Pure optimistic fantasy

Assume, for a moment, that all people of the world made a decision to stop global warming by reducing emissions at the same time as removing carbon dioxide from the atmosphere.

Here, I will not deal with the necessary emission reduction of 90%, but look at the sequestration side: How could people be encouraged to create charcoal and bury it in soil in amounts large enough to make a difference?

It is not hard to persuade growers and farmers to put charcoal in the soil, sine the benign effects are so many and visible that any grower will start, once they see the effects, at home or by someone else. The problem is that he farmers and growers are so few, and the amounts so large. We have to remove 70 gigatonnes (70 000 000 000 000 kg) of carbon dioxide from the atmosphere only to come to a reasonably safe level (350 ppm).

Today, the amount of carbon dioxide in the atmosphere is not diminishing at all. On the contrary, it is increasing with about 8 gigatonnes annually. That represents an increase in carbon dioxide level with more than 3 ppm. The numbers speaks for themselves. I will not discuss how the emission reduction might be done.

So, how to make people interested in carbon dioxide burying? Say, that it is possible to annually char about 12-15% of the global net production of biomass, about the same size as the global forest industry. That would make it possible to annually remove about 2 gigatonnes from the carbon cycle, so it not ends up in the atmosphere again.

Some nations (Sweden, Finland, Norway, the Netherlands, UK and British Columbia in Canada) have started to tax the emissions of carbon dioxide, assuming people by that would reduce their emissions. The Swedish tax is 1 SEK, about $ 0.16, per kilo carbon dioxide .We have an entrance here.

In my fantasy, I will decree a carbon dioxide tax for all emissions, all over the world. No exceptions for heavy polluters, as we have here in Sweden . Say, that the global tax would be half of the one in Sweden (0.5 SEK, or $0.08, £0.04, €0.05 per kilo carbon dioxide emitted)

I can imagine the shriek echoing all over the world after almighty me have imposed that tax. I
also realise that it would not decease the emissions very much, just lead to more money in circulation.

But all these money (2.4 thousand billion dollars, counted as the current emissions) could also be seen as an asset if they are set to the right action.

While fantasizing, we also introduce the notion of a fair carbon dioxide tax. As all people (in this perfect world, ruled by me) have to pay for carbon dioxide emissions, they should also get a chance to earn from drawing carbon dioxide back.

So, I make another decree: Those who bury carbon in the soil shall be paid the same amount as the emission-makers have to pay for their emissions. (Here comes some chemistry in: As carbon dioxide has the molecular weight of 44, but carbon only has the weight of 12, the weight of carbon that is put into the soil must be multiplied with 44/12=3.7 for the sequesterer to get the right payment). Firstly, that would lead to an interesting effect: The busy sequesterer, working in the field, would be quite interested in reducing his “carbon dioxide footprint”, since hat would reduce his net income. He, also, has to pay emission tax if he emits carbon dioxide .

But, most interesting is that everybody, all over the world (perhaps not the guys living on Greenland) would have the opportunity to get a real income from carbon sequestering. Given the above tax rate, the sequestering of two tonnes of carbon per hectare farmland (which is easy, done simply by the crop residues) should get receipts for that corresponding to $ 600. As this easily could be done just using crop residues, it is not competing with food production at all. Furthermore, after digging the char into the soil, the production will increase by more than 50% the following years.

Naturally, objections against this scheme can be numerous, including problems of controllability, bribing etc.

In a charring plant of a larger size, also the pyrolysis gasses (60% of the biomass) can be industrially utilized for numerous uses, or for energy.

But that is another story.

Right observation, wrong conclusion

Some time ago, I got an enthusiastic e-mail from a friend.

He told me he have had a compost heap at home
(Really a heap of leaves, not the neat thing you often find in a residential garden. It had been staying there for years, with just a slight decease in volume).
After having repeatedly listening to me talking of the benefits of adding char to compost and soils, he thought that he should give it a try. So he took some leftover barbeque char and put in the compost heap.

