Sea levels will rise much faster than previously thought leading to the flooding of many cities unless major steps are taken to curb carbon dioxide emissions this century, scientists warn today. They say that the planet will see a huge retreat of ice sheets once a threshold of warming is crossed. That would produce a catastrophic sea level rise of at least 20ft, drowning the centre of London and displacing millions in Britain alone. Temperatures are rising on track to melt the Greenland and Antarctic ice sheets sooner than thought, triggering the 20ft sea rise by 2600 and inundating heavily-populated coastal areas, including much of the Netherlands. Two international teams report today in the journal Science that Arctic summers by 2100 may be as warm or warmer than they were nearly 130,000 years ago, when sea levels eventually rose up to 20ft higher than today. Such a rise had been thought to be at least 1,000 years away. The work is ‘fascinating and scary at the same time’, said Prof Michael Oppenheimer of Princeton University. ‘We should take this as a serious warning sign.’ Profs Bette Otto-Bliesner and Jonathan Overpeck report the findings with colleagues […]