8 ms·

> In its call to action, the group proposed CO2 as one of three key metrics, suggesting ventilation rates that would keep CO2 levels at 800 parts per million or

> In its call to action, the group proposed CO2 as one of three key metrics, suggesting ventilation rates that would keep CO2 levels at 800 parts per million or below. Pre-industrial CO2 levels were at 280ppm, currently we have 420ppm, rising & accelerating. Give it three or four decades and ventilation won't help anymore. Edit: 420, not 480ppm

SoftTalker 2y ago
Houseplants. Lots of houseplants. More seriously, a house air filter with CO2 scrubber is not really something that would be difficult to make.
- J_Shelby_J 2y ago
  I would love that, but how? There is no available residential CO2 scrubbers.
  - jefftk 2y ago
    Bringing in external air (and filtering it, if it's polluted) will be way cheaper than scrubbing CO2 at current levels.
    - unholythree 2y ago
      Definitely. Filtering particulates and tempering the outside air is the way to go in anything but most extreme situations. I suspect even designing a fallout shelter you would want to go that route.
      - dzhiurgis 2y ago
        An ERV costs about ~$1000 plus labour (you can install yourself).
    - somenameforme 2y ago
      This is true, but mostly because the cost of bring in external air is near $0 in most cases - just open a few windows! But there's a lot of absurdly cool ways to scrub CO2 that are not especially expensive, like the video-game level of serendipity+convenience that's the Sabatier Reaction [1]. Combine hydrogen + CO2 at 300C => methane + water. It's already being used on the ISS to keep the air fresh. It'll also be a key component on Mars. There you have basically unlimited CO2 and unlimited hydrogen which yields unlimited methane and unlimited water. Carry out electrolysis on some of the water and you get hydrogen + oxygen. The hydrogen can be fed back into the original cycle, and so you end up left with methane + oxygen which is also known as rocket fuel, uncoincidentally the exact sort SpaceX's Starship is using. Back on Earth you could use this reaction to create practically endless carbon neutral fuel so long as the CO2 was sourced from either the air or a regrown natural capture source like trees or what not. Rockets using this fuel would even have a negative carbon footprint since some of that fuel will get burnt outside the atmosphere. It all seriously feels like a video game where there's just this perfect, but just utterly contrived, rule allowing you to thrive on the next level of difficulty. [1] - https://en.wikipedia.org/wiki/Sabatier_reaction https://en.wikipedia.org/wiki/Sabatier_reaction
      - OutOfHere 2y ago
        The reaction is most interesting, but there are three concerns: (1) It presumably requires concentrated CO2. It's not trivial to concentrate CO2 from the air without the appropriate technology. (2) Pure hydrogen can risk an explosion. (3) What does one do with the methane? Also, it too can risk a fire. For these reasons, this is not a reaction that one would seek to do at home.
        somenameforme 2y ago
        The Sabatier reaction is completely safe. Here [1] is a video of a few kids doing it completely manually with a couple of syringes, a pipe, and a torch. Producing methane is one of the huge benefits. Methane is just a normal fuel - use it to generate electricity, for your oven/stove, heating, whatever. But at home if all you want is CO2 removal then just use some lye, soda lime, or a million other simple capture technologies. Not quite as sexy, but it'll get the job done. <rant> There's no grand technologies required for any of these things. The only reason it's not done at scale is the same reason we can't have nice things in general. Governments are far more interested in war and cock measuring contests than actually solving problems. We spent literally trillions of dollars on Iraq and Afghanistan, and the latest wars will probably dwarf that. Just imagine all the crazy sci-fi scale of things we could have done with all that money. Alas, humanity seems to be running on loop, except now we have nukes, paired alongside what are likely some of the most idiotic 'leaders' in centuries. Want to know the answer to the Fermi Paradox? </rant> [1] - https://www.youtube.com/watch?v=VdNPkW9I0fQ https://www.youtube.com/watch?v=VdNPkW9I0fQ
  - autoexec 2y ago
    Don't the activated carbon prefilters used in many residential air filters work to scrub CO2 at least a little?
    - alexey-salmin 2y ago
      Try calculating how much heavier the filter must become every day to make a difference
    - TylerE 2y ago
      Not in the slightest. Those are for filtering volatile organics.
  - Filligree 2y ago
    There will be. Mind you, I’m not too happy about a future in which nobody can go outside.
  - IncreasePosts 2y ago
    Instead of scrubbing CO2, just adding the other important components like N2 & O2 to reduce the percent of CO2 in the air would probably be easier
    - EVa5I7bHFq9mnYK 2y ago
      No, because CO2 is only 0.04% of the air, O2 is 21% and N2 is 78%.
  - hollerith 2y ago
