Another goal of the VIMS study was to determine if local rates of sea-level rise have increased during the last few decades. As Boon puts it "We know that sea-level is rising, and wanted to find out if it is rising faster now than it did before."
An acceleration in sea-level rise with global warming is predicted by many climate models, and has been observed on a global basis. The IPCC reports that the globally averaged rate of sea-level rise increased from 1.8 mm per year between 1961 and 2003 to 3.1 mm per year between 1993 and 2003. The more recent period coincides with the deployment of satellites that allow for an accurate global picture of absolute sea-level rise.
The results from this part of the VIMS study were inconclusive, largely because available tide-gauge records aren't long enough to allow the researchers to tease a change in the long-term trend apart from year-to-year variability caused by phenomena such as the North Atlantic Oscillation, a see-saw in atmospheric pressure and wind fields between Iceland and the Azores.
The authors conclude "While relative sea level continues to rise at some of the highest rates found along the U.S. Atlantic Coast, there is presently no evidence of a statistically significant increase marking an acceleration in relative sea-level rise" at any of the 5 Bay stations measured. Four of the five stations studied showed an increase in the rate of relative sea-level rise between 1944-1975 and 1976-2007, but none of the increases are statistically significant.
The authors caution that "small but steady increases in relative sea-level rise rate with time are still a possibility." They estimate that an increase "on the order of 0.5 mm per year may be required for a statistically significant acceleration to be c
|Contact: David Malmquist|
Virginia Institute of Marine Science