Come on, do people really believe in Global Warming?

It's not a 'belief'. The data has been presented and the method of that collection has been certified by independent observers as being well within the protocols of the scientific method. The data itself has be verified by several teams of scientists, all working independent of each other. The data therefore must be accepted as 'true' This is called 'consilience'...multiple independent lines of evidence converging on a single coherent account. This is different from a 'belief' as a belief isn't based on any particular collection of unimpeachable data. This world is gradually heating up and the cause in our 'historical' time is the burning of fossil fuels. While true, the Earth has heated up before in 'geological' time, that 'heating' was for different reasons than what we're dealing with today.