    Navies have been removing CO2 from submarines for decades. I think they use sodium hydroxide. Manned space programs must remove CO2 air breathed by astronauts. They used lithium hydroxide for decades (including famously in Apollo 13) but ISTR the international space station has a more sophisticated process.
    - gpm 2y ago
      The ISS has a clever trick of using zeolite beds to absorb CO2 (a rock with pores that selectively hold onto CO2, and H2O but they dry the air first), and then venting it to space to get rid of the CO2 and recharge them.
      - hollerith 2y ago
        I wonder whether they need to heat the zeolites to help them release the co2 or whether exposure to vacuum is enough.
        gpm 2y ago
        If I recall correctly they do heat it (I dug up the documents on this awhile ago, just going from my memory right now).
- johnsimer 2y ago
  IIRC you need ~300 plants to offset every one human in a house
  - jefftk 2y ago
    Yes, it's impractically high: we exhale about 1kg of carbon daily, so your plants collectively need to be getting about 1kg heavier daily to absorb that.
    - CGamesPlay 2y ago
      Don’t the plants exhale oxygen? So they won’t be getting 1kg heavier, closer to 300g, but I don’t know the actual chemistry.
      - alexey-salmin 2y ago
        That's just dry mass and plants are mostly water.
    - SoftTalker 2y ago
      Yeah it was sort of a joke, but having houseplants will make some difference. Not that they would be practical to absorb all the CO2 in the air. On the downside, keeping indoor plants healthy does take some ongoing time and effort and isn't everyone's cup of tea.
      - alexey-salmin 2y ago
        It often makes a negative difference because bacteria in the soil produce a lot of co2.
    - alexey-salmin 2y ago
      It's an order of magnitude worse than that, plants are mostly water, not carbon. They'll gain tens of kilos per day. If you can feed off your house plants alone, then you have a chance of closing the carbon loop. This was tried (e.g. biosphere2) and it's extremely hard even at the industrial scale.
- IvyMike 2y ago
  When plants remove CO2 and release O2, they have to do something with that carbon atom. They can use it to make sap or fruit, but mostly they use it to build more plant. A plant that isn't growing, like, a LOT, can't possibly be removing much CO2.
  - BurningFrog 2y ago
    Most of a tree is CO₂ that the plant has taken out of thin air. This only clicked for me when I started wondering why you never have to refill the soil for a houseplant even when it grows.
    - teh_infallible 2y ago
      Richard Feynman talked about this in his talk about “What is Fire?” https://www.youtube.com/watch?v=N1pIYI5JQLE https://www.youtube.com/watch?v=N1pIYI5JQLE
    - somenameforme 2y ago
      The soil itself is also storing CO2, in a variety of different less than intuitive processes. The most obvious is when parts of the plant die and breakdown into the soil itself.
elevation 2y ago
> currently we have 480ppm Where are you measuring 480? [0] says the recent global average is 419.3. [0] https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide https://www.climate.gov/news-features/understanding-climate/...
- coldtea 2y ago
  Does the global average count where most people live, or does it average New York and Mexico City with rural Idaho and Bretagne?
  - mike_hearn 2y ago
    Believe it or not the standard is to report the CO2 level measured at the top of an active volcano (Mauna Loa). This is for historical reasons, because it's where the first measurements were taken, but also they claim it's more accurate because the measurement site is surrounded by miles of lava and thus there's no trees or vegetation which could absorb CO2 locally nor any human settlements that could emit CO2. There is of course the small problem of it being a volcano. Other measurements come from a collection of sensors on TV or telecom towers. Some of them come from planes. You can see a map of sites here: https://gml.noaa.gov/dv/iadv/index.php?code=sgi https://gml.noaa.gov/dv/iadv/index.php?code=sgi The trend is the same in every site, although absolute readings vary somewhat. There are cleaner sites than Mauna Loa, like in Antarctica, but those show about 10ppm lower. Others give the same reading as at Mauna Loa but with more seasonal variance. It's unclear whether these differences really matter and they tend to be ignored.
    - cozzyd 2y ago
      I have two vials of "the world's cleanest air" from the south pole NOAA observatory
- blueflow 2y ago
  I probably read 420 somewhere and misremembered.
logifail 2y ago
> Pre-industrial CO2 levels were at 280ppm, currently we have 480ppm, rising & accelerating. Give it three or four decades and ventilation won't help anymore Just to add a little context, here's a table from https://www.dhs.wisconsin.gov/chemical/carbondioxide.htm https://www.dhs.wisconsin.gov/chemical/carbondioxide.htm 400 ppm: average outdoor air level. 400–1,000 ppm: typical level found in occupied spaces with good air exchange. 1,000–2,000 ppm: level associated with complaints of drowsiness and poor air. 2,000–5,000 ppm: level associated with headaches, sleepiness, and stagnant, stale, stuffy air. Poor concentration, loss of attention, increased heart rate and slight nausea may also be present. 5,000 ppm: this indicates unusual air conditions where high levels of other gases could also be present. Toxicity or oxygen deprivation could occur. This is the permissible exposure limit for daily workplace exposures. 40,000 ppm: this level is immediately harmful due to oxygen deprivation.
