On the evolution of global ocean tides

TL;DR

This paper investigates the long-term evolution of ocean tides using Laplace's tidal theory, revealing how tidal resonance influences tide heights over geological timescales and impacts Earth's rotational dynamics.

Contribution

It applies tidal resonance theory to Earth's geologic history, providing new insights into the evolution of tide heights and Earth's rotation over millions of years.

Findings

Tide heights were about 5 meters in the past.

Tides are less than 1 meter today.

Tide heights are projected to reach 8 meters in the future.

Abstract

We apply Laplace's tidal theory to the evolution of lunar and solar tides on the geologic timescale of Earth's rotation and focus on the tidal resonance. We study the global tide in the mid-ocean far away from continents. On the short timescale, a linear relationship of tidal height and Earth's rotation is obtained. On the long timescale, the tide is less than 1 metre at present but it was 5 metres in the past and will reach 8 metres in the future because of resonances of tidal wave and Earth's rotation. We conclude that the Earth-Moon orbital separation and the slowdown of Earth's rotation are faster than expected before.