> My latest book,[1] just released, is about a climate change debate between Professor David Karoly of the University of Melbourne and Professor William Happer of Princeton, emeritus. One of the most interesting debate topics was about the attribution of global warming. The host was James Barham of TheBestSchools.org. Barham asked David Karoly in his interview: “If increased atmospheric CO2 is not responsible [for global warming], what is?” TheBestSchools notes that skeptics point out several factors that need to be considered before we can reach this conclusion: > 1. We are, after all, still recovering from the last ice age (in the true sense of the term), which lasted for about 100,000 years and only ended about 12,000 years ago; therefore, why isn’t modest warming simply what we should expect (the null hypothesis) … 2. Over the geological record taken as a whole, it appears that warming trends regularly precede rising CO2 levels, not the other way around. 3. Some studies show a strong correlation between solar activity cycles and Earth surface temperatures.