Epistemic uncertainty in the kinematics of global mean sea-level rise since 1993 and its dire consequences

Abstract

ABSTRACTRecent studies reported an ambiguous global sea level acceleration during the satellite altimetry (SA) era (1993–2017). New SA data created an opportunity to resolve this issue. In this study, two competing kinematic models to represent global mean sea level anomalies are compared. The first model consists of an initial velocity and uniform acceleration. The second model replaces the initial velocity and acceleration with a trend and a representation of a long periodic lunar subharmonic of period 55.8 y, which is determined to be statistically significant at globally distributed tide gauge records. The models also include parameters for the periodic effects of lunisolar origin with periods 18.6 y and 11.1 y annual, and biannual variations in 10-day average of globally SA measurements during 1993–2022. Generalized least squares solutions yielded updated statistically significant estimates for all the model parameters and their statistics for both models. However, the outcome failed to resolve the ambiguity of uniform acceleration in global mean sea level confounded with the long periodic lunar subharmonic of period 55.8 y during this period. This epistemic uncertainty will have a dire impact on climate change risk assessments as demonstrated through the prospective comparison of both kinematic models.

Keywords

• Satellite altimetry
• tide gauge
• GMSL acceleration
• lunar subharmonics
• climate change