Andrew Glikson (Australian earth and paleoclimate scientist) (2018): “The extraction and transfer from the earth crust to the atmosphere of every economically available molecule of carbon, including coal, oil, tar sand oil, shale oil, methane gas, coal seam gasand other forms of hydrocarbon, constitutes the most significant shift in composition of the atmosphere since the PETM hyperthermal event about 56 million years ago and the K-T extinction of the dinosaurs some 66 million years ago. Methane, the most potent common greenhouse gas, billions of tons of which are stored in Arctic permafrost, lakes, shallow seas and sediments, is emitted as the Arctic warms by an average of 3-8 degrees Celsius. This release threatens to melt the large polar ice caps, leading to tens of meters sea level rise and disappearance of species a rate two orders of magnitude faster than they would have without human interference. Compounding this effect is extensive drilling for coal seam gas, perforating the crust in several parts of the world and releasing commercial and fugitive emissions of methane to the atmosphere. Having sent young generations to kill and die in wars, the powers to be are now presiding over the greatest mass extinction of nature since 66 million years ago.
The accumulation of many hundreds of billions tons of unoxidized methane-rich organic matter in Arctic permafrost and of methane hydrates in shallow Arctic lakes and seas (Figure 1), before and since Arctic glaciation about 2.6 Ma-ago, as well as in tropical bogs, has created a reservoir of carbon whose release to the atmosphere may have catastrophic effects on the biosphere. According to the global carbon project up to 1400 GtC (1400 billion tonnes carbon) on land and ~16,000 GtC in the oceans (Figure 1), much of which may be potentially released upon a significant rise in temperatures, would cause widespread melting and defrosting of the polar ice sheets. This would ensue from major warming feedback effects from further combustion of fossil fuels from recoverable resources, estimated as at least >1100 GtC, and potentially from estimated resources of near 2000 GtC (Figure 2).
Even the release and dissipation of some ~500 to 1000 GtC to the atmosphere as methane, which has 25 to 75 times the greenhouse effect of CO2, may exceed the atmospheric greenhouse concentration of ~500-700 ppm CO2e, leading to further extensive melting of the large ice sheets and major sea level rise and to a mass extinction event such as the PETM (Paleocene-Eocene Thermal Maximum) [56 Ma] or even the Permian-Triassic major mass extinction event [250 Ma] ” (Andrew Glikson, “The Methane Time Bomb and the future of the biosphere”, Countercurrents, 29 April 2018: https://countercurrents.org/2018/04/the-methane-time-bomb-and-the-future-of-the-biosphere ).