The idea was presented that an active sun (with lots of sunspots) deflects alot of cosmic rays. When the sun enters a less active period, it doesn't deflect as many. Cosmic rays, for example interstellar protons, collide with the upper atmosphere in large numbers, creating a particle shower of charged ions that catalyze the nucleation of water droplets and form clouds. It's been speculated that this phenomenon causes up to 2% variation in the amount of cloud formation globally. A google search will easily come up with at least one paper that state the effect has been determined to be statistically insignificant, and no correlation has been observed.

That's not to say it isn't true, but this was the principle mechanism proposed in the video that explained the historical correlation between sunspot activity and global temperatures. IMO it's about as solid as the link between atmospheric CO2 and global temperatures. And either one of them is just a nuance of global climate fluctuations that are inherently chaotic. As such I doubt either one is really significant.

I think it's more likely that global climate is controlled directly by Solar Irradiance. Just look at seasonal changes in temperature and you'll have your proof. "Keep It Simple Stupid (KISS)" as the saying goes.

Now, explain to me why 10,000 years ago most of Canada was covered by a mile-thick ice sheet and I'll be impressed. So far neither anthropogenic CO2 nor sunspots explains an ice age. The former is too recent. The latter? Well, only if sunspots indicate massive change in solar output would I accept that theory.

Has anyone explored the effect on Solar Irradiance if the sun swallowed a large planet, or KBO ? What could possibly cause the Sun, a gigantic ball of nuclear fury 1.39 million km in diameter, and containing 98% of the mass of the solar system, to vary in it's output and cause an ice age on Earth? And I wonder if core samples from the ice sheets of Europa would yield corroborating evidence of Solar Variability over long timespans. I'd like to know. Could the earth have tilted to an extraordinary angle due to some wierd core-mantle dynamics, causing extended winter in the north? There's another idea.

Global Warming is "A Convenient Lie". As a political buzzword it has caught on much more rapidly than its predecessors "Greenhouse Effect", "Sustainable Development", et cetera. It may actually serve an important purpose in the more immediate future: outreach. I could call burning fossil fuels unsustainable, a non-renewable resource.... but that was the approach used in the 80's and 90's, and it didn't work.

Global Warming is good advertising. But... still not good enough. It doesn't work for everybody, particularly regions that are dependent, rich even, because of their fossil fuel reserves. I'll quote Canadian Prime Minister Stephen Harper who, when questioned about our country's inability to meet its Kyoto emissions reduction targets said "We're not going to engineer our own defeat." Or something to that effect. Well said, and telling. In alot of ways. We have a politically polarized population, 50% left-wing, 50% right-wing, each side invested in their own ideals and refusing to yield.

We've got 50 years of fossil fuels left in my estimates. Probably more like 30 years. Which problem would YOU like to solve? From which angle should we tackle it? It's an open question.