- IvyMike 2y ago
  The outlier to this the US Navy's experiments. Discussion on an older HN thread: https://news.ycombinator.com/item?id=19863319 https://news.ycombinator.com/item?id=19863319
  - taeric 2y ago
    Thanks for linking that! Will be hunting a bit for any recent takes on these studies. I'm finding I can't really tell any difference in mood/alertness/whatever despite what my sensor thing reports. To the point that I don't know why I bother keeping this thing in the office.
    - dzhiurgis 2y ago
      Same here, but I do love fresh air in my home.
      - taeric 2y ago
        It is only in my office that the values get high. Rest of the house is fine. My suspicion is these devices just can't really tell you much about how localized the readings are. And comparing a number for a large room to a converted closet is not at all meaningful.
robxorb 2y ago
How did we measure CO2 accurately pre-industry? Isn't the rise of industry kind of coincident with the ability to measure gases accurately? And if the trend as accuracy increased was up, wouldn't it suggest initial underestimates? Or is there some reliable way we can measure in retrospect?
- leptons 2y ago
  Sometimes air gets trapped in unusual places. When these types of things are found, that air can be tested with modern equipment. "Ancient air pockets changing the history of Earth’s oxygen" https://www.sciencedaily.com/releases/2016/08/160822174234.htm https://www.sciencedaily.com/releases/2016/08/160822174234.h...
  - robxorb 2y ago
    Thanks, though that study makes no mention of CO2, and concerns instead oxygen from 500m, to 1b years ago, which seems a little far off to be applicable to the order of the around one hundred and fifty years ago being asked about. Have I missed something?
    - leptons 2y ago
      My comment only explains how it's done. I'm sure you can understand that the article I mentioned was just an example. If you're looking for a specific CO2 measurement from air captured exactly one hundred and fifty years ago, I'll leave you to Google that yourself.
      - robxorb 2y ago
        Well, here's the only solid thing with referenced figures that came up. Chart on page one is quite the ride, as I'd have expected for early science: https://21sci-tech.com/Subscriptions/Spring%202008%20ONLINE/CO2_chemical.pdf https://21sci-tech.com/Subscriptions/Spring%202008%20ONLINE/... Everything else I found was unfortunately hand-wavy "scientific consensus says" and the ubiquitous "280ppm" coupled with "pre-industrial" repeated again without reference, nor apparent empirical basis. Not convincing, which for "the science is settled" I'd expect a bit of a higher standard.
gpm 2y ago
CO2 levels are increasing at ~3ppm/year*. In 40 years we're looking at roughly 120ppm. Noticeable but not "we're all going to have headaches and covid" numbers. I mean we might all have headaches and covid, but not directly because of CO2 at outdoor concentrations. * 2.8ppm in 2022-2023, the rate at which CO2 is increasing is very slowly increasing but it's close enough to constant for rough calculations, especially after rounding up to 3.
- genman 2y ago
  The rate is increasing, it is not constant. It used to be 1ppm per year. So it will be not 120ppm extra, it will be more. It might appear not much but when you consider indoor air then when currently room stayed below the recommended CO2 limit, it maybe now be above of it or you need more air changes that will require more energy (to move air and to condition it). And while 120ppm in 40 years might appear not a lot then you should also consider that 40 years is actually very short time - in 120 years it will be about twice as today - there would be no fresh air anymore.
  - aeternum 2y ago
    Earth CO2 concentrations during the Triassic were 6000ppm.
    - seadan83 2y ago
      Perhaps not that high. Regardless, entering that period was marked by a mass extinction.* This source [0] states it well: "The end-Permian mass extinction, the largest biological crisis in Earth history, is currently understood in the context of Siberian Traps volcanism introducing large quantities of greenhouse gases to the atmosphere, culminating in the Early Triassic hothouse. In our study, the late Permian and Early Triassic atmospheric CO2 history was reconstructed by applying the paleosol pCO2 barometer. Atmospheric pCO2 shows an approximate 4× increase from mean concentrations of 412–919 ppmv in the late Permian (Changhsingian) to maximum levels between 2181 and 2610 ppmv in the Early Triassic (late Griesbachian)." [0] https://pubs.geoscienceworld.org/gsa/geology/article/50/6/650/612995/Five-million-years-of-high-atmospheric-CO2-in-the https://pubs.geoscienceworld.org/gsa/geology/article/50/6/65... * looks like we can quibble on 2k ppm or 5k ppm, the salient part is the global mass extinction part. Whether that was a correlation or caused by CO2 is not defined, at any rate it is not really speaking to a very habitable earth for humans.

