I would like to comment about a statement made by Neil deGrasse Tyson during and episode of Cosmos.  He said "The theory of global warming is as much of a theory as the theory of gravity." Now, this is not a direct quote as I cannot remember his exact words but his point was since the theory of gravity is a fact then the theory of global warming is a fact.  He obviously does now know the difference between fact and theory. 

The only thing we know about gravity that can be considered a fact is Newton's Law, which is nothing more than an equation that can be used to predict what happens but cannot say why.  We still do not know what gravity is or why it does what it does.  That is a fact.  So...Neil is correct in his statement, although the point he made is the opposite of the point he wanted to make.  We know the earth has warmed a little but we have not proved why.  It is all theory and theory is not fact. 

Some may say 'but we have evidence to support the theory.'  Of course you do.  It would not be a theory if there was no evidence to support it.  It cannot be called a theory without evidence.  It would only be a hypothesis.   Never forget that theories change all the time as new evidence is discovered.

 "No amount of experimentation can ever prove me right; a single experiment can prove me wrong." - Albert Einstein