Sea levels may rise much higher than previously thought, as a new study on fossil corals has found that warmer climes in the past promoted dramatic melting of polar ice.

Researchers built an extensive database by compiling age and elevation data of fossil corals that live near the sea surface, using a model to factor in the physics of how changing masses of ice sheets would affect regional sea level at the various fossil coral sites, a statement from the Australian National University said.

“In this way, we were able to account for the geographic variability in sea level observations from this time period and compute the highest point that average global sea level attained. The observations from the corals confirmed the sea level patterns that we predicted using the geophysical model,” Andrea Dutton, who is currently based at University of Florida, said.

The research concluded that sea level during the last interglacial period peaked at 5.5 to 9 metres above present sea level.

“Sea level change — in the past, present, and future — is geographically variable and we must consider this variability to infer what the average global sea level was doing in the past. We observed 5.5 to 9 metres of sea level rise,” said Dutton.

“To explain that, polar ice sheets must have melted: part of Greenland, most of the West Antarctic ice sheet, and perhaps some of the East Antarctic ice sheet. Our findings have important implications for future sea levels,” added Dutton.

“For the period we studied, the poles were probably only three to five degrees warmer than present. That amount of polar warming is well within what we are predicted to reach this century. This implies that the polar ice sheets may be very sensitive to small increases in temperature,” the statement quoted Dutton as saying.

“This magnitude of sea level rise — up to 9 metres — is obviously not going to happen overnight. But it could happen within a few centuries, so it is important to consider the long-term commitment we make in terms of total sea level rise when we talk about various targets and emission scenarios, concluded Dutton.

Andrea Dutton, formerly of the Australian National University College of Physical and Mathematical Sciences, teamed up with Kurt Lambeck, ANU professor to analyse fossil corals around the world from the last interglacial period, 125,000 years ago.

Keywords: global warming