Anthropogenic Global Warming is a scientifical theory that has yet to be clearly disproven. Even if it has since been recycled by politicians to fill their own personal agenda, it is originally an hypothesis that was formulated on the sole base of observable facts, outside of any manipulation intend.
Now, get an English dictionary, and find the differences between meaning of the words "hoax" and "hypothesis". Using your own personal definition, Ptolemy's Almagest was also an hoax, since it was ultimately disproven yet used by the Church authorities to fill a political agenda.
Summary: an hoax implies conscious fraud; an hypothesis doesn't.