Sea Level Records Reveal Surprising Variations
26.05.2005 - Other
A new reconstruction of past changes shows that the level of the oceans varied quite dramatically during the period between ice ages, implying that the global climate during these intervals was not as stable as most scientists had previously thought.
One of the best ways to document the rise and fall of sea level over time is by coral dating. Coral thrives in shallow waters with plenty of sunlight; as sea level rises, however, coral grows in stacks from the murky sea floor, forming terraces to reach the sun's rays close to the surface.
William Thompson and Steven Goldstein, both from Woods Hole Oceanographic Institution in Massachusetts, developed a new method for determining the age of coral to generate a record of past sea levels, which they report in this week's issue of Science.
Using their new dating system, Thompson and Goldstein reassessed past measurements of uranium decay, and reconstructed sea-level changes from between 70,000 and 240,000 years ago. And what they found was very surprising, explains Thompson. "This record shows high-frequency changes that are very consistent and persistent."
"The real punchline is that sea level changes more frequently than has been previously thought," says Thompson. "What's more, sea-level change can help to explain the overall climate system. This means that global climate is more variable than has been thought."
