L'Ombre de l'Olivier

The Shadow of the Olive Tree

being the maunderings of an Englishman on the Côte d'Azur

29 August 2008 Blog Home : August 2008 : Permalink

The Science of The Last Centurion

John Ringo's "The Last Centurion", as I have pointed out before, makes some controversial points regarding climate change. Over at Baen's Bar a commenter claims that the science is bad. I replied by pointing out that Ringo's predictions of cold are not his alone and linked to this recent article which makes the case for the sun impacting terrestrial temperatures more than humans do in an easily accessible fashion. The article proposes that cooling is caused by increased Cosmic Ray incidence caused in turn by a weakening solar wind.

The response was to point to a realclimate post on Cosmic Rays and Total Solar Insolation and an attempt at credentialism. My response to his response is below.

Firstly I'm going to play the ball not the man. Hence I shall treat your meteorologist crack with the contempt it deserves except to point out that another metoerologist Anthony Watts has done more to clarify the (mostly abysmal) quality of the US Surface Station network than any climate scientist.

OK back to the sun issue. There are two things at issue here
  1. Whether the sun is in a low sunspot mode at present
  2. Whether low sunspot count correlates with cold earthly temperatures
Taking 1. We are currently in between cycles 23 and 24 and have some 400 non cintiguous days without sunspots. There have been some small shortlived c24 spots but nothing compared to the number of spots that were predicted.

As well as the link above see also the links from it as well as http://www.solarcycle24.com/ and the amusingly wrong predictions from NASA's David Hathaway a couple of years ago.

Dr Hathaway has more recently said that

"It does seem like it's taking a long time," allows Hathaway, "but I think we're just forgetting how long a solar minimum can last."

To me this looks a lot like wishful thinking although I think he is right when he says that we are not yet in a Maunder or even a Dalton minimum. To summarise: I think it is pretty clear that the sun is a lot less active than it used to be a few years back. Arguably Mr Ringo makes his predictions for the big solar switch off one solar cycle later than reality.

2. The question of whether sunspot minima effect earthly temperatures is of course a bit trickier. We've only been observing sunspots systematically for 250-300 years and even though the telescope-less Chinese did record before that the records are limited and hard to compare. For example many of the sunspots observed during this inter cycle minimum are small enough that they would probably not have been observed a century or more ago.

In other words as earthly temperatures have risen we have also become more able to track sunspots. But on the other hand both the Dalton and Maunder minima involved cold terrestrial weather while sunspot maxima have been observed in warmer times. Furthermore there are other links e.g. those noted in this paper from 1999 with the following abstract:

It has been suggested that the length of the solar cycle (SCL) is related to solar forcing of global climate change [Friis-Christensen and Lassen, 1991]. Although no physical mechanism had been proposed, the relation seemed to be supported by interesting correlations with several paleoclimate records and, separately, with the 20th century

Northern Hemisphere instrumental record. Actually, what has been correlated is the quasi-sinusoidal Gleissberg cycle which is slightly greater in the 18th century than in the 20th century. Using the pre-industrial record as a boundary condition, the SCL-temperature correlation corresponds to an estimated 25% of global warming to 1980 and 15% to 1997.

Another paper of interest is http://cat.inist.fr/?aModele=afficheN&cpsidt=1123803

It seems to me that whether or not cosmic ray incidence is the cause (more research needed one suspects) there is likely some correlation between solar activity and earthly temperature. A theory that is strengthened by recent reports that temperatures on other bodies in the solar system have also risen in tandem with the past decade or
two of increase in solar activity.

In summary John Ringo may well have skated over the scientific backing for the book and he has certainly taken a "non-consensus" position but with regards to the climate it isn't quite as unfounded as one might imagine.