Most efforts to detect signs of global warming have been directed to signals in the air temperature field.
Breaking research conducted by Tim Barnett and David Pierce of Scripps Institution of Oceanography at the University of California, San Diego, has shown preliminary evidence of human-produced warming in the upper 3,000 meters of the world's oceans.
Their findings are published in the April 13 edition of the journal Science.
Barnett and Pierce, with colleague Reiner Schnur, cross-referenced data from the U.S.-developed Parallel Climate Model (sponsored by the Department of Energy and the National Center for Atmospheric Research), which factors in the influence of greenhouse gases and direct sulfate aerosols over the last 50 years, and direct observations of heat content change in the ocean over the same period.
They found that as the climate model ocean temperature rose and penetrated into the depths of the oceans, the observed global ocean temperature down to 3,000 meters rose right along with it.
They note that the agreement between the model and the observations is remarkably similar in all the oceans.
"The initial results are certainly compatible at the 95 percent confidence level with the hypothesis that the warming observed in the global oceans has been caused by anthropogenic sources," said Barnett, a research marine physicist in the Climate Research Division at Scripps.
"Our results provide a broader foundation for claims that global warming has been observed and attributed to human activities."
Pierce notes: "This work also provides a new criterion for measuring the realism of computer climate models. As models are improved to better match ocean warming seen over the last fifty years, they should give better estimates of future climate change as well."
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Wigley Testimony (PDF)
U.S. Senate Committee on Commerce, Science, and Transportation
Hearing on ‘The Case for Climate Change Action’
October 1, 2003
Tom M.L. Wigley,
Senior Scientist,
National Center for Atmospheric Research,
Boulder, CO.
"The most recent climate models are able to simulate present-day climate remarkably well – with errors often less than the uncertainties in observational data sets. Here, however, I will not dwell on this aspect of model validation, but concentrate on the second method – comparison of observed and model-simulated changes. I will show that models simulate temperature changes over the past 100+ years with considerable fidelity provided they are driven (or ‘forced’) by observed changes in both natural forcing agents (such as variations in the output of the Sun) and anthropogenic factors (such as changes in greenhouse gas concentrations and aerosol particle changes). Natural forcing factors alone cannot explain the past record."
...
"The simpler model has the advantage that it can be used to examine the effects of uncertainties in the parameters that control the response of the climate system to external forcing. The primary source of uncertainty is the ‘climate sensitivity’ parameter (designated by ‘S’ below). This is usually characterized by the eventual (or ‘equilibrium’) global-mean warming that would occur if we doubled the amount of carbon dioxide in the atmosphere. It has an uncertainty range of 1.5oC to 4.5oC with about 90% confidence. I will give results for sensitivity values of 2oC and 4oC to show the importance of this factor. For more information on sources of modeling uncertainty, see Wigley and Raper (2001)."
Dr. Lindzen, the Alfred P. Sloan Professor of Atmospheric Science at MIT, on CO2 and global warming in his WSJ article dated July 2, 2006.
"There is also little disagreement that levels of carbon dioxide in the atmosphere have risen from about 280 parts per million by volume in the 19th century to about 387 ppmv today. Finally, there has been no question whatever that carbon dioxide is an infrared absorber (i.e., a greenhouse gas--albeit a minor one), and its increase should theoretically contribute to warming. Indeed, if all else were kept equal, the increase in carbon dioxide should have led to somewhat more warming than has been observed, assuming that the small observed increase was in fact due to increasing carbon dioxide rather than a natural fluctuation in the climate system. Although no cause for alarm rests on this issue, there has been an intense effort to claim that the theoretically expected contribution from additional carbon dioxide has actually been detected.
Given that we do not understand the natural internal variability of climate change, this task is currently impossible. Nevertheless there has been a persistent effort to suggest otherwise, and with surprising impact. Thus, although the conflicted state of the affair was accurately presented in the 1996 text of the Intergovernmental Panel on Climate Change, the infamous "summary for policy makers" reported ambiguously that "The balance of evidence suggests a discernible human influence on global climate." This sufficed as the smoking gun for Kyoto.
The next IPCC report again described the problems surrounding what has become known as the attribution issue: that is, to explain what mechanisms are responsible for observed changes in climate. Some deployed the lassitude argument--e.g., we can't think of an alternative--to support human attribution. But the "summary for policy makers" claimed in a manner largely unrelated to the actual text of the report that "In the light of new evidence and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations."
In a similar vein, the National Academy of Sciences issued a brief (15-page) report responding to questions from the White House. It again enumerated the difficulties with attribution, but again the report was preceded by a front end that ambiguously claimed that "The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability." This was sufficient for CNN's Michelle Mitchell to presciently declare that the report represented a "unanimous decision that global warming is real, is getting worse and is due to man. There is no wiggle room." Well, no.
More recently, a study in the journal Science by the social scientist Nancy Oreskes claimed that a search of the ISI Web of Knowledge Database for the years 1993 to 2003 under the key words "global climate change" produced 928 articles, all of whose abstracts supported what she referred to as the consensus view. A British social scientist, Benny Peiser, checked her procedure and found that only 913 of the 928 articles had abstracts at all, and that only 13 of the remaining 913 explicitly endorsed the so-called consensus view. Several actually opposed it.
Even more recently, the Climate Change Science Program, the Bush administration's coordinating agency for global-warming research, declared it had found "clear evidence of human influences on the climate system." This, for Mr. Easterbrook, meant: "Case closed." What exactly was this evidence? The models imply that greenhouse warming should impact atmospheric temperatures more than surface temperatures, and yet satellite data showed no warming in the atmosphere since 1979. The report showed that selective corrections to the atmospheric data could lead to some warming, thus reducing the conflict between observations and models descriptions of what greenhouse warming should look like. That, to me, means the case is still very much open.
So what, then, is one to make of this alleged debate? I would suggest at least three points. First, nonscientists generally do not want to bother with understanding the science. Claims of consensus relieve policy types, environmental advocates and politicians of any need to do so. Such claims also serve to intimidate the public and even scientists--especially those outside the area of climate dynamics. Secondly, given that the question of human attribution largely cannot be resolved, its use in promoting visions of disaster constitutes nothing so much as a bait-and-switch scam. That is an inauspicious beginning to what Mr. Gore claims is not a political issue but a "moral" crusade.
Lastly, there is a clear attempt to establish truth not by scientific methods but by perpetual repetition. An earlier attempt at this was accompanied by tragedy. Perhaps Marx was right. This time around we may have farce--if we're lucky."
They disregard the facts about which frequencies of EM radiation are capable of penetrating more than a few microns of seawater.