Hello Dutch,
It doesn't have to be a following of an individual, though it usually is. The term is largely seen as a pejorative. Members of a cult never consider themselves to be such.
If one accepts that human industrial activity is contributing to climate change then they would not consider themselves to be part of a cult. But those who deny the tragic phenomenon might consider the rest of the world which is convinced of AGW to be a cult.
Although, when
83% of Americans worry at least a little about Climate Change it is sort of absurd for the 17% who don't worry about it at all to call the 83% 'a cult.'