Re: [asa] Interpretations of climate-change data

From: John Burgeson (ASA member) <>
Date: Wed Nov 18 2009 - 12:49:20 EST

"Shotgun" posts seldom accomplish their goals, Moorad.

In skimming through the morass, I noted this part:

"The review also lists more than 30,000 US scientists who have signed
a petition "

Really? This sounds like Sen Inhofe's "3,000 scientists." That
particular list was published and found to include quite a number of
people whose expertise in climate science was about as great as your
local auto mechanic.

Can you give us any more detail on who these 30,000 US scientists are?

On 11/17/09, Alexanian, Moorad <> wrote:
> []
> URL:
> Published: November 2009
> [Permission to reprint or copy this article/photo must be obtained from
> Physics Today. Call 301-209-3042 or e-mail
><> with your request.]
> Letters
> Interpretations of climate-change data
> November 2009, page 8
> In the January 2009 issue of PHYSICS TODAY, Philip Duffy, Benjamin Santer,
> and Tom Wigley attempted (page 48<>) to
> rebut our argument that there is significant climate response to solar
> variability (PHYSICS TODAY, March 2008, page
> 50<>). We find their arguments
> unconvincing.
> The composite curve in their figure
> 1<> is the PMOD composite of
> satellite data for total solar irradiance (TSI), which has no upward trend
> for the period 1980–2000. However, the second well-known composite, ACRIM,
> does show a significant upward trend during that period.
> 1<> We find it curious that
> Duffy and coauthors cite the PMOD composite as the only one of consequence.
> For the period before 1995, any TSI composite is constructed with data from
> ACRIM1, NIMBUS7, and ACRIM2 satellite experiments. The ACRIM composite uses
> these data as they are published by the experimental teams, while the PMOD
> composite is constructed by altering the published data on the basis of a
> TSI proxy model and the low-quality ERBS (Earth Radiation Budget Satellite)
> record. The ACRIM and NIMBUS7 experimental teams have rejected the PMOD
> alterations as arbitrary. 2,3<>
> Recent work 3<> that uses
> measurements of solar magnetic fluxes at Earth’s surface establishes that a
> significant degradation of the TSI record from ERBS occurred during the gap
> in the ACRIM records (1989–92), as the ACRIM team has always claimed. That
> degradation invalidates the trust placed in the PMOD composite and its
> downward alterations of the NIMBUS7 record. Thus one is forced to select the
> ACRIM composite, which shows a TSI increase between 1980 and 2002, as we
> discussed in our Opinion piece.
> Duffy and coauthors’ choice of preferring an arbitrary TSI composite that
> shows no upward trend from 1980 to 2000 clearly undercuts their first major
> claim, that the Sun could not contribute to the warming observed since 1980,
> and consequently everything they deduced from it.
> The second claim by Duffy and coauthors is that climate sensitivity to solar
> variability is low. To support that conclusion, they cite a 2004 study
> 4<> by Gerald North and
> coworkers that summarizes findings obtained from simple energy-balance
> models. However, Duffy and coauthors omitted that study’s major finding:
> that the empirical solar signature exceeds the energy-balance model
> predictions by a factor of two on average, implying that the climate is much
> more sensitive to solar changes than what climate models predict. Also, they
> do not realize that us-ing a 10-year running average in their figure
> 2<> suppresses the solar cycle’s
> 11-year signature on climate.
> The authors also ignore three other important points. First, our findings
> are consistent with secular paleoclimate temperature reconstructions that
> were recently made and confirmed.
> 5<> Second, the glacial epochs
> were induced by small changes in the redistribution of sunlight due to the
> Milankovitch astronomical cycles—variations in the eccentricity, obliquity,
> and precession of Earth’s orbit; that fact suggests significant climate
> sensitivity to changes in TSI inputs. And third, the oscillations of
> greenhouse gases observed between the glacial epochs were not induced by
> human activity but were a complex climate-dynamics response to the small
> redistribution of sunlight produced by Milankovitch cycles; that fact
> contradicts the assumption implicit in all climate models adopted in the
> Intergovernmental Panel on Climate Change 2007 report, that only humans can
