I'll try - just from my general knowledge; no claim of authority!
1) Coal; coal is a case of carbon sequestration. Coal was largely formed in the Carboniferous period, at this point plants had evolved to form wood which uses lignin in its structure. This allowed forests to form, but until the end of the Carboniferous fungi that could degrade and decay lignin were no widespread. This led to a bloom of oxygen in the atmosphere and a crash in carbon dioxide. The earth cooled and there was a mass extinction. Lignin decaying fungi then became widespread releasing the non sequestered carbon (that which hadn't formed into deep deposits of coal) from the lignin. In the carboniferous period the carbon from many 100's of millions of years of volcanic activity was sequestered by plants in coal deposits, since then the ecosystem has faced the need to absorb a smaller amount of carbon from just 300 m years of the volcanic history of the earth. This has resulted in the chemical balance of the atmosphere and oceans we have today, including the way that they interact with geology.
2) Methane in permafrost; I think that this is a much smaller amount of carbon, but the problem is that the iceage processes that have formed these deposits have resulted in a store of methane, rather than CO2, and methane is a very strong greenhouse gas. Injecting a large amount of methane suddenly could lead to a sharp period of warming.
Before coal formed the chemistry of earths oceans and atmosphere was different; there was sulphur in the water column of the oceans. Carbon dioxide was ~8 times the current level. The world was 6' C warmer, and at that time Sol was ~5% dimmer. Sea level was ~170m higher than now, and the seas would have been very acid - due to the carbonic ions.
Going back to a world like that wouldn't be a problem, for some bacteria, for animals with shells or bones, well - not so good. In fact, there probably wouldn't be any because the acid in the ecosystem would prevent calcification - rubber for bones! Expect worms, leeches, jellyfish and insects to profit.
This time round there will be no carboniferous swamps - fungi have the trick of decaying wood now, so the time of large animals on earth will be done, back to the Precambrian, but hotter, polluted (for a million years at least) and radioactive (for a bit longer).
The permafrost past/future is probably more benign; 70 -100m of sea level rise, some acidification - but nothing like enough for the end of skeletons. I think it would likely see a massive reduction of human population, but I doubt that humans or human technology would disappear.
1) Coal; coal is a case of carbon sequestration. Coal was largely formed in the Carboniferous period, at this point plants had evolved to form wood which uses lignin in its structure. This allowed forests to form, but until the end of the Carboniferous fungi that could degrade and decay lignin were no widespread. This led to a bloom of oxygen in the atmosphere and a crash in carbon dioxide. The earth cooled and there was a mass extinction. Lignin decaying fungi then became widespread releasing the non sequestered carbon (that which hadn't formed into deep deposits of coal) from the lignin. In the carboniferous period the carbon from many 100's of millions of years of volcanic activity was sequestered by plants in coal deposits, since then the ecosystem has faced the need to absorb a smaller amount of carbon from just 300 m years of the volcanic history of the earth. This has resulted in the chemical balance of the atmosphere and oceans we have today, including the way that they interact with geology.
2) Methane in permafrost; I think that this is a much smaller amount of carbon, but the problem is that the iceage processes that have formed these deposits have resulted in a store of methane, rather than CO2, and methane is a very strong greenhouse gas. Injecting a large amount of methane suddenly could lead to a sharp period of warming.
Before coal formed the chemistry of earths oceans and atmosphere was different; there was sulphur in the water column of the oceans. Carbon dioxide was ~8 times the current level. The world was 6' C warmer, and at that time Sol was ~5% dimmer. Sea level was ~170m higher than now, and the seas would have been very acid - due to the carbonic ions.
Going back to a world like that wouldn't be a problem, for some bacteria, for animals with shells or bones, well - not so good. In fact, there probably wouldn't be any because the acid in the ecosystem would prevent calcification - rubber for bones! Expect worms, leeches, jellyfish and insects to profit.
This time round there will be no carboniferous swamps - fungi have the trick of decaying wood now, so the time of large animals on earth will be done, back to the Precambrian, but hotter, polluted (for a million years at least) and radioactive (for a bit longer).
The permafrost past/future is probably more benign; 70 -100m of sea level rise, some acidification - but nothing like enough for the end of skeletons. I think it would likely see a massive reduction of human population, but I doubt that humans or human technology would disappear.