In the ironically-named American Thinker, Fred Singer sought to differentiate between climate deniers and climate "skeptics", as previously detailed by John Mason. While Singer did some good myth debunking in the article, he also endorsed some other rather horrid climate myths in the process. In trying to establish himself as a climate "skeptic", Singer merely demonstrated that he's just one step above the most unreasonable climate deniers.
At least Singer did debunk a few of the most ridiculous climate myths in his article; for example, the myth that the greenhouse effect has been falsified or that increasing CO2 has no effect, argued by weatherman Joe Bastardi on Fox News most recently just a few days ago. Singer has none of it:
"Now let me turn to the deniers. One of their favorite arguments is that the greenhouse effect does not exist at all because it violates the Second Law of Thermodynamics -- i.e., one cannot transfer energy from a cold atmosphere to a warmer surface...One can show them data of downwelling infrared radiation from CO2, water vapor, and clouds, which clearly impinge on the surface. But their minds are closed to any such evidence."
Singer also debunked the myth that the CO2 increase is natural, describing deniers who believe this myth as conspiracy theorists:
"Then there is another group of deniers who accept the existence of the greenhouse effect but argue about the cause and effect of the observed increase of atmospheric carbon dioxide. One subgroup holds that CO2 levels were much higher in the 19th century, so there really hasn't been a long-term increase from human activities. They even believe in a conspiracy to suppress these facts."
At Skeptical Science, we always appreciate a good mythbusting and thus applaud that unlike most self-proclaimed climate "skeptics," Singer is actually willing to debunk some of the myths propagated by his fellow denialists. Unfortunately, in trying to position himself between "deniers" and "warmistas," Singer seems to believe that rejecting some climate myths while repeating others qualifies him as a climate "skeptic." We do not agree with his definition of the term.
In fact, Singer actually goes as far into the realm of denial in this article as to claim that global warming stopped in 1978.
"The atmospheric temperature record between 1978 and 2000 (both from satellites and, independently, from radiosondes) doesn't show a warming. Neither does the ocean."
There really is no other way to describe this assertion - Singer is denying the observational data which shows continued warming of both the lower atmosphere and oceans. This isn't the first time Fred Singer has denied global warming, either.
Using the soon-to-be-released Skeptical Science temperature trend calculator (spoiler alert - the tool will be launched in the relatively near future, but some bugs are still being worked out), the lower atmosphere temperature trend from 1978 to 2000 is 0.145 +/- 0.157°C per decade according to Remote Sensing Systems (RSS), and 0.104 +/- 0.164°C per decade according to the University of Alabama at Huntsville (UAH). Granted, these trends are not statistically significant, but they are nonetheless most likely positive.
But why choose the timeframe 1978 to 2000? Last I checked, the current year is 2012; it appears that Singer is trying to cherry pick a convenient date here (and nonetheless failed to find a temperature trend to support his assertion of no warming). The trend from 1978 to 2012 is 0.137 +/- 0.076°C per decade according to RSS, and 0.136 +/- 0.078°C per decade according to UAH. A clear positive, statistically significant trend in both cases. The radiosonde data (instruments on weather balloons) are also in good agreement with the satellites regarding the continued lower troposphere warming (Figure 1).
Figure 1: Satellite and radiosonde estimate of the temperature of the lower troposphere (NCDC)
As for the oceans, as Glenn Tramblyn recently noted, the rate of ocean heating since 1961 is equivalent to detonating 2 Hiroshima bombs per second continuously (Figure 2).
Figure 2: 0-2000 meter global ocean heat content (NODC)
Singer's claim that the oceans have not warmed since 1978 is a denial of facts that even his fellow "skeptics" accept. For example, while Roger Pielke Sr. once claimed the upper oceans had not heated in recent years, he later backtracked and admitted that they have warmed.
At another point in his article, Singer repeats the CO2 lags temperature myth.
"[deniers] argue that oceans warm first, which then causes the CO2 increase. In fact, such a phenomenon is observed in the ice-core record, where sudden temperature increases precede increases in CO2. While this fact is a good argument against the story put forth by Al Gore..."
"The story put forth by Al Gore" is essentially that the strong historical correlation between CO2 and global surface temperature demonstrates that CO2 is the climate's biggest control knob, and Gore is correct on this point. Yes, historically temperature changes have been initiated by orbital cycles approximately 800 years before an atmospheric CO2 increase. At that point, the oceans warmed enough to release CO2 into the atmosphere, which in turn amplified the existing warming and continued to drive global warming for several thousand years.
What the CO2 lag tells us is that this time is different, because this time there is no lag, thanks to humans burning fossil fuels and releasing tens of billions of tons of CO2 into the atmosphere every year. As in the past, this CO2 increase will continue to drive global warming.
