Projecting Sea-Level Rise
To get the projected sea level for each year from 2000 – 2100, we use the following equation:
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In this equation, t0 is the reference time (2000), αR(x) is the relative sea level rise at a location (measured by tide gauges), αA is the observed rate of absolute sea level rise (see below), ΔHA(t) is the absolute sea level increase (obtained from GCMs), and ΔHR(t,x) is the sea level rise at each particular location. The bracketed term indicates the land subduction rate at each location.
The observed rate of absolute sea level rise is determined to be 1.8±0.3 mm/y by Church et al. (2004). They measured this from 1950 – 2000 using the TOPEX/Poseidon satellite altimeter from 1993 – 2001 and global tide gauge records from 1950 – 2000. Because this value is a fifty-year trend, we only use tide guage station in the MUAR (Middle-Upper Atlantic Region) that have records that date back at least 50 years. This leaves us with 18 stations for which we can project sea level for the next century.
We then calculate averages for three thirty year periods: 2010-2039, 2040-2069, and 2070-2099. These are plotted on the bar graphs. TG indicates the projected sea level with no model results included. In other words, this is just using the observed relative sea level rise at each location. We use this as a lower bound for projections. Other acronyms indicate which climate model is being used (CSIRO, NCAR, ECHAM, GFDL, and HADC). The IPCC SRES scenarios being used are A2 and B2.
Error bars are calculated using the error given for the relative sea level rise at a location and the error determined by Church et al. (2004). Any errors in the climate models are not included because we are uncertain of what these errors are.
For information contact Ray Najjar.
Church, J.A., N.J. White, R. Coleman, K. Lambeck, and J.X.Mitrovica. 2004. Estimates of the Regional Distribution of Sea Level Rise over the 1950-2000 Period. American Meteorological Society. 17(13), 2609-2625.
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