SoftTalker 2y ago

Houseplants. Lots of houseplants. More seriously, a house air filter with CO2 scrubber is not really something that would be difficult to make.

J_Shelby_J 2y ago
I would love that, but how? There is no available residential CO2 scrubbers.
- jefftk 2y ago
  Bringing in external air (and filtering it, if it's polluted) will be way cheaper than scrubbing CO2 at current levels.
  - unholythree 2y ago
    Definitely. Filtering particulates and tempering the outside air is the way to go in anything but most extreme situations. I suspect even designing a fallout shelter you would want to go that route.
    - dzhiurgis 2y ago
      An ERV costs about ~$1000 plus labour (you can install yourself).
  - somenameforme 2y ago
    This is true, but mostly because the cost of bring in external air is near $0 in most cases - just open a few windows! But there's a lot of absurdly cool ways to scrub CO2 that are not especially expensive, like the video-game level of serendipity+convenience that's the Sabatier Reaction [1]. Combine hydrogen + CO2 at 300C => methane + water. It's already being used on the ISS to keep the air fresh. It'll also be a key component on Mars. There you have basically unlimited CO2 and unlimited hydrogen which yields unlimited methane and unlimited water. Carry out electrolysis on some of the water and you get hydrogen + oxygen. The hydrogen can be fed back into the original cycle, and so you end up left with methane + oxygen which is also known as rocket fuel, uncoincidentally the exact sort SpaceX's Starship is using. Back on Earth you could use this reaction to create practically endless carbon neutral fuel so long as the CO2 was sourced from either the air or a regrown natural capture source like trees or what not. Rockets using this fuel would even have a negative carbon footprint since some of that fuel will get burnt outside the atmosphere. It all seriously feels like a video game where there's just this perfect, but just utterly contrived, rule allowing you to thrive on the next level of difficulty. [1] - https://en.wikipedia.org/wiki/Sabatier_reaction https://en.wikipedia.org/wiki/Sabatier_reaction
    - OutOfHere 2y ago
      The reaction is most interesting, but there are three concerns: (1) It presumably requires concentrated CO2. It's not trivial to concentrate CO2 from the air without the appropriate technology. (2) Pure hydrogen can risk an explosion. (3) What does one do with the methane? Also, it too can risk a fire. For these reasons, this is not a reaction that one would seek to do at home.
      - somenameforme 2y ago
        The Sabatier reaction is completely safe. Here [1] is a video of a few kids doing it completely manually with a couple of syringes, a pipe, and a torch. Producing methane is one of the huge benefits. Methane is just a normal fuel - use it to generate electricity, for your oven/stove, heating, whatever. But at home if all you want is CO2 removal then just use some lye, soda lime, or a million other simple capture technologies. Not quite as sexy, but it'll get the job done. <rant> There's no grand technologies required for any of these things. The only reason it's not done at scale is the same reason we can't have nice things in general. Governments are far more interested in war and cock measuring contests than actually solving problems. We spent literally trillions of dollars on Iraq and Afghanistan, and the latest wars will probably dwarf that. Just imagine all the crazy sci-fi scale of things we could have done with all that money. Alas, humanity seems to be running on loop, except now we have nukes, paired alongside what are likely some of the most idiotic 'leaders' in centuries. Want to know the answer to the Fermi Paradox? </rant> [1] - https://www.youtube.com/watch?v=VdNPkW9I0fQ https://www.youtube.com/watch?v=VdNPkW9I0fQ
