A phenomenological sequel

The study by S&W has some suspicious results. When their simple ‘phenomenological thermodynamical model’ (PTM) is forced by a signal with shorter time scales (high-frequency response representing the ~11-year solar cycle), it produces weaker response than if the forcing has longer time scales (or lower frequency) – as expected. But if you add a long-term trend to the former, the amplitude of the high-frequency response diminishes further (their Figure 4, reproduced above): The amplitude of the higher frequency response in their upper panel (4mm measured in the print) had diminished by ~50% in the lower panel (2mm). This is probably because the relaxation time response has been increased between the two panels and is greater than 10 in the lower panel. The presence of a trend should not affect the amplitude of the higher frequency in such a simple linear system (see my reproduction above).

Their figure 5 (below) does not correspond with the discussion in their paper (see scanned part of the text). Again, their analysis is sloppy in the estimate of change, underestimating the observed temperature change (T(obs) in Fig 5a, the total warming is stated to be ~0.8K since 1900, but the figure suggests it is greater than 0.8K) and exaggerating the solar contribution T(sol). This way, the fraction T(sol)/T(obs) gives the impression of a more sensitive response to changes in the Sun. They then proceed to use the lower T(obs) estimate for Mann & Jones (2003) for the total temperature change (claiming 0.8K, although this is too low), but taking a solar contribution estimated from the Moberg et al. (2005) temperature with more pronounced variations (the right estimated warming should exceed 1.0K – not 0.8K as they claim). Hence the fraction of solar signal to total change T(sol)/T(obs) is spuriously inflated.

S&W Figure 5Copy of S&W discussion of Fig. 5

But what about GHGs if the sensitivity is so high and the relaxation time is so long? We know from laws of physics and lab measurements that the CO2 levels have been increasing and that CO2 absorb infra red radiation. In fact, the Mauna Loa observations done by infra-red gas analysers measure the absorbing properties of air samples – a pure GHG effect on a microscopic scale without feedback effects. The high climate sensitivity and long time delay suggested by S&W would be scary – imagine the GHG warming that is not yet materialised and would be in the pipeline! (Lindzen who doesn’t believe in the lagged response would indeed be surprised if this was the case!).

S&W propose two mechanisms which may amplify the response to solar variations: (i) GCR (here, here, here) or (ii) UV-radiation.

But S&W ignore the issue about the lack of trend in the GCR (Lockwood & Frohlich, 2007; Benestad, 2005), the fact that trends in the diurnal temperature suggest otherwise (IPCC, 2001, 2007), and that there is not a clear trend in the cloud cover. Thus, explanation (i) is not convincing.

The problem with the UV-explanation (ii) is that the stratosphere has been cooling – some of which is due to the ozone depletion. How could they have ignored that?

Finally, the paper oozes of vague but subjective and cherry-picked statements forming the impression that the climate and solar reconstructions of Mann & Jones (2003) and Lean (2000) (why not use more recent reconstructions, by the way?) respectively are less accurate than others. Apparently because these do not give the desired results.

The paper also offers some incorrect references (Kristjansson et al, 2004, do not support the notion that GCR affect the climate). Furthermore, their paper contains little physics, but is little more than a curve-fitting exercise with no cross-validation.

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