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Sequestering Carbon by Land and Sea
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by Worldchanging Editorial Intern, Alex Lowe:

Global warming could be compared to a runaway train -- something with inconceivable momentum that simply can't be stopped even as scientists and environmentalists try to throw every brake they can find. However, some scientists and engineers propose plans that aim not to stop the train, but to extend the track, either by scrubbing out CO2, large-scale geophysical engineering, or by increasing the rate of carbon sequestration until the problem with greenhouse gases can be controlled.

One of these ideas involves building artificial 'trees' that pull carbon out of the atmosphere and store it. The go-to researcher in this area, Klaus Lackner, says that these synthetic trees could sequester as much as 1,000 times the amount of CO2 as their biological counterparts. Also, Lackner and other researchers have found a better sorbent for capturing CO2 than the sodium hydroxide of earlier models. One advantage of the new sorbent is that the cost of the technology would not be much more than the conventional method of trapping CO2 from a flue stack.

According to Lackner, the usefulness of synthetic trees for sequestering CO2 could extend beyond a transitional technology for ending the age of oil. He explains:

Synthetic trees could well outlive fossil fuels. Consider the availability of cheap renewable electricity which can produce hydrogen from water. This hydrogen combined with CO2 can produce all sorts of synthetic carbon based fuels from methanol to gasoline and diesel. In this way the world could enjoy convenient carbonaceous fuels that are made with renewable rather than fossil energy. Such an energy infrastructure would be clean and have zero impact on the world's carbon balance.

Some scientists favor a more audacious-sounding plan: seed the ocean with iron dust to promote the growth of new phytoplankton. Phytoplankton, the base of the ocean's food chain, removes a huge amount of CO2 from the atmosphere. The extra amount of phytoplankton would increase the ocean's ability to absorb carbon, and buy time for humanity to wean itself off of fossil fuels. The San Francisco-based company Planktos Inc. planned to begin the process this month by seeding the ocean several hundred miles to the west of the Galapagos Islands with 45 tons of micronized iron.

But other groups see this plan as too bold. One of them is the Environmental Protection Agency, which warned Planktos that its activities would constitute dumping and therefore would require a permit in agreement with the U.S. Ocean Dumping Act. Some researchers such as Dr. Gabriel Filippelli say that the iron will dilute too quickly in the ocean to have the desired effect. However, Planktos' CEO Russ George remains steadfast, and says that adequate research on his plan has already been done, and that "fear mongering" was the primary force behind the EPA's warning.

The ecological disruption and potential acidification of the ocean clearly detract from the beneficial possibilities suggested in this proposed solution, but if further research can prove this strategy free of harmful side effects, the rate and volume of sequestration it enables warrant further consideration alongside continued and careful scrutiny.

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Nice balanced perspective here. You can always count on World Changing to frame an issue correctly.

Iron fertilization has potential if it can be implemented with the proper scientific approach. This is a 2 billion year old biologic process for storing CO2 in the deep ocean. I think it's safe to say that life in the Oceans has adapted to iron fertilization, and that negative ecological impacts can be effectively minimized with smart project design.

Of course, it's one thing to push iron off the back of a boat and cause a bloom. It's another thing entirely to measure the carbon sequestered with accurate GHG project accounting that is acceptable in the world's carbon markets. In other words... you can't sell it if you can't measure it, and measuring it ain't easy.

Posted by: Kevin on 25 Jun 07

How's this for ambitious?

The rate a which we decrease energy intensity - the energy required to produce one currency unit ($, etc.) of GDP - changes from 1% to 2% a year.

Concerted family planning efforts help stabilize world population at 9 billion by 2050 or so - the middle of the range of 7.5 to 11 billion predicted by the United Nations.

World annual growth of GDP decreases from an average of 1.6% a year to 1% a year. This is because we only grow those things that really have net societal value. (Yeah, I know, but let's think big here, okay?)

If we do those three things, then, to stabilize CO2 levels at 450 PPM - the critical threshold - we would need 0.5 TerraWatts of non-carbon energy sources yearly. That would be doable.

And by all means, we need to look at sequestration strategies. As far as I learned, the "iron fertilizer" scheme won't work, but there are other promising avenues. I'm biased toward efforts that do more than one thing: if we increase soil carbon, we're sequestering but also improving agriculture, hydrology, etc. If we move toward pragmatic forms of forest farming, we're also gaining multiple benefits.

But the central point of this essay, hard as it may be for some to accept, is that there's too much inertia in the climate system now for us to avoid a difficult time ahead. Our only choice now is between difficult problem and catastrophe - and sequestration, done smartly, may play an important role. It won't be a panacea, allowing business as usual, but neither does health insurance.

Posted by: David Foley on 26 Jun 07

Stop fossil emissions tomorrow, and we still have a huge problem. Soil (especially temperate grassland soils) offers the best practical opportunity to stop global warming if we can get the fossil fuel burning stopped. If we use the soil sink as "offset" to continued fossil fuel burning we will waste our one opportunity.

But the soil as sink is not even on most people's mental maps. Academic estimates of soil potential are somewhat less than impressive, all based on industrial agricultural practices and the recovery of soil carbon on stopping them. This is shortsighted. Grass farming (see OMNIVORE's DILEMMA on Joel Salatin for example) and holistic management have achieved orders of magnitude more carbon storage than most organic farming or no-till or land idling or conversion to pasture under conventional grazing management.

Trees, despite much hopeful reporting, have less potential. There are about 560 gigatons of carbon in plant and animal biomass, about 770 in the atmosphere, and about 1500 in soil organic carbon. Tree carbon either rots or burns, releasing its carbon back to atmosphere. Soil carbon can be stable for hundreds of years.

There is very little familiarity in government, academia, or nonprofit organizations about soil organic matter and how rapidly it can be developed under the right management (e.g. well managed high density grazing of perennial grass stands). There is far more buzz about biochar or terra preta concepts, because 1) they involve technology, pipes and chambers and valves, and we love that, 2) it's an ingredient or additive, and we love those too. Soil organic matter, by contrast, is a biological process. It's hard to invest in, or develop intellectual property rights over, and there's no big market waiting to be developed. It directly threatens petrochemical interests.

Allan Yeomans, in his book PRIORITY ONE: TOGETHER WE CAN BEAT GLOBAL WARMING, explains all of this and more in his dynamite book. For US edition see

As Churchill said the Americans will eventually do the right thing but not before exhausting the alternatives. The right thing is to stop fossil fuel burning AND develop organic matter in the soil. But so much of the discussion is around the "alternatives" that Churchill mentioned.

Posted by: Peter Donovan on 26 Jun 07

Good points, Peter. At our little place in Maine, we increased soil organic matter on 0.4 acres (about 0.16 hectare) from less than 1% to 7.7%. Some conservative calculations showed that we sequestered at least 19 tons (about 17.25 tonnes) of carbon in the process. And we've reaped many other benefits. But I'm not sure that this is the only strategy we should work on - some of the "pipes and additives" schemes have merit too.

Posted by: David Foley on 27 Jun 07



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