I agree Mark. I don't see how they can blame it all on Human activity. There are so many variables. Sure, anything that produces Greenhouse gases will effect the Worlds climate ie Industry, autos, Volcanoes ETC. But so does the Earth/Sun cycle, Sunspots, El Nino and La Nina--both long term and short term aspects of them. A long time ago Scientist say many Volcanoes erupted in a short time period and warmed the Earth so much that the Oceans main current stopped moving. This causes a mass extinction of Ocean life. Marine life is very sensitive to water temperature changes.
Some people think warming is a good thing but once the permafrost melts and desalinates the Oceans, life on Earth is pretty much doomed. Will this happen no matter what we do? Probably. Human activity is likely speeding the process up according to a good many Scientist.