'Drastic' Antarctic melt could double global sea-level rise
Global sea levels could rise by more than double the current estimate, according to a new analysis of climate change in Antarctica. The modelling assessment says that Antarctic melting alone could contribute more than a metre to sea level by the end of this century. By 2500, it could cause levels across the world to rise by 13m.
In 2013, the Intergovernmental Panel on Climate Change (IPCC) predicted that, without any restrictions on carbon emissions, the seas around the world likely rise by up to 98cm by 2100. However, the IPCC estimates contained a minimum contribution from Antarctica.
Other analyses since then have projected bigger increases, with a recent study suggesting that the oceans were rising faster than at any time in the past 2,800 years and by 2100 they could be up to 1.31m higher.
The exact level of Antarctica's impact on these projections has been vigorously debated. Late last year, a research paper suggested that projections of a contribution of a metre or more were not plausible. But this new study argues that by 2100 the world could see 1.14m of sea-level rise from Antarctica alone.
The scientists say that their model is able to provide a more accurate prediction because it incorporates the impacts of some physical processes for the first time. While other models have focussed on the impact of warmer waters melting the ice shelves from below, this new study also includes the effect of surface melt-water and rain trickling down from above and fracturing supporting ice, hastening its slide to the sea.
The model also calculates the impact of the disintegration of floating ice shelves. If this happens, it will reveal walls of ice so tall that they cannot support their own weight. The scientists involved expect that these extra factors will kick in over the coming decades, as warming from the atmosphere (not just from warmer waters below) becomes the dominant driver of ice loss.
The authors believe that there is "good news" in their report. If global emissions of carbon are curtailed significantly then the extra factors that substantially boost Antarctic melting will be avoided.