The East Antarctic Ice Sheet is highly sensitive to even relatively modest warming scenarios. It isn't as stable and protected as we once thought. We now have a very small window of opportunity to rapidly lower our greenhouse gas emissions, limit the rise in global temperatures and preserve the EAIS.
A new study led by Durham University, UK, shows that the worst effects of global warming on the East Antarctic Ice Sheet (EAIS) could be avoided if temperatures do not rise by more than 2°C above pre-industrial levels.
The team's analysis shows that if warming continues beyond 2100, sustained by high emissions, then East Antarctica could add several metres to global sea level rise over the coming centuries.
The Durham-led study showed that with dramatically reduced greenhouse gas emissions and only a small rise in temperature, the EAIS might be expected to contribute around two centimetres of sea level rise by 2100 - much less than the ice loss expected from Greenland and West Antarctica.
If emissions remain high beyond 2100 then the EAIS could contribute around one to three metres to global sea levels by 2300, and two to five metres by 2500. Crucially, if the target of the Paris Agreement is met, significant ice loss from East Antarctica could be reduced or even prevented, with the EAIS's contribution to sea-level rise remaining below half a metre by 2500.
Lead author Professor Chris Stokes, of the Department of Geography, Durham University, UK, said: “A key conclusion from our analysis is that the fate of the East Antarctic Ice Sheet remains very much in our hands.
“This ice sheet is by far the largest on the planet, containing the equivalent of 52 metres of sea level and it’s really important that we do not awaken this sleeping giant.”
The researchers also reviewed how the ice sheet responded to past warm periods, when carbon dioxide concentrations and atmospheric temperatures were only a little higher than present.
For example, the last time that carbon dioxide concentrations exceeded the current value of 417 parts per million was during a period known as the mid-Pliocene, around three million years ago. Temperatures were only 2-4°C higher than present at that time – in the range of the temperature changes we could experience later this century – but global mean sea level eventually reached 10-25 metres higher. Worryingly, evidence from sea-floor sediments around East Antarctica indicates that part of the ice sheet collapsed and contributed several metres to sea level rise during the mid-Pliocene.
They said that unlike the very rapid and extreme warming that we have experienced over the last few decades, that can only be explained by greenhouse gas emissions from human activity, past warming occurred over much longer timescales and was largely caused by changes in the way the Earth orbits the Sun.
Professor Nerilie Abram, a co-author of the study from the Australian National University in Canberra, said: “A key lesson from the past is that the East Antarctic Ice Sheet is highly sensitive to even relatively modest warming scenarios. It isn’t as stable and protected as we once thought.
“We now have a very small window of opportunity to rapidly lower our greenhouse gas emissions, limit the rise in global temperatures and preserve the East Antarctic Ice Sheet.”
“Taking such action would not only protect the East Antarctic Ice Sheet, but also slow the melting of other major ice sheets such as Greenland and West Antarctica, which are more vulnerable and at higher risk.”
“Therefore, it’s vitally important that countries achieve and strengthen their commitments to the Paris Agreement.”
The research was led by Durham University working with King’s College London, and Imperial College, London (UK); the Australian National University, University of New South Wales, University of Tasmania and Monash University (Australia); Université Grenoble Alpes (France); the University of Colorado Boulder, NASA Goddard Space Flight Center and Columbia University (USA).
It was funded by the: UK Natural Environment Research Council; the Australian Research Council Special Research Initiatives in the Australian Centre for Excellence in Antarctic Science, and Securing Antarctica’s Environmental Future; the Centre for Southern Hemisphere Oceans Research; the Australian Antarctic Program Partnership; the European Union’s Horizon 2020 research and innovation programme; and the National Aeronautics and Space Administration.
There is a world of difference in just 2°C. Let's not put this number to the ultimate test.
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