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Study links fastest sea-level rise in 2,000 years to increasing global temperatures

The rate of sea level rise along the US Atlantic coast is greater now than at any time in the past 2,000 years and shows a consistent link between changes in global mean surface temperature and sea level, according to a new open-access study published in the journal Proceedings of the National Academy of Sciences (PNAS).

The research, funded by the National Science Foundation (NSF), was conducted by Andrew Kemp, Yale University; Benjamin Horton, University of Pennsylvania; Jeffrey Donnelly, Woods Hole Oceanographic Institution; Michael Mann, Pennsylvania State University; Martin Vermeer, Aalto University School of Engineering, Finland; and Stefan Rahmstorf, Potsdam Institute for Climate Impact Research, Germany.

Kemp and colleagues developed the first continuous sea-level reconstruction for the past 2,000 years, and compared variations in global temperature to changes in sea level over that time period. The team found that sea level was relatively stable from 200 BC to 1,000 AD. In the 11th century, sea level rose by about half a millimeter each year for 400 years, linked with a warm climate period known as the Medieval Climate Anomaly. Then there was a second period of stable sea level during a cooler period called the Little Ice Age. It persisted until the late 19th century.

Since the late 19th century, sea level has risen by more than 2 millimeters per year on average, the steepest rate for more than 2,100 years.

To reconstruct sea level, the scientists used microfossils called foraminifera preserved in sediment cores extracted from coastal salt marshes in North Carolina. The age of the cores was estimated using radiocarbon dating and other techniques.

To test the validity of their approach, the team compared its reconstructions with tide-gauge measurements from North Carolina for the past 80 years, and global tide-gauge records for the past 300 years. A second reconstruction from Massachusetts confirmed their findings.

The records were corrected for contributions to sea-level rise made by vertical land movements.

The reconstructed changes in sea level over the past millennium are consistent with past global temperatures, the researchers say, and can be determined using a model relating the rate of sea level rise to global temperature.

Support for the research also was provided by the National Oceanic and Atmospheric Administration, United States Geological Survey, the Academy of Finland, the European Science Foundation through European Cooperation in Science and Technology and the University of Pennsylvania.

Resources

  • Andrew C. Kemp, Benjamin P. Horton, Jeffrey P. Donnelly, Michael E. Mann, Martin Vermeer, and Stefan Rahmstorf (2011) Climate related sea-level variations over the past two millennia. PNAS 2011 doi: 10.1073/pnas.1015619108

Comments

HarveyD

Not enough to convince the deniers.

sheckyvegas

WE ALL GONNA DIE! SAVE ME, JOHN CUSACK!

...or Joan Rivers. Whoever...

Stan Peterson

I would rather believe Dr. Axel-Mourner, a renowned sea-level expert and previous Chairman of the IPCC committee concerned with sea-level rises, until he broke with the rigged IPCC. It occurred when laymen fools altered his committee's scientific findings, and rewrote them to create a rising sealevel theme, exactly opposite to their findings.

Another phony study by the purveyors of Mann-made hockey shticks! As I recall Stargazer James Hansen, turned self-appointed climatologist and sea-level expert, testified before Congress that Manhattan would be flooded by now, back in 1988.

Oops. When you stick around long enough, your false Profit-cies rise up to bite you in the arse.

ai_vin

Actually Harvey, this wouldn't be enough to convince me. Reconstructions always have a degree of uncertainty and this study reconstructed sea level using microfossils preserved in sediment cores extracted from coastal salt marshes in JUST North Carolina. That means it could just be from local effects. I would need to see reconstructions with data collected from multiple sites so we could create a map of sea level changes.

And lest the deniers think I've converted to their religion - Stan, please cite your source for your claims.

ai_vin

Let me clarify that: A map of present-day global sea levels could be made from satellite data and maps of recent (recent being relative) sea level changes could also be made from old data. My issue is with the pre tide-gauge reconstructions; with limited sites they can only be used to test recent changes.

Aaron Turpen

So.. since the end of the Little Ice Age, the Holocene has continued its upward trend in temperature and sea level rise at a steady pace.

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