Dr. David Denkenberger co-founded and is a director at 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 156 publications (>5600 citations, >60,000 downloads, h-index = 38, most prolific author in the existential/āglobal 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 300 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, Radio New Zealand, 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, Australian National University, and University College London.
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I agree there is some overlap between these principles and EA principles. But I still think the EAs are more willing to debate them. For instance, the first implies torture is never justified (and this is a common view in UU), but some EAs will debate the cases where it could be justified. Also, maximizing utility does not necessarily push you to justice and equity. Spiritual growth does not apply to most of EA. And EAs generally question environmental/ābiodiversity principles.
Global panĀdemic preĀvenĀtion: how disĀease spreads across borĀders and the three counĀtries deĀterĀminĀing panĀdemic outcomes
To be clear, my relocation post was for getting ready to relocate quickly in response to a trigger such as a new infectious, fatal disease being discovered.
No, I donāt think mirror bio is coming sooner.
I would like to know why you donāt think it would make sense to relocate to a place like New Zealand or Australia. My thought is that they demonstrated that they had the will and the functioning government to suppress COVID, and can take advantage of their isolation. You may be able to prevent your family from getting the disease in the US, but then you may have to deal with no electricity or water or fuel if the vital employees are unable or unwilling to show up to work. Australia could likely keep industry functioning conventionally, but even New Zealand might be able to improvise biofuels or go back to animal power.
But EA seems increasingly ideological to me, it seems to be a lot less concerned with asking and answering a genuinely open question, and a lot more concerned with causing people to follow established paths to impact.
That may be true, though I would note that EA should have been more open to new causes in the beginning, until it did a bunch of research and found promising cause areas. I will also note that there is evidence that EA is still open to new cause areas, such as the recent shift from focusing on AI catastrophes to making AI futures go well (not to mention many individual EAs shifting between cause areas within EA).
But if EA were more ideological, does this mean it is dying? Maybe it is a worse fit for some people as a community. But I think the most important question is, āIs EA having more positive impact?ā I agree that that is not just a function of jobs switched and money moved. But overall, I think it is having more positive impact, so I would not call that dying.
As in my other comment, I am mixing deference to orthodoxy and leaders. I have similar experience duration in academia. I think questioning things like political left positions and the value of education is more discouraged in academia than questioning the common beliefs in EA. I think it also depends on the field. In some academic fields, there are specific camps with a lot of tribal behavior. Thereās a quote that science advances one funeral at a time. I think that EAs are more open to changing their opinions. There is also a lot of tribal behavior between fields in academiaāI think there is significantly more bias towards oneās strand of academia than towards oneās strand of EA. Maybe thatās not deference to leaders, but the questioning of the value of oneās field in academia is uncommon. Whereas in EA, there is lots of questioning whether different strands are net negative.
However, I do agree that some EAs like taking contrary opinions and might defer to a random blogger against scientific consensus. Those EAs often have a low opinion of peer review, and are probably more often wrong than the scientific consensus.
Iām blending deference to leaders and orthodoxy here. In UU, questioning of traditional theology is encouraged; questioning the views of the political left, much less so. Of course EA has its own orthodoxy, but questioning and criticism of it is much more encouraged. I think there has been more criticism of Moskovitz, Karnofsky, MacAskill, and Ord in EA than typical leaders in UU (e.g. ministers), but maybe your experience is different?
Habryka has claimed that most EA talent is in Anthropic; I havenāt tried to evaluate this, and it depends on how you measure talent, but it doesnāt seem too far off.
Habryka was talking about the subset of EA that does AI SafetyāEA as a whole has much more talent than that.
One thing that this piece is missing: the extent to which Anthropic is now implicitly the cultural/āfinancial/āleadership center of EA.
It seems very plausible to me that the rest of EA will mainly end up serving as a recruiting pipeline for Anthropic. Iām interested in understanding the extent to which this is already happening.
