Long-term climate change is represented by 30-year changes in a climate variable, one being temperature change...whether 30-year temperature change is due to humans (ie, human CO2) can be ascertained readily by examining the changes in the NASA's global temperature dataset
(click on image to enlarge - data sources)
The adjacent chart is not one likely to be publicized by the green-sharia scientists at NASA's GISS; nor will "journalists" at the NY Times and Washington Post report on it. To do so would make them apostates to the anti-CO2 religion jihad.
Regardless, the empirical temperature observations that NASA documents clearly indicates that the monotonous increase in atmospheric CO2 levels have had little impact on long-term (30 years) temperature change.
As the chart depicts, 30-year temperature changes resemble a sine wave (oscillation) that has nothing to do with human CO2 - instead, that sine wave pattern is natural, and easily overwhelms any CO2 impact.
Additional global temperature and climate charts.