Hi David. Earth and Venus were in the same place at the same time, forming from the same star-dust, and about the same size, so it's not surprising that <Earth and Venus have about as much carbon in the crust, ocean and atmosphere combined, but on Venus it is all in the atmosphere and on Earth only 4 parts per million is of the total.
Earth appears to have gone through such a cycle before reaching minimum carbon and temperature in the Permian. >
Earth, being further from the sun, got cooler quicker. Venus, being slightly smaller at 0.815 Earth mass would not have exactly the same tectonic processes, nor other processes. But it is big enough to hold onto its atmosphere.
Earth hasn't reached minimum carbon yet. Nor minimum temperature. It is still stripping carbon out and cooling. That's why the ice age began.
Earth is in a crystallization process, and life is the stripping agent for carbon from the atmosphere, depositing it in permanent graveyards via geophysical processes.
Life on Earth developed and ran its course for long before the Permian. Sex began a billion years ago and 2 billion years ago life was well underway. The carboniferous was about carbon and not in the sense of diamonds.
For eons, life has been stripping carbon out and geophysical processes have been burying it in increasing permanent deposits with only some of it recycled through subduction, volcanoes, oil, HC gas, and CO2 leakage after subduction.
Earth's crust has been constantly growing as sedimentary layer is piled on freezing crust, with volcanoes expelling magma and ophiolite deposition piling more on top, and limestone filling gaps.
Earth has enjoyed FAR more carbon in the atmosphere than is available to life today. We are in the last throes of life on Earth, with a plunge into a permanent ice age likely any time soon. 4 parts per million is pretty thin gruel. Venus is still in overdose and far too hot. Perhaps 10 parts per million in the ecosphere would be pleasant for us.
We don't have a chance of getting Earth to that sustainable level, but we can, with continued effort, maintain conditions as they are for a couple of centuries, especially with China and India coming on stream, as there is a LOT of fossil hydrocarbon and coal available.
Unfortunately, Peak People and Peak Oil are looming [as early as 2040, or sooner if H5N1 has its way]. With not so many people, we won't have the economic impetus to extract oil and coal, so our carbon dioxide output will dwindle without massive government subsidies on carbon usage, or at least tax-free status.
At some stage, the vast carbon absorption processes will overwhelm our efforts and anyway, we will likely move on to easier methods of moving than burning coal and oil. Earth will then continue its relentless, merciless and inevitable stripping of carbon from the ecosphere and burying it in oceanic crust.
If we want more carbon than is necessary to maintain warm conditions, we can compress power station exhaust to liquid CO2 and bury it 500 metres under the ocean where it will stay liquid in a puddle while it dissolves [being heavier than water]. That was Mq's invention in 1987 [patented by Mitsubishi a couple of years later - I had no idea such an obvious thing could be patented]
Interestingly, 500 metres is quite a long way and quite a bit of electricity could be generated by turbines in the pipelines. I haven't done even a boe calculation on that, but maybe there would be enough electricity generated to run the compression process. Maybe a kilometre or two of pipeline should be used to run the liquid CO2 deeper and gain more electricity. The extra cost would just be the pipe, so I suspect that a long and deep pipeline would be worthwhile.
Power stations should be near subduction trenches, to get a good, deep flow. Oil supertankers could berth handily too.
Perhaps people would migrate from squalid cold cities to warm modern cities where huge power stations could run cheaply and CO2 management would be economic.
Of course the modern cities should NOT be right at sea level, although the power stations would need to be fairly close to the sea for cooling and convenient fuel delivery. Sea levels rise, very suddenly, due to bolide deflections of the surface and that happens every couple of hundred years. The sea level rise to worry about isn't due to gradual warming, it's due to sudden tsunami.
Plenty of people would prefer to take their chances at sea level, to enjoy the view, boating and swimming until they and their children die from tsunami. People inland could take over from them and rebuild - the foundations, roads and a lot of structures would survive a tsunami and would just need sediment removal and a bit of this and that.
We have managed to get CO2 from 280 ppm to 360 ppm, which is a good effort, if we can claim all of it [maybe it was more to do with other processes, of which there are a lot]. That might be enough to maintain warm conditions.
I am NOT offering my usual double your money back guarantee as there are very powerful countervailing ice-age processes. We might be "peeing in the ocean" to coin a phrase, or, "farting against thunder" [noting the increase in methane over the same period from 320 ppm to 370 ppm [not such a good effort as CO2, but not bad as methane is an excellent greenhouse gas]].
Against our efforts, there is the plant cycle in which desert growth with its reflectivity cooling Earth, pushes plants further from the equator as Earth warms during interglacial times. Meanwhile, plants take over from permafrost in the north [and south, though there's not much land in the south].
Desert expansion acts as a cooler, but ice regression acts as a warmer. When ice has retreated as much as it can be made to [plants having an increasingly tough time in Arctic darkness during winter and thin gruel of sunshine during summer], the deserts still continue to encroach on the plants, continuing the cooling process, until there isn't enough warming being done by plants and animals to maintain the temperature.
The next winter sees an extended snow cover, which doesn't melt the following summer. The following winter, a more extended snow cover happens and it doesn't all melt the following summer. The third winter, the snowline is rapidly moving south [and north] and things are cooling even quicker as plants are buried, but plants can't migrate to deserts quickly enough to restore balance as deserts are dry and hot and it takes time for Redwood trees to grow and even small plants have to get a foothold.
By the fourth winter, people above the snow-line will be thinking of moving south en masse. They will be able to stay ahead of the encroaching snow fields and expanding glaciers.
Within a decade, the ice-age will have re-established itself. People will return to places their ancestors left 10,000 years ago.
Only 4 parts per million is a LOT more buried carbon than I imagined. I knew there is a LOT of limestone and other carbon deposits, but didn't realize life had stripped that much out. I suppose it has been on the job for 2 billion years, so even without planning, it should have made good progress.
Lucky we arrived. Or was it luck? Maybe it was part of a plan by Gaia to produce us just in time to hold the line against her demise. Gaia does look after herself and she didn't give birth to us because we are particularly nice looking.
We are the only animal so ugly that we spend a LOT of effort designing and producing clothing to wear to cover our hideous bodies and make us look passable, if still not as swanky as a peacock or as striking as a tiger, or artful as a zebra. Even possums and plain birds have got nice fur and feathers and look very nice in their prime.
Hermit crabs do change clothing, but that's more of a pragmatic concealment process to avoid being dinner, than to make themselves look good.
Mqurice |
