Sea level is rising at an alarming rate, say scientists

Posted February 16, 2018

The acceleration is driven mainly by more and more of the ice in Greenland and Antarctica melting away, according to the scientists, who are warning that more data needs to be gathered to prepare for the effects of sea level rise.

However, the team suspected these estimates could double, saying: "The observed acceleration will more than double the amount of sea-level rise by 2100 compared with the current rate of sea-level rise continuing unchanged", the study read. "This is nearly certainly a conservative estimate", said lead author Steve Nerem, noting that their estimate does not include any unforeseeable factors that could bring a major change in sea level.

As Steve Nerem, Associate Director of the Colorado Center for Astrodynamics Research at the University of Colorado Boulder and one of the study's authors, told ThinkProgress, the study's conclusions are based on the assumption that "the ice sheets [will] just continue going along at what they've been doing for the last 25 years".

"This estimate is useful for understanding how the Earth is responding to warming, and thus better informs us of how it might change in the future", write the researchers in their published paper.

Of the 3 inches (7.5 centimetres) of sea level rise in the past quarter century, about 55% is from warmer water expanding, and the rest is from melting ice. Second is the melting of ice at poles that adds more and more water to the seas.

"The acceleration predicted by the models has now been detected directly from the observations".

Using satellite data rather than tide-gauge data that is normally used to measure sea levels allows for more precise estimates of global sea level since it provides measurements of the open ocean. In addition, global sea level can fluctuate due to climate patterns such as El Niños and La Niñas (the opposing phases of the El Niño Southern Oscillation, or ENSO) which influence ocean temperature and global precipitation patterns.

Outside scientists said even small changes in sea levels can lead to flooding and erosion.

The warming of oceans and the melting of ice sheet and glaciers, particularly in Antarctica and Greenland, have contributed to the hastening sea level rise.

The study highlighted that if the oceans keep on to growing at this pace, sea level will rise 65cm by 2100.

The researchers used data from other scientific missions such as GRACE, the Gravity Recovery and Climate Experiment, to determine what was causing the rate to accelerate.

They also cross-referenced tide gauge and satellite data to correct anomalies in the TOPEX satellite record proposed in an earlier research co-authored by John Church of the Climate Change Research Centre at the University of New South Wales (UNSW). Lastly, they hope that this global data can be used at a local level, so that satellite data can be used to predict what will happen in your backyard.

Although this research is impactful, the authors consider their findings to be just a first step.

This new research shows that, rising sea waters could be climbing up around half an inch a year by 2100.

Professor Nerem said analysis of tidal gauge records and decadal changes in satellite data in the past had indicated global mean sea level rise was accelerating, but it had been hard to pin down a number. However, detecting acceleration - even over a long period of time - is hard.