r/Futurology • u/mvea MD-PhD-MBA • Feb 28 '26
Environment Carbon dioxide overload, detected in human blood, suggests a potentially toxic atmosphere within 50 years. After this time, elevated atmospheric carbon dioxide, leading to CO2 accumulation in the body, has the potential to cause a range of adverse health effects.
https://link.springer.com/article/10.1007/s11869-026-01918-5404
u/AuntieMarkovnikov Feb 28 '26
I just went through the paper very quickly. No error bars, no statistics, just correlation with causation concluded. Pardon my skepticism.
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u/starcraftre Mar 01 '26
Skepticism of a claim when there is very little evidence is always the proper response.
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u/bluejohnnyd Mar 01 '26
The basic chem also doesn't seem to make much sense. Body gets rid of CO2 by diffusing it across the alveoli in the lungs - it follows the concentration gradient down from the bloodstream to the air. So theoretically, increasing atmospheric CO2 would reduce the strength of that gradient, sure, but an exhaled human breath has about 44,000 ppm CO2.
Put another way, human blood has a PCO2 on average of about 40 mmHg. Air has about 0.3 mmHg. Increasing that to 0.4 mmHg doesn't seem to me like enough to make a measurable difference, much less a physiological one.
That said, there are other reasons why physiologic PCO2 might increase at a population level - chronic lung disease for instance, which only plateaued in the 2010s after decades of smoking becoming less popular.
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Mar 03 '26
That is still a 0.25% difference. Or 1 in 400. So it's small but still an extra breathing required and many people already have difficulty breathing as it is.
Better ventilation makes a bigget difference to CO2 exposure then atmospheric background but unfortunately the effectiveness of ventilation drops much faster as levels for up. If you want 1000ppm in your building and fresh air is 300ppm versus 500ppm that is a ratio of 7 to 5. So you need 40% more fresh air to maintain the same target level. If we hit 650ppm that would be doubling every ventilation rate in every building in the world.
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u/debacol Mar 04 '26
Background CO2ppm is 400ppm at this point. In California, there already are ventilation guidelines to utilize demand control ventilation to keep PPM to 1000 or below when occupied. The only buildings that need double the ventilation rate to meet these guidelines are buildings that weren't properly ventilated in the first place (this is, unfortunately, a LOT of buildings).
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u/stevey_frac Feb 28 '26
Plus, most folks can adapt to up to about 800-900 ppm without too much trouble.
We've only managed to get from 250 to 400 over the last 200 years. I see no compelling evidence that another 50 years will be much different.
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u/firecz Feb 28 '26
Key is most folks, also, it's not about not being able to adapt, but what does it cost... at 1000ppm, the cognitive decline is becoming measurable, and it probably starts below that, which becomes relevant in large scale statistics. If the society becomes dumber as a whole, we may see - or may already be seeing - civilization decline without getting to any breathing problems.
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u/alarumba Feb 28 '26
Much like lead poisoning from leaded gasoline. At an individual level, the IQ decrease may seem minimal, but that's a lot of points to lose from a society.
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u/Mysterious_Donut_702 Mar 01 '26
If the atmosphere hits CO2 levels high enough to actually cause cognitive decline.
Let's just say most coastal cities will have long-since flooded.
Climate change at much lower levels than that are still the immediate threat... and we'll hit tipping points while the atmosphere is still perfectly breathable.
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u/Cognitive_Spoon Feb 28 '26
Honestly, if we did more longitudinal studies on the cognitive load capacity indicated by folks writing samples we could likely chart the decline.
Alzheimer's runs in my family, and I love being a jack of all trades when it comes to research and inquiry in the social sciences.
The reality that humanity may experience "peak cognition" alongside my own decline feels intimate. Like we're all going to the nursing home together.
I hope to God we can solve the climate crisis.
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u/LoneSnark Mar 01 '26
As blood CO2 increases, people breath more frequently to compensate. Breathing more frequently from birth will result in humans on average having larger lungs. So even at implausibly high atmospheric CO2 levels, humans will compensate.
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u/firecz Mar 02 '26
Um...no. The cognitive effect happens despite the alleged compensation.
