Greenhouse gas

Carbon dioxide (CO2) and methane (CH4) are both greenhouse gases. The first remains in the atmosphere a hundred years while the second stays there for only a dozen years.
At the scale of the century, methane is still 25 times more powerful than carbon dioxide in global warming potential (GWP)!

At equal quantities, methane is therefore more powerful in the greenhouse effect than CO2. But there are not as many methane emissions as there are carbon dioxide emissions.