Global Sea Level Rise Gravely Underestimated, Tripled since Early 1990s, Study Finds

Until 2007, rate of decrease in Greenland’s ice sheet height in centimeters per year. Photo: Wikipedia

  • Rise of global sea level resulting from global warming has been largely underestimated, according to a new study.
  • It has found that global sea level rise accelerated threefold between 1993 and 2012 – from 1.1 to 3.1 millimeters per year.
  • Study demonstrates that sea level rise is a serious threat, its lead author says.
  • It has shown that that the impact of Greenland and Antarctica’s ice sheets melting rapidly in recent decades has been greater than expected.
  • Findings bode trouble for coastal areas around the world.

Against the backdrop of global warming, the rise of the global sea level has been drastically underestimated, and has in fact tripled since the early 1990s, according to the findings of a new study.

Encroaching oceans have been pinpointed as one of the most damaging impacts of global warming.

Trapped greenhouse gases in the Earth’s atmosphere cause temperatures to increase, seawater warms and expands, and ice melts into the sea, resulting in a rise in the water level.

The result has been a calamity in which some coastal cities and low-lying islands are already being inundated.

‘Much Larger Acceleration’

The study revealing the grave nature of the global sea level rise problem is entitled “Reassessment of 20th Century Global Mean Sea Level Rise".

It has been published in the scientific journal Proceedings of the National Academy of Sciences (PNAS) of the United States of America.

“The acceleration in global mean sea-level rise is much larger than previously thought,” Soenke Dangendorf, the paper’s lead author, has told German state-run international news outlet Deutsche Welle.

“It underlines that sea level rise is a serious threat,” emphasizes the researcher from the University of Siegen in Germany.

Dangendorf worked with an international team of scientists from Spain, France, Norway, and the Netherlands.

They discovered while for much of the 20th century global sea level rose relatively slowly – by about 1.1 millimeters (0.04 inches), annually, that changed in a significant way in the early 1990s.

According to the study’s findings, between 1993 and 2012, sea levels rose at a much faster rate of 3.1 millimeters annually.

The study by Dangendorf and his colleagues is not the first to highlight that the rate of sea level rise is speeding up.

However, its findings suggest a significantly faster rate of increase than past research.

Ice Sheets over Glaciers

Dangendorf points out that one of the reasons for the recent acceleration has been the melting of ice sheets over recent decades.

“We have always had a great uncertainty over the contribution of the large ice sheets, which store 100 times more sea level equivalents than glaciers,” the researcher states.

The new research demonstrates that the impact of Greenland and Antarctica’s ice sheets melting rapidly over the last 20 or 30 years has been greater than expected.

What is more, it is likely to result in a greater future sea level rise than previously predicted, a forecast which might bode a lot of trouble for coastal areas around the world.

“Cities like Miami, Florida, which are already impacted by sea level rise will experience much more coastal flooding and much stronger storm surges than have been observed so far,” Dangendorf says.

Dangendorf and his team took historical data from tide gauges, which were used to measure coastal changes until 1992, and compared them to more precise satellite information gathered in subsequent decades.

Since satellites capable of monitoring sea levels were only launched in the early 1990s, in order to make the data as consistent as possible, the researchers adjusted the earlier results from tide gauges to reflect different factors that may affect sea-level rise in a given local region.

It is widely acknowledged that it is hard to predict the scope of global sea level rise resulting from global warming.

Projections published in the Fifth Assessment Report by the United Nations’ Intergovernmental Panel on Climate Change warned of an increase of around 30 centimeters (1 foot) to 1 meter (more than three feet) by 2100.

The World Meteorological Organization (WMO), a UN body, recently announced that a new record temperature has been measured for the Antarctica.

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