This is just a hunch, a thought, I'm hardly an expert on the subject. However, there may be a good reason ancient people worshipped the Sun as a god. Imagine how nice it felt to wake up to a warm sunny day when you had no heat. Imagine how appreciative you would be when spring returned and trees began leafing out and your crops began to grow. We know how nice it is to see the clouds disappear, and see the ice and snow melt. Maybe the Sun, the ultimate source of energy, around which the Earth revolves, the Sun which drives our winds, ocean currents and daily weather, maybe variations in solar energy output could influence global warming and cooling. This seems a bit more logical to me that a little bit of carbon dioxide. Would you like to bet billions or trillions of dollars on it?
The Sun's diameter is about 110 times that of the Earth.
From Canada's National Post
Bright sun, warm Earth. Coincidence?
"For the past century and a half, Earth has been warming. Coincidentally (or perhaps not so coincidentally), during that same period, our sun has been brightening, becoming more active, sending outmore radiation.""...the world's leading solar scientists are all convinced that the warming of recent years is not unusual and that nearly all the warming in the past 150 years can be attributed to the sun.""Mr. Abdussamatov concedes man made gasses may have made "a small contribution to the warming in recent ears, but it cannot compete with the increase in solar irradiance.""Mr. Soon (of the Solar and Stellar Physics Divisionof the Harvard-Smithsonian Center for Astrophysics) showed as long ago as the mid-1990s that the depth of the Little Ice Age -- the coldest period in the northern hemisphere in the past 1,500 years --corresponded perfectly with a solar event known as the Maunder Minimum. For nearly seven decades there was virtually no sunspot activity. Our sun was particular quiet. And for those 60 to 70years, the northern half of our globe, at least, was in a deep freeze. Is it so hard to believe then that the sun could be causing our current warming, too?"http://www.canada.com/nationalpost/news/story.html?id=551bfe58-882f-4889-ab76-5ce1e02dced7