Friday, April 04, 2014

Eastern US Sea-Level Rise, Modelling vs. Observations

Someone asked about how sea-level projections for the eastern U.S. seaboard compare to observations.

It's only been a few years since the hotspot was detected, but here's how modeled results compare to observations for the period 1992-2002, from Yin et al, Nat Geo (2009):

On the left are the observations, on the right is a simulation using the GFDL CM2.1 model. The authors write
The simulated dynamic SSH [sea surface height] during the 1990s is realistic compared to the observation, especially in terms of the sharp SSH gradient across the narrow Gulf Stream and North Atlantic Current.
Then their projections using this model are, for New York City and Washington DC:

where they have considered two different contributions to sea-level rise: the "steric" changes due to thermal expansion and salinity variations of seawater, and "dynamic" changes to the adjustment of the sea surface in response to changes in the AMOC (Atlantic Meridional Ocean Current).

So the line you probably want to focus on is the solid red line, which is both contributions for the A1B scenario. Sea-level projections along the east coast are about another 50 cm higher by 2100. (It will probably continue to rise after that, of course.)

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