The earth has certainly gone through a lot of hot times and cold times.  What I do is study deep time by looking at Co2 levels and relative temperatures and we are coming out of a cold time and moving into a hot time.  However, for this particular time in history, we should be moving back into a cold time.  

If we consider the entire ice ages of the last 2 ½ million years, we’ve been in a 10,000 year calm of warmth, and it’s time to go cold again. And yet, it doesn’t seem to be in our cards because of all the carbon dioxide we have put into the system.  In fact, we are now at levels that the world has not seen for the last 40 million years and we will soon be at carbon dioxide levels that existed 100 million years ago when we had a true hot house world.  

So, the game has been changed.