The problem isn't that there's no room for disagreement. It's that the quality of the disagreements and critiques are so low, it's impossible to believe there's

The problem isn't that there's no room for disagreement. It's that the quality of the disagreements and critiques are so low, it's impossible to believe there's no alternative motive at work. Your post is a great example of this type of trash. You start off comparing one of the most researched fields, involving decades of effort spread amongst thousands of researchers around the world with a small number of people who did not even have an understanding of the mechanisms (genetics, embryology, etc) with which they were dealing. The GP's analogy works quite well, our certainty of cigarettes causing lunch cancer is about the same as the IPCC's certainty of anthropomorphic climate change. Second, apart from the normal peer-review of specific papers, there have been several large-scale attempts to "review" all of climate change. A great example is the "Climategate" fiasco, which after a review by a sceptic funded the oil industry, turned out to have been nothing but an attempted hit job on the scientists involved. Third, there is actual review and revision going on within the IPCC. One of the major differences between the 2007 and 2014 IPCC reports is the narrowing of the predicted temperature ranges. Deniers however don't seem to have the evidence to work within the normal scientific process, so instead they must engage of various types of deception and PR work to get their points across. So no, it certainly has not become a weirder field of study. It's just that people threatened by facts are trying to apply political tactics to a non-political field, much like creationist attempts to revise or silence evolution.