John Church

Commonwealth Scientific and Industrial Research Organisation

Neil White, Siobhan O’Farrell, Kurt Lambeck, Gisela Estermann

We have recently completed a new estimate of monthly sea-level distributions from January 1950 to December 2000 (Church et al., 2004). This time series provides narrower estimates of the rate of sea-level rise as well as the first observational estimate of its regional distribution. We expect to complete an extension of this time series back to close to 1900 (and before if possible) and up to as close as possible to present day by the end of 2004. We are also working on new estimates of ocean heat uptake for the period 1950 to 2000 using the same techniques in an attempt to overcome the deficiencies of the Levitus et al. (2000) estimate (Gregory et al., 2004). The objective of this proposal is to compare these 20th century observed time series with the IPCC model results (sea-level rise and ocean heat uptake) to test their ability to reproduce the observations. The model sea-level rise would be a combination of ocean thermal expansion and changes in glaciers calculated by standard procedures. On the longer time scale (probably beyond March/May 2005) we would also compare the regional distributions of sea-level rise in the models with the observational estimates. While the focus is on testing models of the 20th century, the results have implications for the projections and thus we would anticipate examining a subset of the projections, beyond the AR4 March/May 2005 timeline.
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 to 2000 period. Journal of Climate, 17 (13), 2609-2625. Gregory, J.M., H.T. Banks, P.A. Stott, J.A. Lowe and M.D. Palmer, 2004. Simulated and observed decadal variability in ocean heat content. Geophysical Research Letters, in press. Levitus, S., J. Antonov, T. P. Boyer, and C. Stephens, 2000: Warming of the World Ocean. Science, 287, 2225-2229. Data Required We would require monthly data sets for all models for the 20th century and the corresponding control runs (Item 1 and 6 in the Announcement in the CLIVAR Exchanges). We would anticipate examining a subset of the projection runs listed in Items 1 to 4. Ocean Data: Essentially all ocean data would be required, including Sea surface elevation, surface heat, freshwater and momentum fluxes, sea floor depth, three-dimensional fields of ocean temperatures, salinity, density and velocities (including the surface). Atmospheric data: Essentially all surface data including air pressure, precipitation, evaporation, temperature, all components of heat flux, wind stress.