Have you ever heard of the Paleocene–Eocene Thermal Maximum? During this time in earth’s history, the middle temperature was 8 K higher than today. That is much higher than even the most pessimistic predictions for our climate change, that atleast I have head of yet (which mostly don’t exceed +6 K). It also happened during a relatively short timespan (around about 20.000 years … basically nothing in geoogical terms). All of this without our influence. So, if you ask me, if we contribute something to the global warming: Of course we do, carbondioxide is a known greenhouse gas after all. The only matter to discuss is how much of it is natural and how much is manmade, because obviously the planet is more than capable of drastically changing it’s climate all by itself … and although this climate change coinciding with the industrial revolution is an important indicator, that we should not simply forget, causality and correlation are not interchangable.