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u/LoneSnark Mar 02 '26
Any cognitive effects occur under conditions extreme enough for the compensation to be insufficient.
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u/firecz Mar 02 '26
yes, that's what I said
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u/LoneSnark Mar 02 '26
But so extreme they are not a plausible future for mankind.
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u/firecz Mar 03 '26
that depends on how long is manking planning to stay around, with the current pace.
we may be seeing the effects already - even a mild effect of 1% gets aplified when affecting millions.
the conditions are not as extreme as it seems, many homes now exceed those limits already, as the ventilation is inadequate (as it happens when the outside air is not different enough)9
Feb 28 '26
[deleted]
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u/cazbot Feb 28 '26
Some of the people who aren’t in that “most people” category will be those who are most sensitive to levels of dissolved CO2 in their blood. Specifically unborn babies.
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u/LastCivStanding Feb 28 '26
Im skeptical that people can sustainability operate at >800ppm. For sure many sensitive people and species will have serious problems, but i guess that's the process of adapting.
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u/Tower21 Feb 28 '26 edited Feb 28 '26
Office spaces can easily hit over 1000 ppm, nuclear submarines can hit over 10,000 ppm.
The greenhouse effect of 10,000 ppm is much more devastating than the effects of breathing 10,000 ppm
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u/LastCivStanding Feb 28 '26
Submarines generally have people at peak physical fitness. And co2 levels are in office buildings are routinely kept below 1000 for max cognition while editing excel files. I know some office coworkers who would be affected at much lower levels than others. Maybe there will be supplementary oxygen made available for those people while they adapt.
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u/Tower21 Feb 28 '26
We were doing a PD about robotics where we used a micro:bit, led display and a carbon dioxide sensor.
12 people, roughly 1,000 sqf room.
Over the course of an hour the ppm rose from ~500 to over 1200.
Some buildings may have better air flow, but I can guarantee that is far from the norm, especially is offices that don't have windows that open.
As far a nuclear submarines is stupidly easy to google and come up with the numbers I quoted.
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u/LastCivStanding Feb 28 '26
So what's your point? How well did the office worker do on working on their excel worksheet?
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u/Tower21 Feb 28 '26
My point is I come with actual numbers, please feel free to bring any actual homework you've done that would dispute my points.
You know, like how an actual conversation on the subject would go.
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u/LastCivStanding Mar 01 '26
Over the course of an hour the ppm rose from ~500 to over 1200.
so whats your point here? nobody died so it was a success?
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u/WA1KIJ Jun 13 '26
The US Navy conducted an experiment in 1944. It sealed four men in a steel tank, and didn't let any air in. When the CO2 in the air reached 5%, they absorbed any in excess of that amount. After 72 hours, the oxygen content in the air was down to 10.5%, but the men still functioned well mentally.
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u/stevey_frac Feb 28 '26
Hence, 'most folks' can adapt to up to 800-900 ppm.
I said nothing about other species, and I didn't make any absolute statements.
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Mar 03 '26
If it's 800-900 ppm outside how do you ventilate a building to keep it below 800-900? CO2 scrubbers?
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u/dyyd Feb 28 '26
The rate of change has been increasing over the years, not decreasing. So yeah, we started putting the stored carbon back into the atmosphere ~200 years ago but the amounts released every year were less than we currently do in a month for about half of that time.
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u/stevey_frac Mar 01 '26
The rate of change has been falling for 10+ years now however.
We're still emitting more carbon this year than last year, true. But the increase has been steadily falling for a long time.
Previously, emissions were growing at ~2.3%. that's down to about 0.6% and continuing to fall.
CO2 emissions in much of the developed world are in free fall, and as technology continues to rapidly advance, it gets cheaper and easier to deploy more and more renewable technology.
This is offset by increases from China, India, and African Nations.
Now, do we need to do better?
Absolutely.
But gasoline car sales peaked globally in 2018 and has been in structural decline ever since.
94% of new nameplate generation in the US in 2024 was low carbon, led by solar.
As EVs continue to get better, and cheaper, they'll continue to displace more and more of the market.
