&gt;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.<p>Except... that data does exist. Sediment cores do contain evidence of past levels of atmospheric carbon dioxide to a fairly high degree of accuracy, and we have sediment cores going back up to about million years ago, or so.<p>&gt;Global warming caused by CO2 has never been proven<p>Sure, you can&#x27;t do a double-blind randomized control experiment with the earth, but when two variables are clearly correlated with a time difference, over millions of years, controlling for confounding factors, it&#x27;s pretty clear that one causes the other.<p>&gt;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>According to Scientific American [1], the last ice age ended because of a rise in atmospheric carbon dioxide.<p>[1] <a href="http:&#x2F;&#x2F;www.scientificamerican.com&#x2F;article&#x2F;what-thawed-the-last-ice-age&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.scientificamerican.com&#x2F;article&#x2F;what-thawed-the-la...</a>