However, methane is a greenhouse gas in its own right, and 100x worse [1] than CO₂. And some unknown amount, I guess 2% to 10%, of methane leaks into atmosphere during the mining and transport and use of natural gas. Depending on the exact amount of this leaking, natural gas might even be the worst offender, per unit energy produced.
[1] 100x worse on a 20 years time scale, 30x worse on a 100 years time scale.
[1] 100x worse on a 20 years time scale, 30x worse on a 100 years time scale.