For decades, scientists, doctors and dietitians said that eating fat caused heart disease, and you should decrease your fat in your diet.  Only in the last couple of years has this &quot;fact&quot; been deemed wrong.<p>I don&#x27;t think you would have found a single scientist, doctor or dietitian since the 70s that would have disagreed with the above.  It was taken as fact and anyone who thought differently would have been a laughing stock.<p>The same goes with global warming caused by CO2.  It makes for an easily digestible theory, but it doesn&#x27;t explain many known facts.  Global warming caused by CO2 has never been proven, obviously, since you can&#x27;t do experiments on a global scale.  So there&#x27;s already a lot of faith that you would need to take into consideration.  There&#x27;s circumstantial evidence at best.  But still a lot of unknowns about climate and the vast changes that the Earth has  undergone over the last 6B+ years, so to say that we know that the current warming trend is caused by CO2 to me is not science.<p>If you read this thread, it&#x27;s humorous to read all of the people who think that there is data going back millions of years that links CO2 to climate change.  It&#x27;s a great example of how regular people just take whatever is spoon fed to them without thinking &quot;really, does that make sense?&quot;<p>For example, North America was covered in ice at one point, and the temperature increased dramatically over the last hundreds of thousands of years.  What caused this, and could the same process be responsible for the warming we have seen in the last several decades?<p>The 5000 year old Iceman found in the Alps attempted to cross the Alps when there was very little snow.  We know this because of the clothes that he was wearing when his body was found.  So obviously the climate was much different 5000 years ago than today.  What caused this change, and could the same process be responsible for the warming we see now?<p>We know that during the Medieval Warming Period, it was a lot warmer than it is now. What caused this change, and could the same process be responsible for the warming we see now?<p>I would like these questions answered before I change my opinion.  As a man of science, I see too many people flocking like sheep to the answer of CO2 causing climate change.  Just like the whole fat-in-the-diet belief, too many people don&#x27;t really think, they assume that the scientists are right, which is not thinking, in my opinon.