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Lookup NU author(s): Dr Christopher Watson,
Professor Matt King
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The rate of global mean sea-level (GMSL) rise has been suggested to be lower for the past decade compared with the preceding decade as a result of natural variability(1), with an average rate of rise since 1993 of +3.2 +/- 0.4mm yr(-1) (refs 2,3). However, satellite-based GMSL estimates do not include an allowance for potential instrumental drifts (bias drift(4,5)). Here, we report improved bias drift estimates for individual altimeter missions from a refined estimation approach that incorporates new Global Positioning System(GPS) estimates of vertical land movement (VLM). In contrast to previous results (for example, refs 6,7), we identify significant non-zero systematic drifts that are satellite-specific, most notably affecting the first 6 years of the GMSL record. Applying the bias drift corrections has two implications. First, the GMSL rate (1993 to mid-2014) is systematically reduced to between +2.6 +/- 0.4mm yr(-1) and +2.9 +/- 0.4mm yr(-1), depending on the choice of VLM applied. These rates are in closer agreement with the rate derived from the sum of the observed contributions(2), GMSL estimated from a comprehensive network of tide gauges with GPS-based VLM applied (updated from ref. 8) and reprocessed ERS-2/Envisat altimetry(9). Second, in contrast to the previously reported slowing in the rate during the past two decades(1), our corrected GMSL data set indicates an acceleration in sea-level rise (independent of the VLM used), which is of opposite sign to previous estimates and comparable to the accelerated loss of ice from Greenland and to recent projections(2,10), and larger than the twentieth-century acceleration(2,8,10).
Author(s): Watson CS, White NJ, Church JA, King MA, Burgette RJ, Legresy B
Publication type: Article
Publication status: Published
Journal: Nature Climate Change
Print publication date: 01/06/2015
Online publication date: 11/05/2015
Acceptance date: 02/04/2015
ISSN (print): 1758-678X
ISSN (electronic): 1758-6798
Publisher: Nature Publishing Group
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