According to Sam Carana the methane needs to be measured at 1 year global warming potential - not the 100 year that the climate models use. This means current 2000 ppb methane is almost 400 ppm co2 equivalent, putting the planet only less than 400 ppm co2 to trigger the "cloud tipping point" that heats up earth another 8 Celsius global average. The hot ocean release of ESAS methane would put us into the cloud tipping point then. So this could happen any moment now.
So this is possible since the climate models use only a long term projection of methane without factoring in the positive amplified feedbacks from short-term methane. see below methane on left converted to co2 equivalent ppm on right. So a "one year" methane rate is used with a 200 conversion to co2 compared to the 100 year methane rate normally used for climate models.
https://arctic-news.blogspot.com/2024/08/carbon-dioxide-growing-rapidly.html
https://arctic-news.blogspot.com/2024/10/models-downplay-wrath-of-what-they-sow.html
https://arctic-news.blogspot.com/p/the-importance-of-methane-in-climate.html
Updating the IPCC AR5 methane 10-year GWP value of 104.2 with an extra 14% results in a GWP of 119. Accordingly, this WMO level of 1889 parts per billion (ppb) for methane in 2020 translates into a carbon dioxide equivalent (CO₂e) of 224 ppm.
It gets even worse for an abrupt eruption of methane from the seafloor of the Arctic Ocean. If such an eruption occurred instantly, a one-year GWP of 200 seems more appropriate.
I already debated someone - Elliot Jacobson - trying to dismiss the "Sam Carana" analysis above.
The Clouds Feedback and the Clouds Tipping Point
The clouds feedback refers to disappearance of the lower clouds, more specifically the stratocumulus decks. Stratus cloud decks cover about 20% of subtropical oceans and are prevalent in the eastern portions of those oceans—for example, off the coasts of California or Peru. The clouds cool and shade Earth as they reflect the sunlight that hits them back into space. Tapio Schneider et al. calculated that these clouds begin to break up when carbon dioxide equivalent (CO₂e) levels rise above the tipping point of 1,200 ppm.
Disappearance of these clouds will make the temperatures go up strongly and rather abruptly. By the time CO₂e levels will have risen to this clouds tipping point of 1,200 ppm CO₂e, temperatures will already have gone up a lot in line with the warming from rising CO₂e levels. On top of this, the clouds feedback itself triggers an additional surface warming of some 8°C globally.
Study:
Possible climate transitions from breakup of stratocumulus decks under greenhouse warming - by Tapio Schneider et al., published February 25, 2019. https://www.nature.com/articles/s41561-019-0310-1
Kelvin is not the same as Celsius, although they have the same size increments, meaning a change of 1 degree Celsius is the same as a change of 1 Kelvin;
A methane concentration of 2000 ppb corresponds, at a Global Warming Potential (GWP) of 200, with 400 ppm CO₂e. Together with the daily average CO₂ concentration of 428.63 ppm this adds up to a joint CO₂e of 828.63 ppm, i.e. only 371.37 ppm away from the clouds tipping point.
This 371.37 ppm CO₂e could be added almost immediately by a burst of seafloor methane less than the size of the methane that is currently in the atmosphere (about 5 Gt). There is plenty of potential for such an abrupt release, given the rising ocean heat and the vast amounts of methane present in vulnerable sediments at the seafloor of the Arctic Ocean, as discussed in earlier posts such as this one and at the threat page.
https://arctic-news.blogspot.com/2024/06/have-feedbacks-taken-over.html
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