Earth’s Constant Mean Elevation: Implication for Long-Term Sea Level Controlled by Oceanic Lithosphere Dynamics in a Pitman World

Abstract

AbstractOn a spherical Earth, the mean elevation (approximately −2440 m) would be everywhere at a mean Earth radius from the center. This directly links an elevation at the surface to physical dimensions of Earth, including surface area and volume, which are at most very slowly evolving components of the Earth system. Earth’s mean elevation thus provides a framework within which to consider changes in height of Earth’s solid surface as a function of time. In this article, the focus will be on long-term, nonglacially controlled sea level. Long-term sea level has long been argued to be largely controlled by changes in ocean basin volume related to changes in the area-age distribution of oceanic lithosphere. As generally modeled by Walter Pitman and subsequent workers, the age-depth relationship of oceanic lithosphere, including both the ridge depth and the coefficients describing the age-depth relationship, are assumed constant. This article examines the consequences of adhering to these assumptions when pl...