Many anthropologists and sociologists don't like Jared Diamond because of his ecological deterministic view.
I'm not absolutely sure what ecological determinism is. I generally don't like him because he tends to blame humans for all the world's ecological ills but doesn't bother to prove it. He's a raging liberal. But even liberals make valid points at times and I think the El Nino phenomenon accounts for enormous fluctuations in rainfall. The Nazca and Moche civilizations also fell because of El Nino-caused drought.