It seems we've been "fudging the numbers" in a sense, when comparing the global warming potential of methane to CO2. When global warming potential (GWP) of a gas is calculated, a time frame is assumed. The IPCC decided to use a 100 year time frame.
With a 100 year time frame methane heats up the planet 21 times as much as CO2. The problem with that assumption is that we don't have 100 years. A 20 year time frame would be much more realistic, given the urgency of climate crisis. With a 20 year time frame...
... any CH4 released today is at least 56 times more heat-trapping than a molecule of C02 also released today. And because of the way it reacts in the atmosphere, the number is probably even higher, according to research conducted by Drew Shindell , a scientist at NASA’s Goddard Space Center. [emphasis mine]
What if we were to use the IPCC’s 20-year comparison instead of its 100-year comparison? For starters, it would force us to get much more serious about tackling the sources of methane emissions. Here in the US, the top methane sources are the decomposition of wastes in landfills, agriculture (from ruminant digestion), and leaks from natural gas drilling and transmission. A new emphasis on methane would require us to get smarter about capturing methane at landfills, reduce the market incentives that encourage Americans’ meat-heavy diets, and ensure that methane isn’t leaking from fracking operations.
But beyond the policy specifics, adopting the 20-year global warming potential comparisons would be useful for changing how we think about climate change.
And we appear to be approaching some irrevocable tipping points that will create powerful negative feedback loops, the most worrisome being the release of methane stores at the bottom of the ocean and locked into sub-Arctic permafrost.
Image from Arctic Methane Release Tipping Point Diagram
With 56 times as much warming as CO2 in mind, we'd take this feedback more seriously.
That 28% statistic about the contribution of CH4 does not include water vapor, whose effect vastly outweighs all other greenhouse gases, but is hard to quanitfy because its concentration is highly variable and doesn't "decay" from the atmosphere in the traditional sense.
There is a reason why the Earth did not in fact become Venus at times like the Paleocene-Eocene Thermal Maximum, when there must have been no permafrost in the Arctic. It will still get pretty bad though.
When I read estimates like this of how delicate is the stability of our planet's habitability, I feel as if scientists are like a Dad, telling his 3-year old son not to touch the blowtorch trigger in his hand, and 99.9% of adults are ignoring a warning they don't comprehend like that about-to-immolate himself kid.
Ruth, you provide us with a vivid image of your feelings. There are still those who do not understand how serious this is. The child imbeded in these flames clearly shows terror, too late. The father and the scientists speaks from knowledge; people don't hear, or don't care, or don't understand the significance before the explosion.
My guess is our soils and forest will dry up as will the grasslands and all make fine material for fire. We have a new one brewing just north of us in British Columbia.