[ljf]

Quoting here but;

Methane has more than 80 times the warming power of carbon dioxide over the first 20 years after it reaches the atmosphere. Even though CO2 has a longer-lasting effect, methane sets the pace for warming in the near term. At least 25% of today's global warming is driven by methane from human actions.

[feoren]

No, 80x is about right for the 20-year time horizon; Wikipedia lists it as 86. You're right that the 20-year Global Warming Potential is lower than the 100-year, but the 20-year is already what the poster you were replying to was using. The 100-year is around 25 to 31.

[ljf]

They edited it after my comment, as they note.

[guelo]

Also, the extra warming from methane can trigger unrecoverable tipping points, such as melting ancient glaciers and permafrost, whose effects will last for thousands of years.

[chrisco255]

What is meant by 25% of today's global warming? 25% from what baseline? From what median? From what time period?

[strainer]

It is somewhat deceptive framing, because methane can not accumulate in the atmosphere the way CO2 does. Its levels in the atmosphere will break down relatively quickly if we reduce output, unlike CO2. But the present level of methane in the atmosphere basically captures about 30% as much heat as the present level of CO2. That still leaves CO2 as significantly larger immediate problem and the much larger future problem. We must do what we can, observing that every little counts - a little, and every lot counts a lot.

[ljf]

Don't forget what methane breaks down into... Water vapour and co2. So it's not like it breaks down and is no longer an issue n

[chrisco255]

Yeah but that CO2 is already part of the ppm that is measured. And water vapor of course, has the ability to cool or heat depending on the position in the atmosphere and amount of particulates for it to condensate on (to form clouds).

[strainer]

You shouldn't formulate the system like that - without any proportion. The proportions are what matters.

[hotpotamus]

I'd assume the previous 10,000 or so years wherein humans created civilization up to about 1980.

[chrisco255]

No, we don't have anything close to a precise global temperature over the entire Holocene (the period you describe, that we are presently in, coinciding with the end of the most recent glacial period). We at best have spotty tree rings, ice core samples (which are inherently limited to arctic regions), and other various rough proxies which have a higher margin of error than we have observed in even the past 100 years.

Good, broadly available, consistently measured temperature data from daily mercury record keeping was mainly only really done in UK and colonial U.S. until the late 1800s. Even then most of the world did not maintain standards for temperature stations until the early to mid 20th century. Global temperature estimates that actually span the whole globe were not really possible until the weather satellite era, around the late 1970s. So there is a big problem when comparing the precision and breadth of modern temperature data with historical estimations for a number of reasons. Not least of which is that we do not really see the sample rates of historical data necessary to estimate the periodic, even as small as decadal, swings to any high degree of accuracy.

[feoren]

I'm guessing: rate of carbon-dioxide-equivalent being added to the atmosphere each year.