Global warming is all about the way that the world's atmosphere is slowly warming.

No two years are the same, and a warm year can be followed by a hot one and then a cold one. So we have to understand that there is not an easy answer to whether the Earth is warming up or not. What scientists do is to look at values over a long period of time and see if they can find some long-term answer. Most scientists think the Earth is warming, but some do not.