That sinking feeling
CLIMATES and sea-level changes are intimately related. An increase in mean global temperature is directly proportionate to the sea level, the circulation patterns of ocean waters. This summarises the central theme of the book under review, an excellent synthesis of 26 published papers which address the complex phenomenon of climate change, associated sea level rise, and their implications for environmental and societal systems.
There is definite chronological and geological evidence that shows globally coherent connections between climates and sea level changes. During the last interglacial period --- 18,000 BP (before present) -- global temperatures were 4oC-5oC colder and the sea level 100m lower. The increase in global mean temperature led to the melting of the ice sheets covering large parts of the Northern hemisphere. Over the past 1,000 years, the sea level has been rising by about 0.1-0.2mm per year. The world's remaining ice cover contains enough water to raise the present sea level by over 75m.
The earth is a complex, dynamic and interactive system and predictions of climate change and associated sea level rise have to be viewed in terms of the geological, biological and hydrological processes. It is not the prospect of climate change but the magnitude and the potential rates of climate change induced by greenhouse gases which is of immediate concern.
There still exist lacunae in our understanding of the processes involved. A major problem is the measurement of change in the sea level which uses biased tide gauge data gathered from tidal stations located mostly in the the Northern Hemisphere. The raw data is severely limited by the effects of vertical land movements and anthropogenic effects which have a wide local to regional variation.
The contributions in this volume cover the practical problems involved in the collection and interpretation of sea level rise based on tide gauge records, projections of future sea level rise, contributions to sea level change from small glaciers and major icesheets, and impact assessment studies of sea level rise and storm surges on low lying areas. The authors have critically examined the methods and principles involved and emphasised on the urgent need for more specific and complete data.
Fairly technical in nature, this book would be of great interest to researchers working in the fields of climatology, oceanography, meteorology, glaciology and geology.