Originally Posted by onwebcam

What is this mysterious other factor?

The Sun
http://solarscience.msfc.nasa.gov/SunspotCycle.shtml

Imagine that. That big thing that gives us light warms things up on occasion..

Should we tax the use of the sun? Or is this the roundabout way of doing it? I mean after all we are going to move to solar and wind power eh?