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The amount of carbon (C) on Earth is constants. As far as i understand, all carbon that is not found in the atmosphere or the oceans in the form of CO2 or CO is stored either in the biomass (plants, animals, including humans, bacteria, mushrooms, etc.), or in fossils and fossil fuels (coal, petroleum, natural gases), or in non-organic form as graphite and diamonds. Is this correct? Does it follow that the only way to stop anthropogenic climate change and decrease the amount on CO2 in the atmosphere is to stop extracting fossil fuels and to start converting CO2 from the atmosphere into graphite or diamonds or into some form of petroleum and pump it back under ground?

I have asked a related question about carbon distribution on Earth.

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  • $\begingroup$ Really quite a lot of carbon is stored as calcium carbonate (limestone), and I think it would drop due to carbonate formation if we stopped emitting it, but I'm no expert. $\endgroup$ – Nathaniel Nov 10 '14 at 0:21
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    $\begingroup$ This is a bit of a wrong-headed question. Climate change is already happening, and stopping it is not possible. Stopping the acceleration of climate change might be possible. There are too many political, economical, and sociological forces at work that preclude stopping it, let alone reversing it, at least for the near-term future (two decade or so). $\endgroup$ – David Hammen Nov 11 '14 at 18:43
  • $\begingroup$ Maybe i should have said "to stop causing further climate change"... $\endgroup$ – Alexey Nov 12 '14 at 14:30
  • $\begingroup$ I modified the question to say anthropogenic climate change... as this is certainly what you are talking about. Natural climate change cannot be stopped realistically. You might want to say "warming" instead. $\endgroup$ – farrenthorpe Dec 18 '14 at 16:59
  • $\begingroup$ @farrenthorpe, you have changed my title question. It was naïve, but i was asking if CO2 has to be converted into petroleum to stop the air composition change (which causes a climat change). $\endgroup$ – Alexey Dec 18 '14 at 20:48
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Summary

Most of the remaining stocks of hydrocarbons (coal, natural gas, oil) will have to remain unburnt. In almost all cases, that will mean leaving them in the ground. We already have proven technology to prevent new emissions of anthropogenic greenhouse gas emissions, and in most cases, the technical and economic barriers are solved: the remaining problem is purely political.

Let's make sure we're talking about the same thing

Let's get our terminology straight first. The big issue is rapid climate change; and we can do something about that, because the current rapid climate change we are starting to experience, is anthropogenic - it is human-caused. So, "climate change" here refers not to historic natural processes over thousands to millions of years, but the present anthropocentric-induced processes that are happening over decades. That is the most common usage of the phrase these days, but it still can be useful to state it explicitly once in a while so that we know we are discussing the same thing.

Stocks and flows

Climate change is a result of changes in the stock of greenhouse gases in the atmosphere.

Those stocks have increased a lot over the last 180 years or so, and are continuing to change, because we've messed about with the flows. In particular, we've increased the rate of emissions from sources, without increasing the rate of take-up of sinks.

The bathtub analogy: we've opened the bath taps further, so water's flowing in faster. But we haven't widened the drain, so the level of water in the bath is rising, and soon will overflow and flood the house. It's not the rate at which water enters the bath that's the problem in and of itself: it's the level of water in the bath, and that's rising quickly because the inflow is much faster than the outflow. Similarly, what matters for climate and climate change is the level of greenhouse gases in the atmosphere, and the level of CO2 absorbed into the oceans.

Even if new net emissions went to zero this year (technically impossible without the collapse of human civilisation, which would rather defeat the whole exercise), we'd still see increasing heat content of the Earth over the next few years, as things move towards equilibrium, based on the current levels of greenhouse gases which represent a historic increase over the levels that prevailed over the last few thousand years during which human civilisation has developed.

So, to prevent further climate change, we have to balance out sources and sinks. So we can do either, or a combination, of two things: we can decrease the rate of emissions from sources down to the level where existing sinks can absorb them; and we can increase the rate at which sinks absorb.

Reducing sources

Stopping burning fossil fuels is the easiest and simplest way to decrease the rate of emissions. To the best of my knowledge, we now have alternatives for almost all of the major emissions sources, with the possible exception of methane emissions from livestock farming. Some are very well-established, like hydro and onshore wind electricity generation. Some are maturing quickly, like PV, offshore wind. Some are successful in the lab, and ready to move to commercial-scale prototypes, such as decarbonised production of steel, clinker, and liquid hydrocarbons.

Increasing sinks

Carbon sequestration is one way to increase the sinks. It's been trialled at small scale, and remains problematic. The way that's been done so far is to pump the carbon dioxide underground. At the moment, no business has been willing to accept the open-ended liability that is posed by the risk of leakage. So at the moment, the market is saying that this is not a viable technology. That might change. It's also worth noting that at the moment, the market also wants to use CO2 sequestration as a means of extracting even more oil (Enhanced Oil Recovery, EOR), which just makes the whole problem worse.

One way that is fast, effective and affordable is increasing the amount of carbon in biomass. Reforestation and afforestation are two ways to do this, and would help reverse a lot of the human-caused loss of forest ecosystems, if done well.

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    $\begingroup$ Stopping burning fossil fuels is the easiest and simplest way to decrease the rate of emissions. That is wishful thinking. We presently have no viable alternatives to the huge amount of fossil fuels that humanity consumes, and we won't for decades. $\endgroup$ – David Hammen Nov 10 '14 at 4:40
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    $\begingroup$ @DavidHammen I'm not sure what you mean - we have viable alternatives for all of them. Electricity, heating, cooling are technically and economically easy, and quick to scale. Fossil-free liquid fuels are technically a solved problem, but need to move from lab to commercial scale. Happy to discuss in Earth Science Chat, or please do post a question over on Sustainable Living $\endgroup$ – EnergyNumbers Nov 10 '14 at 7:34
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    $\begingroup$ Humanity is burning the equivalent of about 2.5 cubic miles of oil in hydrocarbons per year. That's an immense amount of energy. There's no way to replace that huge amount of energy and stop burning fossil fuels in the next 30 years, and that's optimistic. Even more immense is the amount of political will that will fight that change. You have to be realistic. Then there's Japan and Europe. They are switching from nuclear power to coal. Finally, there's China and India. They are building coal plants at a ferocious rate. $\endgroup$ – David Hammen Nov 10 '14 at 14:55
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    $\begingroup$ @DavidHammen I'm still happy to discuss in Earth Science Chat - I'm really keen to find out how it is that you see things. If you'd like to ask some specific questions, then please do come on over to Sustainable Living - I think you'll be pleasantly surprised, as we do indeed have viable scalable alternatives for all of those fossil hydrocarbons. $\endgroup$ – EnergyNumbers Nov 10 '14 at 15:39
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No, we do not need to stop extracting petroleum, we need to stop burning petroleum, as well as other fossil fuels, because combustion converts solid C to gaseous C, and hence goes up to the atmosphere, increasing the amount of greenhouse gases that warm the planet.

No, we do not need to convert existing CO2 into diamonds. Plants are pretty good taking up CO2 from the atmosphere, and storing the C as wood, that goes later into the soil as plant litter, where it can be stored long-term (and over millions of years may even become diamonds, petroleum or coal!). There are C losses as CO2 into the atmosphere, via either plant or soil respiration, but that is another wide topic. To be more precise, terrestrial plants and oceans remove each year more than half of the CO2 we emit into the atmosphere, for free!

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