Royal Society Proceedings A Lockwood & Fröhlich

July 11, 2007 at 10:56 am | Posted in Climate change, Fröhlich, Lockwood, Royal Society | 9 Comments

The Journal Article ‘Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature’ is online in all its forms via these two Royal Society Publishing pages:

http://www.journals.royalsoc.ac.uk/content/h844264320314105/

http://www.pubs.royalsoc.ac.uk/index.cfm?page=1086

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  1. Lockwood & Frohlich’s thesis depends entirely on the PMOD TSI composite time series and its lack of a significant TSI trend during solar cycles 21-24. The PMOD composite was constructed to agree with the linear regression solar proxy model of Judith Lean and took considerable liberties with the satellite TSI database to accomplish it.

    Frohlich and lean modified the results of the Nimbus7/ERB and ACRIM1 experiments published by their science teams to agree better with Lean’s model. To construct a multidecadal composite it is necessary to relate the ACRIM1 and ACRIM2 results acrosss the two year gap between them. There are two choices to do this and they give quite different results. The best ‘ACRIM gap’ comparative database is the Nimbus7/ERB which produces a composite demonstrating significant TSI upward trending during solar cycles 21 – 23, then a return to cycle 21 values in cycle 24. The other ‘gap’ database, the ERBS/ERBE, clearly inferior to the Nimbus7/ERB in calibration, precision and sample rate, produces no significant trend. The difference between Nimbus7/ERB and ERBS/ERBE results during the ‘gap’ are readily shown to be uncorrected degradation of the ERBS/ERBE data. Nevertheless Frohlich and Lean chose the ERBS/ERBE connection to relate the ACRIM experiments and the resulting PMOD composite shows no significant trend. This facilitates their conclusions about solar trending and climate change but does not represent the most objective use of the extant TSI satellite database.

    Had these authors compared the effects of using the PMOD and ACRIM composites (ACRIM uses published results and the Nimbus7/ERB connection across the ‘gap’) their paper would have yielded different conclusions. It would also have less of the flavor of a public relation effort in support of the IPCC’s anhropogenic global warming scenario.

  2. Dr. Willson,

    It’s overwhelmingly likely that Lockwood & Frohlich (“LF”) chose the PMOD composite, and argue for its superiority, not because it returns a desired result, but because Frohlich is one of its authors. Likewise it’s no surprise you argue for the superiority of the ACRIM composite, as you’re one of its authors.

    Regardless, some of the statements in your comment are incorrect. Chief among them is this:

    Lockwood & Frohlich’s thesis depends entirely on the PMOD TSI composite time series and its lack of a significant TSI trend during solar cycles 21-24.

    LF examine not just TSI (as estimated by the PMOD composite of satellite measurements), but sunspot counts, the radial component of the interplanetary magnetic field, neutron counts, and solar cycle length. Every data set they analyze contradicts the hypothesis that modern global warming is due to changes in solar activity.

    You further state:

    The best ‘ACRIM gap’ comparative database is the Nimbus7/ERB which produces a composite demonstrating significant TSI upward trending during solar cycles 21 – 23, then a return to cycle 21 values in cycle 24.

    The claim of an upward trend during solar cycles 21 – 23 using the ACRIM composite is based on the (in my opinion) naive characterization of the trend based on the average value at the minimum of the solar cycle. This quite ignores the fact that according to the ACRIM composite, the maximum of cycle 21 is distinctly higher than the maximum of any subsequent observed cycle. The method of LF, which computes an integrated TSI during an entire solar cycle, is clearly superior; when such an approach is applied to the ACRIM data, increase is seen only from cycles 21 to 22; even using the ACRIM composite, there is no statistically valid basis to claim any increase in TSI (other than the solar cycle itself) after about 1995.

    I further mention that even if one accepts your own analysis of your own composite, the trend you identify in TSI from cycles 21 – 23 is stated as 0.01%/decade. Over two full solar cycles, this amounts to an increase of 0.3 W/m^2, which produces an increase in climate forcing of a mere 0.075 W/m^2 — only marginally greater than the climate forcing due to anthropogenic power generation. Using a climate sensitivity of 0.75 deg.C/(W/m^2), this would produce a global temperature change of a scant 0.06 deg.C.

    The notion that changes in solar activity, and especially that changes in TSI, can be responsible for modern global warming is, to use a colorful phrase, “dead as a doornail.”

  3. tamino (whoever you are):

    Your points are incorrect.

    First: the ‘other’ solar activity features you mention that LF examine are only proxies for TSI, not potential climate forcings themselves.

    Second: The minimum-to-minimum values are hte most appropriate for elucidating any trend in the solar background TSI which is what matters on climate timescales.

    Third: The ACRIM composite trend during cycles 21-23 is 0.04%/decade, not 0.01, so the argument of your last paragraph is moot.

  4. Dear Dr. Richard C. Willson,

    Thanks for your comments. Before anyone else writes in, I have added the ACRIM (and PMOD) composite TSI time series figures from the ACRIM website to my Flickr column, because I want to refer to the ACRIM one and ask you a quick question to clarify your last point:

    When I look at the TSI trend (solar cycles 21 — 23 minima) in the ACRIM Composite TSI Time Series (Daily Means) figure 9 on the ACRIM website, it reads 0.004%/decade (a tenth of what you quoted in your correction of tamino’s number) which makes tamino’s point stronger, doesn’t it?

