Short version-some people who were (mostly) not scientists and certainly don’t know how to do research properly conducted a series of studies that had foregone conclusions supporting their position on climate policy. For Prall, Cook and Lewandowsky the foregone nature of the conclusions was explicit-they wrote on various websites that they were conducting the studies with a predetermined end. For Oreskes it was implicit, but easy to see, as she structured her research carefully, not to show the breadth of opinion on climate change, but rather to conceal it.
h/t Don B.