Quote Originally Posted by GregortT View Post
Sunspot do go in cycles, but since they're cyclical they are not a cause of global warming (at least not the global warming that we are talking about) because the duration of the cycle is only 11 years, while the warming that is generally discussed is over the course of the last century or so. As was stated above, such global temperature phenomina have occured in the past over several centuries (if not millenia), so you could argue that even an entire century is simply too short a time-scale to tell. Remember: a century may seem like a long time to us, but it's almost negligible compared to the age of the Sun or the Earth. On those scales, an 11 year sunspot cycle is practically the blink of an eye.
True, the sunspot cycle itself, while contributing to fluctuations in weather, do not directly affect climate, as far as we know. What they are showing at that link is different. I quote:
"The recent trend of a .05 percent per decade increase in Total Solar Irradiance (TSI) in watts per meter squared, or the amount of solar energy that falls upon a square meter outside the Earths atmosphere. The trend was measured between successive solar minima that occur approximately every 11 years." (Bold emphasis is mine.)

It's my understanding that these kinds of measurements have only been available for the last 30 years or so, but that IF this kind of trend has been going on for the last century then it very well could be affecting our climate.

This site (http://zebu.uoregon.edu/~soper/Sun/cycle.html) states that during the period between 1645 to 1715 there was virtually no sunspot activity and the climate here on Earth was "unusually cold."

The point I'm trying to make is that, while there is no question of mankind having SOME influence on global warming, there is so much else happening that it is impossible to truly understand exactly how large an influence that is. The solar cycle is only one of the possible culprits. Tectonic activity within the Earth also plays a major role. Scientists have also recently (within the past 20 years) discovered huge deposits of methane ice buried under the sea bed. Disturbances, such as undersea mudslides and earthquakes, can uncover enormous quantities of this ice which then sublimates, releasing methane gas, a major greenhouse gas. All of these things seem to have a far greater influence on the global climate than anything we can do.

Sure, reducing our "carbon footprint" can reduce greenhouse gases somewhat. How much good it will do is questionable. One thing is practically certain. Any changes we make will be far less effective, and far more expensive, than politicians and conservationists want you to believe.