That was last autumn. He forgot everything until some weeks ago when he happened to stroll by. The heap had disappeared! Instead of the heap of semi-mouldered leaves, there was a much smaller heap of something rather looking like soil, with lots of earthworms in it. Plus the char.

Then he went to the computer and mailed me: --“ I am a believer …!”

-----------------------------------

In last week’s number of Science, (2 May), David Wardle, Marie-Charlotte Nilsson och Olle Zackrisson delivers an article: "Fire-Derived Charcoal Causes Loss of Forest Humus". They have done exactly the same observation, that charcoal increases soil meabolism, using a controlled measurement method during a ten-year long test. They used three types of 1 gram bags containing respectively charcoal, humus and humus + charcoal, letting them stay in the soil for up to ten years.

The investigation revealed that the reduction in weight of the bags containing both charcoal and humus was much larger than the bags containing only charcoal or only humus.
Just like my friend with the compost heap found out.

So long, so well. A fair conclusion would have been that the charcoal increases the soil metabolism. Not mentioned in the report, but the also found increased vegetation around the bag with humus + char.

Sadly, they did not stay with that. They also jumped to a conclusion where they claim that the increased microbial activity break down humus particles at a rate that counteracts the carbon sequestration effect of the carbon.

The latter conclusion, however, is wrong.
Since the humus particles would have been broken down later anyhow, a faster breakdown will not counteract the carbon sequestration made by the incorporation of carbon particles in soil.
Just like the compost heap of my friend; waiting some more years would have changed an un-charred heap into the same composted state as the one with char added.

The decomposition rate of the humus in the soil has nothing to do with the carbon sequestration capacity of the charcoal. This capacity is only influenced by the longevity of the charcoal in soil (which is many thousands of years)

Critical numbers: Where should Humanity Aim?

James Hansen and his associates are currently working with a manuscript called "Target Atmospheric CO2: Where Should Humanity Aim?", available in the link above.
In it, they conclude that, to be out of the immediate danger of tipping our life support system into a state where it no longer can be considered a life support system to us (the humanity), the carbon dioxide level in the atmosphere should be below 350 ppm.

The carbon dioxide level in the atmosphere is 385 ppm today.

This means that the atmosphere contains about 74 Gt too much carbon. Every year, about 7 Gt more is released. Say, as a thought experiment, that all emissions, 100%, are stopped within 20 years (don't ask me how), leading to a total breakdown of our current society. Even that would mean additional emissions of about 70 Gt more, leading to a CO2 concentration of 418 ppm (if the oceans don't suck up anything more, perhaps 400 ppm if they are friendly enough to do that).
CO2 levels like that would probably lead us far beyond several tipping points.
Even if not, the resulting climate would not feed the population, not to talk about the potential for floodings.

So, if disaster is threating whatever we do, should we give up?

No, since there is one more possibility: If the efforts to decrease emissions are combined with a massive sequestration of carbon, then it is possible to back away from the ominous carbon dioxide levels.
As the incorporation of plant charcoal in the soil obviously has a lot of benign effects (Google: Terra Preta ), increasing crops, reducing nutrient loses and so on, why shouldn't we start immediately?

The carbon numbers II

I have several times been asked about the amount of carbon existing in excess in the atmosphere, and the possibilities to remove it within reasonable time. Therefore, I will provide the figures as far as I know them, and the reasoning behind them.
If you can't stand numbers, stop reading here.

The global annual net primary production (NPP) varies, but is estimated to be between 70 and 100 Gt per year, by different sources. This is the annual biomass growth in the plant cover of the Earth. For ease of calculation, let's take 80 Gt as the number. Say that 50% of this is thin roots and leaves, not usable for charring. Remains 40 Gt C that is theoretically available for charring each year.
Assume furthermore that efforts to create charcoal for carbon sequestration results in an annual sequestration of 2 Gt C as charcoal. That would mean an addition of four tonnes of char per hectare globally, certainly a war-like effort. The global forest product production 2004 was abut 9.5 Gt (FAO), with a carbon content that can be estimated to 3.8 Gt C, so we are speaking of a herculean, warlike efforts in charring, about half the size of the global forest industry.
However, char can be made from not only forest products, but also straw and husks from agriculture, as well as forest products that are useless to the industry, which makes it at least theoretically possibie to reach a goal of 2 Gt. That is about 8.5% of the above figure of coarse biomass production.

