Chris S recently posted a lengthy comment, an extended excerpt from a recent Proceedings of the Royal Society paper. Full citation is: Solar change and climate: an update in the light of the current exceptional solar minimum
Proc. R. Soc. A 8 February 2010 vol. 466 no. 2114 303-329
The abstract is here.
It makes for a very interesting read with lots to think about so I though I would promote it to a post of its own….
The history of science reveals a series of ‘controversies’. These often develop into a state where there is little debate within the relevant academic community (and what there is tends to be on peripheral issues), yet widespread popular debate remains. This usually occurs because the research has challenged the beliefs of a significant fraction of the population at large. The nature of the controversies, however, has changed. Where, for example, the advances made by Galileo and Darwin faced opposition because they challenged the established teachings of organized religion, climate scientists in the developed world have faced opposition from their more secular societies because they challenge beliefs that justify lifestyles and/or political allegiances (Malka et al. 2009; Nisbet 2009). But there is a crucial difference about the climate change debate compared with many of its predecessors: humankind could often afford to wait for previous controversies to abate and the main damage done was an unnecessary delay to the implementation of some of the benefits of the research. There is evidence that public opinion on climate change has changed rapidly in many countries and among many demographic groups (e.g. Staudt 2008; Sampei & Aoyagi-Usui 2009), but there is also evidence that time for effective action is extremely short (Kriegler et al. 2009; Vaughan et al. 2009).
There is a third new dimension to the public debate about anthropogenic climate change–the Internet. Georg Christoph Lichtenberg (1742-1799) was the first professor of experimental physics in Germany. He was, himself, no stranger to controversy and often satirized the misuse of science. His notebooks from the second half of the eighteenth century are full of comments of remarkable relevance to the role that the Internet has played in the climate science debate. For example, he wrote ‘the most dangerous untruths are truths slightly distorted’ and ‘blind unbelief in one thing springs from blind belief in another’ (Katritzky & Lichtenberg 1984). The Internet has played a useful role in conveying some of the understanding, images and data that lead climate scientists to their conclusions. However, it has also become a haven for un-refereed pseudo-science with dangerously incorrect inference. It has served to give the false impression that there is a serious, widespread academic debate on the basic nature of climate change. The most popular argument runs like this: ‘The Sun drives Earth’s climate system. Therefore changes in the Sun must drive changes in Earth’s climate system’. The first sentence is, of course, absolutely correct; but understanding why the second sentence does not follow from the first requires scientific training and study. The urgency of the need to resolve this distinction between academic and popular understanding places scientists in a dilemma. By trying to find easy-to-understand yet irrefutable ways to demonstrate the fallacy of the above argument (and others that are more intricately constructed but no less misleading), one risks appearing to give scientific credibility and exposure to ideas of no scientific merit.
Scafetta & West (2007) and Scafetta (2009) have proposed that the use of a single response time is not adequate and the climate system has a relative rapid response of approximately 1 year and second of about a decade. Using a combination of the two, they then deduce from a multivariate fit that 65 per cent of the GMAST rise can be attributed to TSI change. Section 10 considers the energetic implications of this. Neither Lockwood (2008) nor Scafetta (2009) quotes the statistical significance of their best multivariate fits, but Lockwood (2008) did compare the 2Ï deviations from the best fit for GHG and solar forcings. There are a number of complications with this kind of fit; for example, unknown inter-correlations between the inputs can influence the results. In evaluating the significance of any correlation derived one must allow for the degrees of freedom in the fit. Lockwood (2008) used seven fit parameters (a weighting factor for each of four inputs plus a lag for each except for the GHG forcing as it was taken to vary linearly with time). The formulation of Scafetta (2009) would, to be completely general, require 16 fit parameters (two lags for each of four inputs, which should all be treated in the same way, with a weighting function for each input/lag pairing). The significance of any such multivariate fit is dramatically reduced (especially when the effect of the autocorrelation of each sequence in reducing the effective number of independent samples is also considered). Further comments have been made by Benestad & Schmidt (2009). One key factor to note is the importance to the analysis of Scafetta (2009) of using the ACRIM TSI composite, on the grounds of the analysis of Scafetta & Willson (2009), but as discussed in Â§5, the justification for this is based on the application of an entirely inappropriate TSI reconstruction. The reason that this matters is that the PMOD composite shows that the mean TSI has fallen since 1985 (Lockwood & FrÃ¶hlich 2007), so that even the decadal scale lag proposed by Scafetta (2009) cannot explain the fact that temperatures rose until 1998 unless the ACRIM composite is used. The ACRIM TSI composite is the only one that shows a long-term peak in 1992 (see figure 4 and Lockwood & FrÃ¶hlich 2008), which would allow the long time-scale response proposed to match the apparent plateau in the HadCRUT3v GMAST data.
Just how poor and ill-informed some of the debate appearing on the Internet can become is illustrated by recurrent reports that global temperature rise is associated with changes in the corpuscular emissions of the Sun. The total energy input from the thermal solar wind plus suprathermal solar particles into the atmosphere and inner magnetosphere (some of the latter may be deposited in the upper atmosphere at a later time) is of the order of 1013âW or, per unit surface area of the Earth, 0.02âWâmâ2. Even if we take the extreme case that this input was entirely absent during the MM (known not to be the case), we would require an amplification by a factor exceeding 250. Furthermore, this very little energy is deposited in the upper atmosphere (the thermosphere) and there is no known viable mechanism in the published literature that will allow it to influence the global troposphere, let alone with this huge amplification factor. It is true that the history of solar-terrestrial physics shows that one cannot use the absence of a known mechanism as more than an indication: Lord Kelvin famously dismissed the growing evidence for solar influence on the geomagnetic field as ‘mere coincidence’, using an argument based on magnitudes (Kelvin 1893). The argument turned out to be wrong because it did not allow for the existence of the solar wind (which was not suggested until 1901 by George Fitzgerald). However, that situation is not at all analogous to the present situation concerning climate change. Lord Kelvin was not proposing an alternative explanation and he was quite right to point out that chance agreements do occur in datasets of limited duration (but wrong to dismiss the possibility that it was real). In the case of climate change, there is no doubt that global mean temperatures have risen, so that the effect is known to be real. Furthermore, there is a viable explanation of that effect, given that the amplification of radiative forcing by trace GHG increases by a factor of about 2 is reproduced by global coupled ocean-atmosphere models. What is alarming is that in the face of this strong scientific evidence, some Internet sources with otherwise good reputations for accurate reporting can still give credence to ideas that are of no scientific merit. These are then readily relayed by other irresponsible parts of the media, and the public gain a fully incorrect impression of the status of the scientific debate.
It is important not to make the mistake made by Lord Kelvin and argue that there can be no influence of solar variability on climate: indeed, its study is of scientific interest and may well further our understanding of climate behaviour. However, the popular idea (at least on the Internet and in some parts of the media) that solar changes are some kind of alternative to GHG forcing in explaining the rise in surface temperatures has no credibility with almost all climate scientists.