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The largest ice sheet in the world could melt and cause sea levels to rise by up to 13 feet even if we hit the Paris Climate Agreements target

21 September 2018 | Mitigation

The largest sheet of ice in the world, the East Antarctic Ice Sheet, which contains half the world's freshwater, could melt if rising temperatures persist, scientists warn.

The East Antarctic Ice Sheet, known as the EAIS, is around 60 times bigger than Britain and measures some 27 million km³.

Scientists have discovered that even if the 2°C (3.6°F) target set by the Paris Climate Agreement is achieved, sea levels could be set to rise up to 13 feet (4 metres).

The fall-out from such a significant rise in global sea levels would be catastrophic for Earth's climate as well as coastal communities, experts say.

Research on marine sediment from Antarctica indicates the EAIS has previously retreated during extended warm periods in the history of our planet, when temperatures were comparable to today's world.

Known as interglacial periods, these warm phases during history have occurred sporadically over the last 450,000 years.

The researchers studied the Wilkes Subglacial Basin, one of three major areas where the EAIS sits on land that lies below sea level, and looked at sediment layers that had settled on the seafloor during four previous warm intervals.

Researchers found chemical 'fingerprints' in the sediment that revealed the changing patterns of erosion as the ice sheet advanced and retreated over time.

During these geological periods, the global sea levels were between 18 feet and 40 feet (six and 13 metres) higher than they are today, scientists claim.

The researchers studied the Wilkes Subglacial Basin (pictured), one of three major areas where the EAIS sits on land that lies below sea level. The researchers studied sediment layers that had settled on the seafloor during four previous warm interval

HOW COULD A WARMING ANTARCTICA IMPACT SEA LEVELS?

Antarctica holds a huge amount of water.

The three ice sheets that cover the continent contain around 70 per cent of our planet’s fresh water - and these are all to warming air and oceans. 

If all the ice sheets were to melt due to global warming, Antarctica would raise global sea levels by at least 183ft (56m).

Given their size, even small losses in the ice sheets could have global consequences. 

In addition to rising sea levels, meltwater would slow down the world’s ocean circulation, while changing wind belts may affect the climate in the southern hemisphere. 

In February 2018, Nasa revealed El Niño events cause the Antarctic ice shelf to melt by up to ten inches (25 centimetres) every year.

El Niño and La Niña are separate events that alter the water temperature of the Pacific ocean.

The ocean periodically oscillates between warmer than average during El Niños and cooler than average during La Niñas.

Using Nasa satellite imaging, researchers found that the oceanic phenomena cause Antarctic ice shelves to melt while also increasing snowfall. 

In March 2018, it was revealed that more of a giant France-sized glacier in Antarctica is floating on the ocean than previously thought.

This has raised fears it could melt faster as the climate warms and have a dramatic impact on rising sea-levels.

The international research team, led by Dr David Wilson of Imperial College London, used evidence from the late Pleistocene – which took place between 126,000 to 12,000 years ago – to inform how the EAIS might react to a warming climate in the future.

Dr Wilson said: 'What we have learned is that even modest warming of just two degrees, if sustained for a couple of thousand years, is enough to cause the ice sheet in East Antarctica to retreat in some of its low-lying areas.

'With current global temperatures already one degree higher than during pre-industrial times, future ice loss seems inevitable if we fail to reduce carbon emissions.'

Scientists had previously focused on the West Antarctic Ice Sheet, EAIS's neighbour, which predominantly sits on land below sea level.

The EAIS has avoided any significant ice melt as it lies above sea level and is believed to be more resilient. If it was to start melting the sea level rise would be significant as it contains half of Earth's freshwater 

Most of the ice melt from Antarctica today originates from this region of the frozen continent.

The EAIS has so far avoided any significant ice melt as it lies above sea level and is believed to be more resilient to the rising global temperatures. 

Dr Wilson said: 'Studying ice sheet behaviour in the geological past can inform us about future changes.

'By building a picture of how the ice sheet has grown and shrunk as temperatures have fluctuated, we can understand the response of the EAIS to future warming.'

Co-author Professor Tina van de Flierdt, of Imperial College London's Department of Earth Science and Engineering, added: 'On multi-centennial to millennial time scales, ice sheets will dominate global sea level rise and pose a challenge to coastal regions around the globe.

'Decarbonising our economy is needed to keep global warming below 1.5 to 2 degrees, as targeted by the Paris Agreement, and to avoid major sea level rise in the future.'

 

 

Source: Daily Mail