I’ve just noticed that this article is duplicated at WUWT. In his bio there, Rud Istvan explains his view that although climate change will have little impact on food production during the 21st Century, food scarcity will still be a serious problem.
He says absolute food scarcity will occur when population reaches about 9 billion and that it will be “very ugly”.
So, although he has reached a sane conclusion about the relationship between Co2, temperature and crop yields, he is, in fact, still barking mad.
He should read some of Norman Borlaug’s studies on how food scarcity has been, is, and will be diminishing over time, and that in 50 years time feeding 10 billion people will be easier than feeding 7 billion today.