Scientists have found evidence in Bermuda's limestone that the earth's sea level was once more than 70 feet higher than it is today which may be critical for anticipating the possible effects of future climate change.

The clues for this ancient rise in sea level was found by Storrs Olson, a research zoologist at the Smithsonian's National Museum of Natural History, and geologist Paul Hearty of the Bald Head Island Conservancy.

They discovered sedimentary and fossil evidence in the walls of a limestone quarry in Bermuda that documents a rise in sea level about 400,000 years ago during an interglacial period of the Middle Pleistocene in excess of 21 metres above its current level.

The nature of the sediments and fossil accumulation found by the two scientists was not compatible with the deposits left by a tsunami but rather with the gradual, yet relatively rapid increase in the volume of the planet's ocean caused by melting ice sheets.

According to Hamara News, a rise in sea level to such a height would have ramifications well beyond geology and climate modelling. For the organisms of coastal areas, and particularly for low islands and archipelagos, such a rise would have been catastrophic.

Said Mr. Olson, one of the world's leading paleornithologists: "We have only to look at Bermuda to begin to assess the impact for terrestrial organisms or seabirds dependent on dry land for nesting sites.

"This group of islands in the Atlantic was so compromised as a nesting site for seabirds that at least one species of shearwater became extinct as well as the short-tailed albatross, marking the end of all resident albatrosses in the North Atlantic."

Determining the timing and extent of the rise in sea level is not only important for interpreting the influence that it may have had on biogeographical patterns and extinctions of organisms on islands and low-lying continental coastal areas, but also critical for anticipating the possible effects of future climate change, he said.

And he explained that with future carbon dioxide levels possibly rising higher than any time in the past million years, it is important to consider the potential effects on polar ice sheets.

Said Mr. Olson: "These findings are incredibly important and have major relevance because of their potential predictive value since this sea-level rise took place during the interglacial period most similar to the present one now in progress.

"It thus becomes essential that the full extent and duration of this event be more widely recognised and acknowledged."