They fail to acknowledge that you cannot detect long term trends with short-term data

Durkin’s “Swindle” film has just been shown nationwide on Australian TV and furious Warmists have concentrated their attack on the fact that his graphs of solar effects ended in 1980.

It has been known for some time that solar output has been in decline for the last 20 years or so and this is held to undermine the claim that recent global warming can be explained by variations in output from the sun. Apparently provoked by the Durkin film, Lockwood & Froehlich recently produced a paper (“Recent oppositely-directed trends in solar climate forcings and the global mean surface air temperature”) that drew further attention to recent solar trends as being inconsistent with the Durkin contentions. They examined a whole range of solar measurements and showed that, by most measures, solar output was falling rather than rising in recent years. And that paper has been widely promoted as “debunking” Durkin’s contention that variations in solar output are the only good long-term explanation of climate change.

I have now had a preliminary look at the Lockwood paper and note that there is a very large dog in it that did not bark. If solar output does not explain recent temperature variations, what does? With the monomania about CO2 among Warmists, one would have expected a graph of CO2 levels plotted against temperature. There is no such graph. In other words, CO2 levels do not explain recent temperature variations very well either. The fact that CO2 levels have continued to rise in recent years while surface temperatures peaked in 1998 would appear to be the elephant in the bedroom. If solar output levels and terrestrial temperature have diverged in recent years, so too have CO2 levels and terrestrial temperature.

The important point in the matter, however, is one that climate skeptics have been making for years: There are MANY variables that affect terrestrial temperature from time to time — not just CO2 and not just the sun. And to tease out the effect of any one variable, you have to look at a fairly long data series — so that fluctuations due to other sources will be smoothed out. It is partly for this reason that most of the plots of climate against temperature extend over many centuries. A period of just 20 years is too short to detect long-term trends. One needs long-term data to detect long-term tends and there are any number of graphs showing a long term relationship between solar output and terrestrial temperature.

Additionally, many effects may be lagged: the influence concerned may take some time to show up. One reason for this is the vast reservoir of heat, CO2 and much else that girdles the earth: The ocean. It takes some time for a surface temperature variation to show up in the amount of heat stored in the ocean. When the recent drop in solar output works its way through all the systems — such as the ocean — that it affects we might therefore expect global COOLING. It is COOLING that the solar data suggests as imminent, not warming.

In the circumstances, one is mildly surprised that Warmists mention solar output at all. Surely even a Warmist realizes that the sun affects terrestrial temperature!

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