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.
At the same time, the supremely self-confident Viscount (Christopher) Monckton, the most vociferous of the advocates, came across as a clever undergraduate debater crossed with a snake-oil salesman. Various expensively-suited figures connected to big business hovered in the background. Whatever their arguments, they were not an attractive bunch.
Far more sympathetic were the astronomers and solar physicists with whom I have spoken over what has been an eight-year study. Helped by a grant from the Sloan Foundation in New York, I travelled to 18 countries, on every continent, meeting scientists as far apart as Antarctica and Arizona, Tromsø (in arctic Norway) and Tokyo, Beijing and Bolivia, Jaipur and the Jet Propulsion Lab in California. All of them agreed on one point: that improved technology and new discoveries have meant that we are on the verge of — may even have begun — a golden age in solar research.
We understand more not only about the Sun’s heat and luminosity, but what causes sunspots, when they will occur, how solar flares operate and what effects solar magnetic forces have on our planet. Modern telescopes are becoming ever more powerful, while we can create laboratory versions of plasmas whose behaviour mimics phenomena such as the explosion of stars, coronal ejections and solar prominences — huge gaseous arches that extend outwards from the Sun’s surface.
And with the Solar Dynamics Obervatory, Hinode (a Japanese satellite), Stereo and Soho, there are more spacecraft than ever before studying the Sun. Within four or five years, Nasa is to launch Solar Probe Plus, which will reach to within ten solar radii, or 4,360,000 miles, of the Sun — so close that it will be able to look at the solar plasma as it is evolving.
It is an exciting time, and I have found one conclusion unavoidable: as far as global warming is concerned, Al Gore’s claim that “the science is all settled” is far from the truth. How can it be otherwise, when we are about to learn so much more about our nearest star? The Sun still has plenty of surprises for us. And as for our weather — as Joyce’s Leopold Bloom so charmingly put it — it is “as uncertain as a child’s bottom”.