The term Global warming isn't necessarily a hoax. They were right about that. The earth is in a macro timeline coming out of a small ice age and heading into a warming period. On a smaller scale of time say the past 10 years we have been on a cooling trend.
The hoax is the way they hide the other data to prove their case. There as been much study to show CO2 isn't what causes global warming it is just the after affect of global warming. When the oceans warm they can release more CO2 when they cool they can take in more CO2. Thats why when you look at a graph of Temperature and CO2 , CO2 lags behind Temperature. It take years to affect the temperature in the oceans.