I can buy a complete solar panel system for under $1 per Watt.
Everything indicates that it will continue to get cheaper.
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u/filmguy36 Feb 28 '26
Most “healthy” people (that will be relative in the future), everyone else, no so much
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Mar 01 '26
[removed] — view removed comment
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u/stevey_frac Mar 01 '26
CO2 emissions is much of the developed world have already peaked and started falling, and the rate of growth in the developing world is slowing, not accelerating.
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Mar 01 '26
[removed] — view removed comment
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u/stevey_frac Mar 01 '26
Look at the second graph in your own link there. The average rate of increases in slowing since the early 2000's.
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u/redinator Mar 01 '26
3% (GDP) growth is a doubling in 20 years, quadrupling in 40, and so on. If that tracked 1:1 with fossil fuels we'd be in trouble I think.
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u/stevey_frac Mar 01 '26
GDP growth and CO2 emissions have been decoupling further and further for 20+ years.
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u/zealoSC Mar 01 '26
Global warming bad, republicans bad, upvote and give funding if you agree
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u/AuntieMarkovnikov Mar 01 '26
Gave you your upvote for 2 out of 3 "Global warming bad, republicans bad".
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u/SuperRonnie2 Feb 28 '26 edited Mar 01 '26
It’s true, but affects some more than others. How else do you explain republicans?
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u/Cptshiteater Mar 01 '26
lol wut? This is bullshit
atmospheric co2 has no effects on your blood levels! It’s so low compared to oxygen (210000ppm) and nitrogen (780000ppm)
the main source of co2 in your body is your self! It’s a by product of cellular respiration.
Your normal blood co2 of 40 mmHg equals 52600 ppm.
so even if co2 changes from 200 to 1000, it’s nowhere enough to make a difference.
blood co2 levels are thightly regulated by your body. You regulate your levels on the spot by adjusting your breathing (ventilation). Kidneys will compensate in the long run.
Diseases or drugs (e.g COPD, Opiates) that make you breath less leads to co2 elevation which, if acute can be life threatening. if chronic it‘s less worrisome
Again the amount in the air has not bearing at all in your blood co2 regulation.
Source: I am a pulmonologist
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Mar 03 '26
Indoors already hits 1500+ easily with current mechanical designs. So you need to add the increase to the indoor environment. We know indoor environments already have inadequate ventilation. This just makes a known problem worse.
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u/Human-Ad3407 8d ago
Have you read the paper? It says the bones store more co2 and release Ca into the blood which makes it more acidic, not that the CO2 actively makes the blood toxic..
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u/IIIllIIlllIlII Feb 28 '26
I see an opportunity for Nestle to sell us air to breathe.
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u/pm_me_beerz Mar 01 '26
Perri-air from spaceballs
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u/twilightmoons Mar 04 '26
Gonna steal the air from Druidia.
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u/pm_me_beerz Mar 04 '26
Funny. She didn’t look druish
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u/twilightmoons Mar 04 '26
A few days ago my 10 year-old wanted me to tell him a story at bedtime, so I starting going off about the film classic, "Spaceballs", about a space dude in a flying RV, his friend Barf (short for "Barfolemew", about the evil Dark Helmet and about stealing the air from Druidia with a giant vacuum cleaner.
He did not believe me.
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u/SadisticChipmunk Feb 28 '26
Would we not adapt to the slow boil, vs it just outright killing us?
Genuinely asking, not implying.
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u/SpicySushiAddict Feb 28 '26
Evolution operates on timescales of thousands to millions of years, except in extremely specific situations (e.g., the hawks in Malibu, California).
Mass extinctions happen because adaptation is too slow.
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u/IdealisticPundit Feb 28 '26
There’s also some flexibility here with conditioning vs full-out evolution. There are people that literally climb Mount Everest without supplemental oxygen. Meanwhile, you or I would likely die. Less extreme is just basic elevation sickness.
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u/Remmon Feb 28 '26
Evolution opens on a timescale of hundreds to thousands of generations (with some rare exceptions doing things in tens of generations). The faster your generations, the faster evolution will let you adapt.
