Sea-Level Changes and Earth's Rate of Rotation
Keywords:Sea-level change, Earth's rate of rotation, length of day, global sea level, world ocean level
The mean global sea-level changes today and in the near past (and by that also in the near future) have not been able to establish in a satisfactory way, either by mathematical treatments of tide-gauge data, by geophysical modelling or by geological considerations. We here propose 8 new means of studying global mean sea level; viz. changes in the Earth's rate of rotation (the variations in the length of the day). Any global change in sea level must be seen in the Earth's rate of rotation as this is a direct function of any change in its radius. The decadal changes in rotation swing around a sinusoidal, about century long, mean trend that might represent such a global sea level factor. This factor is consistent with a sea level rise in the order of 11 cm in 100 years (which is a fraction of often claimed values for the hypothetical greenhouse generated sea level rise today and in the near future). This can be taken as a measure of the maximum possible rise in global mean sea level during the last 150 years. It can, however, not be excluded that it represents the interchange of angular momentum with a more slowly moving oceanic intermediate or bottom water currents. If so, there would be no significant global rise in mean sea level during the last 150 years. The recording of LOD changes is a powerful tool for monitoring and predicting global sea level changes.