> modify greenhouse gas concentrations.
> Finally, the assumption underlying the piece by Duffy and coworkers is that
> the anthropogenic global warming theory is settled, those who claim
> otherwise are in error, and their studies should be dismissed. Yet an
> international team of scientists has published a comprehensive research
> review 6<> disproving that claim
> by summarizing and organizing the findings of thousands of scientific
> papers; their review contradicts several conclusions of the IPCC 2007
> report, which ignored many of the papers reviewed in Climate Change
> Reconsidered. 6<> The review
> also lists more than 30,000 US scientists who have signed a petition stating
> that there is no convincing evidence to support the anthropogenic global
> warming theory. We remind readers about the dangers of dogma replacing
> science.
> References
> 1. 1. C. Fröhlich, J. Lean, Geophys. Res. Lett. 25, 4377
> (1998)<>
> [INSPEC]<>;
> C. Fröhlich, Space Sci. Rev. 125, 53 (2006)
> [INSPEC]<>.
> 2. 2. R. C. Willson, A. V. Mordvinov, Geophys. Res. Lett. 30, 1199
> (2003)<>
> [SPIN]<>,
> doi:10.1029/2002GL016038<>.
> 3. 3. N. Scafetta, R. C. Willson, Geophys. Res. Lett. 36, L05701
> (2009)<>
> [SPIN]<>,
> doi:10.1029/2008GL036307<>.
> 4. 4. G. R. North, Q. Wu, M. Stevens, in Solar Variability and Its Effects
> on Climate, J. M. Pap, P. Fox, eds., Geophysical Monograph 141, American
> Geophysical Union, Washington, DC (2004), p. 251.
> 5. 5. A. Moberg et al., Nature 433, 613
> (2005)<>
> [MEDLINE]<>;
> A. Eichler et al., Geophys. Res. Lett. 36, L01808
> (2009)<>
> [SPIN]<>,
> doi:10.1029/2008GL035930<>.
> 6. 6. C. Idso, S. F. Singer, Climate Change Reconsidered: The Report of
> the Nongovernmental International Panel on Climate Change, Heartland
> Institute, Chicago (2009),
> [LINK]<>.
> Nicola Scafetta
> (<>)
> Bruce J. West
> (<>)
> Duke University
> Durham, North Carolina
> The rather passionate rebuttal of the Scafetta and West solar variability
> hypothesis by Philip Duffy, Benjamin Santer, and Tom Wigley seems to clearly
> show some weaknesses in the Scafetta and West model. Nevertheless, Duffy and
> coauthors ignore a data trend that weakens the argument for climate change
> based almost solely on greenhouse gas emissions. Their own figure
> 2<> clearly illustrates that
> although GHG emissions have continued to increase at an enormous rate,
> global temperatures have not increased over the past decade and have
> actually slightly decreased overall since the record-setting warmth of the
> 1998 El Niño maximum. Also, last year’s apparently anomalous low
> temperatures occurred during a year of extremely low solar activity (and a
> possibly weak La Niña), despite the aforementioned increase in GHG emissions
> and without a significant volcanic eruption.
> Although the various current climate models are getting better at
> re-creating the past, they still fail in accurately predicting the future,
> especially with their emphasis on GHG emissions. So it certainly doesn’t
> hurt to examine other models such as Scafetta and West’s. If there exists a
> single climate model from a decade ago that based climate change
> predominantly on GHGs and that predicted the past 10 years of cooling, I
> would love to see a reference to it.
> Benjamin R. Jordan
> (<>)
> Brigham Young University–Idaho
> Rexburg
> Duffy, Santer, and Wigley reply: Solar irradiance measurements have been
> made by a number of satellites covering different time periods. Several
> investigators have stitched together the multiple records into composites,
> correcting for small instrumental differences (for a comparison, click here
> <> ). Nicola Scafetta and Bruce
> West make much of the fact that our figure showed the PMOD composite rather
> than their favorite, ACRIM. The differences between the two, however, are
> insignificant in terms of implications for climate; neither produces
> anything close to the observed late-20th-century warming, even if one
> assumes a climate sensitivity much greater than the most commonly accepted
> value. Furthermore, the superiority of the ACRIM composite is not
> established. 1<>
> Scafetta and West’s characterization of the 2004 paper by Gerald North and
> coworkers (reference 4 in Scafetta and West’s letter) contradicts that
> paper’s abstract. Far from finding that “the climate is much more sensitive
> to solar changes than what climate models predict,” North and coworkers find
