Originally Posted by UncleHoney
Clouds and cosmic rays maybe.
Nice idea but does not hold water (if you will forgive the pun), the problems with it are legion ....
1) The number of cosmic rays impacting the Earth has not changed significantly over the time period when we have seen the fastest increase in global warming.
2) Cosmic rays are absorbed higher in the atmosphere than where clouds usually form. There is not much moisture up there to condense into clouds.
3) CRs produce a lot of charged particles which are not large enough by themselves to form condensation centers, so the CR theory postulates that they merge but have you ever tried to force two magnets together with the same polarity (hard, isnt it?)
4) Lastly, there are two schools of thought as to whether high thin clouds will help heat the planet (by trapping more heat) or cool it by reflecting more sunlight back out into space.
Svensmark says this is "a new theory" but to my knowledge it has been pushing around since the mid 90's in one form or another.