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

Abstract

Two of the most important topics in Sea Level Science are addressed in this paper. One is concerned with the evidence for the apparent acceleration in the rate of global sea level change between the 19 th and 20 th centuries and, thereby, with the question of whether the 20 th century sea level rise was a consequence of an accelerated climate change of anthropogenic origin. An acceleration is indeed observed in both tide gauge and saltmarsh data at different locations around the world, yielding quadratic coefficients 'c' of order 0.005 mm/year 2 , and with the most rapid changes of rate of sea level rise occurring around the end of the 19 th century. The second topic refers to whether there is evidence that extreme sea levels have increased in recent decades at rates significantly different from those in mean levels. Recent results, which suggest that at most locations rates of change of extreme and mean sea levels are comparable, are presented. In addition, a short review is given of recent work on extreme sea levels by other authors. This body of work, which is focused primarily on Europe and the Mediterranean, also tends to support mean and extreme sea levels changing at similar rates at most locations.

How historical information can improve estimation and prediction of extreme coastal water levels: application to the Xynthia event at La Rochelle (France)

“…However, extreme WL exhibit long-term trends that cannot be ignored. Over the 20th century, these trends have been shown to be similar to those of mean sea level (MSL) at most locations worldwide (Woodworth et al, 2011). To account for this behaviour in the systematic data set, the linear trend is calculated for the entire tide-gauge record and removed from the data.…”

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].…”

Changes in extreme regional sea surface height due to an abrupt weakening of the Atlantic meridional overturning circulation

“…Changes in regional extreme sea levels have been related mostly to changes in the mean sea level, storm surges and wind set-up (Marcos et al, 2009;Lowe et al, 2010;Woodworth et al, 2011b). However, in a recent study of water levels from tide gauges, Merrifield et al (2013) identified, apart from tidal and seasonal components, non-tidal residual components as an important contribution to annual maximum water levels.…”