[thstone]

Your question goes straight to the heart of the global temperature debate which currently seems to have (at least) two competing theories: Solar driven and C02 driven.

In the solar driven theory, increased sun activity causes C02 levels to rise which warms the planet. This warm period is then followed by a slower cooling period as the increased sun activity wanes and the planet absorbs the excess C02. This theory appears to fit the ancient historic data based on Antarctic ice cores.

In C02 driven theory, the use of fossil fuels and resulting increase of C02 emissions overwhelms the natural solar driven thermal cycle and has changed what would classically be expected to be a cooling period (because of lower sun activity) into a recent warming period. This theory appears to fit recent (50 to 80 year) data and this is the "smoking gun" that most people use as their reference point in saying that global warming is "proven" to be caused by man.

However, the water gets pretty muddy when all of the data from the past 50-years is analyzed in regards to the influence of the sun, C02, and global temperatures. At this point, there is no overall scieentific consensus on what causes what or how significant of an influence any particular driver (solar or C02) might have on global termperature.

The scientific community continues to research and debate these two theories today and neither has been proven to be the only correct theory.

Without a clear concrete scientific basis some people are concerned about using these theories as the basis for public policy decisions while others contend that waiting for the science to be fully proven only delays implementing some obvious fixes that are likely to be required regardless of the outcome of the scientific theory and that we might as well start now.

This can be a touchy subject. Hope that I didn't make anyone mad.