I don't think global warming is a lie. However, the world we live in is at the moment is "unnormal" the earth' is normaly pending between cold and hot.
Ever since humans started to burn oil the earths temprature has been rising (not much but it has)
it is also proven that carbon dioxide keeps the suns heat from escaping earth atmosphere making earth's temprature rise. But i don't know if this is enuth to melt the north pole ice, but i do know that it is helping to increase the earths temprature.