Actually, he didn't. FWIW, he provided more evidence in support of his global warming skepticism than he did in support of his other skepticism, skepticism that you didn't question.
But, I'll play along. How much support should he have given for each of his arguments to satisfy you?
Had the author made a weaker claim I'd have read the rest of the article with much less skepticism!
Telling us how he could have satisfied you wrt a different argument is interesting but he question was "How much support should he have given for each of his arguments to satisfy you?"
Note that he suggested skepticism wrt multiple things, suggesting that general skepticism is a good idea, yet you're only discussing one of them.
Suppose we conclude that skepticism wrt global warming is unwarranted. What, if anything, does that say about his general conclusion?
Likewise, I use your treatment of his examples. As I pointed out, he provided better support for his global warming skepticism, which you rejected, than he did for his other skepticism, which you accepted.