Global sea levels could rise as much as 1.2 metres (4 feet) by 2300 even if we meet the 2015 Paris climate goals, scientists have warned.
The long-term change will be driven by a thaw of ice from Greenland to Antarctica that is set to re-draw global coastlines.
Sea level rise threatens cities from Shanghai to London, to low-lying swathes of Florida or Bangladesh, and to entire nations such as the Maldives.
It is vital that we curb emissions as soon as possible to avoid an even greater rise, a German-led team of researchers said in a new report.
By 2300, the report projected that sea levels would gain by 0.7-1.2 metres, even if almost 200 nations fully meet goals under the 2015 Paris Agreement.
Targets set by the accords include cutting greenhouse gas emissions to net zero in the second half of this century.
Ocean levels will rise inexorably because heat-trapping industrial gases already emitted will linger in the atmosphere, melting more ice, it said.
In addition, water naturally expands as it warms above four degrees Celsius (39.2°F).
The report also found that every five years of delay beyond 2020 in peaking global emissions would mean an extra 20 centimetres (8 inches) of sea level rise by 2300.
‘Sea level is often communicated as a really slow process that you can’t do much about … but the next 30 years really matter,’ lead author Dr Matthias Mengel, of the Potsdam Institute for Climate Impact Research, in Potsdam, Germany, told Reuters.
None of the nearly 200 governments to sign the Paris Accords are on track to meet its pledges.
Global emissions of carbon dioxide, the main greenhouse gas given off by burning fossil fuels, rose last year after a three-year plateau.
Professor John Church, of the Climate Change Research Centre at the University of New South Wales, who was not involved in the study, said 100 million people now live within one metre of the high tide mark.
‘With the order of 100 million people living within 1 m of current high tide level, the world is vulnerable to rising sea levels,’ he said in a statement.
‘More people are moving to live within the coastal zone, increasing the vulnerable population and infrastructure.
‘Adaptation to sea level rise will be essential.’