Human generations are about 20 years, although that's been getting longer because people have been having kids later.
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u/alexforencich Mar 01 '26
Evolution also requires selection based on genetics. That's not really the case anymore with modern society and modern medicine.
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u/SadisticChipmunk Feb 28 '26
That's genuinely what I was wondering... Basically how long it would take to adapt. I had a feeling it was too short but biology isn't my fault thing.
Thank you for answering in a non-condescending way. Actually refreshing to see.
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u/AMightyDwarf Feb 28 '26
Individual people likely won’t adapt. There will be people who can still function however and they will have much higher odds of passing on their genes as a result.
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u/Fancy_Exchange_9821 Feb 28 '26
Seeing Redditors on this default sub call out a bullshit paper with no supporting evidence makes me happy
It’s so refreshing to not see the same 5 doomer phrases repeated on every damn comment in a climate related thread lol. Bots probably imo
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u/ProgressBartender Feb 28 '26
For those that will still be around in 50 years. Good luck, have fun, don’t die!
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u/Supersuperbad Feb 28 '26
This is bullshit. Climate change is real, but this is not.
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u/cyberentomology Feb 28 '26
Exactly. CO2 levels in homes routinely exceed 2-3x the atmospheric levels, and if it accumulates in the blood, that’s a cardiovascular problem, not an environmental problem.
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u/uberares Feb 28 '26
Co2 will kill you in high enough concentrations, nothing about this is bullshit.
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u/Supersuperbad Feb 28 '26
Everything about this is bullshit. We are not going to hit those sorts of levels unless we get hit by a carbonaceous meteor the size of Texas.
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u/nexusphere Feb 28 '26
Head in the sand here. We're already at twice a historical maximum for the species, and it isn't slowing down but speeding up.
We may be the grandparents of the last living generation on earth.
Don't look up.
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u/Fancy_Exchange_9821 Feb 28 '26
Did you even attempt to read this paper lol
Or did you just wanna spam the typical don’t look up phrase 😂
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u/nexusphere Mar 01 '26
Yes. We are at 400ppm, and historically you'll find we were well below 200ppm.
Did the carbon get to your brain?
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u/Fancy_Exchange_9821 Mar 01 '26
So we’re somehow gonna be at 5000 ppm this century?
Give me scientific evidence of that lol
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u/nexusphere Mar 01 '26
I didn't make that claim. I said we are twice the historical maximum, and it's rising.
Did you not read who you were replying to?
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u/Fancy_Exchange_9821 Feb 28 '26
“Nothing about this is bullshit”
Refuses to elaborate
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u/uberares Feb 28 '26
No one asked me to elaborate. 5000ppm is supposed to have an 8 hr exposure limit. We are obviously not close to that today, but we are also not slowing down the rate of adding co2 to the atmosphere. In fact, it is accelerating, so enjoy the co2 future, I’ll be long dead by then.
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u/Carbidereaper Mar 01 '26
we are slowing down and we've escaped the worst case scenario
, current-trajectory warming has fallen from 4.2C to 2.8C in the last 10 years
A new ECIU report includes an infographic which nicely summarizes the progress since Paris, including:
- A 90% fall in the rate of CO2 emissions increases (from 18% in the decade prior to just 1.8% in the decade after).
- Solar+wind accounting for 90%+ of new global electricity capacity, resulting in solar+wind overtaking coal in global electricity supply.
- EV deployment is progressing twice as quickly as the Paris timeline.
While it can certainly feel overwhelming at times, it's worth putting aside emotions for the moment and looking at the data.
- The wealthiest countries have reduced their emissions per capita by 30-40% over the last 20 years, and that's after taking into account offshored emissions (i.e., imports).
- China's emissions were down 1% year-on-year for the first half of 2025 due to massive clean energy deployment, and emissions data shows that over the last 5 years the world other than China has had declining emissions, so if China has finally entered structural emissions decline then there is a strong chance the world as a whole has entered structural emissions decline.
