After my Climategate piece an enraged reader wrote 'Holland is actually under sea level. Norwich isn't. I can't read past that elementary mistake'. I made a suitably gentle reply to the effect that there was no mistake as I had not said Holland or Norwich were above or below sea level but that both were perilously close to it. However, as I pondered the issue, ruminated on other comments I have received about the piece I have come to appreciate how passionate people are about the global warming debate. The term I would use about the dispute is 'bitter' and those who argue that there is a consensus and the science is settled really haven't looked at the literature or the blogs on this. Henry Kissinger was once asked why academic disputes were so bitter? His pithy reply: 'it is because they have so little to lose'. We often forget that in academic life the coinage is reputation and in this debate there are a lot of reputations to lose.
One result of reading this literature was that I dug out some doctoral work performed by a student of mine in the early 90's. The sudent concerned was attempting to establish whether Kondratieff's could be discovered in the historical evidence of economic activity. Kondratieff's are cycles of 70 years or more. Our investigation took us to the tin mines of Cornwall and the records of their output which go back to the 10th century. No Kondfratieff's. We also looked at output of bread from the manors and also battle fatalities. No evidence of Kondratieff's. The disappointed student attempted a wide range of statistical and mathematical techniques including Fourier Analaysis but still no evidence in the data of a long cycle. What did emerge was a medium strength cycle centred around 11.4 years - information from the Royal Observatory at Greenwich confirmed that we had picked up the solar sunspot cyles in the data. Key question: why should sunspots affect the mining of tin? Our best hypothesis was that mining and agricultural labour are interdependent activities. When the harvests are plentiful people stick to farming, when times are not so good they go down the mines. So, a very tiny example of the impact the changing sun has on climate.
Which leads me to my concluding thought on the vexed debate on the causes of climate change. To paraphrase Clinton's dictum: 'it's the sun stupid'. Maybe.