How does rising atmospheric CO2 affect marine organisms?

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The Past Half-Century of Sea Level Rise
Domingues, C.M., Church, J.A., White, N.J., Gleckler, P.J., Wijffels, S.E., Barker, P.M. and Dunn, J.R. 2008. Improved estimates of upper-ocean warming and multi-decadal sea-level rise. Nature 453: 1090-1093.

What was done
Domingues et al., as they describe it, derived "improved estimates of near-global ocean heat content and thermal expansion for the upper 300 meters and 700 meters of the ocean for 1950-2003, using statistical techniques that allow for sparse data coverage and applying recent corrections to reduce systematic biases in the most common ocean temperature observations."

What was learned
In describing their results, the seven scientists say they "show a slight increase from 1950 to about 1960, a 15-year period to the mid-1970s of zero, or slightly negative trend and, after the 1976-1977 climate shift, a steady rise to the end of the record," noting that their "ocean warming and thermal expansion trends for 1961-2003 are about 50 percent larger than earlier estimates but about 40 percent smaller for 1993-2003, which is consistent with the recognition that previously estimated rates for the 1990s had a positive bias as a result of instrumental errors." In addition, when they add their observational estimate of upper-ocean thermal expansion to other contributions to sea-level rise (thermal expansion in the deep ocean, the ice sheets of Antarctica and Greenland, glaciers and ice caps, and terrestrial storage), they find that "the sum of contributions from 1961 to 2003 is about 1.5 0.4 mm/year," which they note is "in good agreement with [their] updated estimate of near-global mean sea-level rise (using techniques established in earlier studies) of 1.6 0.42 mm/year."

What it means
With respect to James Hansen's claim -- which was made in testimony to the U.S. House of Representatives on 26 April 2007 -- that "there is increasing realization that sea level rise this century may be measured in meters if we follow business-as-usual fossil fuel emissions," it would appear that centimeters would have been a more appropriate choice of units.

Reviewed 3 September 2008