An Anomalous Recent Acceleration of Global Sea Level Rise

Abstract

Tide gauge data are used to estimate trends in global sea level for the period from 1955 to 2007. Linear trends over 15-yr segments are computed for each tide gauge record, averaged over latitude bands, and combined to form an area-weighted global mean trend. The uncertainty of the global trend is specified as a sampling error plus a random vertical land motion component, but land motion corrections do not change the results. The average global sea level trend for the time segments centered on 1962-90 is 1.5 6 0.5 mm yr 21 (standard error), in agreement with previous estimates of late twentieth-century sea level rise. After 1990, the global trend increases to the most recent rate of 3.2 6 0.4 mm yr 21 , matching estimates obtained from satellite altimetry. The acceleration is distinct from decadal variations in global sea level that have been reported in previous studies. Increased rates in the tropical and southern oceans primarily account for the acceleration. The timing of the global acceleration corresponds to similar sea level trend changes associated with upper ocean heat content and ice melt.

Evidence for Century-Timescale Acceleration in Mean Sea Levels and for Recent Changes in Extreme Sea Levels

“…Figure 2 indicates this recent acceleration in the Falkland Islands. These larger rates over the last one or two decades are consistent with the picture of a general recent global acceleration with particular contributions from the tropics and from higher southern latitudes (Merrifield et al 2009a). Other recent studies of southern hemisphere sea level change that have made use of sections of historical information include those of Watson et al (2010) and Testut et al (2006), although these investigations are limited to study of 20 th century changes.…”

Recent Change—Sea Level and Wind Waves

“…Long Baltic Sea sea level records from different sources (not only PSMSL) have been used in a wide range of research papers for global sea level studies (e.g. Douglas 1992; Nakada and Inoue 2005;Jevrejeva et al 2006Jevrejeva et al , 2008Merrifield et al 2009;Woodworth et al 2009;Church and White 2011;Houston and Dean 2011) and regional Baltic Sea studies (e.g. Andersson 2002;Omstedt et al 2004;Chen and Omstedt 2005;Jevrejeva et al 2006; (Table 9.1).…”

Nonlinear subsidence at Fremantle, a long‐recording tide gauge in the Southern Hemisphere

“…For example, the vertical stability of the Australian continent and its suitability as a datum for MSL observations has been debated for decades [e.g., Emery, 1986, 1988;Bryant et al, 1988;Amin, 1993;Belperio, 1993;Feng et al, 2004;Sandiford, 2007;Moucha et al, 2008;Watson, 2011;Lewis et al, 2012]. Hay et al [2015], Haigh et al [2014], Hogarth [2014], Holgate and Woodworth [2004], Jevrejeva et al [2014], Jorda [2014], Merrifield et al [2009], Olivieri and Spada [2013], Watson et al [2015], and Woodworth et al [2009Woodworth et al [ , 2011; those that claim deceleration include Boretti [2012], Boretti and Watson [2012], Parker et al [2013], and Watson [2011]; those that claim neither include Schr€ oter [2010, 2014].…”