Interesting. Also important to keep in mind that he was a sci-fi writer who believed that clairvoyance and astral projection are real things.
I'll give a short take on some of his biggest points.
1. He uses weather patterns from single points to make a case against global climate change. Fundamentally unsound.
2. His use of very few selections from very few studies is misleading. The body of work, in its entirety must be studied, not just the parts that confirm your bias.
3. He apparently confuses sunspot cycles with changes in Total Solar Irradiance. Hard to tell because his info is wrong. He claims that sunspot activity was at a peak(2008) but in reality the peak was hit in the 1960's and has continued downward since.
4. He correctly states that the future is very hard to predict. I am unclear on his point however. Do you think he means that because it is hard we should stop trying or that we shouldn't take precautions just in case? If so, that's like saying "hurricanes are hard to predict so I'll live in a paper shack on a barrier island".
I do agree with him on the fact that causes(environmentalism, etc) can become religious in nature for some. What I disagree with is his idea that because you have extremist environmentalists that it colors the entire idea of environmentalism. Extremists in any arena are usually not a good thing. I also agree that science should be the foundation of any and all policies.
I've enjoyed his fiction for years so its no surprise that I enjoyed reading these fictional works as well.