[epall]

Methane deteriorates in the upper atmosphere fairly quickly, whereas CO2 sticks around. Methane is a dramatically better insulator than CO2, so in the short run its impact is higher, but when you stretch out the timescale, your methane is deteriorating while the CO2 sticks around, so the relative impact tilts slowly toward CO2.

[cbennett]

While you are right that methane wont naturally stick around for ever, and that it breaks down sooner than CO2. After googling around a little, I finally managed to find the source of the author's two numbers, and in the end I am more troubled than ever :/

>>At issue is the global warming potential (GWP), a number that allows experts to compare methane with its better-known cousin, carbon dioxide. While CO2 persists in the atmosphere for centuries, or even millennia, methane warms the planet on steroids for a decade or two before decaying to CO2. In those short decades, methane warms the planet by 86 times as much as CO2, according to the Intergovernmental Panel on Climate Change. But policymakers typically ignore methane's warming potential over 20 years (GWP20) when assembling a nation's emissions inventory. Instead, they stretch out methane's warming impacts over a century, which makes the gas appear more benign than it is, experts said. The 100-year warming potential (GWP100) of methane is 34, according to the IPCC.[1]

Doesn't 'reducing' (really, normalizing) the GWP for the ~80 yrs of the 100yr period (when it is not existing) seem sort of like an accounting trick? In other words, if 20GT of CH4 were released next year from the Bering Sea into the atmosphere (this would be spectacularly bad), the overall shock to the climate/atmosphere systems is precisely the same.

[1]https://www.scientificamerican.com/article/how-bad-of-a-gree...