Melting ice sheets in Greenland, Antarctica increasing pace of sea level rise

Sea Level soaring accelerates

"That assumes that there is no rapid, dynamical change in the ice sheet", he said, referring to his projected rates of rising sea levels.

"When you try to extrapolate numbers like this you're assuming sea level change and acceleration are going to be the same as they've been over the past 25 years".

Melting ice sheets in Antarctica and Greenland are responsible for accelerating sea level rise over the past 25 years, according to a study published February 12.

These increases were measured using satellite altimeter measurements since 1992, including the Topex/Poseidon, Jason-1, Jason-2 and Jason-3 satellite missions, which have been jointly managed by multiple agencies, including NASA, Centre national d'etudes spatiales (CNES), European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the National Oceanic and Atmospheric Administration (NOAA).

It also shows how climate models are important in interpreting satellite records, such as in this study where it allows the study group to estimate the background effects of the 1991 eruption of Mount Pinatubo on global sea level.

"This is nearly certainly a conservative estimate", Nerem said. The acceleration rate uncovered in this study would more than double sea level rise by 2100 in comparison to steady sea level rise without acceleration.

The figure calculated by Professor Nerem's study is similar to those predicted by the Intergovernmental Panel on Climate Charge (IPCC) under its upper 8.5 scenario, which assumes increasing greenhouse gas emissions. The report read: "It is very likely that in the 21st century and beyond, sea level change will have a strong regional pattern, with some places experiencing significant deviations of local and regional sea level change from the global mean change".

"This is a game-changer as far as the climate change discussion goes."
A second part of the study used satellite data tracking tiny fluctuations in gravity due toice mass loss to trace the acceleration back to melting ice in Greenland and Antarctica. "I mean, we still have other measurements but those measurements have a lot bigger errors, it's a lot harder to tell what's going on, and so it's critical to have the satellite measurements and really I think everybody needs to put in a plug for the satellites so that NASA continues to give us these observations". "The ice sheets are contributing measurably to this acceleration", he said.

Satellite data is vital to this research, said Nerem.

Now the researchers want to apply the same techniques to a longer period of time, as well as adding in extra measurements from local records, which should help communities prepare for the worst. Provided the huge alterations we are observing in the ice sheets today, that is not likely.

One of the important tools that will enable them to do that will be the launch of a new GRACE satellite in April. When it comes to that lowest curve, said Dutton, "what this paper is saying is we know that that's not reasonable".

Want more science from across the ABC?




Other news