Originally Posted by
Flying Binghi
Hmmm… do tell Beer Baron. That 25x greater effect figure you claim. Is that the claimed greenhouse effect of methane in an atmosphere that also includes water vapour and CO2. Or is it comparing an atmosphere that only contains C02 to an atmosphere that only contains methane ?
It’s not my claim, here are what scientists (not pilots) at MIT have to say:
Let’s say a factory releases a ton of methane and a ton of CO2 into the atmosphere today. The methane immediately begins to trap a lot of heat—at least 100 times as much as the CO2. But the methane starts to break down and leave the atmosphere relatively quickly. As more time goes by, and as more of that original ton of methane disappears, the steady warming effect of the CO2 slowly closes the gap. Over 20 years, the methane would trap about 80 times as much heat as the CO2. Over 100 years, that original ton of methane would trap about 25 times as much heat as the ton of CO2.
As to your question, it would appear they are comparing adding methane or CO2 to Earth’s atmosphere as opposed to a hypothetical atmosphere of 100% CO2 or CH4. You can ask MIT for their methodology.
MIT reference