Fast-forward ebb and flow

Published March 1, 2000

The common description of global sea-level changes is a simple one.

When most of the planet is cold (during an ice age, for example), a lot of water is locked up in the form of ice, and the regions of permanent ice expand. Sea levels are low during these periods. During warming, the ice melts, and sea levels rise. As with global warming, for example. Or so the theory goes.

But one researcher is challenging the Conventional Wisdom. Robert Baker of Australia’s University of New England hypothesized recently in the journal Marine Biology that major sea-level changes are actually the norm.

Baker performed carbon-dating tests and height measurements of worm coatings on rocks that, though now above sea level, were at one time submerged. Using these observations, Baker surmised that sea levels have not been steadily rising since the Ice Age, but in fact underwent rapid changes about 3,000 to 5,000 years ago. More specifically, Baker contends sea levels could have fallen by about one meter in just 10 to 50 years.

His studies also suggest sea levels were actually once higher than they are today.

These results are controversial in the oceanographic community. Nonetheless, science must address the observations of rapidly falling sea levels within the past 5,000 years.

Robert E. Davis is an associate professor of environmental science at the University of Virginia.


Baker, R., 2000. Marine Biology, in press.