Sea levels could rise 2m by 2100 – study
Sea levels could rise nearly twice as much as previously predicted by the end of this century if carbon dioxide emissions continue unabated, an outcome that could devastate coastal communities, according to new research published yesterday. The main reason? Antarctica. Scientists behind a new study published in the journal Nature used sophisticated computer models to decipher a long-standing riddle about how the uninhabited continent behaved during ancient periods of global warming.
With new understanding of the way major glaciers melt and collapse, the computer models found that similar climate conditions in the future could lead to monumental and irreversible increases in sea levels by 2100.
If high levels of greenhouse gas emissions continue, they concluded, oceans could rise by more than two metres by the end of the century. The melting of ice from Antarctica alone could cause seas to rise more than 15m by 2500.
The startling findings paint a far grimmer picture than current consensus predictions, which have suggested that seas could rise by about 1m at most by 2100.
Those estimates had suggested that expanding ocean waters and the melting of relatively small glaciers would be the main drivers of sea level rise, and did not envision extensive melting from Greenland or Antarctica.
The projection ‘‘nearly doubles’’ prior estimates of sea-level rise, which had relied on a ‘‘minimal contribution from Antarc- tica’’, said Rob DeConto of the University of Massachusetts at Amherst, who authored the study with David Pollard of Penn State University.
Should the new research prove correct, it could trigger a ‘‘tectonic shift’’ in expectations for the speed and severity of the sea level problem, said Ben Strauss, director of the programme on sea level rise at Climate Central, an independent organisation of scientists based in New Jersey.
He said the century beginning in 2100 could see truly catastrophic shifts, unless societies made sharp cuts in greenhouse gas emissions.
‘‘Under the high-emissions scenario, the 22nd century would be the century of hell,’’ Strauss said.
‘‘There would really be an unthinkable level of sea rise. It would erase many major cities and some nations from the map . . . That century would become the century of exodus from the coast.’’
Places as far apart as South Florida, Bangladesh, Shanghai, and parts of Washington, DC could be engulfed by the rising waters, Strauss said. Even by 2100, Miami Beach and the Florida Keys could begin to vanish. New Orleans essentially could become an island guarded by levees.
The researchers behind the new study have made it clear that their model has limitations and that human behaviour can alter the possible outcomes.
For instance, the worst-case scenario – of seas rising nearly 1.2m due to Antarctic ice loss alone by 2100 – assumes that very high emissions continue for carbon dioxide and other greenhouse gases.