Sea level rise may be higher in Bangladesh than predicted

The Daily Star, BSS, Dhaka, 30 July 2010

With the current level of continuation of human effects on climate, coasts of Bangladesh and India might experience higher sea level rise compared to mean level predicted for the planet. Researchers from the University of Colorado of the United States found this in their new study, published in Nature Geoscience this week, leading science and development network SciDev Net said.

The same rise may occur in the mid Indian Ocean islands Mascarenhas archipelago, Indonesian and Sumatran coasts, but not in the Maldives, east coast of Kenya and African Tanzania. According to the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC) sea level on an average would rise by between 190mm and 590mm by the end of this century.

The study found that global sea level has risen during the past decades as a result of thermal expansion of the ocean and freshwater addition from melting continental ice. However, the level of rise is not globally uniform as regional sea levels can be affected by changes in atmospheric circulation and oceanic circulation. The study revealed that sea level has decreased substantially in the south tropical Indian Ocean whereas it has increased elsewhere because of the atmospheric and oceanic circulation.

On the basis of all-season records, there is no significant sea-level rise around the Maldives which might only experience substantial sea-rises during the winter monsoon, which might have significant impact on the country because of its low elevation, the study report said.

The study revealed that Zanzibar, a small African country in the Indian Ocean, could experience fall in sea rise, while Seychelles and the east coasts of Kenya and African Tanzania may see little or no rise. The variations in sea-level rises at different parts of the world were known using observational and satellite data combined with climatic and ocean circulation models, including the results from the IPCC Fourth Assessment Report, said Prof Weiqing Han of Colorado's Department of Atmospheric and Oceanic Sciences and lead author of the study. He said the sea-level rise occurs in the south subtropical-mid-latitude basin, the eastern equatorial region, the Bay of Bengal and the Arabian Sea. Conversely, the Seychelles, east coasts of Kenya and Tanzania see little or no sea-level rise.

Prof Han said mapping variations in regional sea-level changes in different parts of the Indian Ocean could help developing countries better adapt to the effects of climate change. The information will be crucial for effective risk assessments in future and help inform adaptation and response options for human society, he said. However, the extent of the variations has not been known till now, Han said adding along the coasts of the north Indian Ocean, tide-gauge data show an average rise of 12.9cm per century.

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