I'm a denier for several reasons. There is no substantive evidence that the planet has warmed significantly or that any significant warming will occur in the future .. Climate research has largely degenerated into pathological science, and the coverage of global warming in the media is tendentious to the point of being fraudulent. Anyone who is an honest and competent scientist must be a denier.
Global warming predictions cannot be tested with mathematical models. It is impossible to validate computer models of complex natural systems. The only way to corroborate such models is to compare model predictions with what will happen in a hundred years .. the theory of catastrophic global warming cannot be tested or empirically corroborated in a human time frame.
.. Scientific theories are never denied or believed, they are only corroborated or falsified. Scientific knowledge, by its very nature, is provisional and subject to revision .. Anyone who thinks scientific knowledge is final and complete must necessarily endorse as a corollary the absurd proposition that the process of history has stopped.
A scientific theory cannot be "denied." Only a belief can be denied. The person who uses the word "denier" thus reveals that they hold global warming as a belief, not a scientific theory. Beliefs are the basis of revealed religion. Revelations cannot be corroborated or studied in the laboratory, so religions are based on dogmatic beliefs conservatively held. Religions tend to be closed systems of belief that reject criticism. But the sciences are open systems of knowledge that welcome criticism. I'm a scientist, and therefore I must happily confess to being a denier.