https://www.youtube.com/watch?v=Fzwg46khzXI
oops.
the Younger Dryas and Preboreal intervals, approximately 11,600 years ago. Assuming that past geological methane emissions were no lower than today,, our results indicate that current estimates of today’s natural geological methane emissions (about 52 teragrams per year), are too high and, by extension, that current estimates of anthropogenic fossil methane emissions are too low. Our results also improve on and confirm earlier findings,, that the rapid increase of about 50 per cent in mole fraction of atmospheric methane at the Younger Dryas–Preboreal event was driven by contemporaneous methane from sources such as wetlands; our findings constrain the contribution from old carbon reservoirs (marine methane hydrates, permafrost and methane trapped under ice) to 19 per cent or less (95 per cent confidence).
Abrupt Warming did not cause "abrupt eruption" of marine methane
oil industry is claiming natural methane leaks have been underestimated by bad science
We suggest a new methane source partitioning over gradients of human disturbance and demonstrate that 76.3% (75.8%–79.4%) or 561 (443–700) Tg CH4 yr−1 of global emissions can be attributed to moderately impacted, man-made, artificial, or fully anthropogenic sources and 23.7% (20.6%–24.2%) or 174 (115–223) Tg CH4 yr−1 to natural and low impacted methane sources. Finally, we identify current research gaps and provide a plan of action to reduce current uncertainties in the Global Methane Budget.
science doubles down by saying 25% of methane emissions are not natural
the details on man-made methane leaks
Science assuming "gradual thaws" of methane from permafrost are wrong!!
With the Arctic Ocean containing a large percentage of the planet's total continental shelf area, a significant inventory of marine hydrate (∼116 Gt C) exists across this basin at relatively modest depths (K. Kretschmer et al., 2015). Consequently, the scientific community is actively assessing the potential for a large-scale thaw and release of methane hydrate from the Arctic seafloor. Early estimates of high rates of methane emissions from hydrate dissociation on the East Siberian Arctic Shelf (Shakhova et al., 2014) have been revised substantially downwards by numerous subsequent studies (Berchet et al., 2016; Thornton et al., 2016, 2020; Tohjima et al., 2020).
the claim is that an "abrupt eruption" from ESAS methane is now considered not likely
citing
, , , , , , et al. (2020). Estimation of CH4 emissions from the East Siberian Arctic Shelf based on atmospheric observations aboard the R/V Mirai during fall cruises from 2012 to 2017. Polar Science, 27, 100571. https://doi.org/10.1016/j.polar.2020.100571
The resulting range of the annual CH4 emissions was from 0 to 4.5 TgCH4 yr−1. As just described above, the rather wide range of emission estimates suggests that the estimate of the ESAS emissions has still large uncertainty and that many more studies are required for more accurate emission estimates.
Nevertheless current CO2 emissions are worse than previous Ice Age cycles of "abrupt warming"!!
We show that the current magnitude of thaw has not yet exceeded that of previous deglaciations, but that permafrost carbon release has the potential to exert a strong feedback on future Arctic climate as temperatures exceed those of the Pleistocene.
https://www.nature.com/articles/s43247-023-00886-3
some view permafrost as a rather stable or only slowly reacting component in the climate system on millennial times scales, suggesting that even with release of substantial carbon, the slow timescale of release would be compensated by other components of the Earth system (vegetation, peat, ocean), resulting in minimal feedback to climate. This has led to the conclusion that permafrost carbon could therefore not be an important factor in abrupt carbon cycle shifts when compared to human-driven, oceanic, or terrestrial tropical components11,12,13. With atmospheric CO2 concentrations now reaching nearly 420 ppm, values not observed in the last 3 million years, and expected to reach concentrations not observed in 30 million years by 2300 under high emissions scenarios14, there is now even more urgency to understand the consequences and associated feedbacks to climate15 from the warming and thaw of this large permafrost carbon pool2,15. Furthermore, permafrost carbon dynamics are not yet included in most IPCC Earth system models16, and this omission suggests that even with the strictest emission reductions, climate targets could be overshot17,18.
