There are different data sets, and there are cycles within cycles within cycles (see the link below on superposition of effects, and then look at the wavy line of temperature history, and ask what causes all those fluctuations...man?...sun?...atmosphere?...whatever).
There have been short term periods of cooling which the Right latches on to to say that there is no warming. They are correct in some time frames, but not others. If you look back 5 years, the Left may be correct (warming!), but if you look back 15 years, the Right may be correct (cooling!), but if you look back 50 years, the Left may be right (warming!)...regardless, if you look back 18,000 years, there is definitely a warming trend. After all, South Bend used to be under what, a mile of ice?...and the oceans were, what, 120 meters lower because of that? But, THAT warming undermines the alarmist's argument, because it had nothing to do with humans. So, the Left needs us to look only at their sample set, and not any others. That is why they need to silence the Right to get their policies passed.
Link: https://en.wikipedia.org/wiki/Superposition_principle