Very nice, thank you. I assume you've read "Unsettled" by Koonin. I wonder if you have found any good references for the chances of glaciation in the absence of AGW. The references I find to this are now all in the vein of, "Well the next glacier is at least 10k years away, so no threat and so shouldn't be part of our calculation." They all seem to be suffering from motivated reasoning... AGW bad.

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I think there is moderately good evidence that that problem has already been solved by anthropogenic warming, starting seven or eight thousand years ago with the invention of agriculture resulting in a massive increase in human population and large scale deforestation. That's the Early Anthropogenic Hypothesis, which I discussed some time back on my blog.


But if one is listing consequences that are very unlikely but have very large consequences, I think it should be included.

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Thank you, So man has already had a positive effect on the climate by pushing back the next ice age. We all should get some credit for that... to counterbalance all the crappy things we've done.

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Part of the problem with AGW hysteria is that the benefits of fossil fuels are ignored and the costs of solar and wind generation are ignored. The real world always gives you choices with costs and benefits, and all you can do is trade-off between the choices. If you aren't counting the other side of the scale, then you will NEVER arrive at a good trade-off. NEVER.

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“ the U.S. Atlantic coast shifts in by about a hundred feet for every foot of sea level rise. ”. That seems very wrong to me. An extra foot in many places wouldn’t breach a beach at high tide.

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I found that figure in a book but have not been able to find the book again, which is why I didn't cite it.

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Welcome to Substack.

About the population costs and benefits: I wonder whether you included the benefit *to the newly-created people* of getting to live, which is probably the biggest potential benefit.

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Are the predicted mass third-world migrations resulting from climate change likely?

If so, this is a negative externality that will absolutely dwarf any conceivable positive ones. Europe and the US will be at risk of societal collapse if hundreds of millions of unselected third-world people move to thse places.

To anyone who thinks this is sensationalist: Sub-saharan africa is a mess because of the people living there, its not something intrinsically wrong with the climate or resources of these places, it's the people. We know for a fact that unselected immigrant populations from these countries do not rapidly assimilate into developed countries, and we should expect doing so to be much much easier under current relatively lower immigration rates than potential future higher immigration rates. Which is to say: We don't know how to assimilate unselected third world migrants at the moment, and these migrants have impose a huge per capita cost on developed countries in the form of fiscal impact and crime. There's absolutely no reason to think this will become less the case with radically more immigration, so even if it doesn't get worse the costs these additional immigrants will impose on developed countries will already be staggeringly large (and this says nothing of the political, cultural and institutional externalities of these people), though in reality the per capita cost will be dramtically higher.

Americans and especially euopeans demonstrate self-destructive levels of compassion and tolerance towards these kinds of people, but under such conditions it should be expected that enough of them will rightfully object to their way of life and their societies being completely upended in these ways, and this will have enormous political and social consequences.

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Thanks for your advice regarding linking substack. No good deed goes unpunished, so naturally I will be reading anything you write.

That said, I sincerely enjoyed this. We need more humility and the ability to say, I do not know. You'd actually probably enjoy my latest post - it's even somewhat relevant :)

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Or it's possible that you were responding to something I didn't write?

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-- Current trajectory puts us on track for between 2.1 °C and 3.9 °C

**uncertainty is skewed towards a stronger climate response

**does NOT factor in long-term carbon cycle feedbacks

--permafrost thawing, forest fires, etc...

**does NOT factor in worst-case climate responses

**some simulations suggest stratocumulus decks may abruptly be lost

-- if this happens, there could be additional ∼8 °C global warming

**IPCC projections have been conservative (emissions trajectories, sea level rise, attribution,...)


--benefits of CO2 fertilization are limited:

**excess CO2 produces no benefit for C4 plants

**C3 plants need RuBisCo activase to benefit

--RuBisCo activase is sensitive to heat

--other effects will be much more significant

**growing temperatures

**extreme drought

**invasive species benefit most from CO2

-- weeds show strongest responses

-- and resist herbicides

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Rest of my comment got cut-off... not going to rewrite but happy to dialogue. Here are some helpful references for the parts of comment that were preserved:


2) https://skepticalscience.com/co2-plant-food-advanced.htm

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Regardless of the theoretical benefit of CO2 fertilization, more plants are growing bigger and faster.

