Global warming is many things, but one thing it is not is science! It was a laughed-at science until the 1980's, when Margrat Thatcher needed an issue to get elected, so she brought in this obscure "science" to scare ppl into electing her. And it worked, and it's been working ever since.
The global climate is exretmely complicated, it's not easy to measure the global mean temperature, and it's even harder to discern global trends from localalized weather patterns. And we haven't been taking data for that long, so we don't even have enough info to predict anything. As a science, it is hotly contested and nowhere near "fact". But as a scare tactic for politicians, it has been proven over and over.
The term "climate change" is another term introduced by politicians. Rather than take a strong stand and say that the worl is warming, it's politically better to be flexible - They can't be wrong if they use a term that means nothing at all.
Not to mention Global waring has started to get a bad rap as a scare tacit, and changing the vocabulary is a way to get around that. the climate is changing doesn't mean anything! no offense at all, but of course the world's climate is changing - it's never been static and never will be static. A short look at just human history proves that, and a longer look at prehistory will confirm it.