Wow - permafrost carbon is not even included in IPCC models!!
focusing on the rapid changes during the deglaciation, especially pronounced in the Bølling–Allerød (BA) and Younger Dryas (YD) periods. We consider all relevant natural sources and sinks of methane and examine the drivers of changes in methane emissions as well as in the atmospheric lifetime of methane. We find that the evolution of atmospheric methane is largely driven by emissions from tropical wetlands, while variations in the methane atmospheric lifetime are small but not negligible
https://cp.copernicus.org/articles/19/1081/2023/cp-19-1081-2023.html
https://www.eurekalert.org/news-releases/951626
So the study is behind paywall except for snippets and this news release.
Yeah it doesn't cite the dismissal of their previous findings - just details why the ESAS is heating up.
But a newer study does corroborate the claims of Shakhova's research group!
Compiled observation data suggested that subsea permafrost might be a major DOM source to the Arctic Ocean, which could release tremendous carbon upon remineralization via its degradation to CO2 and CH4 in the water column.
1 Pg = 1000 Tg
Given the huge amount of organic carbon stored in the subsea permafrost and the fast ongoing Arctic warming, accelerating release of small size DOM is projected from the Arctic shelf underlain with offshore permafrost. The estimated benthic efflux rates of DOM ranges from 10 to 2240 g C m−2 yr−1 and an estimated annual release of ~0.7–1.0 Pg C from the Arctic shelf underlain with offshore permafrost, much higher than total inputs from Arctic rivers and coastal Yedoma, and primary productivity.
So the claim is that the methane is organic and thus will be neutralized - but this is wrong!
Although currently thawing, prior microbial decomposition and organic matter aging limit decomposition rates to less than 48 Tg OC/yr (25–85) constraining emissions due to thaw and suggesting that the large permafrost shelf carbon pool is largely insensitive to thaw.
The below study looks at the preformed pressurized methane directly
The Arctic is warming dramatically, with potentially catastrophic impacts on climate through rapid mobilization of the labile giant reservoirs of carbon sequestered in permafrost, including release of CH4 from decaying hydrates associated with thawing subsea permafrost Shakhova [9]. Nevertheless, there are huge uncertainties regarding the composition, inventories and functioning of these different cryosphere-carbon pools[1]. One possible feedback is release of previously produced CH4 preserved within seabed deposits, such as natural gas fields and coal beds, and collapse of the CH4 hydrates underlying the Arctic seabed [10], [5]. The lack of understanding of this process creates some of the largest uncertainties in climate research related to cryosphere–climate–carbon couplings. One of the reasons is associated with an increase in the concentration of CO2 and CH4 − the main greenhouse gases in the Earth's atmosphere.Long-term large-scale comprehensive studies have shown that one of the main sources of increasing methane emissions into the atmosphere is the East Siberian Arctic shelf (ESAS), off northern Russia, where the self-accelerating process of decomposition of underwater gas hydrates has already begun[11]. This vast yet shallow region has recently been shown to be a significant modern source of atmospheric CH4, contributing annually no less than terrestrial Arctic ecosystems (Shakhova et al., 2014), which is comparable with CH4 anthropogenic emission from territory of the United States −the main contributor of man-made CH4 [12], [13] Several sites that were drilled 30 years ago were recently re-drilled, which revealed that the thaw horizon has been moving down by several meters in just a few decades.
https://acp.copernicus.org/articles/24/6359/2024/
Surface networks in the Arctic may miss a future methane bomb
Subsea permafrost thaw has been observed in the ESAS (East Siberian Arctic Shelf) and the importance of this region has been highlighted, for instance by Shakhova et al. (2015, 2019) and Wild et al. (2018). Future estimates suggest that around 50 Gt of methane could be released from gas hydrates in the ESAS alone over the next 50 years (Shakhova et al., 2010), consistent with present annual estimates (e.g. Berchet et al., 2016).
the continuous leakage of an old geological reservoir to the water column suggests the
existence of perforations in the subsea permafrost, serving as conduits of deeper methane to gas-charged shallow sediments.