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First, your empirical claim is grossly misleading. Agricultural productivity growth has declined to its lowest level in sixty years. Evidence suggests that climate change is an important (perhaps the primary) driver of that decline.

Second, your implicit methodology is wrongheaded. In assessing the expected value of a climate response, evidence about physical processes should often trump the observed relationship between variables for two reasons:

--The relationship between variables is often non-linear (and even non-monotonic). The present example (relationship between temperature anomaly and yields) is a case in point. Observations are either confined to a narrow range of values of a parameter or rely on a dubious paleoclimate record.

--The climate is a complex dynamical system. Observed relationships will be confounded by at least dozens (most likely, hundreds) of other significant inputs. Further, in the case of a dependent variable like agricultural yields, many of the most important inputs are exogenous to the climate system.

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I am not convinced that you are responding to what I said.

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> That is in a model in which per capita consumption roughly triples by then. So the difference between the world without climate change and the world with climate change is, by his model, the difference between an increase in per capita income by 2100 of 300% and an increase of 292.5%.

A tripling would be an increase by 200%, no?

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It's a grift. Think of all the sinecures it produces! The people who profess to care with no skin in the game are just the useful idiots getting mulcted.

And, pleasure to see you are on Substack, I'm a great fan.

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Jan 30, 2023·edited Jan 30, 2023

Impressions: mixed.

Common version of the orthodoxy is: climate is not weather, so few degrees of global warming will not result in experience of "everything is some degrees warmer, crop yields are improved". Along these lines, IPCC AR 6 makes many specific claims concerning food and water systems and adaptation options. It would more convincing if these IPCC claims were tackled head-on, point-by-point.

Referring to IPCC claims has an added benefit for a lay reader like me, who has a great difficulty judging how seriously to take any particular random cited study or Fermi estimates based o "maps showing yield of various crops can be found online" as you put in a presented pdf. IPCC presumably is both the presumed authority and their report present the major arguments in favor of the orthodoxy. Referring to their materials, can argue that their material is correct but the orthodoxy draws wrong conclusions or overstates them; or refer material they cite and point out where their assumptions go wrong.

Sea level rise argument appears most convincing: urban habitation and assets are slowly rebuilt and thus easily move in any case, thus adaptation does not appear impossible or prohibitively expensive. However, it would be good to refer IPCC estimates, such as AR6 Cross-Chapter Paper 2.

Changes to agriculture appear most significant to me. For instance, AR6 Chapter 4 section 4.5.1 outlines drought driven yield loss estimates for various crops, which appear significant even if RCP8.5 is discounted; Section 5.4.3 and Figure 5.3 present negative crop yield estimates for most crops including C02 fertilization effects); quickly scanning, only soybeans and potatoes (root crops) are projected to benefit anywhere. This seems at odds with the claim " Is there any significant amount of land that is too hot to grow crops? So far as I can tell, there is not." in the same pdf of yours. (Cross-Chapter Paper 3 discusses desertification, but I didn't attempt to read any part of it for this comment).

Adaptation by cultivar changes is discussed in Section, which is surprisingly non-committal section; cost of global adaptation is cited at only tens of billions which to me sounds super cheap (considering that US GDP alone is counted in trillions). More careful analysis of the references cited therein would be interesting, and make claims of increased crop yields in extreme latitudes to offset losses more credible.

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Jan 31, 2023·edited Jan 31, 2023

I will bet you any amount of money you care to wager that yields per acre and total yields will be higher in 2050, 2075, 2100, then today.

Seems odd to worry about desertification in an overall environment with more precipitation.

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Why it is odd? Please tell! I wrote a long-ish commit longing for more engagement with the claims made by the current orthodoxy and why and when it could be dismissed. More one-liners don't really help here.

