This is the second post in the series rebutting John Cook’s 10 most used climate myths at Skeptical Science. Climate myth 2 “Its the Sun”.
Sun and climate moving in opposite directions
“Over the past few hundred years, there has been a steady increase in the numbers of sunspots, at the time when the Earth has been getting warmer. The data suggests solar activity is influencing the global climate causing the world to get warmer.” (BBC)
Cook actually presents a decent and interesting chart that shows total solar irradiance (TSI) declining slowly while temperatures rise. TSI variance is in fact the only and minuscule natural climate forcing considered by the IPCC . Cooks TSI chart is model based since satellite measurements began around 1980. Since then TSI variance has had negligible impact upon climate.
Figure 1: Annual global temperature change (thin light red) with 11 year moving average of temperature (thick dark red). Temperature from NASA GISS. Annual Total Solar Irradiance (thin light blue) with 11 year moving average of TSI (thick dark blue). TSI from 1880 to 1978 from Krivova et al 2007 (data). TSI from 1979 to 2009 from PMOD (see thePMOD index page) Figure and caption from Sceptical Science.
So what’s up? Why is this not a climate myth? The simple explanation lies in the fact that the sceptic argument is normally founded on solar magnetic field strength and not on TSI at all. And so once again Cook misses, misrepresents or misunderstands the sceptic argument completely.
So why should variations in solar magnetic field influence climate on Earth and where is the evidence that it may have done so? It is worth pointing out that there are competing theories. All or none may have a measurable impact. This is NOT settled science. But it could be a very large piece of climate jigsaw, not yet properly understood but with potentially large impacts. At this point I was going to lay out the various lines of evidence for solar influence on Earth’s climate but that has grown into a quite substantial post that will come separately in a day or two.
[Note added 16:20, 18th Feb: Commenter William points out that Skeptical Science has an advanced tab which does go into great detail about a range of solar variables, so I stand corrected. Thank you William. Each variable is successively debunked and dismissed. Above I do say “All or none may have a measurable impact” and so any conclusion here is based on how one judges and weighs evidence. In my next post I will lay out the evidence for solar influence in a rather more balanced way.]