"The National Academy of Sciences is a private organization chartered by Congress to advise the government of scientific matters."
It is a shame that the National Academy of Sciences has allowed its reputation to be sullied by releasing a report with unsubstantiated assertions. This insistence that global warming is caused by humankind activity is nothing more than a new version of the "Chicken Little" story. Chicken Little concluded that the sky is falling because he got a bump on his head from something falling from the "sky." These academicians are saying that global warming is caused by humankind, instead of asking a few more questions about our natural climate change and variation. It is a shame to see questionable assumptions being recycled so boldly.