- autoexec 2y ago
  Don't the activated carbon prefilters used in many residential air filters work to scrub CO2 at least a little?
  - alexey-salmin 2y ago
    Try calculating how much heavier the filter must become every day to make a difference
  - TylerE 2y ago
    Not in the slightest. Those are for filtering volatile organics.
- Filligree 2y ago
  There will be. Mind you, I’m not too happy about a future in which nobody can go outside.
- IncreasePosts 2y ago
  Instead of scrubbing CO2, just adding the other important components like N2 & O2 to reduce the percent of CO2 in the air would probably be easier
  - EVa5I7bHFq9mnYK 2y ago
    No, because CO2 is only 0.04% of the air, O2 is 21% and N2 is 78%.
- hollerith 2y ago
  Navies have been removing CO2 from submarines for decades. I think they use sodium hydroxide. Manned space programs must remove CO2 air breathed by astronauts. They used lithium hydroxide for decades (including famously in Apollo 13) but ISTR the international space station has a more sophisticated process.
  - gpm 2y ago
    The ISS has a clever trick of using zeolite beds to absorb CO2 (a rock with pores that selectively hold onto CO2, and H2O but they dry the air first), and then venting it to space to get rid of the CO2 and recharge them.
    - hollerith 2y ago
      I wonder whether they need to heat the zeolites to help them release the co2 or whether exposure to vacuum is enough.
      - gpm 2y ago
        If I recall correctly they do heat it (I dug up the documents on this awhile ago, just going from my memory right now).
johnsimer 2y ago
IIRC you need ~300 plants to offset every one human in a house
- jefftk 2y ago
  Yes, it's impractically high: we exhale about 1kg of carbon daily, so your plants collectively need to be getting about 1kg heavier daily to absorb that.
  - CGamesPlay 2y ago
    Don’t the plants exhale oxygen? So they won’t be getting 1kg heavier, closer to 300g, but I don’t know the actual chemistry.
    - alexey-salmin 2y ago
      That's just dry mass and plants are mostly water.
  - SoftTalker 2y ago
    Yeah it was sort of a joke, but having houseplants will make some difference. Not that they would be practical to absorb all the CO2 in the air. On the downside, keeping indoor plants healthy does take some ongoing time and effort and isn't everyone's cup of tea.
    - alexey-salmin 2y ago
      It often makes a negative difference because bacteria in the soil produce a lot of co2.
  - alexey-salmin 2y ago
    It's an order of magnitude worse than that, plants are mostly water, not carbon. They'll gain tens of kilos per day. If you can feed off your house plants alone, then you have a chance of closing the carbon loop. This was tried (e.g. biosphere2) and it's extremely hard even at the industrial scale.
IvyMike 2y ago
When plants remove CO2 and release O2, they have to do something with that carbon atom. They can use it to make sap or fruit, but mostly they use it to build more plant. A plant that isn't growing, like, a LOT, can't possibly be removing much CO2.
- BurningFrog 2y ago
  Most of a tree is CO₂ that the plant has taken out of thin air. This only clicked for me when I started wondering why you never have to refill the soil for a houseplant even when it grows.
  - teh_infallible 2y ago
    Richard Feynman talked about this in his talk about “What is Fire?” https://www.youtube.com/watch?v=N1pIYI5JQLE https://www.youtube.com/watch?v=N1pIYI5JQLE
  - somenameforme 2y ago
    The soil itself is also storing CO2, in a variety of different less than intuitive processes. The most obvious is when parts of the plant die and breakdown into the soil itself.