> “a faint response to the solar cycle” with amplitude “roughly what we would
> expect (a few hundredths of a degree) based on simple energy-balance model
> estimates.” That finding contradicts Scafetta and West’s argument that the
> climate is mysteriously hypersensitive to solar variations.
> We used a 10-year running mean in our figure
> 2<> precisely because it masks the
> 11-year solar cycle; our point was that there is no significant multidecadal
> trend due to solar variability.
> Scafetta and West’s discussion of glacial and interglacial cycles does not
> support their assertion that climate is exceptionally sensitive to solar
> variations. As is well established, glacial and interglacial temperature
> differences result from extremely large changes—not “small” ones as Scafetta
> and West claim—in the spatial and seasonal patterns of incoming solar
> radiation, which trigger two powerful but slow feedbacks: changes in
> atmospheric carbon dioxide and changes in surface reflectivity resulting
> from the advance and retreat of land ice sheets. Certainly, neither feedback
> can be responsible for late-20th-century warming.
> Although this is irrelevant to the main point of contention, climate models
> do not assume that “only humans can modify greenhouse gas concentrations.”
> Naturally occurring CO 2 variations are included either by prescription or
> through modeling of climate and carbon-cycle feedbacks.
> Finally, a recent paper 2<>
> explains in detail the serious flaws in the work of Scafetta and West.
> Primarily, multicollinearity between different climate forcing agents makes
> it impossible to unravel their relative effects by considering only a single
> forcing, as Scafetta and West attempt. Reference 2 further shows that the
> statistical method they used leads to grossly incorrect results; when
> applied to a situation with a known solar contribution, it gives a greatly
> and unrealistically enhanced solar effect.
> In response to Benjamin Jordan, we note that observed temperatures reflect
> both natural variability and the effects of forcings such as greenhouse
> gases and solar variability. So in an era of increasing greenhouse gases,
> each year need not be warmer than the previous, even as temperatures trend
> generally upward. Climate models correctly predict that phenomenon.
> 3<> However, because climate
> simulations are not initialized from observations in the same way that
> weather forecasts are, they are not expected to predict the timing of
> natural variations, including cooling episodes. Hence, the lack of any
> warming trend since 1998 is not cause for concern about climate models.
> In summary, we do not claim that the climate is insensitive to solar
> forcing, only that the sensitivities to different types of forcing appear to
> be very similar. We are open to the possibility that unknown feedbacks might
> amplify solar forcing; however, Scafetta and West have provided no evidence
> of such and no reason to discard an explanation of late-20th-century warming
> that is consistent with theory, models, and observations—namely, increased
> greenhouse gases.
> References
> 1. 1. See, for example, M. Lockwood, C. Fröhlich, Proc. R. Soc. A 464,
> 1367 (2008).
> 2. 2. R. E. Benestad, G. A. Schmidt, J. Geophys. Res. D 114, 14101
> (2009)<> ,
> doi:10.1029/2008JD011639<>.
> 3. 3. See, for example, D. R. Easterling, M. F. Wehner, Geophys. Res.
> Lett. 36, L08706 (2009)<>
> [SPIN]<>,
> doi:10.1029/2009GL037810<>.
> Philip Duffy
> (<>)
> Climate Central Inc
> Palo Alto, California
> Benjamin Santer
> Lawrence Livermore National Laboratory
> Livermore, California
> Tom Wigley
> National Center for Atmospheric Research
> Boulder, Colorado
> []
> Raw solar irradiance measurements (top) and three composites—estimated
> irradiance records that continuously span the entire period of observations.
> Raw measurements reflect differences in instrument calibrations among
> different satellites. The composites attempt to correct for those
> differences. Although the relative merits of each composite are debatable,
> the differences are insignificant in terms of implications for climate; none
> of the composites can explain the warming of the late 20th century.
> copyright © American Institute of Physics
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Received on Wed Nov 18 12:49:32 2009

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