An error in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, which wrongly predicted the disappearance of Himalayan glaciers by 2035, fueled doubts about the authority, honesty and rigor of the IPCC as a leading institution in climate science and, correspondingly, raised questions about whether global warming is anything more than a hoax put forward by environmentalists. The late and confusing reaction of the IPCC to these allegations only worsened the matter. By comparing assessment reports issued by (...) the IPCC, this paper asks the question: ‘Why, despite extensive peer review, did the Himalayan glacier melting rate error get published?’ I chronicle exactly what happened, consider why it happened as it did, and show how these answers require us to rethink the concept of ‘peer review’ in scientific practice. I also identify several future directions for peer review if it wants to stay ahead of the game, bearing in mind the forthcoming IPCC Assessment Reports. (shrink)