I do think a lot of EAs are desperately hoping for an Anthropic IPO so they can help save millions of lives, prevent billions of animal-suffering years, build up resilience to pandemics, and do much more AI safety work. So Anthropic may become the financial center of EA, but at this point itās only in expectation. Also, I donāt see how Anthropic is the cultural/āleadership center of EA. Jobs at Anthropic are a tiny percent of the jobs that 80k recommends. Maybe Iām not aware of it, but I donāt think people at Anthropic get a significant fraction of the current karma on the EA Forum, and Iām pretty sure not historically. Could you explain more your reasoning?
EA has a culture of deferring to leaders and people in positions of expertise, and for good reasonāitās impossible for everyone to figure out everything from first principles, and relying on othersā judgement is essential for doing good at scale.
A lot of people have said this, but compared to what? I assume compared to the ideal. Compared to the communities I have spent the most time in, I would say:
Environmentalism: defers far more
Unitarian Universalism: defers a lot more
Academia: defers significantly more
LessWrong: defers a little bit less
Longer-standing EAs also donāt seem to engage much with EA infrastructure. Of the EAs I know whoāve been around for a while, I donāt know any who are part of a local group, and only a small handful actively engage on the Forum.
Many past leaders of EA no longer seem to support it, and many seem to actively disavow it.
I would love to hear more anecdata from other early EAs (I realize surveys would be really hard to run). I think it was around 2017 that @Benjamin_Todd estimated an attrition rate of about 2% per year from early EAs, so it would be interesting to hear an update on that. And again, it would be good to compare to other movements.
I dug in a little more, and I think your Earth cooling estimate is high at $2.5ā3.0B/āGW with water chillers. An NREL study was more like $0.7B/āGW with water chillers. Also, we may be able to dispense with the water chiller (as you have assumed in space), and then it could be even cheaper. So I doubt itās actually going to be cheaper to cool in space. However, your point that cooling in space doesnāt wreck the economics still stands.
Julia and I had been giving half since 2014, but in 2025 we drew on our savings to donate 81%.
Impressive!
Since weāre in a good enough position financially and donating seems very urgent, I now think we should stop contributing to have more to donate going forward...
Even though weāre drawing down our savings to donate, our net worth rose 18% over the last year (adjusted for inflation).
Of course returns vary, but if you gave away 80% of your income and your net worth still increased, that means you are close to retirement, so I agree it doesnāt make sense to continue to contribute to retirement.
Iād put about 10% on futures where things go very badly, where Iām not here to write a followup and youāre not here to read one.
As per your comment on LW, biorisk is a large proportion of the risks in the next 2 years. Are you personally preparing to protect yourself and family from mirror bio or to relocate?
Although Iāve referred to there being approximately 1 OOM more capital invested than granted in any one year, thereās some nuance ā of the granted funds, all of them are in fact being allocated in that year (by definition); whereas of the invested funds, some of the assets may well have allocated to impact funds some years ago.
This could be 1 OOM effect, if you invest for 10 years, so thatās pretty important.
Although 90% (or whatever) of your assets could be invested in impact investing funds, you probably wonāt allocate all of your assets to impact investments. For example, you will probably want to hold some of your capital in listed equities, and you might consider it too hard to find effective impact investments in that asset class.
If you do a significant fraction, itās pretty easy to reduce your overall return significantly (if you are trying to maximize returns), which really cuts into your charitable impact. So overall, it doesnāt look very promising to me.
Hey David, thanks for this excellent comment.
Iām glad it was helpful!
If we correct the absorptivity for Earth IR and take the low end view factor, I get your 522 W/ām2. That looks like a ~1% increase in total cost for ODCs if youāre right.
I was using 550 km, so I agree that higher up, you would have more net radiation leaving the radiator.
As for your bent configuration, that is creative to avoid the sun incidence. However, then you would have radiation from the solar panels to the radiator, and since the solar panels will be warmer than the Earth, I think it will work out worse overall.
Agree loss from averaging over radiator temp looks.
Incomplete?
Your other points make sense.
Iām glad to see this rigorous analysis!
I was skeptical of the cooling being cheaper in space. It is true that you can radiate to a much colder temperature in space, about ā60Ā°C equivalent. It does look like space cooling would be cheaper with your future launch costs for your constellation model. However, for your modular station model, you would need around 1 m diameter pipes to start, which would weigh a lot and pose a large single source of failure. Also, you would have to pump long distances, increasing the pump mass and energy use.