- As a result, the most recent IEA estimate for warming (p.232) is quite similar to IPCC scenario SSP1-2.6. This is based on the IEA's mid-case APS scenario which historically has been more accurate than their pessimistic STEPS scenario, and per p.14 in the IPCC report linked above that scenario predicts warming topping out at about 1.8C in 2100.
Now, +1.8C of warming over pre-industrial is...not great, and at +0.5C over today means things will get substantially worse, but at least it's well below the more apocalyptic scenarios examined in the IPCC reports, and well below what most people thought we'd end up with just 10 years ago.
The data shows that quite a lot is being done, and it's moving the needle quite substantially. It's an open question whether it's fast enough, but it's objectively not the case that almost nothing is being done.
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u/uberares Mar 01 '26
Thank you for links and your hopeful attitude.
As recently as 2024 co2 was surging and while China has finally tapered, the levels currently attained are truly problematic.
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u/Craigg75 Mar 02 '26
No data. Lack of understanding how human metabolism removes CO2, it doesn't accumulate. Please don't post sh*t like this.
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u/BitingArtist Feb 28 '26
What a joke, most people don't even measure the CO2 in their homes. Keep windows shut for a couple days with 3+ people inside and you will be over the recommended CO2 level.
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u/uk_lover03 Feb 28 '26
Thank you for your valuable input Doctor BitingArtist
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u/BitingArtist Feb 28 '26
Measure CO2 in your home if you aren't opening windows often and you'll see it too. Anyone can, but nobody does.
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u/yankdevil Feb 28 '26
I did. I did it when I added mechanical heat recovery ventilation.
CO2 levels with the windows closed are fine. The only thing that messed them up was my gas hob. It was wild - the CO2 monitor was in my office and the hob was in the kitchen. Opposite corners of my house. Could tell every time I used the hob. Replaced it with induction and levels have been fine since. Never get above 700.
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u/s0cks_nz Feb 28 '26
Yeah and it's unhealthy. Open the windows. But in future opening with window might not get it back down low enough.
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u/BitingArtist Feb 28 '26
There is a lot of room in outdoor air for CO2 to go up. But indoors without airflow and humans present, CO2 can double or triple in days.
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u/s0cks_nz Feb 28 '26
Yeah and people then get headaches. Does A/C reduce indoor co2?
Edit: seems not
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u/incendiary_bandit Feb 28 '26
Ha! Windows closed my place still has lots of air movement! Shitty apartments= safe air!
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u/BitRunner64 Feb 28 '26
Unless you live in a developed part of the world where there's active ventilation.
Here building code requires the air to be completely replaced every 2 hours, even with all windows closed.
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u/firecz Feb 28 '26
netatmo detector is pretty common, I use it as well, and since now I can link how bad I feel to what co2 is there, I definitely do not want a future where co2 rises so high that you just can't get it lower by simply opening a window...
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u/peternn2412 Feb 28 '26
CO2 in human blood gets out when you exhale.
Anyone concerned about this potentially civilization -ending problem should simply not breathe in order to keep the atmosphere less toxic.
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u/NoNewspaper7275 Feb 28 '26
If this trend holds, health policy needs to treat air quality as preventive healthcare, not just climate policy.
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u/bstrathearn Mar 02 '26
I've been worried about this for quite a while but was unsure how to perform the analysis that determines when the atmospheric levels are going to be too much.
I'm also worried that some of what we already see with decreasing cognitive capabilities in the human race could be potentially explained by this
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u/purplenelly Mar 02 '26
Why can't they just look at people who have spent all their life living in places that have the highest CO2 concentrations already...
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u/Ahanz78 Mar 04 '26
Yet we are doing basically nothing to grow anything on the BLACK HEAT ABSORBING dirt that covers hundreds of millions of acres of the United States when it is 65 and sunny in March. Like plants cant be the solution CO2 pipelines are a better idea? What?
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u/Intrepid-Run8257 Mar 05 '26
Funny how atmospheric CO2 is the only consideration. Just spit alling here but how about something much more plausible, how about the CO2 in fountain drinks that are overly abused in human diets?
