Stefan Rahmstorf, from the Potsdam Institute for Climate Impact Research, said that while the results for the scenario with climate mitigation suggest a good chance of limiting future sea-level rise to one meter, the high emissions scenario would threaten the survival of some coastal cities and low-lying islands.
He said that from a risk management perspective, projections of future sea-level rise are of major importance for coastal planning, and for weighing options of different levels of ambition in reducing greenhouse-gas emissions.
Projecting sea-level rise, however, comes with large uncertainties, since the physical processes causing the rise are complex.
They include the expansion of ocean water as it warms, the melting of mountain glaciers and ice caps and of the two large ice sheets in Greenland and Antarctica, and the pumping of ground water for irrigation purposes.
Lead author Benjamin Horton from the Institute of Marine and Coastal Sciences at Rutgers University in New Jersey, said that it this therefore useful to know what the larger community of sea-level experts thinks, and we make this transparent to the public.
The survey finds most experts expecting a higher rise than the latest IPCC projections of 28-98 centimeters by the year 2100. Two thirds (65 percent) of the respondents gave a higher value than the IPCC for the upper end of this range, confirming that IPCC reports tend to be conservative in their assessment.
The experts were also asked for a "high-end" estimate below which they expect sea-level to stay with 95 percent certainty until the year 2100. This high-end value is relevant for coastal planning. For unmitigated emissions, half of the experts (51 percent) gave 1.5 meters or more and a quarter (27 percent) 2 meters or more. The high-end value in the year 2300 was given as 4.0 meters or higher by the majority of experts (58 percent).