Latest Sea Level Rise Amount and Rate Information

Context: sea level has been rising off and on since the end of the last ice age. The current rate is over 3 mm per year, a rate than can threaten infrastructure and coastal communities.  At the beginning of 2009, the rate stood at about 3.3 mm per year (ed. or half that (below)).

(Source: Sea Level Change at the University of Colorado)

Analysis: Sea level rise or fall can be an indicator of warming or cooling, but the sea has been rising since the last ice age ended, less than 10 thousand years ago. In the prior inter-glacial period about 125,000 years ago, there was no summer ice at the North Pole and the sea level was 15 feet (5m) higher than today. If our interglacial period (The Holocene) continues, with or without further warming, we might see the same levels. The most important indicator is an acceleration in the rate of change, which would be required if there were any real warming. Most scientists do not see an acceleration. Let us remember that American indians walked to Nantucket Island and Martha's Vineyard and they probably lived on Georges bank, where tree trunks are still caught by fishing trawlers. It was always interesting to this author to find oyster shells in nearly 70 meters (220 ft) deep water off New York City  - these shells looked like they had been shucked yesterday, yet oysters only grow in shallow waters. In a 2009 study, the authors used GPS measurement to correct for local vertical movement of the Earth at key tide gages, finding a "global rate of geocentric sea level rise of 1.61 ± 0.19mm/yr over the past century". Their study shows no acceleration and no changes in rate during warm or cold periods of the last 110 years. It is virtually a straight-line rate of increase, independent of Earth's temperature.