Newsnight: Expert discusses keeping global warming below 1.5C
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A new study published by researchers at Imperial College London has examined the conditions of the Antarctic ice sheet some 18 to 16 million years ago, during the Early Miocene. The sub-epoch of the Miocene saw extended periods of both warming and cooling climates, which led to a drastic change in global sea levels. At their warmest, the seas rose by an astounding 196ft (60m) – the equivalent of Antarctica losing all of its present ice coverage.
However, scientists have been unclear about how much of that water came from the West Antarctic Ice Sheet (WAIS), or the bigger East Antarctic Ice Sheet (EAIS). That is, until now.
A new paper published in the journal Nature has found that the extent of the WAIS was much bigger during the colder periods of the Miocene than previously thought.
The study was carried out by Imperial researchers as part of the International Ocean Discovery Program.
Their findings suggest Antarctica’s melting ice millions of years ago contributed more water to global sea-level rise than previously thought.
And that could prove critical to better understanding how global warming will affect the WAIS in the future.
Until now, scientists believed the WAIS was relatively small about 10 million years ago, before the Late Miocene.
The bulk, if not all, of the rising sea levels were also attributed to the bigger EAIS during periods of warming in the last 23 million years.
Lead author and PhD student Jim Marschalek, from the Department of Earth Science and Engineering at Imperial, said: “Our observations from the past help inform predictions of how the West Antarctic Ice Sheet, which is considered particularly vulnerable to rapid ice mass loss today, will respond under various future warming scenarios.”
With the threat of global warming shooting past 2C above pre-industrial levels, scientists around the globe are scrambling to figure out how the Antarctic will react to climate change.
The WAIS is considered particularly vulnerable to a warming atmosphere and ocean waters, both of which drive the melting of glaciers and surface ice.
A better understanding of how the ice sheet behaved in the past will help inform scientists’ models and forecasts for both the short term and the next several hundred to thousand years.
Unfortunately, the findings indicate immediate action is needed to curb the spread of planet-warming greenhouse emissions.
Co-author Professor Tina van de Flierdt, from the Department of Earth Science and Engineering at Imperial, said: “While Antarctica is losing mass at an accelerating rate today, projected sea-level rise by the end of this century is nowhere close to the levels that we know existed in the geological past when temperatures were one, two, or three degrees warmer.
“Hence the past is an important window to tell us what we are committing the planet to with certain amounts of warming.
“The good news is that the large ice sheets are relatively sluggish to respond to environmental change, so we might still be able to avoid major ice loss in many areas.
Antarctica: Scientists find area where no life exists
“The bad news is that the low-lying areas of the ice sheet have a ‘tipping point’, and we do not yet fully understand where this point of no return lies.”
The key to preventing a complete collapse of the Antarctic, the expert added, is to keep global warming below 2C – ideally to 1.5C.
This could be achieved by slashing the globe’s greenhouse emissions by 50 percent by 2030.
Countries like the UK and US have already committed to becoming net-zero by 2050, but many scientists fear the progress towards these ambitious targets has been uninspiring.
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