We could be 16 years into a methane-fueled 'termination' event significant enough to end an ice age

Very true. And, the additional context of the abrupt phase is super valuable in telling us where we are in our current timeline of shifting climate patterns. There's definitely important research here that significantly advances understanding.

It's just the "scratching their heads", 'how could this have happened, it's so unexpected' bloviating that's constantly prattled over in any of these articles... Drives me crazy. Should drive everyone crazy.

We're in the midst of a seriously massive great extinction, quite possibly greater than the Chicxulub impact event, and researchers have been trying to put a stop to it for decades, sounding every alarm in the process. Everyone knew, but a small percentage of powerful people have driven us all headlong into the fire. Those most at fault even funded and then hid some of the most significant research into the topic years before the scale of it became wider public knowledge. We should be blaming, accepting blame and being stark in our declarations about what, in general at the very least, is happening, is about to happen and why. The constant hand waving is fucking bullshit.

Yep. Buckle up.

About a year ago I was walking around with someone down near the river, just a nice place with open grass and some charming buildings off in the distance, and all of a sudden I started getting pretty emotional, like almost crying. She didn't know me as a super-emotional guy and was confused, and I related to her what made me upset -- basically, all of this is going away. In 50-100 years this little paradise place is gone. Guaranteed. I don't know how long exactly it'll be or what will be here instead, but it definitely won't be this nice grass and the well-kept buildings and boats on the river.

I like the place, it's wonderful; and it's going away, not to come back. Not that long from now.

thanks to the catalyst of human influence

My peripheral vision wisely read that as "cataclysm".

Yep.

Buckle up.

i'm looking at figure 3 in the academic source.

delta carbon-13 is a measure of the ratio of carbon-12 vs. carbon-13 in a sample, in this case in samples of atmospheric methane gas. the lower the value, the fewer carbon-13 isotopes there are relative to carbon-12 isotopes. carbon-13 is stable, it doesn't radioactively decay.

https://en.wikipedia.org/wiki/Δ13C

so if you can date samples of atmosphere trapped in ice cores and measure the amount and isotopic composition of the methane then you can construct a graph like that figure 3. different processes result in distinct isotopic signatures for the methane released into the atmosphere. what their chart shows is that from about 1100 c.e. to 1900 c.e. the delta carbon-13 ratio dropped by about 2 per-mil while atmospheric methane concentration rose, which they attribute to a decrease in biomass burning sources of methane and an increase in agricultural sources of methane.

then in 1900 c.e. there's a big increase in atmospheric methane along with a big increase in delta carbon-13. fossil fuel sources of methane are much heavier than natural sources, so as trapped methane was released into the atmosphere it produced a sharp change in the isotopic ratio.

but then about 15 years ago the isotopic signature sharply reversed course even as methane concentration started suddenly rising more rapidly. so something weird is going on these past two decades where we've possibly already started feedback loops that result in releasing trapped permafrost methane, for example. the paper suggests it's mostly from tropical wetlands, but the focus of the paper is on the isotopic observations.

thanks!