Gauging elevation

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Geophys. Res. Lett. 36, L12607 (2009)

Credit: © ISTOCKPHOTO/MIKE BENTLEY

A new study verifies the merit of using Global Positioning System (GPS) data to reduce uncertainty in measuring sea level rise. Most estimates of sea level rise over the past century are based on long tide-gauge records, which must be corrected for the vertical displacement of land from sedimentation and other causes. In the past, a variety of correction methods have been tried, yielding estimates with a range of one to three millimetres per year.

Guy Wöppelmann of the University of La Rochelle, France, and colleagues previously proposed that GPS data could potentially be used as a universal correction method for tide-gauge data. Now they have used GPS data collected from 227 global stations over a ten-year period to adjust global estimates of sea level rise. Their modified estimate of global mean sea level rise over the last century — 1.61 millimetres per year — is in good agreement with the most recent estimates made from altimetry and gravity observations. The scatter associated with regionally averaged trends is significantly reduced, however, when changes in land elevation are taken into account.

The authors say that their geodetic approach can be used to considerably improve estimates of sea level rise.

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Armstrong, A. Gauging elevation. Nature Clim Change 1, 87 (2009) doi:10.1038/climate.2009.68

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