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Look I was all about climate and science generally from say 1990-2005 or so. But I am also a skeptic and have a brain.

You only need to listen to so many hundreds of interviews and so many hundreds of articles before you develop a pretty good model of the dysfunctions in this field. And the dysfunction is that it is a religion/ideology to a significant fraction of these people and they simply are not conducting fact lead research and are instead taking an unrelated thesis "climate change is going to be catastrophic" and beating whatever pegs they find, round, square, triangular into a round whole to fit it.

And an IPCC report no matter how well intentioned built out of those raw materials is bound to be compromised.

Here is my experience with the "science" (yes this includes talking to say people at climate think tanks with Phds and frontline researchers).

Scientist 1: OMG in 2075 there will be no more sea ice and polar bears will go extinct. The world is dying! (and yes you will see "the world is dying" rhetoric coming out of scientists mouths regularly).

"While that is regrettable and I don't want that, and am willing to do my part, how is that evidence the world is dying, what are the actual impacts on humans beyond no polar bears?"

Oh the world is a fragile delicate ecosystem we barely understand and with no polar bears eating seals the seals will eat to much fish and the fish population will collapse and the whole artic food web will collapse.

"That seems like an awfully specific prediction from someone who claims we barely understand how this works."

Well it could happen!

"Ok, but that isn't the level of contingency you convey in your article...couldn't it also be helpful to the food web?"

No because I define the 'health' of the food web, by how much it looks like the food web when I was an undergraduate.

"But didn't we already have a lot of human impacts and climate change by then? Why is that the target? Besides the main thing impacting the food web of the oceans is not climate change or the presence or absence of polar bears, but overfishing"

You just hate polar bears! Look at this guy he hates polar bears.

Scientist 2: Changes in the temperature have changed the range of the Northeastern Iowa Maple Fungus and now it is ravaging the trees of southeastern Minnesota. The forests of Southeastern Minnesota are being destroyed!

"Ok that isn't good, how is it spreading?"

It is spreading as the trees from northeast Iowa migrate north into northeast Minnesota, we have already seen 25 miles of migration since 1900, and by 2100 the forest mix may have moved 50 miles northward.

"Ok so the forests in southern Minnesota will have the mix that the ones in northern Iowa had 50 years ago, and the one in northern Iowa will have the mix the ones in southern Iowa had. That sounds not ideal, and people don't like change, but are the forests really going to be 'destroyed'? It sounds like there will still be forests, jsut the percentages of various trees will be different.

Well but the tree mix impacts albedo and that has all sorts of chaotic impacts on the local climate and microclimates and who knows what might happen! This is an important farming area and rainfall could down.

"Oh that great that area has a lot of problems with flooding and ample water for irrigation."

No no no, didn't you hear me say we don't know what would happen, rainfall could go way up too, and then there could be lots more flooding you don't want that right?

"More flooding would be bad, but it kind of sounds like you are determined to make this bad, no matter what the data is."

SCIENTIST 3: Yes I know it is very bad! OMG with all this AGW there is going to be widespread drought and famine everywhere, crop yields will crash, people will starve.

"Isn't climate change going to lead to more rain, why will there be an increase in drought? Also haven't we already seen significant warming, and yet yields are only up over that period?"

But that is because farmers have been benefiting from a period of extra glacier melt from all the warming. Extra warm summers have lead to extra melt from glaciers and much needed extra water in the dry season. And farmers need that extra melt water to survive, and it will all be gone if the glaciers melt away.

"But not everywhere has a wet winter and dry summer. Also if we stop global warming, then there won't be that extra melt water either, just the 'normal' amount. it seems like you are jsut taking the worst possible interpretation of every potential impact"

Also the rain is only going to fall in places that don't want rain, and then the increased heat will lead to more evaporation and drought from the places that do want more rain.

"That seems awfully convenient for your argument, also wasn't SCIENTIST 2 just telling me that this whole process is chaotic and that the climate models have very little actual likelihood of predicting specifics accurately?"

Oh no no on, we have the most accurate, up-to date-models, and while there is a lot of uncertainty generally, we can confidentially predict that whatever thing you don't want to happen, will happen.

