He doesn't tell us about these scientists, only that one is a Canadian named Jan Veizer, and the others are at Armagh Observatory in Ireland. He doesn't tell us where their results were published. He doesn't tell us how their results were received by the scientific community. He doesn't tell us of any other studies which challenge these two groups of researchers. Science is not as simple as Mr. Perkins wants it to be.
Scientists do disagree with each other.
They hold different opinions about the same data. This is the way of science. Science is difficult and most of the time new results and measurements are difficult to interpret, or to understand in the context of the larger body of existing scientific knowledge. Mr. Perkins appeals to common sense in order to bring his point home to the reader that may not have any scientific training. He says that this last, colder than usual winter is proof that the global warming Chicken Littles are wrong.