Coastal flooding; myths and facts in past, present and future sea level changes
by
Nils-Axel Mörner
Paleogeophyscs & Geodynamics

Flooding of coastal lowlands and islands has the potential of generating “catastrophes”. The boundary between myths and reality is vague for the past, and, as a matter of fact, even for future predictions. The postglacial rise in sea level undoubtedly implied flooding of vast areas. The smaller-scale oscillations in sea level in during the Middle and Late Holocene affected coastal conditions, too. Tsunamis and storms may lead to instantaneous destruction.

In the last 5000 years, global mean sea level has been dominated by the redistribution of water masses over the globe. In the last 300 years, sea level has been oscillation close to the present with peak rates in the period 1890-1930. Between 1930 and 1950, sea fell. The late 20th century lack any sign of acceleration. Satellite altimetry indicates virtually no changes in the last decade. Therefore, observationally based predictions of future sea level in the year 2100 will give a value of +10 +10 cm (or +5 +15 cm), by this discarding model out-puts by IPCC as well as global loading models. This implies that there is no fear of any massive future flooding as claimed in most global warming scenarios.

Novel prospects for the Maldives do not include a condemnation to future flooding. The people of the Maldives have, in the past, survived a higher sea level of about 50–60 cm. The present trend lack signs of a sea level rise. On the contrary there is firm morphological evidence of a significant sea level fall in the last 30 years. This sea level fall is likely to be the effect of increased evaporation and an intensification of the NE-monsoon over the central Indian Ocean.

Date received: February 28, 2002