Director, Associate Professor @ Alliance to Feed the Earth in Disasters (ALLFED), University of Canterbury
2413 karmaJoined Apr 2015Working (6-15 years)Christchurch, New Zealand



Dr. David Denkenberger co-founded and directs the Alliance to Feed the Earth in Disasters (ALLFED.info) and donates half his income to it. He 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 an expanded microchannel heat exchanger, which he patented. He is an associate professor at the University of Canterbury in mechanical engineering. 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 134 publications (>4000 citations, >50,000 downloads, h-index = 32, second 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, Phys.org, and Science Daily. He has given interviews on 80,000 Hours podcast (here and here) 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.

How others can help me

Referring potential volunteers, workers, board members and donors to ALLFED.

How I can help others

Being effective in academia, balancing direct work and earning to give, time management.


I think the reviewer may be concluding from the above that, given no international food trade, calorie consumption would be much lower, and therefore increasing food production via new food sectors would become much more important relative to distribution. I agree with the former, but not the latter. Loss of international food trade is more of a problem of food distribution than production. If this increased thanks to new food sectors, but could not be distributed to low-income food-deficit countries (LIFDCs) due to loss of trade, there would still be many famine deaths there. Many LIFDCs are in tropical regions too, where there is a smaller decrease in crop yields during a nuclear winter (see Fig. 4 of Xia 2022).

Another factor is that if countries are aware of the potential of scaling up resilient foods, they would be less likely to restrict trade. Therefore, I'm thinking the outcomes might be fairly bimodal, with one scenario of resilient food production and continued trade, and another scenario of not having resilient food production and loss of trade, potentially more than just food trade, perhaps with loss of industrial civilization or worse.

Yet, at least ignoring anthropics, I believe there would be a probability of full recovery of 100 % (= 1 - e^(-10^9/(66*10^6))) even then, assuming:

  • An exponential distribution for the time to go from i) human extinction due to such an asteroid to ii) evolving a species as capable as humans at steering the future, with mean equal to the aforementioned 66 M years.
  • The above evolution could take place in the next 1 billion years during which the Earth will remain habitable.

I think this assumes a scenario where, after the asteroid that causes human extinction, the next billion years are large asteroid/comet free, which is not a good assumption.

This was very helpful! I found the diagrams particularly useful. Visible lighting design for rooms has a similar problem of uniform illumination, but it is mitigated by the fact that there is significant reflection of the light, which I presume does not apply for far UVC. 
Has there been any work on planning to relocate existing UV systems to the most critical tasks, if an extreme pandemic hit soon, of making more super PPE/UV systems?

One unpublished study by a Russian academic and a CDC researcher allegedly estimated that the cost of 1 ACH by ventilation is about $135.91 USD and by GUV is about $14.44 USD.[131] 1DaySooner and Rethink Priorities have estimates that "The price of current systems is currently too high for at-scale deployment, though there are reasons to think the price can be lowered significantly;" they estimate that the cost of upgrading all U.S. buildings for improved indoor air quality would be about $120 billion - $420 billion.[132] 

The units do not appear to be complete - cost of 1 ACH for how big of space? Footnote 131 requires a password. Footnote 132 says “all public buildings in the US” not “all US buildings.” If public building is defined as this, I would guess that would control less than 10% of transmission in the US.


Why is flesh weaker than diamond?

I don't think this is a fair comparison. If nature wanted skin to be harder, it can do that, for instance with scales (particularly hard in the case of turtle shells). Of course your logic explains why diamond is harder than bone. But if you want a small thing that could penetrate flesh, we already have it in the form of parasites.

One of the points in the book Strangers Drowning was that very dedicated altruists (some EAs included) live like it is war time all the time. Basically, the urgency of people dying from poverty, animals suffering, and humanity's future at risk demand the sacrifices that are typically reserved for war time. Another example is if existential risk were high, some argue that we should be on "extreme war footing" and dedicate a large portion of society's resources to reducing the risk. I'm interested in your perspective on these thoughts.

Thanks for the correction! I have fixed it and added a link (the link was in the main document, but it's good to have it in the executive summary as well).

This is a decent summary, but there are a couple corrections:

ALLFED increased paid team members, but much less than doubled (we have capacity to expand more quickly with additional funding).

We do have 17 advisory board members, but they represent 4 countries, not 9 (the 9 countries were represented by the 17 team members at the retreat).


Nice post!

The model does not predict much differences between the different scenarios until 2020-2030. Therefore, we only know that the model has not been falsified so far, but it is still unclear what the path is we are currently on.

I think it would be helpful to see an overlay of our actual trajectory. Though the absolute values of the models are not that different for the period 2000 to 2020, the slopes are quite different. I think there was a paper analyzing the fits including the slopes. The increase of production of food since the year 2000 has been much larger than any of the models predicted. Also, I think the increase in industrial capacity is higher than any of these models. Interestingly, some people interpret this as us overshooting farther, so then we will fall more dramatically. But because we generally have not seen reduction in slopes, I don't really see evidence for this, so I think that the optimistic interpretation is more likely to be right, basically that we have innovated around limits to growth so far.

Thanks for all you have done!

Finally, EAs have treated EtG as increasingly more weird, especially offline, defeating the original argument for engaging.

This is very disappointing, especially because, if you disregard "still deciding", EtG was the second most popular route to impact among EAs in the 2022 survey.

(leading a - dare I say - successful effective nonprofit)

Sure - go ahead and dare. :)

My day job is associate professor of mechanical engineering at University of Canterbury in New Zealand, and I volunteer for ALLFED. Nearly 100% of my donations are to ALLFED. I think that ALLFED is the most cost-effective way of improving the long run future at the margin (see here and here, though I'm not quite as bullish as the mean survey/poll results in those papers), but there are orders of magnitude of uncertainty, and I think more total money should be put into AGI safety.

As one who donates 50%, it doesn't seem like it should be that uncommon. One way I think about it is earning like upper-middle-class, living like middle-class, and donating like upper-class. Tens of percent of people work for tens of percent less money in sectors like nonprofits and governments. And I've heard of quite a few non-EAs who have taken jobs for half the money. And yet most people think about donating that large of a percent very differently than taking a job that pays less. I'm still not sure why - other than that it is uncommon or "weird." 

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