With regards to the statement, “This is in good agreement with estimates that Earth’s temperature would be reduced by 0.6oC through particulate blocking of the sun by 0.2%,” I read through the Teller et al. (1997) reference and I can find nothing that supports that claim.
Further, most estimates for changes to global temperatures in response to changes in various forcings (including solar forcing) amount to about 0.8oC of warming per W/m^2 increase in atmospheric forcing. Thus, a 0.2% decrease in incoming solar irradiance should result in about 0.16oC of cooling.
11. 2nd page, 4th paragraph. This one-sentence-long paragraph is just a restatement of topics that have already been addressed. First, it’s not clear that solar activity is “closely correlated” with U.S. temperatures. If more reputable TSI data are used, the “correlation” is not so clear. Second, the “correlation” is apparently the result of scaling the temperature axis “by eye” rather than by some sort of defensible algorithm based on the physics involved. Third, the temperature data should be global temperature data rather than U.S. data. Fourth, “world hydrocarbon use” is an inappropriate measure of the degree of greenhouse gas forcing (at a minimum, the cumulative CO2 production should be used instead of the yearly consumption rate).
12. 2nd page, 5th paragraph. It is probably true that most people would not notice a 0.5oC temperature increase. However, the global temperature increase (1oC) has been twice the U.S. value (0.5oC). Further, the concern is not really so much the temperature increases we’ve already experienced, but it is the temperature increases to come that are cause for concern. It’s also worth noting that there’s no reason to suppose that Earth’s climate and biospheric systems are as insensitive to temperature changes as is human skin.
13. 2nd page, 6th paragraph. It is noted that over the past century, the U.S. has experienced a slight increase in rainfall, fewer tornadoes, and no increase in “hurricane activity.” It’s not clear what these data are supposed to prove, though. First of all, the concern is global climate change – not U.S. climate change. Second, although increases in rainfall are expected for some areas, increased drought is expected in others. It’s not clear at all what the expected effect of global climate change is for tornadoes. Tornadoes are much too small to be represented in the grid structure of most climate models. There is also considerable debate as to whether hurricane frequency and/or intensity will increase as Earth warms.
Robinson et al. (2007) present the data in Figures 7, 8, 9, and 10 (
not plotted here) as if it somehow was in direct contradiction to the predictions made for global warming, but they make two mistakes: (1) the data they show are for only for the U.S.; and (2) the weather events they choose to plot cannot be directly compared against predictions for a warmer world. So these graphs amount to nothing more than a school of red herrings.
14. 2nd page, 6th paragraph, sea level rise discussions. Figures 11 (
not plotted here) and 12 show the changes in sea level over the past two centuries. It’s not entirely clear what point they’re trying to make by noting that the sea level rise data show “3 intermediate uptrends and 2 periods of no increase.” Actually, the periods of “no increase” are really just periods where the rate of sea level rise is somewhat reduced (but not zero). Interestingly enough, the paper Robinson et al. (2007) references for the sea level data (Jevrejeva et al. 2006) observes that the periods of reduced sea level rise rate correspond temporally to periods when volcanic activity was increased... except, that is, for the observed sea level rise since about 1980 where volcanic activity has been higher but the rate of sea level rate is still high (See Figure 6 in Jevrejeva et al. 2006).
Robinson et al. make the statement that “if this trend continues... sea level would be expected to rise about 1 foot during the next 200 years,” without noting that the principal concern with respect to global warming is that the rate of sea level rise is predicted to increase.
----------------------------------------------------
Figure 12: Glacier shortening (4) and sea level rise (24,25). Gray area designates estimated range of error in the sea level re cord. These measurements lag air temperature increases by about 20 years. So, the trends began more than a century be fore in creases in hydrocarbon use.
----------------------------------------------------
15. 3rd page, 1st paragraph. Again, the statement is made that because the “trends” in sea level and glacier shortening appear to have begun before major increases in “hydrocarbon use,” then “hydrocarbon use” must not be the cause. This argument misses that point that there are multiple, competing factors acting on the climate including solar effects, volcanism, manmade aerosols, and greenhouse gases. To determine whether greenhouse gases are affecting the climate, it is essential to include an analysis of the other factors known to affect climate. Refer to
Chapter 9 of the IPCC WG1 report for a discussion of how attribution studies are conducted in climate science.
16. 3rd page, 2nd paragraph. “Much of that CO2 increase is attributable to the 6-fold increase in human use of hydrocarbon energy.” That’s true, although it’s more accurate to say that all of the observed CO2 increase can be attributed to human activities including fossil fuel combustion and vegetation burning for land clearing. See
this discussion of how we know that recent CO2 increases are due to human activities.
The claim that “Figures 2, 3, 11, 12, and 13 show human use of hydrocarbons has not caused the observed increases in temperature” is not supported by the data provided in the Robinson et al. (2007) paper for reasons already discussed.
17. 3rd page, 3rd paragraph. The claim is made here that increased CO2 concentrations have improved the “extent and diversity of plant and animal life.” No reference is given for this statement and no data are provided to support the statement.
