This is a subject well worth exploring in greater detail. The key is all else is NOT equal.
Just on the subject of Air Conditioning. I would speculate that there is immense room for improvement in the technology behind how people keep themselves comfortable in both cold and warm environments. In addition while it seems like there will be fewer people there well may be more well educated economically motivated people available to contribute to developing the technologies of the future.
Thank you Roger for injecting population into the climate debate. That is long overdue. It seems absurd that a clear and irreversible decline in global population has never been accounted for in any of the climate models. This is going to be a big issue.
I think you and Matt should be more clear about what future for the developing world even the less pessimistic ADEM scenario assumes. If my math is roughly correct, few of the countries encompassed by your blurb in the initial graph will actually join any of the countries outside of that blurb with that assumption. If they would, your "less warming than SSP 2-4.5 once adopted for better population predictions" argument wouldn't hold up.
Present day Egypt seems to be what today's lesser developed world can hope to achieve by 2100. Meh.
That may be a perfectly realistic scenario, but it is a ruthless world that strives no further. And using such a low-ambition scenario to call off the warming alarm is borderline cynical. If basically forces the west to uphold vast inequalities to avoid overshoot.
And just to be clear, I'm not suggesting that neither your nor Matt use these analysis to "call off the warming alarm". But they will be used in that manner by motivated people in power.
I believe that the endangerment finding's apparent lack of impact on the rate of decarbonisation is less important than the enormous capital that the finding pushed in the direction of renewables. Misallocated capital in my opinion. I would expect (hope) that funds intended drive the "transition" will be now reallocated to something of greater value to humanity.
I would be interested in further discussion regarding your statement “ More emissions mean greater increases in global temperatures and thus greater climate change.” I’m not sure I would agree with this since many other factors, including both natural and anthropogenic, impact how weather patterns shift over time. Various proxy studies show the rate of temperature changes at times in the Holocene to equal or exceed modern warming without significant anthropogenic causation. According to UAH Satellite records, the global temperature has declined about 0.6°C the past year, but emissions have not declined.
• The log(energy use)/log GDP plot seems to be non-linear, bending over somewhat at the high end. What would it look like if linear-linear? Might have an interesting story to tell.
• I'm surprised that you doubt that the rescinding of the EF is a major policy shift. The Biden administration certainly tried to accelerate decarbonization with its EV (and other) mandates. The lack of visible impact is due to (1) that administration's incompetence; and (2) the natural lag between promulgation of a policy and the policy's impacts. More than many other things, this likely will serve as a brake on inflation.
Roger states that "more (CO2) emissions mean greater increases in global temperatures and thus greater climate change"
He (and others) seem not to have noticed that the world is no longer warming, but, since early 2025, it has been in a strong La Nina situation, which should persist for about 2 years.
If he is really an honest broker, he needs to explain why CO2 is no longer causing any warming.
462426 please comment on fairly recent studies stating that the co2 effect on temp is decreasing and implying that there will be little further increase in temperature in the near term;also is it true that temp.goes up before co2 increases?
Thank you, Brian. The "DTM" makes intuitive sense and matches my general understanding of global population numbers and trends. But I remain unclear on recent statements about global decline and its causes. I have some sense about why a decline is occurring in the U.S. and western Europe. Is that overwhelming increases elsewhere as death rates fall in response to increasing wealth or???
You bet. Roger will provide an excellent analysis soon... but the overall trend, at least in my opinion, was this:
1) Population growth in the last 150 years was due to fewer kids dying young (better food, hygiene, medicine, etc.) but the total fertility rate remained high and thus the population increased quickly.
2) Urbanization/industrialization replaced rural/folk economies. In cities kids are no longer assets, they are expensive liabilities. And because not so many are dying anymore, families can have fewer because nearly all of them will live into adulthood.
3) As people have fewer kids the population pyramid "inverts" and you have more older folks than younger... the death rate starts to climb and the population begins to shrink due to demographic shift. Left to natural devices... I think the population pyramid would've re-balanced with a total fertility rate of ~2.1 (replacement). But that leads us to #4.
4) On a personal note, I think our culture of individual satisfaction promotes a "carefree childless existence," which is just exacerbating the natural population decline from #3 above. This is why we're seeing total fertility rates fall below replacement level (2.1) in much of the developed world.
This is a subject well worth exploring in greater detail. The key is all else is NOT equal.
Just on the subject of Air Conditioning. I would speculate that there is immense room for improvement in the technology behind how people keep themselves comfortable in both cold and warm environments. In addition while it seems like there will be fewer people there well may be more well educated economically motivated people available to contribute to developing the technologies of the future.
I did not receive my usual email notice about this post. I don't know if it has anything to do with your arrangements with the Dispatch or not.
Thank you Roger for injecting population into the climate debate. That is long overdue. It seems absurd that a clear and irreversible decline in global population has never been accounted for in any of the climate models. This is going to be a big issue.