Jim Hansen and Pushker Kharecha of NASA Goddard Institute for Space Studies have pointed out some faults in my calculations in the following paragraph, why I below present it in the revised form :
The carbon dioxide "cloud" is presently about 475 Gt too large (counted as accumulted emissions of C, carbon). Due to buffering from seas and other ecosystems, the atmosphere only contain 220 Gt of carbon The number is the difference between the atmospheric content in pre-industrial time (280 ppm) and that of today (384 ppm). (Of this figure, about 33% is from deforestation). (Figures from Richard A Houghton, Woods Hole Research Center, one of the IPCC guys, and Jim Hansen/Pushker Kharecha of NASA) Imagine that you could take all this away and convert it into charcoal. That amount would add about 955 tonnes of char per hectare agricultural land globally. This wll give the soils a carbon content f about 25%, not very far from the Terra Preta soils. But with the above efforts, 2 Gt p.a., it would take about two hundred years to reach that point.

The global carbon dioxide effluents of today are equivalent of about 7 Gt C. Assume, for a moment, that the people and their leaders around the world will face the imminent danger of a sudden and irreversible climate change and decide to do everything possible to avoid it. They decide to start the above sequestration combined with a sudden braking in carbon emissions, e.g. an 85% reduction in 25 years, leveling out on roughly 1 Gt C per annum, leading to a net sequestration of about 1 Gt C per annum.
Then, given that the reduction is even over time, one could expect that the carbon dioxide cloud could start reversing after about 18 years.

I hope sincerely, that that is not too late.

The carbon numbers

I have several times been asked about the amount of carbon existing in excess in the atmosphere, and the possibilities to remove it within reasonable time. Therefore, I will provide the figures as far as I know them, and the reasoning behind them.
If you can't stand numbers, stop reading here.

The global annual net primary production (NPP) varies, but is estimated to be between 70 and 100 Gt per year, by different sources. This is the annual biomass growth in the plant cover of the Earth. For ease of calculation, let's take 80 Gt as the number. Say that 50% of this is thin roots and leaves, not usable for charring. Remains 40 Gt C that is theoretically available for charring each year.
Assume furthermore that efforts to create charcoal for carbon sequestration results in an annual sequestration of 2 Gt C as charcoal. The global forest product production 2004 was abut 9.5 Gt (FAO), with a carbon content that can be estimated to 3.8 Gt C, so we are speaking of a herculean, warlike efforts in charring, about half the size of the global forest industry.
However, char can be made from not only forest products, but also straw and husks from agriculture, as well as forest products that are useless to the industry, which gives us a large possibility to reach a goal of 2 Gt. Which is about 8.5% of the above figure of coarse biomass production.

The carbon dioxide "cloud" is presently about 475 Gt too large (counted as C, carbon). The number is the difference between the atmospheric content in pre-industrial time (280 ppm) and that of today. (Of this figure, about 33% is from deforestation). (Figures from Richard A Houghton, Woods Hole Research Center, one of the IPCC guys.)
Imagine that you could take this amount away and convert it into charcoal. That amount would add about 95 kg char per hectare agricultural land globally. 38 bags of barbecue char. Not very much . But with the above efforts, 2 Gt p.a., it would take more than three hundred years to reach that point.

The global carbon dioxide effluents of today are equivalent of about 7 Gt C. Assume, for a moment, that the people and their leaders around the world will face the imminent danger of a sudden and irreversible climate change and decide to do everything possible to avoid it. They decide to start the above sequestration combined with a sudden braking in carbon emissions, e.g. an 85% reduction in 25 years, leveling out on roughly 1 Gt C per annum, leading to a net sequestration of about 1 Gt C per annum.
Then, given that the reduction is even over time, one could expect that the carbon dioxide cloud could start reversing after about 18 years.
I hope sincerely, that that is not too late.