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A conversation with Dave Denkenberger on interventions to help survive a global food crisis, on 8 October 2013


        Dave Denkenberger, Ph.D.—Energy Efficiency Engineer, Ecova. Research Associate at the Global Catastrophic Risk Institute (GCRI)

        Nick Beckstead—Research Fellow, Future of Humanity Institute at Oxford University; Board of Trustees, Centre for Effective Altruism


Purpose of the call: I wanted to learn more about interventions that would make civilization more likely to eventually recover if a global catastrophe occurred.

Why this person: Seth Baum (Executive Director, GCRI) recommended that I speak to Dave Denkenberger on the topic of increasing resilience to extreme global food crises. I previously attended an online lecture on this topic on 22 August 2013 by Dave Denkenberger.

Summary: A nuclear war, a large asteroid collision, or a large supervolcanic eruption could put large amounts of particles in the atmosphere and substantially interfere with agricultural production for years, potentially resulting in large numbers of deaths from starvation. I spoke with Dr. Denkenberger about three potential methods of rapidly scaling up non-agricultural food production for the U.K. in these scenarios. Dr. Denkenberger believes extremely few other people are thinking about how to prepare for this scenario. We discussed what the methods are and how they could be tested.

The problem

A nuclear war, a large asteroid collision, or a large supervolcanic eruption could put large amounts of particles in the atmosphere and substantially interfere with agricultural production for years. Furthermore, agriculture could be disrupted by intentional or accidental release of organisms that destroy crops. In principle, billions of people could starve to death in these scenarios. The probability of this happening in any given year is highly uncertain, but Dr. Denkenberger believes the likely order of magnitude is 0.1% per year, or 10% this century.

Possible interventions

Dr. Denkenberger has a paper under review which discusses methods for rapidly scaling up food production in the face of a food crisis like this. The proposals in Dr. Denkenberger’s paper could be researched and tested. We discussed three specific research possibilities that Dr. Denkenberger believed were most relevant to the U.K. Dr. Denkenberger believes that further exploring the politics and economics of these food solutions would also be important.

Edible methane-digesting bacteria


There is a type of bacteria that grows on methane, using it both as a carbon source and an energy source. If it were pasteurized, people might be able to eat this bacteria, though it wouldn’t be a good source of carbohydrates.

What is it?

The ideal experiment here would be to retrofit an existing bioreactor into a system that could grow these methane-digesting bacteria. Dr. Denkenberger believes the experiment would be relatively simple, potentially the kind of thing a graduate student could do a simple demonstration of in a year.

What could we learn?

We would learn something about the efficiency of this strategy, the technical feasibility of ramping it up with existing infrastructure, and what it would cost to do it. If it worked, it might provide food for on the order of $1 per person per day. Of course, if it had to be scaled up quickly, it could easily cost substantially more. The key resources necessary are natural gas, the vessels where you can do the reaction, maintenance and controls.

People to talk to/references

Dr. Denkenberger contacted a bioreactor expert and asked him whether it would be feasible to do this. He could put me in touch with this person.

Roslev, P, Iversen, N & Henriksen, K 1997, ‘Oxidation and assimilation of atmospheric methane by soil methane oxidizers’, Appl. Environ. Microbiol., vol. 63, no. 3, pp. 874–880.

Industrial cellulose to food conversion


We currently have the ability to convert cellulose (found in wood, grass, and inedible parts of plants) into ethanol. This is a cellulosic biofuel. In order to create cellulosic biofuel, we typically convert cellulose to sugar, and then convert sugar to ethanol.

What is the intervention?

We could convert cellulose to sugar and eat the sugar. If this works, it would allow us to rapidly scale up food production in a global food crisis. However, converting cellulose to sugar creates some toxins. Dr. Denkenberger believes the toxins are present in low levels and would be unlikely to be damaging to humans.

Further research could involve testing this type of food on animals or humans.

If this works, what is the potential upside? How many people could we feed with what kinds of resources?

Ethanol costs about $4 per gallon, which is about $1 per pound. Food from cellulose would presumably cost less because there is one fewer step. Of course, if it had to be scaled up quickly, it could easily cost substantially more.

