Dr. David Denkenberger received his B.S. from Penn State in Engineering Science, his masters from Princeton in Mechanical and Aerospace Engineering, and his Ph.D. from the University of Colorado at Boulder in the Building Systems Program. His dissertation was on his patented expanded microchannel heat exchanger. He is an assistant professor at University of Alaska Fairbanks in joint in mechanical engineering and Alaska Center for Energy and Power. He co-founded and directs the Alliance to Feed the Earth in Disasters ( and donates half his income to it. He received the National Merit Scholarship, the Barry Goldwater Scholarship, the National Science Foundation Graduate Research Fellowship, is a Penn State distinguished alumnus, and is a registered professional engineer. He has authored or co-authored 104 publications (>2000 citations, >50,000 downloads, h-index = 23, third most prolific author in the existential/global catastrophic risk field (, including the book Feeding Everyone no Matter What: Managing Food Security after Global Catastrophe. His food work has been featured in over 25 countries, over 200 articles, including Science, Vox, Business Insider, Wikipedia, Deutchlandfunk (German Public Radio online), Discovery Channel Online News, Gizmodo,, and Science Daily. He has given interviews on 80,000 Hours podcast and Estonian Public Radio, WGBH Radio, Boston, and WCAI Radio on Cape Cod, USA. He has given over 80 external presentations, including ones on food at Harvard University, MIT, Princeton University, University of Cambridge, University of Oxford, Cornell University, University of California Los Angeles, Lawrence Berkeley National Lab, Sandia National Labs, Los Alamos National Lab, Imperial College, and University College London.

Wiki Contributions


Intervention report: Agricultural land redistribution

Very interesting! You may want to note that in Figure 9, log refers to log base e (ln), not log base 10.

Shallow evaluations of longtermist organizations

This is most likely my fault; I think I got confused between and

We tried to buy the .org domain, but unfortunately it was not for sale.

Essentially I'd expect any preparation to at least fail partially, fail to get implemented, be ignored, not survive in institutional memory, etc.

There are definitely a lot of failure modes, though part of the money should go to updating institutions as staff turn over.

Thanks for updating the Guesstimate.

Separately, your numbers still seem fairly high. Suppose that in 1980 you had $100M and knew that there was going to be a pandemic (or another global financial crisis) in the next 100 years, but didn't knew the details; it seems unlikely that you could have made the covid pandemic or the 2008 financial crisis more than 10% better.

Good question. I think these are quite different because billions of dollars had been put into preparedness, at least for a pandemic. Though billions of dollars have been put into preventing a nuclear war (and reducing weapon stockpiles), we could not find anything preparing for feeding populations for a multiyear catastrophe. I think generally there are logarithmic returns, which means the first amount of money spent on a problem has much greater marginal cost effectiveness.

Shallow evaluations of longtermist organizations

Thanks for considering ALLFED. We try to respond to inquiries quickly. We have looked back, and have not be able to locate any such inquiries. We will be finalizing our 2020 report with financial details soon.

Thanks a lot for the engagement in the cost-effectiveness model. To clarify, the cost of preparation does not include the scale up in a catastrophe. The idea is that the resilient foods (we are rebranding away from “alternative foods”) could be scaled up without large-scale preparation (e.g. countries would repurpose the paper factories to produce food after the catastrophe, rather than spending billions of dollars ahead of time). Most of the promising resilient foods have already been commercialized. In this paper, we found that if there were no resilient foods, expenditure on stored foods in a catastrophe would be approximately $90 trillion and about 10% of people would survive. However, if resilient foods could be produced at $2.5 per dry kilogram retail, 97% of people would survive but the total expenditure would only be ~$20 trillion. So one could argue that resilient foods would actually save money in a catastrophe. But we did not include that effect in the cost-effectiveness model.

I expect that affecting a large amount of the Earth's future impact (i.e., 3 to 50% of the future impact of humanity) would be very hard even in extreme circumstances.

Just to make sure we are on the same page, if there were a 10% probability of full-scale nuclear war in the next 30 years and there were a 10% reduction in the long-term future potential of humanity given nuclear war, and if planning and R&D for resilient foods mitigated the far future impact of nuclear war by 50%, then that would improve the long-term potential of humanity by 0.5 percentage points (the product of the three percentages).

What are the 'PlayPumps' of cause prioritisation?

Opposing the Green Revolution in Africa here:

"Borlaug's initial efforts in a few African nations have yielded the same
rapid increases in food production as did his initial efforts on the 
Indian subcontinent in the 1960s. Nevertheless, Western environmental 
groups have campaigned against introducing high-yield farming techniques to Africa, and have persuaded image-sensitive organizations such as the Ford Foundation and the World Bank to steer clear of Borlaug."

The Green Revolution wasn't even GMOs - just dwarf crop varieties, fertilizers, and pesticides. Not only did opposition to this mean many more people dying of malnutrition, but also more rainforest cut down, so more loss of biodiversity and climate change. 

Do we need to keep increasing energy consumption?

