Stardate 20011116.0548 (On Screen): Studies of iceberg melting patterns shows that over the last 12,000 years there has been a 1500 year cycle of warming and cooling caused by slight changes in the amount of sunlight reaching the earth, due to changes in the output of the Sun. This agrees with tree-ring studies. Evidently extremely small changes in solar output (%0.1) can result in substantial warming and cooling of the earth, because both are self-reinforcing cycles due to the fact that snow is white and reflects light back into space. (So the more snow you have, the more likely you are to get snow.) Interestingly enough, for the last 200 years we've been in the warming part of that solar cycle and in about the next hundred years we'll be coming to the peak of it, after which the earth will begin to cool again. The prediction is that in about 1100 years there will be another mini-ice-age such as the one which froze Europe in the 14th century.
Which of course begs a question: what has carbon dioxide got to do with it? Well, apparently nothing. It's possible that carbon dioxide also has an effect, but it may well be that much, perhaps even most, of the current warming cycle is due to solar variation and has nothing whatever to do with human activities. But you sure wouldn't know it from reading this article:
"The climate system is extremely sensitive to weak forces, such as solar variability," Bond said. "That should make us that much more worried about greenhouse warming."
Greenhouse warming is believed to be caused by an increase in the atmosphere of carbon dioxide from the burning of fossil fuels, including oil, gas and coal.
I think that Bond is reaching here. While it's true that the study shows that the ecology of the earth is sensitive to small perturbations, it's also true that the study shows that the earth would be warming now even if there were no humans on it. If anything, his study plays down the significance of human activity, and suggests that in about two hundred years the earth will begin to cool despite human activity. His statement about greenhouse warming is a political statement not based on his scientific research. (discussion in progress)