Second, the finding that methane is released from a large pool of preformed methane, as opposed to methane from slow decomposition of thawing subsea permafrost organic matter, suggests that these releases may be more eruptive in nature, which provides a larger potential for abrupt future releases.
Steinbach, J., Holmstrand, H., Shcherbakova, K., Kosmach, D., Brüchert, V., Shakhova, N., et al. (2021). Source apportionment of methane escaping the subsea permafrost system in the outer Eurasian Arctic Shelf. PNAS 118, e2019672118. doi:10.1073/pnas.2019672118
Source apportionment of methane escaping the subsea
permafrost system in the outer Eurasian Arctic Shelf
Julia Steinbach a,b,c,1 , Henry Holmstrand a,c
, Kseniia Shcherbakova d, Denis Kosmach d, Volker Brüchert b,c ,
Natalia Shakhovae,f,g , Anatoly Salyukd, Célia J. Sapart h,i , Denis Chernykh d, Riko Noormets j, Igor Semiletov d,e,f ,
and Örjan Gustafsson a,c,1
The triple-isotope fingerprinting suggests, however, that methane may not primarily originate directly from the subsea permafrost; the continuous leakage of
an old geological reservoir to the water column suggests the
existence of perforations in the subsea permafrost, serving as
conduits of deeper methane to gas-charged shallow sediments.
Second, the finding that methane is released from a large pool of
preformed methane, as opposed to methane from slow decomposition of thawing subsea permafrost organic matter, suggests
that these releases may be more eruptive in nature, which provides a larger potential for abrupt future releases.
https://www.nature.com/articles/s43247-022-00490-x.pdf
Continental margin sediments contain large reservoirs of methane stored as gas hydrate.
Ocean warming will partly destabilize these reservoirs which may lead to the release of
substantial, yet unconstrained, amounts of methane. Anaerobic oxidation of methane is the
dominant biogeochemical process to reduce methane flux, estimated to consume 90% of
the methane produced in marine sediments today. This process is however neglected in the
current projections of seafloor methane release from gas hydrate dissociation. Here, we
introduce a fully coupled oxidation module to a hydraulic-thermodynamic-geomechanical
hydrate model. Our results show that for seafloor warming rates > 1 °C century−1, the
efficiency of anaerobic oxidation of methane in low permeability sediments is poor, reducing
the seafloor methane emissions by <5%. The results imply an extremely low mitigating effect
of anaerobic oxidation of methane on climate warming-induced seafloor methane emissions
this feedback could cause an abrupt transition into a warmer
climate state. Although crossing such a threshold is deemed as
highly unlikely within the next century 16 , this remains a major
concern on millennial timescales 4,6,17 .
https://www.pnas.org/doi/epdf/10.1073/pnas.2107632118
A proportion of thermogenic
methane in addition to the dominant microbial methane was
found in gas emission craters in Western Siberia (4). For the
subsea permafrost in the East Siberian Arctic Shelf, it was argued
that thawing can make the permafrost layer permeable for gas
stored as hydrates or as free gas within the permafrost layer and
also for subpermafrost gas (5). Isotopic signatures of methane
released in the East Siberian Arctic Shelf are consistent with an
origin as old, deep, and likely thermogenic methane (6).
To conclude, our observations hint at the possibility that permafrost
thaw does not only release microbial methane from formerly frozen
soils but also, and potentially in much higher amounts, thermogenic
methane from reservoirs below and within the permafrost. As a result,
the permafrost–methane feedback may be much more dangerous
than suggested by studies accounting for microbial methane alone.
Gas hydrates in Earth’s permafrost are estimated to contain 20 Gt of
carbon (14). Additionally, subpermafrost natural gas reservoirs may be tapped.
