Repeat something a sufficient number of times and, eventually, people will believe it, no matter whether it is true or not. It is one of the most effective tricks of propaganda and it has been used more than once against science, for instance in the demonization of the "Limits to Growth" study. During the past few years, it has been applied repeatedly, even obsessively, against the "hockey stick," the reconstruction of past temperatures on which Michael Mann and coworkers had been working from the 1990s.
It is rare in the history of science that a single piece of experimental evidence has been the object of so many attempts of demolition. Yet, all the serious reviews of the original data have basically confirmed the initial results. Being unsuccessful in demolishing the science, the attacks have moved against the scientist, Michael Mann himself, who has been subjected to an unbelievable denigration campaign, defamed, insulted, and even physically threatened. Recently, the campaign against Mann has targeted his new book, "The Hockey Stick and the Climate Wars", with a large number of negative reviews and derogatory remarks which appeared in the reviews of the book on the Amazon site. Most of these seem to be the work of web identities created expressly for this purpose.
What is amazing in this story is how people are fighting back! If you look at the comments on the Amazon site, you see how the derogatory comments have been overwhelmed by favorable comments written by real people who signed with their names. Climate science is still under heavy attack but, clearly, there is a core of concerned people who care about the future.
Michael Mann's "The Hockey Stick and the Climate Wars" is a book about our future. You need to read it to understand what kind of threats we are facing and how we can work for a better future.