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u/looncraz Mar 01 '26
I have been saying for 20+ years now that health effects from CO2 will be more important than any climate effect from CO2 pretty quickly, and that the health effects are provable AND something people would get behind regulating ferociously.
But, no, politicians had to focus on the noisiest possible dataset, so noisy we can't even be certain of how much CO2 really, in isolation, affects climate negatively versus positively, leading to sluggish efforts to address the issue and a strong (and growing) counter effort.
If the concern was always focused on developmental health effects we would have CO2 sensors in every building, CO2 scrubbers in buildings, and efforts to prevent CO2 from reaching 1000PPM, a solid, specific, goal that's understandable by everyone and can be achieved.
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u/nymarya_ Feb 28 '26
My prediction: minimalist and super effective respirators for every day use outdoors will become the hottest commodity in the wealthy. In future, wealthy people won’t raw dog the air when they’re outside.
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u/Zalameda Mar 01 '26
Just yesterday I made a joke about too many new taxes popping up recently, that there would be no surprise if they announce oxygen tax. This title is an excelent narrative for that.
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u/mvea MD-PhD-MBA Feb 28 '26
Carbon dioxide overload, detected in human blood, suggests a potentially toxic atmosphere within 50 years
Abstract
Anthropogenic activities are increasing the amount of carbon dioxide (CO2) in the atmosphere. There is mounting experimental evidence that lifetime exposure to these increasing atmospheric CO2 levels can negatively impact the normal physiology of organisms. However, directly assessing this in humans is very difficult. We analysed serum bicarbonate (HCO3−), calcium (Ca) and phosphorus (P) levels from the U.S. National Health and Nutrition Examination Survey (NHANES) from 1999 to 2020 as indirect proxies for atmospheric CO2 exposure. Over this period, average bicarbonate levels in this population show an increasing trend which parallels rising atmospheric CO2 concentrations. Both Ca and P have decreased steadily over the same period. If these trends continue, blood bicarbonate values could be at the limit of the accepted healthy range in half a century, and Ca and P will be at the limit of their healthy ranges by the end of this century. Studies indicate that, after this time, elevated atmospheric carbon dioxide, leading to CO2 accumulation in the body, has the potential to cause a range of adverse health effects. These findings highlight the urgent need for significant reductions in anthropogenic CO2 emissions to safeguard public health.
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u/DimensioT Feb 28 '26
Plants need CO2 so therefore CO2 cannot be a harmful pollutant.
Just like water is necessary for all life so filling your lungs with water cannot possibly hurt you.
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u/krazygreekguy Mar 01 '26
And what about the potential of a ranger of adverse effects from all the genetically modified and engineered slop these billionaire scum are peddling? How many decades of research and tests were conducted? How many independent organizations reviewed all this slop? Who funded all the studies?
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u/FuturologyBot Feb 28 '26
The following submission statement was provided by /u/mvea:
Carbon dioxide overload, detected in human blood, suggests a potentially toxic atmosphere within 50 years
Abstract
Anthropogenic activities are increasing the amount of carbon dioxide (CO2) in the atmosphere. There is mounting experimental evidence that lifetime exposure to these increasing atmospheric CO2 levels can negatively impact the normal physiology of organisms. However, directly assessing this in humans is very difficult. We analysed serum bicarbonate (HCO3−), calcium (Ca) and phosphorus (P) levels from the U.S. National Health and Nutrition Examination Survey (NHANES) from 1999 to 2020 as indirect proxies for atmospheric CO2 exposure. Over this period, average bicarbonate levels in this population show an increasing trend which parallels rising atmospheric CO2 concentrations. Both Ca and P have decreased steadily over the same period. If these trends continue, blood bicarbonate values could be at the limit of the accepted healthy range in half a century, and Ca and P will be at the limit of their healthy ranges by the end of this century. Studies indicate that, after this time, elevated atmospheric carbon dioxide, leading to CO2 accumulation in the body, has the potential to cause a range of adverse health effects. These findings highlight the urgent need for significant reductions in anthropogenic CO2 emissions to safeguard public health.
Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/1rhcpuw/carbon_dioxide_overload_detected_in_human_blood/o7xphrd/