If the methods had been tested in advance, it might be possible to rapidly convert cellulosic biofuel production into food production.

People to talk to/references

Aaron Socha, expert on cellulosic biofuels.

Langan, P, Gnanakaran, S, Rector, KD, Pawley, N, Fox, DT, Chof, DW & Hammelg, KE 2011, ‘Exploring new strategies for cellulosic biofuels production’, Energy Environ. Sci., vol. 4, pp. 3820–3833.

Wyman, CE, Decker, SR, Himmel, ME, Brady, JW, Skopec, CE & Viikari, L 2005, ‘Hydrolysis of cellulose and hemicellulose’, in Polysaccharides: Structural Diversity and Functional Versatility, Marcel Dekker, Inc., New York, pp. 995–1033.

Zhu, JY & Pan, XJ 2010a, ‘Woody biomass pretreatment for cellulosic ethanol production: Technology and energy consumption evaluation’, Bioresource Technol., vol. 101, pp. 4992–5002.

Fertilizing the ocean to scale up fisheries

What is it?

The intervention is to dump macronutrients (primarily nitrogen and phosphorous) into the ocean in order to scale up fish production. Dr. Denkenberger believes that this would be economically favorable even today, though it probably has low political feasibility. This intervention requires some sunlight in order to work because the intervention works by growing algae to feed fish, but it could work with limited sunlight.

Some work as has already been done on iron supplementation. This was tested as a method of carbon sequestration, and it didn’t work very well for that. It worked as a method for increasing algae and probably fish populations.

Dr. Denkenberger believes that it would take 1.5 years to grow enough food for everyone in the world if this project took place with small fish with a short reproduction cycle (such as anchovies).

How would it be tested?

A small-scale fertilization pilot could be conducted and the resultant algae and fish concentrations could be measured before and after fertilization.

What are the risks of doing this experiment?

Too much fertilizer could result in eutrophication, but Dr. Denkenberger believes this could reliably be avoided. Experimenting with this would be called geoengineering and would be highly controversial for that reason.

People to talk to/references

The Ocean Carbon and Biogeochemistry (OCB) program is a scientific community-driven coordinating body that promotes U.S. research and international cooperation to investigate the ocean’s role in the global Earth system.[1] They would be a useful contact for macronutrient fertilization.

Watson, AJ, Law, CS, Scoy, KAV, Millero, FJ, Liddicoat, MI, Wanninkhof, RH, Barber, RT & Coale, KH 1994, ‘Minimal effect of iron fertilization on sea-surface carbon dioxide concentrations’, Nat., vol. 371, pp. 143–145.

Nellemann, C, Hain, S & Alder, J 2008, In Dead Water: Merging of Climate Change with Pollution, Over-Harvest, and Infestations in the World’s Fishing Grounds, United Nations Publications, Norway.

Who else is working on this?

Dr. Denkenberger discussed many possible preparations in his paper and sought feedback from subject matter experts on each, but did not encounter anyone else working on preparations to rapidly scale up food production for these specific scenarios. He believes extremely few people are thinking about these issues.

Dr. Denkenberger believes that some of these strategies could be implemented quickly in a global food crisis scenario even if research and preparations are not done in advance. He believes such efforts would be more likely to happen and more likely to be successful if research and preparations were done in advance. Dr. Denkenberger gave a talk on these issues to a US Homeland Security group, and they said they tend not to think about scenarios as extreme and unlikely as these. Dr. Denkenberger said that, in principle, there could be classified government plans for global food crisis scenarios, though we both felt this was unlikely because we couldn’t think of plausible reasons to want this information to be classified.

Questions discussed in our conversation

1.       What could we do to be better prepared for the kind of global food crisis that could happen if there were an asteroid collision, nuclear winter, or supervolcanic eruption?

2.       What would it take to do the kinds of experiments you are recommending?

3.       What would the potential upsides be?

4.       Who else is working on these issues?

5.       How could I learn more about the research programs you are recommending?

[1] Ocean Fertilization. “What is Macronutrient Fertilization?.” URL: Accessed: 2013-10-28. (Archived by WebCite® at