The Sun threatens us and baffles us. Occasionally, we baffle ourselves. A couple of weeks ago, the Daily Telegraph reported: "Stronger Sun makes Earth cool, not hot, say experts." The article cited a study of the Sun conducted between 2004-7, and concluded that as solar activity fell during one of the Sun's 11-year cycles, the light and heat reaching the Earth rose — the opposite of what many scientists were said to have previously believed.
So what does that tell us about that vexing subject, global warming? Professor Joanna Haigh of Imperial College London, who led the study, which was first published in Nature, summed up: "It may suggest that we don't know that much about the Sun...We cannot jump to any conclusions based on what we have found." A sensible note of caution, although one may wonder whether the study was needed in the first place since as recently as 2005 the Russian astronomer Khabibullo Abdusamatov predicted that the Sun would reach a peak of sunspot activity in 2011, which would cause "dramatic changes" in temperatures — downward, not upward.
We have known for some time that the Sun is about 15 per cent broader than it was 4.5 billion years ago, and is radiating about 25 per cent more heat than it was at its birth — but that various pollutants prevent all this energy from reaching us. From about 1960 to the early 1990s, the average amount of sunlight, both in duration and strength, that has reached us has decreased by as much as 10 per cent. So the picture of the Sun's effect upon us is a complex one.
Nasa's Soho satellite has photographed our nearest star in extreme ultraviolet light (Photo: Nasa/Soho)
I have just completed a history of the Sun (Chasing The Sun, Simon & Schuster, £30) in all its myriad aspects, from solar mythology through to its place in literature, music and art to the latest research in solar nuclear fission. I had to confront the issue of global warming. The debate between the "global warmers" and the "deniers" was so heated that I dreaded having to deal with the subject, for all its importance, but duly went through all the research literature. I had no agenda and approached the issue with an open mind. It seemed to me that the arguments that rises in CO2 were warming the Earth presented a compelling case: one molecule of the stuff in the course of its lifetime traps a thousand times more heat than is released in producing it, and removal of excess CO2 is going to become less efficient as the planet heats up, facts that are very hard to refute. And the many natural disasters — from droughts and tsunamis to ice caps melting — made me want to make the obvious connection.
I decided I should attend a couple of the Deniers' conferences, both of which attracted more than 400 delegates. They were odd affairs, held in a New York hotel, with speakers rousing their audience to chant anti-warming songs as if they were part of a revivalist meeting.