I think inference would be challenging because the satellite is in view for only a few minutes. I guess most queries take less time than this, but would you keep handing off the session memory?
Baseline A (100% renewable off-grid, $20,307/ākW-continuous): Solar at 28% CF, $1.10/āW installed, 4,643 W nameplate per kW-continuous ($5,107). Battery storage 80 kWh at $175/ākWh ($14,000 or 69% of total). Other $1,200. 5-year LCOE: $463/āMWh. Battery storage dominates because 99.9%+ uptime without fossil backup requires multi-day autonomy.
This is much more reasonable than people claiming that going off grid is cheaper than grid electricity with the same reliability. Still, you note that this capacity factor is reasonable for the desert, but typically there is around a two times seasonal variation. Since 80 hours of storage canāt handle that, you would need to oversize your PV more. But it wouldnāt change the results that much (~10%). And the gas turbine in your Baseline B solves this seasonal problem.
We include Baseline A however, since backlogs for turbines versus the abundance of solar and battery available suggest that it may be the fastest way to quickly scale energy production on Earth.
If you want 80 hours of storage for 100 GW, that is 8 TWh, which is years worth of current production, so I think youād have to pay a premium.
P_net = 2ĪµĻTā“ ā Ī±S ā Ī±F(Al Ć S + ĻT_earthā“)
where Īµ = 0.92 (AZ-93 selective white paint emissivity), Ī± = 0.09 (solar absorptivity), S = 1,366 W/āmĀ², F ā 0.25 (Earth view factor), Al = 0.3 (albedo), T_earth ā 253 K.For the longwave radiation coming from the earth, you would get Īµ absorption, not Ī± absorption. So the equation should be:
P_net = 2ĪµĻTā“ ā Ī±S ā Ī±F(Al Ć S) ā ĪµF(ĻT_earthā“)Also, the view factor to the Earth is 0.25 for one side of the radiator, but you are counting both sides for the emission, so I think the view factor should be 0.5.
So then at 20Ā°C: emitted 770 W/āmĀ², absorbed 248 W/āmĀ², net rejected 522 W/āmĀ² (not 633 W/āmĀ²).
Also note that if your fluid temp is 20Ā°C, the radiator will be lower average temp because of conductive thermal gradient. But with 1 mm of high-modulus pitch-based carbon fibre reinforced polymer, it doesnāt look like too much of a loss.
Footnote 17 seems to end abruptly: āThe scenarios in a bit more detail are as follows:ā
Okāso if one believes that wild invertebrate lives are net positive, then offsetting with animal welfare interventions means more feed is required, resulting in fewer wild invertebrates (and more deaths from pesticides, but I think this is small compared to the impact on the population of soil invertebrates of farming more land), meaning less utility overall. So this person would prefer an offset that is a scalable way of convincing people to go vegan. Though this may seem contradictory, I think there is a large variation in difficulty of going vegan (taste preferences, opportunity cost of time, impact on health, etc), so it is most effective if the people for whom it is easier to go vegan are exposed to the arguments.
However, if the person thinks that wild invertebrates lives are net negative, they would prefer the animal welfare interventions offset, because not only would that help the farmed animals, but it would also reduce the bad utilities of wild invertebrates lives.
Are you suggesting that all non-vegans offset the impact on wild animals? How does one do that, even if it were agreed that wild animals had net positive lives?
There is huge uncertainty once you consider wild animalsāmore feed could increase wild animal welfare.
Seaweed is also an important resilient food for global catastrophesāit can be scaled up quickly as it grows even faster if the sun is partially blocked, and it is cost effective.
Iāve mainly worked at the cause area level, where I think these considerations are less relevant. But I have observed that if people are so enthusiastic about an area that many will volunteer (or take lower salaries), that does make progress in an area easier.
Yeah, the funding situation in nuclear security is still dire. Depending on how you count, the cuts in US government funding various things that charities may want to make up for were greater than $50 billion per year.