New Study Details Alarming Acceleration In Sea Level Rise

http://thinkprogress.org/climate/2014/10/15/3579893/sea-level-rise-faster-6000-years/

by Ari Phillips Posted on October 15, 2014

Melting polar and glacial ice and thermally expanding ocean water have accelerated sea level rise to the highest rate in at least 6,000 years according to a new study in the Proceedings of the National Academy of Sciences. Using data from ancient sediment samples from around Asia and Australia, researchers looked back at 35,000 years of sea level history, finding that over the last 6,000 years little changed — until 150 years ago.

Using indicators of the era’s sea level, like location of ancient tree roots and mollusks, the scientists’ reconstruction found no evidence that sea levels fluctuated by more than about eight inches during the relatively stable period that lasted between 6,000 and about 150 years ago. Then, since the onset of the industrial revolution, sea levels have already risen by about that same amount. The scientists attribute climate change and rising temperatures that cause polar and glacial ice to melt and thermal expansion of the oceans as the primary cause for the rapid and extremely unusual increase in sea level. Water expands as it warms, and there is enough warming water in the ocean to cause a significant impact on sea levels.

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We know from the last interglacial period that when temperatures were several degrees warmer than today there was a lot more water in the oceans, with levels around four to five meters higher than today,” lead author Kurt Lambeck, a professor at Australian National University, told the Guardian. “The question is how fast that change occurs when you increase temperatures.”

Lambeck said that the sea level increase of the past 100 years is “beyond dispute” and that “what we’ve seen is unusual, certainly unprecedented for these interglacial periods.” He also said this is a process that can’t just be turned off and that “sea levels will continue to rise for some centuries to come even if we keep carbon emissions at present day levels.”

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We know from the last interglacial period that when temperatures were several degrees warmer than today there was a lot more water in the oceans, with levels around four to five meters higher than today,” lead author Kurt Lambeck, a professor at Australian National University, told the Guardian. “The question is how fast that change occurs when you increase temperatures.”

Lambeck said that the sea level increase of the past 100 years is “beyond dispute” and that “what we’ve seen is unusual, certainly unprecedented for these interglacial periods.” He also said this is a process that can’t just be turned off and that “sea levels will continue to rise for some centuries to come even if we keep carbon emissions at present day levels.”