Should we reject Negative Emissions Technologies, except for organic agriculture?
Geoengineering is commonly defined as a large-scale technological intervention in the Earth’s climate system. Proposals have included the injection of sulphate aerosols into the atmosphere to cool the climate, and various ways of drawing down atmospheric carbon dioxide into the crust, plants or soil. Of virtually all these geoengineering proposals, there is nearly universal condemnation among climate justice activists: In no way will we accept the empty promise of a technofix in the end game, as fossil capital fights against effective mitigation of ongoing climate change.
Nevertheless, there is general support for a sustainable agricultural drawdown of atmospheric carbon dioxide, such as in the recent article by Daniel Tanuro, a prominent Belgian ecosocialist. Tanuro’s piece, “The specter of geoengineering haunts the Paris climate agreement” (Climate & Capitalism, January 25, 2016), contributes to the reignited a debate brought about by the recent Paris Climate Conference (COP21) on the how Negative Emissions Technologies (NET) have been put forward as a technofix in otherwise very weak mitigation scenarios (e.g., Kevin Anderson’s biting critique on the Paris Agreement, “Talks in the city of light generate more heat,” Nature, December 21, 2015).
I largely agree with Tanuro’s take on the Paris Agreement, and with his support for using organic agriculture and sustainable forestry for carbon-sequestration from the atmosphere. Carefully vetted industrial NET will be necessary to have any chance to prevent climate catastrophe, but only when coupled with the agroecological transformation of agriculture and radical reduction in carbon emissions from fossil fuel combustion.
Coupled with the complete phase-out of fossil fuels in the next few decades, implementing carefully selected NET will be imperative to have any chance of keeping warming below 1.5 °C by 2100, and avoiding tipping points to climate catastrophe in the interim. In particular, reacting carbon dioxide and water with mafic and ultramafic rocks, such as basalt and peridotite, to produce carbonates is one promising NET (Gislason and Oelkers, “Carbon Storage in Basalt,” Science, April 25, 2014).
Whether the carbon is stored in the soil, forests or crust, carbon sequestration from the atmosphere is the only geoengineering approach that is imperative, in order to bring the atmospheric carbon dioxide level below the safe level of 350 ppm and maintaining it below this level (the atmospheric carbon dioxide level is now 400 ppm). This sequestration program will be imperative for the rest of this century and beyond because approximately half of the anthropogenic carbon dioxide emissions go into the ocean and biota, which continuously re-equilibrate with the atmosphere (Cao and Caldeira, “Atmospheric carbon dioxide removal: long-term consequences and commitment,” Environmental Research Letters, June 30, 2012).
But is organic agriculture and sustainable forestry sufficient for this goal? Probably not, since the physics of climate change tell us sequestration must be as rapid as possible. The higher the atmospheric carbon dioxide level the more intense the warming impacts, hence the sooner and faster sequestration begins the greater the prospects of preventing catastrophic climate change (C3) (Matthews and Caldeira, “Stabilizing climate requires near-zero emissions,” Geophysical Research Letters¸ February 27, 2008).
Efforts to boost sustainable agriculture, specifically with agroecologies and permaculture, are imperative to replace industrial/GMO agriculture, both to confront the challenge of climate change and to eliminate big negatives of the present system of unsustainable agriculture. But the carbon sequestration fluxes of these approaches, including sustainable forestry and wetland restoration, are not big enough to drive the most effective prevention program needed to avoid C3.
Some even claim that a transition to sustainable agriculture alone can “reverse global warming” without the elimination of greenhouse gas emissions from fossil fuel sources. For example, Biodiversity for a Livable Climate’s position has been: “We can return to pre-industrial atmospheric carbon levels in a few decades or less, and cool the biosphere even faster than that.” But, as I have argued elsewhere, the maximum flux is far too small to achieve what is claimed, even if fossil fuel emissions cease immediately (“‘Restoring Ecosystems to Reverse Global Warming’?: A Critique of Biodiversity for a Livable Climate’ claims,” October 4, 2015, PDF).
Carbon sequestration from the atmosphere will require a very ambitious program involving a combination of technologies, including the transformation of agriculture into agroecologies, as well reacting carbon dioxide and water with mafic rocks in the crust to produce carbonates; this is not “clean coal”, or carbon capture and storage (CCS). The concluding lines from recent paper are very relevant:
“We conclude that CDR [Carbon Dioxide Removal from the atmosphere] can be a game changer for climate policy in the sense that it significantly improves feasibility and cost considerations for achieving stringent climate stabilization. It is, however, a complement, not a substitute to the traditional approach of mitigating emissions at their source” (Kriegler et al, “Is atmospheric carbon dioxide removal a game changer for climate change mitigation?” Climatic Change, February 22, 2013).
Tanuro is correct to point out that chemical sequestration of carbon from the atmosphere will require a lot of energy, indeed a significant fraction of future primary energy consumption. With the present global consumption a baseline (18 trillion watts, primary energy consumption), and growing global population, incremental energy will be required for the following new challenges facing our planetary civilization:
- Carbon sequestration from the atmosphere into the soil and crust to bring down the atmospheric carbon dioxide level below the safe level of 350 ppm and maintaining it below this level.
- The clean-up of the biosphere, notably toxic metals and other chemical and radioactive waste from the nuclear weapons, energy, and chemical industries—a heritage of its long-term assault from the Military Industrial Complex.
- Adaptation to ongoing climate change, especially by the global South with its disproportionate impacts.
All three imperatives will require very significant energy supplies from future wind/solar power, incremental to present uses. The actual level of this increment needs study but some preliminary estimates are now available (for some technical details, see “Correction to Schwartzman, D. and P. Schwartzman, 2013,” January 12, 2016, PDF).
A greater energy capacity than present will likely be required to realize these objectives, with a complete transition to a global wind/solar power infrastructure by 2050, including its roughly 30% gain in efficiency, at least 22 trillion watts will be required to guarantee the minimum energy per person necessary for a state-of-the-science quality of life (3.5 kilowatt/person x 0.7 x 9 billion people; note that the latest United Nations  projection for 2050 is 9.7 billion people).
Further, additional capacity will be necessary especially for ongoing carbon-sequestration from the atmosphere and climatic adaptation, with the total required likely approaching 25 to 30 trillion watts.
Finally, Tanuro is right on point: “No time to lose.” Radical changes in both the political and physical economies are necessary to make this all happen, and curbing carbon emission and opening up an ecosocialist path must be first priority.