I think you and Matt should be more clear about what future for the developing world even the less pessimistic ADEM scenario assumes. If my math is roughly correct, few of the countries encompassed by your blurb in the initial graph will actually join any of the countries outside of that blurb with that assumption. If they would, your "less warming than SSP 2-4.5 once adopted for better population predictions" argument wouldn't hold up.
Present day Egypt seems to be what today's lesser developed world can hope to achieve by 2100. Meh.
That may be a perfectly realistic scenario, but it is a ruthless world that strives no further. And using such a low-ambition scenario to call off the warming alarm is borderline cynical. If basically forces the west to uphold vast inequalities to avoid overshoot.
And just to be clear, I'm not suggesting that neither your nor Matt use these analysis to "call off the warming alarm". But they will be used in that manner by motivated people in power.
I believe that the endangerment finding's apparent lack of impact on the rate of decarbonisation is less important than the enormous capital that the finding pushed in the direction of renewables. Misallocated capital in my opinion. I would expect (hope) that funds intended drive the "transition" will be now reallocated to something of greater value to humanity.
Excellent article as always. Thanks for sharing.
I would be interested in further discussion regarding your statement “ More emissions mean greater increases in global temperatures and thus greater climate change.” I’m not sure I would agree with this since many other factors, including both natural and anthropogenic, impact how weather patterns shift over time. Various proxy studies show the rate of temperature changes at times in the Holocene to equal or exceed modern warming without significant anthropogenic causation. According to UAH Satellite records, the global temperature has declined about 0.6°C the past year, but emissions have not declined.
Two thoughts...
• The log(energy use)/log GDP plot seems to be non-linear, bending over somewhat at the high end. What would it look like if linear-linear? Might have an interesting story to tell.
• I'm surprised that you doubt that the rescinding of the EF is a major policy shift. The Biden administration certainly tried to accelerate decarbonization with its EV (and other) mandates. The lack of visible impact is due to (1) that administration's incompetence; and (2) the natural lag between promulgation of a policy and the policy's impacts. More than many other things, this likely will serve as a brake on inflation.
Roger states that "more (CO2) emissions mean greater increases in global temperatures and thus greater climate change"
He (and others) seem not to have noticed that the world is no longer warming, but, since early 2025, it has been in a strong La Nina situation, which should persist for about 2 years.
If he is really an honest broker, he needs to explain why CO2 is no longer causing any warming.
A strong La Nina can temporarily stall long-term warming. You already provided the answer.
462426 please comment on fairly recent studies stating that the co2 effect on temp is decreasing and implying that there will be little further increase in temperature in the near term;also is it true that temp.goes up before co2 increases?
Yes and... I concur with the sustained rise in energy demand (I've belatedly discovered the convincing arguments of Jean-Baptiste Fressoz! https://theclimatehistorian.substack.com/p/the-great-energy-transition-myth ). The and? With wise policies that constrain our "expanding bull's eye" habit, that peak in numbers can also contribute to reduced exposure and vulnerability to climatic and coastal hazards, yes? https://revkin.substack.com/p/how-to-spread-readiness-where-vulnerability
I’m about half way through JBF. Very good but I’m not 100%. On my list of books to review here, which is growing a lot faster than the reviews!
I would welcome a thoughtful article describing background (fundamental?) causes for the population decline.
One of my favorite topics to teach my student's every falls is population geography... they always mark the Demographic Transition Model as one of the key takeaways from the semester. https://populationeducation.org/what-demographic-transition-model/
Thank you, Brian. The "DTM" makes intuitive sense and matches my general understanding of global population numbers and trends. But I remain unclear on recent statements about global decline and its causes. I have some sense about why a decline is occurring in the U.S. and western Europe. Is that overwhelming increases elsewhere as death rates fall in response to increasing wealth or???
You bet. Roger will provide an excellent analysis soon... but the overall trend, at least in my opinion, was this:
1) Population growth in the last 150 years was due to fewer kids dying young (better food, hygiene, medicine, etc.) but the total fertility rate remained high and thus the population increased quickly.
2) Urbanization/industrialization replaced rural/folk economies. In cities kids are no longer assets, they are expensive liabilities. And because not so many are dying anymore, families can have fewer because nearly all of them will live into adulthood.
3) As people have fewer kids the population pyramid "inverts" and you have more older folks than younger... the death rate starts to climb and the population begins to shrink due to demographic shift. Left to natural devices... I think the population pyramid would've re-balanced with a total fertility rate of ~2.1 (replacement). But that leads us to #4.
4) On a personal note, I think our culture of individual satisfaction promotes a "carefree childless existence," which is just exacerbating the natural population decline from #3 above. This is why we're seeing total fertility rates fall below replacement level (2.1) in much of the developed world.
This is a great idea! Now on the list 👍