Cambios del nivel del mar

Abstract

The sea level changes continuously due to global factors that act at variable speed and periodicity. Local factors make the concept of global sea level curves unrealistic, although all of them follow similar patterns. The periodic variation of orbital parameters of the Earth’s orbit is the main forcing factor of the more conspicuous climate changes (theory of Milankovitch), which give rise to changes in sea level. Using the Oxygen isotopic curves as a proxy of sea level for the last four million years (My), we can see that the dominant forcing factor shifted from precession to inclination and, in the last million years, to eccentricity of the orbit. These periodicities are superimposed and modulate each other producing relatively complex curves. In addition, there are pervasive shorter-lived, smaller magnitude changes in sea level, known as suborbital changes, which have been recognized for, at least, 5 My. They are independent of the dominant forcing factor. In recent times anthropic addition of greenhouse gases has interfered severely with the natural system. Ideas put forward by the International Panel for Climate Change (IPCC) concerning sea level changes are presented, in order to provide a better understanding of the problems involved.