"That seems very unlikely, almost like the model has been trained to provide outputs you want."

Well of course if it isn't providing the outputs we want how would we know it was working?


Now I am being uncharitable for the purposes of brevity, and making a point. But that is my general read on all this. I am actually pretty pro immediate action on climate change. If I was global dictator we would have a carbon tax tomorrow.

But I feel the scientists have done a piss poor, and at times actively deceptive job of controlling for their biases and desires. Yes to Dr. Franklin Kearns who studied anteaters in the jungle for 15 years, the extinction of anteaters is a global catastrophe. To humans generally it is not.

Now I am not arguing climate change won't have all sorts of multi-billion dollar negative impacts. It absolutely will! It will cost trillions. But there will also be a lot of benefits, and that is mostly not looked into with even 5% of the interest as the costs. And the IPCC report both isn't as dispassionate as people claim, and can only work with the raw materials scientists produce, and the raw materials are highly ideological.

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Jan 29, 2023·edited Jan 29, 2023

This is probably my favourite substack post of all time, I really hope other people read it and criticize it, especially people who are very epistemically rigorous. I have been reading your blog for quite a long time now and have kept a mental synthesis of all of your posts on climate change, so to see it all come together is amazing.

I do have some minor nit-picks that mostly come down to stylistic choices, the most obvious is neglecting to explicitly mention that when attempting to calculate the optimum quantity of people or CO2 what matters is the net externality of the marginal unit of people or CO2. I fear that whilst not explicitly mentioning it (and also not talking about how P=MC=MB in your sketch of price theory) and other things makes this post more accessible, it opens you up to weak but "smart" sounding criticism one of my favourite examples on a different but related topic being Greg Mankiw's "David Friedman's Slippery Slope".

I have also read a lot of criticism of you on a variety of topics and it seems that lots of the "smart" sounding criticism could easily be avoided if you marginally increase the degree to which you use technical language, the reason being people knowledgeable enough to understand the language probably realize the argument your making is more subtle or intelligent than other people making similar sounding but weaker arguments, and people who don't understand the language would hopefully read up on the surrounding literature to avoid sounding stupid or uninformed and hopefully learn something (they could also accuse you of using superfluous language to make a bad argument sound better, but this would have the effect of people who are familiar with the language discounting those critics which is probably good).

On a similar note it probably makes sense to include a lot more hyperlinks to other work, such that people who read something that sounds wrong can read up on it and conclude you are right as opposed to dismissing you based on something that probably isn't even relevant to the argument your making.

I think Steven Landsburg also has made very similar overall arguments to the ones you have made, in particular emphasising the point that in a market economy resource consumption is a private cost not a cost imposed on others, which is contrary to the way people usually think about population, where people just see a fixed number of resources and then see how increasing the number of people decreases the resources per person and makes everyone poorer (this is obvious, but wrong and shows people even supposedly smart people lack a good model of how a market economy works). Your 1972 article is very similar to Landsburg's style of thinking. Although I think you undersell your argument, that is it seems to me that one can with a reasonable degree of belief say almost a prior that both overpopulation is not a problem and that even under Laissez-faire there is a underproduction of people due to the positive externality of ideas (scientific innovation etc.) seeming massive (compared to negative externalities) and of course not being properly accounted for either by parents or their children. There is also utilitarian arguments that make this underproduction of people seem even more dire than what economic efficiency suggests, but that's quite a long argument to properly grasp the problem. I also think you undersell your arguments with respects to the benefits of climate change put that's also a very long and complicated argument, and in the eyes of most people harder to defend.

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I considered including the point about resource conservation, which I like to put as "a baby is not born with a deed to a per capita share of the Earth's resources clutched in his fist," but I thought it distracted from this essay, where the population argument serves mostly as a lead in to the climate argument. I have pointed it out elsewhere.

Of course, a legitimate response is that we don't live in a world with a guarantee of secure property rights, and a baby is born, at least in many countries, with an invisible deed to a vote when he grows up.

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