Thursday, May 24, 2012

Finding fingerprints in sea level rise

Terra Daily via SPX: It was used to help Apollo astronauts navigate in space, and has since been applied to problems as diverse as economics and weather forecasting, but Harvard scientists are now using a powerful statistical tool to not only track sea level rise over time, but to determine where the water causing the rise is coming from.

As described in the Proceedings of the National Academy of Sciences (PNAS), graduate students Eric Morrow and Carling Hay demonstrate the use of a statistical tool called a Kalman smoother to identify "sea level fingerprints" - tell-tale variations in sea level rise - in a synthetic data set. Using those fingerprints, scientists can determine where glacial melting is occurring.

"The goal was to establish a rigorous and precise method for extracting those fingerprints from this very noisy signal," Professor of Geophysics Jerry Mitrovica, who oversaw the research, said. "What Carling and Eric have come up with is very elegant and it provides a powerful method for detecting the fingerprints. In my view everyone is soon going to be using this method."

At the heart of the new technique is the idea, first proposed by Mitrovica and others more than a decade ago, that variability in sea level changes amount to a "fingerprint" researchers can use to identify the source of water pouring into the oceans.

With the public unconvinced about the effects of climate change, Mitrovica proposed the fingerprint idea as a way to refute the argument that melting ice sheets would cause a uniform sea level rise, he said, "like what you see when you turn on the tap in the bathtub - it all goes up uniformly." Rather than a uniform rise in sea level, skeptics pointed to records that showed levels rising in some areas and dropping in others as evidence that man-made climate change was a myth....

Photo by PD, Wikimedia Commons, public domain

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