Tuesday, March 18, 2008

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?


erich said...

I've seen various numbers on Biochar's effects on soil GHG emissions, ranging from 80% reduction in N2O, to an over all reduction of 1/3 , accounting for NH4 & N2O together.

The Japanese work in tea plants showed N2O reductions at very small application rates.

These co-benefits will vary with soil types, but once validated , a premium of CO2 equivalent payments should be added to each ton carbon (C) a farmer puts to the soil.

I would love to see an extrapolation accepting the 1/3 reduction of NH4 & N2O on your numbers calculation.


Chris Dudley said...


I came across your work in a presentation Jim Hansen gave in February which is linked at his web site. I looked to me as though you have some specific propsals on ways to price carbon or ration it and I was particularly taken by what seems like a theory of rights in the statement: "And you should be the only one who has the right to sell emissions permits" but I'm a little vauge about this. I'm guessing that you mean that those who sequester should be able to chose if their efforts are an offset to current emissions or a capturing of past emissions. Is that correct?

While I can see the benefits of biochar, I am a little worried that their permanance has not been demonstrated in all soil ecologies. On the other hand, coral and shellfish sequester carbon as calcium carbonate which can be quite permanant, so I feel that restoration of the health of our estuaries and oceans should be a big part of sequestration efforts. I've made an estimate here of the scale of sequestration that might be accomplished.

Folke said...

Yes, that is a better formulation. What I mean is; selling emission permits could not be man-to-man affair, it should have some relation to real material exchange in nature, i.e. you can not sell an 'idea' (issued by EU or who-knows-whom), you can only sell a right to emit when you have done some real counteracting service, as sequestration.
For the longevity of charcoal in soil: The charcoal in the Amazonian rain forest Terra Preta is certainly 500 years old, since they stopped producing it about 500 years ago. C14 measurements of the older Terra Preta soils point at 6000 years. Ogawa’s measurements (with ozone) points at 50,000 years.
As for the oceans and estuaries: It is probably this effect that stands for the difference between the calculated emissions by Houghton, 425 Gt C, and the actual atmospheric increase of 220 Gt C. However, I don't think we can rely on the continuation and increase of this effect, especially since we already have seen the atmospheric carbon dioxide level rise to dangerous levels already.
By that, I DON'T say that any available sequestration method should be abstained from.

erich said...

Dr. Lukas reports 10X N2O soil emission reductions:

Beyond Zero Emissions interviews Dr Lukas Van Zweitan senior research scientist of the NSW Department of Primary Industries (DPI). Who is working hand-on with soil research focusing on Bio Char (Terra Preta de Indio / Agri Char)

"we've found with some of the biochars in that we've had very, very significant reductions in nitrous oxide emissions from the soil; between five- and ten-fold reductions in nitrous oxide emissions."



Mark said...

Erich, I got "page not found" with the above link, although http://beyondzeroemissions.org/ looks pretty good.

Folke, I don't understand the significance of nitrous oxide emissions from soil - could you give a clue please?



Folke said...

I found the page load and clear. Just try again!
Because of it heat reflection capacity and longevity in the atmosphere, N2O is considered a serious greenhouse gas, more than 300 times than the effect of CO2. The redaction of emissions from soils with added char seems promising. Perhaps one could try with char in the manure storages in stables too? Adding charcoal to the dung groove behind the animals? Or elsewhere?

Anonymous said...

In California Sierra Pacific Industries is promoting their report that claims that clearcutting (they call it intensive managment) will produce more carbon sequestation faster than other methods. This study is full of misleading and tilted data and they are using it to further justify clearcutting the rest of their massive holdings in California. Can good scientists not paid by the timber industry will dispute this report?