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Sustained levels of moderate global warming could melt the gigantic Antarctic ice sheet – with catastrophic consequences, warns a new search.
Experts predicted that the warming of the Antarctic from only 35 ° F could melt the Earth's largest ice cap – about 60 times larger than Britain.
If the sheet were to melt, scientists claim that it would raise the global sea level by more than 13 feet.
New research on the Antarctic marine sediment layers indicate that the East Antarctic Ice Sheet (EAIS) has been removed during prolonged warm periods in the past, when the temperatures were similar to those predicted for this century.
The international research team, led by Dr. David Wilson of Imperial College London, used earlier data from Earth's history, the late Pleistocene, to explain how the SEIA could respond to global warming.
Scientists had already paid a lot of attention to the West Antarctic Ice Sheet, which is mainly based on land below sea level and contributes to most of the Antarctic ice melt. .
The EAIS, by contrast, relies mainly on land located above sea level. It is the largest ice cap on the planet, about 60 times the area of the United Kingdom.
It contains about half of the world's fresh water but is supposed to be less sensitive to global warming.
But the new findings, published in the journal Nature, suggest that the 35 ° F warming in Antarctica, if it were to last a few millennia, would lead to a melting in an area of AAIS below sea level .
The researchers warned that this has serious consequences for sea level rise and the threat of global warming for human civilization.
Wilson said, "The study of ice cap behavior in the geological past can inform us about future changes.
"By drawing a picture of ice sheet growth and shrinkage as temperatures have fluctuated, we can understand the reaction of EAIS to future warming."
The researchers studied the subglacial Wilkes Basin, one of the three main areas where EAIS is found on land below sea level.
According to the researchers, if all the ice in the basin were to melt, the sea level could rise by 13.1 feet.
The glaciers, which come from ice caps, crush rocks on the mainland and then transport these sediments to the neighboring Southern Ocean, leaving behind a trace of erosion through the ice cap.
To understand how warming has affected the ice cover in the past, the team chemically analyzed layers of ocean bottom sediments from the Wilkes subglacial basin.
The researchers studied the sediment layers that had settled on the seabed during four previous warm intervals that occurred between (interglacial) glaciations over the past 450,000 years.
They found chemical "footprints" in the sediments, revealing the evolution of erosion as the ice sheet moved and retreated.
The results show that the ice sheet had retreated from its current size during some of the interglacial glaciations, while temperatures were barely two degrees higher than the pre-industrial period.
The results also show that the most extreme changes in the ice cap occurred during two interglacial periods 125,000 and 400,000 years ago, when the global level of the sea was between 19 and 42 feet higher than that. aujourd & # 39; hui.
And the loss of ice due to the EAIS has probably contributed significantly to the sea level rise in the past.
Wilson added, "What we have learned is that even modest warming of only two degrees if maintained for a few thousand years is enough for the East Antarctic Ice Sheet to retreat into some of his lowlands.
"With current global temperatures already one step higher than those of the pre – industrial era, future ice loss seems inevitable if we fail to reduce carbon emissions.
Professor Tina van de Flierdt, also co-author of Imperial's Department of Earth Sciences and Engineering, added:
"The decarbonization of our economy is needed to keep global warming below 1.5 to 2 degrees [Celsius]as covered by the Paris Agreement and to avoid a major rise in sea level in the future. "
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