It is unquestionably Global Warming - aka Climate Change!
I think that it is both a mix of naturally occurring Global Warming as has happened in the past history of our earth, and it is also vastly helped along by human activities such as burning fossil fuels etc.!
EDIT: Oh, and please disregard Leo(T.C.K.)'s nonsense post over at ut99.org about the "aluminatti" and "chemtrails" etc. It is completely BS