How does rising atmospheric CO2 affect marine organisms?

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The Status of Earth's Ocean Heat Content
Willis, J.K., Lyman, J.M., Johnson, G.C. and Gilson, J. 2009. In situ data biases and recent ocean heat content variability. Journal of Atmospheric and Oceanic Technology 26: 846-852.

The authors write that "as the earth warms due to the buildup of greenhouse gases in the atmosphere, the vast majority of the excess heat is expected to go toward warming the oceans (Levitus et al., 2005; Hansen et al., 2005)," but they note that "a large and apparently significant cooling in OHCA [ocean heat content anomaly] between 2003 and 2005 was reported by Lyman et al. (2006)," casting doubt on the theory in some people's minds and doubts on the measurements in other people's minds.

What was done
To help resolve this important issue, Willis et al. analyzed potential biases in expendable bathythermograph (XBT) data, as well as data obtained from the Argo array of profiling floats, which were used in making the OHCA calculations.

What was learned
In the words of the four researchers, "the cooling reported by Lyman et al. (2006) is shown to be an artifact caused by both [an] XBT warm bias and [a] cold bias in the Argo data," with the end result that "OCHA does not appear to exhibit significant warming or cooling between 2003 and 2006."

What it means
Willis et al. state that the ocean cooling reported by Lyman et al. (2006) "would have implied a very rapid increase in the rate of ice melt in order to account for the fairly steady increase in global mean sea level rise observed by satellite altimeters over the past several years." They also note that the absence of a significant cooling signal in their adjusted OHCA results "brings estimates of upper-ocean thermosteric sea level variability into closer agreement with altimeter-derived measurements of global mean sea level rise." And we note, last of all, that the lack of either a warming or a cooling trend in the OHCA data matches perfectly with the fact that there was no warming or cooling of the atmosphere between 2003 and 2006 either, so that the cessation of global warming, which has held sway for the past decade, appears to apply to both land and sea.

Hansen, J. and Coauthors. 2005. Earth's energy imbalance: Confirmation and implications. Science 308: 1431-1451.

Levitus, S.J., Antonov, I. and Boyer, T.P. 2005. Warming of the world ocean, 1955-2003. Geophysical Research Letters 32: 10.1029/2004GL021592.

Lyman, J., Willis, K. and Johnson, G.C. 2006. Recent cooling in the upper ocean. Geophysical Research Letters 33: 10.1029/2006GL027033.

Reviewed 23 September 2009