    Yet, when I look at your presentations last fall to AGU, you stated just as you did above:

    “the ACRIM TSI composite, detects a significant upward trend in TSI of 0.04 percent per decade during solar cycles 21-23. (Willson & Mordvinov, 2003)”

    and this is shown as annotation on Figure 26 in that presentation.

    So, is the ACRIM trend 0.004% per decade (as in Figure 9 on the ACRIM website), or is it 0.04% per decade (as in Figure 26 in your presentation)?

    Choosing minima to identify trends is a far less rigorous method than that used by Lockwood & Fröhlich. They calculated an integrated TSI using running means over intervals varying in length from 9 to 13 years at 3 monthly intervals to smooth the variations in solar cycles out of the picture, so longer-term trends could be identified objectively.

    By comparison, looking at minima alone is like “eyeballing” the densest part of the curves for patterns that appear clearly to the human eye. (This is similar in appeal to the way in which people are shown a graph of global mean surface air temperatures starting in 1998, and are then asked to point to an upward trend … with insufficient data and background to know they are being tricked).

  5. Dr. Willson,

    First: the ‘other’ solar activity features you mention that LF examine are only proxies for TSI, not potential climate forcings themselves.

    It’s unfortunate that you have chosen to be disingenuous. The strength of the interplanetary magnetic field is used as a proxy for galactic cosmic rays, which (through the modulation of cloud condensation nuclei) is the chief proposed mechanism to modulate climate, now that it’s clear even to the “skeptics” that climate forcing due to TSI is dead as a possible explanation of modern global warming. Cosmic ray counts (specifically, neutron counts) are also a proxy for galactic cosmic rays.

    Have you even read the paper by Lockwood & Frohlich?

    Second: The minimum-to-minimum values are hte most appropriate for elucidating any trend in the solar background TSI which is what matters on climate timescales.

    If you actually believe this (that the minimum-to-minimum value is a better indicator of the trend in forcing than the integrated irradiance throughout the solar cycle), then not only do you deceive yourself, you make yourself look ridiculous in the process.

    Third: The ACRIM composite trend during cycles 21-23 is 0.04%/decade, not 0.01, so the argument of your last paragraph is moot.

    How silly of me. According to this graph on the ACRIM website, the 0.04%/decade figure spans a single solar cycle, while the more up-to-date 0.01%/decade trend spans two solar cycles. Yet you have chosen to label it “cycles 21 – 24.” Curious that you refer to the end of cycle 21 but the beginning of cycle 24. Is this another example of the work of the mathematically challenged, or is it a “public relation effort” in opposition to “the IPCC’s anhropogenic global warming scenario.”?

  6. re: “How silly of me”

    Well – we agree at least on one thing – you are certainly silly!

  7. Dr Wilson and Tamino,

    From my layman’s perspective, you both seem to make some points, but I am still unable to figure out which TSI reconstruction is superior. It seems the PMOD recon depends somewhat on modeling, which would seem to be a point against it, and the ACRIM recon depends on cycle min to min trends which would seem to be a point against it.

    Is there a middle ground somewhere? Can the PMOD recon be run without a dependence on modeling? Can ACRIM incorporate max to max trends as well?

    Also, can you both provide a link to an independent third-party review of the PMOD vs ACRIM reconstructiosn?

  8. Dear ngs,

    Welcome.

    From my MoP (Member of the Public) perspective, the most important question is: what is the most effective change I can make to my lifestyle to combat climate change?

    Dr. Willson has not yet answered my simple question about the order of magnitude difference in the two similar graphs on the ACRIM website. I hope he does. If he answers your convoluted mutiple queries instead, he would be taking an ideal opportunity to further muddy the waters.

    Let’s see what happens …

    Dear tamino,

    Thanks for your comments which are, as always, informative, invariably accurate, and helpful to those of us who are learning about climate change and related topics.

    Dear Dr. Richard C. Willson,

    I hope you are willing to treat us with respect even though neither ngs, nor tamino, nor I use our full names online. (Bono and Sting seem to do OK without using their full names in public!)

    We are still interested in your response, even though you have unjustifiably belittled tamino and ignored my question about whether 0.04 or rather 0.004 is correct in an up-to-date version of this statement “the ACRIM TSI composite, detects a significant upward trend in TSI of 0.04 percent per decade during solar cycles 21-23. (Willson & Mordvinov, 2003)”. Access to the most up-to-date ACRIM information online would be useful.

  9. Dear ngs,

    I hope all is well with you. This week I have very limited internet access, so have changed my blog settings to reduce the number of comments (and SPAM) that tend to build up unmoderated. Registered WordPress users can still comment, and I shall remove this restriction in a little while. OK?

    In the meantime, I guess you could formulate a few questions on another recent paper published by The Royal Society, this time by Holland & Webster and titled ‘Heightened tropical cyclone activity in the North Atlantic: natural variability or climate trend?’


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