To claim otherwise is to deny the fundamental physics which Singer summarizes in the myth debunking discussed in the first section of this post. It is unfortunate that the temptation to score points against Al Gore leads Singer into scientific incoherence and self-contradiction.
Singer spends much of his article criticizing the forthcoming Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5), which is currently still in draft form, but which he has reviewed. His main criticism is that the AR5 concludes that most of the observed global warming since the mid-20th Century is due to human greenhouse gas emissions. This conclusion is clearly correct (Figure 3).
Figure 3: Net human and natural percent contributions to the observed global surface warming over the past 50-65 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), and Gillett et al. 2012 (G12, orange).
Specifically, Singer attempts to undermine the IPCC conclusions by focusing on global surface temperature changes during the early and mid-20th Century.
"Most everyone seems to agree that this earlier increase (1910-1940) is caused by natural forces whose nature the IPCC does not specify. Clearly, the decline of 1940-1975 does not fit the picture of an increasing level of carbon dioxide"
While we can't speak for the unpublished AR5, the IPCC Fourth Assessment Report (AR4) published in 2007 most certainly did specify some of the causes of the 1910-1940 warming in great detail, as we recently demonstrated when Judith Curry made the same incorrect claims (see AR4 Chapter 9.4.1.5):
"A number of studies detect a significant natural contribution to early 20th-century warming (Tett et al., 2002; Stott et al., 2003b; Nozawa et al., 2005; Shiogama et al., 2006). Some studies find a greater role for solar forcing than other forcings before 1950 (Stott et al., 2003b), although one detection study finds a roughly equal role for solar and volcanic forcing (Shiogama et al., 2006), and others find that volcanic forcing (Hegerl et al., 2003, 2007) or a substantial contribution from natural internal variability (Tett et al., 2002; Hegerl et al., 2007) could be important. There could also be an early expression of greenhouse warming in the early 20th century (Tett et al., 2002; Hegerl et al., 2003, 2007)."
And contrary to Singer's claim, the slight 1940-1975 cooling does indeed fit the picture of an increasing CO2 level, since it's accurately reproduced by climate models, with human aerosol emissions offsetting much of the CO2-caused warming during this period (Figure 4).
Figure 4: IPCC AR4 Figure 9.5. Comparison between global mean surface temperature anomalies (°C) from observations (black) and AOGCM simulations forced with both anthropogenic and natural forcings. All data are shown as global mean temperature anomalies relative to the period 1901 to 1950, as observed (black, HadCRUT3) and as obtained from 58 simulations produced by 14 models with both anthropogenic and natural forcings. The multi-model ensemble mean is shown as a thick red curve and individual simulations are shown as thin yellow curves. Vertical grey lines indicate the timing of major volcanic events.
In short, like Curry, Singer does not accurately represent either the human-caused global warming theory or IPCC report.
Finally, Singer makes a very ironic accusation of the IPCC.
"[the IPCC] makes arbitrary assumptions about clouds and water vapor, which produce the most important greenhouse forcings. One might therefore say that the IPCC's evidence is nothing more than an exercise in curve-fitting."
Curve-fitting involves using many parameters and allowing them to vary with no physical constraints until the curves best fit the observational data. This is something actually done by many of Singer's fellow "skeptics" (e.g. Roy Spencer, Syun-Ichi Akasofu, Craig Loehle, and Nicola Scafetta). Unlike them, the climate models used in the IPCC reports constrain their parameters using observational data and physical reality.
The IPCC also does not make 'arbitrary assumptions' about the cloud and water vapor feedbacks. There is a great deal of research showing that the cloud feedback is likely positive, and unlikely to be strongly negative, most notably Dessler (2010). And numerous recent studies using empirical observational data have confirmed the positive water vapor feedback. For example, Dessler et al. (2008):
"Height-resolved measurements of specific humidity (q) and relative humidity (RH) are obtained from NASA's satellite-borne Atmospheric Infrared Sounder (AIRS)...The water-vapor feedback implied by these observations is strongly positive, with an average magnitude of λ q = 2.04 W/m2/K, similar to that simulated by climate models."
Also see the discussion of the water vapor feedback in AR4. These positive feedbacks are very inconvenient for climate "skeptics" like Singer, for whom climate sensitivity is the endgame, and whose low climate sensitivity arguments rely on the water vapor and/or cloud feedbacks being strongly negative. However, like it or not, the research supporting positive water vapor and cloud feedbacks exists, and to deny its existence is, well, denial.
If Fred Singer wants to differentiate himself from climate deniers as a true skeptic, he will have to stop denying the inconvenient data. It's good that Singer applies skepticism to some claims, but why doesn't he apply it universally? That is how true skeptics behave.
Posted by dana1981 on Friday, 23 March, 2012
 |
The Skeptical Science website by Skeptical Science is licensed under a Creative Commons Attribution 3.0 Unported License. |