This implies relative sea level change is primarily a localized phenomenon related to subsidence or post-glacial rebound [land height changes] rather than melting ice or steric sea level changes [thermal expansion from warming].
Evidence for a differential sea level rise between hemispheres over the 20th century
Guy Wöppelmann1,*, Marta Marcos2, Alvaro Santamaría-Gómez1,3, Belén Martín-Míguez4,
Marie-Noëlle Bouin5, Médéric Gravelle1
Tide gauge records are the primary source of sea level information over multi-decadal to century timescales. A critical issue in using this type of data to determine global climate-related contributions to sea level change concerns the vertical motion of the land upon which the gauges are grounded. Here we use observations from the Global Positioning System for the correction of this vertical land motion. As a result, the spatial coherence in the rates of sea level change during the 20th century is highlighted at the local and the regional scales, ultimately revealing a clearly distinct behavior between the northern and the southern hemispheres with values of 2.0 mm/year and 1.1 mm/year, respectively. Our findings challenge the widely accepted value of global sea level rise for the 20th century.