, at the coast, the bottom of the glacier is quite shallow.

The Thwaites glacier is the size of Florida and is located in the Amundsen Sea. It is up to 4,000 meters thick and is considered a key in making projections of global sea level rise

The Thwaites glacier has experienced significant flow acceleration since the 1970s.

From 1992 to 2011, the centre of the Thwaites grounding line retreated by nearly 14 kilometres (nine miles).

Annual ice discharge from this region as a whole has increased 77 percent since 1973.

Because its interior connects to the vast portion of the West Antarctic Ice Sheet that lies deeply below sea level, the glacier is considered a gateway to the majority of West Antarctica’s potential sea level contribution.

The collapse of the Thwaites Glacier would cause an increase of global sea level of between one and two metres (three and six feet), with the potential for more than twice that from the entire West Antarctic Ice Sheet.

Source link