Did the Royal Society acquit the sun of blame for global warming? Here’s one astronomer (and former BBC science correspondent) who’s not quite so sure:
Last week’s research is a simple piece of science and fundamentally flawed. Nobody looked beyond the hype; if they had, they would have reached a different conclusion. The report argues that while the sun had a significant effect on climate during most of the 20th century, its influence is currently dwarfed by human effects. It says that all known solar influences since about 1990 are downward and because global temperature has increased since then, the sun is not responsible. No. The research could prove the contrary. Using the global temperature data endorsed by the Inter-national Panel on Climate Change, one can reach a completely different conclusion. Recently the United States’ National Oceanographic and Atmospheric Administration said that 2006 was statistically indistinguishable from previous years. Looking at annual global temperatures, it is apparent that the last decade shows no warming trend and recent successive annual global temperatures are well within each year’s measurement errors. Statistically the world’s temperature is flat. The world certainly warmed between 1975 and 1998, but in the past 10 years it has not been increasing at the rate it did. No scientist could honestly look at global temperatures over the past decade and see a rising curve. It is undisputed that the sun of the later part of the 20th century was behaving differently from that of the beginning. Its sunspot cycle is stronger and shorter and, technically speaking, its magnetic field leakage is weaker and its cosmic ray shielding effect stronger. So we see that when the sun’s activity was rising, the world warmed. When it peaked in activity in the late 1980s, within a few years global warming stalled. A coincidence, certainly: a connection, possibly. My own view on the theory that greenhouse gases are driving climate change is that it is a good working hypothesis – but, because I have studied the sun, I am not completely convinced.