18. 3rd page, 4th paragraph. “There are no experimental data to suggest this.” This is a rather cute bit of deceptiveness. It’s rather difficult to run experiments that involve the whole Earth ... that is, other than the uncontrolled experiment we’re already conducting by pumping greenhouse gases into the atmosphere. Contrary to the impression Robinson et al. (2007) tries to give, though, there is plenty of direct, experimental evidence demonstrating the basic physics underlying the theory that global climate change is caused by manmade greenhouse gases.
19. 3rd page, 5th paragraph. “The empirical evidence – actual measurements of Earth’s temperature and climate – shows no man-made warming trend. Indeed, during four of the seven decades since 1940 when average CO2 levels steadily increased, U.S. average temperatures were actually decreasing.” Here we go again with U.S. temperatures. The concern here is global warming. Further, it’s clear that Robinson et al. are confused about how attribution studies need to be conducted. It takes more than just plotting U.S. temperature along with “hydrocarbon use” on the same graph to determine the fraction of temperature change that can be attributed to human activities.
Also, “...and humans have been responsible for part of this increase...” is misleading. Human activities quite clearly account for all of the observed increase in atmospheric CO2 concentrations over the past century.
20. 3rd page, 6th through 9th paragraphs. This is all opinion and wild speculation with no evidence, references, or science to back it up. No further comment is necessary.
21. 4th page, 1st paragraph. Same comment as 20.
ATMOSPHERIC AND SURFACE TEMPERATURES
22. 4th page, 2nd and 3rd paragraphs. The Sargasso Sea temperature cannot be said to be representative of global (or even hemispheric) temperatures. The idea that the Earth would “rebound” from a cold period such as the Little Ice Age is unsupportable. Changes in global temperature are principally attributable to changes in forcings (solar, volcanic, greenhouse gases, etc.). The Earth went into the Little Ice Age cold period (to whatever extent it was a global phenomenon) because of changes in solar and volcanic forcing.
23. 4th page, 4th paragraph. It is stated that “temperatures have been higher than they are now during much of the last three millennia.” However, no reference is given to support that statement. Sargasso Sea temperature measurements cannot be used to support the claim that global temperatures have been higher in the past few millennia. Further, the argument that the “historical record does not contain any report of ‘global warming’ catastrophes” is off the mark. First of all, historical records do show that climate changes contributed to the demise of societies throughout history (see Collapse by Jared Diamond). Second, the principal concern with global warming is the increasing global temperature expected to occur in coming decades, so comparing today’s global temperatures to past temperatures isn’t terribly appropriate. Instead, we should compare past temperatures to the approximately 2
oC higher temperatures expected in the coming century. If we do that, we find that the last time global temperatures reached that level was approximately 3 million years ago. And at that time, sea level was about 25 to 35 meters higher than present. Undoubtedly there were many other regional climate differences as well.
24. 4th page, 5th paragraph. It is stated that “The 3,000-year range of temperatures in the Sargasso Sea is typical of most places.” but no citation is given for this statement. Further, it’s not clear what this statement is supposed to mean. The remainder of this paragraph attempts to make the argument that “individual records” are more meaningful than hemispheric or global averages. That is a rather strange argument to make given that the concern here is global warming. The Essex et al. (2007) paper that is cited in support of this argument is, in my opinion, just a cute bit of sophistry. Their argument is that it’s inappropriate to try to compute an “average” temperature of a system as complicated as the Earth’s climate. Their argument basically comes down to the point that averages tend to obscure the details of the variations within the system. Sure, that’s true, but that’s exactly the point of taking an average of a complicated system – it helps us to see the forest instead of getting distracted by the multitude of trees.
25. 4th page, 6th paragraph and Table 1. This paragraph discusses the results of an analysis by Soon et al. (2003) that was published in the Energy & Environment, which is a well-known “journal” that seems to exist principally to publish “skeptical” articles. In this case, the Soon et al. article was soundly debunked by several groups. Here are two critical reviews, the first in Science, by
Raymond Bradley, Malcolm Hughes and Henry Diaz, and the second a statement
from the AGU.
26. 4th page, 7th paragraph. It is claimed here that “mean and median world temperatures in 2006 were, on average, approximately 1
oC to 2
oC cooler than in the Medieval Period.” To back up this statement, they reference a Web page. That’s not exactly peer-reviewed science in a reputable journal. In addition, the authors of this “paper” (Idso and Idso) are
well-known global-warming “skeptics” with ties to the fossil fuel industries.
27. 4th page, 8th paragraph. Other than the use of the phrase “cycle of recovery,” which is intended to again imply the
misleading notion of a “recovery” from the Little Ice Age, this paragraph is largely accurate.
28. 4th page, 9th paragraph. This paragraph is a restatement of arguments made earlier in the paper.
.....
There are, of course, many more errors and distortions in the Robinson et al. (2007) paper, but there comes a point when enough should be enough. The errors described above should be sufficient evidence for any fair-minded person to conclude Robinson et al. (2007) is not a serious scientific paper. Instead, it appears to be nothing more than a clumsy attempt to distort the evidence for anthropogenic global warming in order to sow confusion in the minds of people not already familiar with the evidence.
Mike Powell
PE, MS Chemical Engineering
Kennewick, Washington