I've worked in energy efficiency, so I've thought about this a lot. Pure energy efficiency is getting the same utility with less energy. However, energy conservation is generally regarded as situations where you have to give something up, such as thermal comfort, convenience, travel, second homes etc. One successful example of energy efficiency is appliances in the United States such as clothes washers, refrigerators, and dishwashers now use about 1/4 as much energy as they did a few decades ago at negative costs for CO2 saved. I think there are still many opportunities to reduce energy use cost effectively and get the same utility. But once you go to non-cost-effective energy efficiency or directly limiting activities, the economic costs (taking into account non-monetary factors) get extremely high. I've run a few numbers and have gotten around $1,000 to $10,000 per ton CO2, versus ~$100 per ton CO2 for things including renewable energy and air capture. So I don't think we should be directly limiting activities.

A bunch of reasons why you might have low energy (or other vague health problems) and what to do about it

I would add sleep apnea as a possible cause of fatigue. The test is relatively inexpensive, and the CPAP machine can be a game changer.

Should aid organizations accept ETH donations?

Yes, these are extremely energy efficient ways of saving lives. I think most people would think it is ethical to save lives from radon gas causing cancer, despite the solution being more ventilation. If it costs $5 million to save a life (typical value in the US), since electricity costs about $0.10 a kilowatt hour, then we would be willing to spend 50 million kWh to save a life! In reality, not all of the cost goes to energy, but a lot of the cost would be saved in the form of heating fuel, which is much less than $0.10 a kilowatt hour. This can be used to show that the energy used to fly flowers grown in Africa to Europe is also a relatively energy efficient way of saving lives.

Some quick notes on "effective altruism"

Though I was surprised when I read the results of the first EA survey because I was expecting the majority of non-student EAs would donate 10% of their pretax income, I don't think that saying that EA donations are extremely low is quite fair. The mean donation of EAs in the 2019 survey was 7.5%. The mean donation of Americans of pretax income is about 3.6%. However, with a significant number of EAs outside of the US giving less, the fact that many EAs are students, and the since I think that the EA mean is by person rather than weighted by donation (as the US average number is), I would guess EAs donate about 3-5 times as much as the same demographic that is not an EA. I do think that we could do better, and a lot of good could come from more donations.

Why I find longtermism hard, and what keeps me motivated

Nice piece! Though this does not work for all longtermist interventions, some find it motivating that AGI safety, alternative foods, and interventions for losing electricity/industry (and probably other interventions) likely save lives in the present generation more cost-effectively than GiveWell top charities. This book argues that doing more to mitigate catastrophes can be justified by concerns of the present generation.

Big List of Cause Candidates

Congratulations on winning the comment award! I definitely agree we should broaden the scenarios at which we look. You can see some work on the long term future impact of lesser catastrophes here and here.

  • Solar storm disruption

Yes, and other catastrophes that could disrupt electricity/industry, such as high-altitude detonation of a nuclear weapon causing an electromagnetic pulse, coordinated cyber attack on electricity (perhaps narrow AI enabled), or an extreme pandemic causing the desertion of critical jobs may be important to work on.

  • CO2 emissions from fossil fuels and other climate change rendering the atmosphere unbreathable (this would be a good old fashioned X-risk, but seems like one that no-one has discussed - in Toby's book he details some extreme scenarios where a lot of CO2 could be released that wouldn't necessarily cause human extinction by global warming, but that some of my back-of-the-envelope maths based on his figures seemed consistent with this scenario)
  • CO2 emissions from fossil fuels and other climate change substantially reducing IQs

Even 7000 ppm (0.7%) CO2 only has mild effects, and this is much higher than is plausible for Earth's atmosphere in the next few centuries.

  • Various 'normal' concerns: antibiotic resistant bacteria; peak oil; peak phosphorus;

It is possible that overreaction to these could cause large enough increases in prices to make poor of the world significantly worse off, which could cause political instability and eventually lead to something like nuclear war. But I think it is much lower probability than those that could directly reduce food supply abruptly by order of magnitude 10%.

  • substantial agricultural collapse; moderate climate change;

I think the moderate climate change, perhaps 2°C over a century, is difficult to find a direct route to a collapse. However, it would make a 10% food production shortfall from extreme weather more likely. And there are many other catastrophes that could plausibly produce a 10% food production shortfall, such as:

1 Abrupt climate change (10 C loss over a continent in a decade, which has happened before)

2 Extreme climate change that is slow (~10 C over a century)

3 Volcanic eruption like Tambora (which caused the year without a summer in 1816: famine in Europe)

4 Super weed that out-competes crops, if a coordinated attack

5 Super crop disease, if a coordinated attack

6 Super crop pest (animal), if a coordinated attack

7 Losing beneficial bacteria abruptly

8 Abrupt loss of bees

9 gamma ray burst, which could disrupt the ozone layer

  • major wars;

This could be a 10% infrastructure destruction, so I think it could destabilize. Disruption of the Internet for an extended period globally could also cut off a lot of essential services.

  • reverse Flynn effect;

Even if the Flynn effect has stalled in developed countries (has it?), I still think globally over this century we are going to have a massive positive Flynn effect as education levels rise.

Other concerns that I don't know of, or that no-one has yet thought of

Agreed, which is a reason that resilience and response are also important.

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