elevation 2y ago

> currently we have 480ppm Where are you measuring 480? [0] says the recent global average is 419.3. [0] https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide https://www.climate.gov/news-features/understanding-climate/...

coldtea 2y ago
Does the global average count where most people live, or does it average New York and Mexico City with rural Idaho and Bretagne?
- mike_hearn 2y ago
  Believe it or not the standard is to report the CO2 level measured at the top of an active volcano (Mauna Loa). This is for historical reasons, because it's where the first measurements were taken, but also they claim it's more accurate because the measurement site is surrounded by miles of lava and thus there's no trees or vegetation which could absorb CO2 locally nor any human settlements that could emit CO2. There is of course the small problem of it being a volcano. Other measurements come from a collection of sensors on TV or telecom towers. Some of them come from planes. You can see a map of sites here: https://gml.noaa.gov/dv/iadv/index.php?code=sgi https://gml.noaa.gov/dv/iadv/index.php?code=sgi The trend is the same in every site, although absolute readings vary somewhat. There are cleaner sites than Mauna Loa, like in Antarctica, but those show about 10ppm lower. Others give the same reading as at Mauna Loa but with more seasonal variance. It's unclear whether these differences really matter and they tend to be ignored.
  - cozzyd 2y ago
    I have two vials of "the world's cleanest air" from the south pole NOAA observatory
blueflow 2y ago
I probably read 420 somewhere and misremembered.

logifail 2y ago

> Pre-industrial CO2 levels were at 280ppm, currently we have 480ppm, rising & accelerating. Give it three or four decades and ventilation won't help anymore Just to add a little context, here's a table from https://www.dhs.wisconsin.gov/chemical/carbondioxide.htm https://www.dhs.wisconsin.gov/chemical/carbondioxide.htm 400 ppm: average outdoor air level. 400–1,000 ppm: typical level found in occupied spaces with good air exchange. 1,000–2,000 ppm: level associated with complaints of drowsiness and poor air. 2,000–5,000 ppm: level associated with headaches, sleepiness, and stagnant, stale, stuffy air. Poor concentration, loss of attention, increased heart rate and slight nausea may also be present. 5,000 ppm: this indicates unusual air conditions where high levels of other gases could also be present. Toxicity or oxygen deprivation could occur. This is the permissible exposure limit for daily workplace exposures. 40,000 ppm: this level is immediately harmful due to oxygen deprivation.

IvyMike 2y ago
The outlier to this the US Navy's experiments. Discussion on an older HN thread: https://news.ycombinator.com/item?id=19863319 https://news.ycombinator.com/item?id=19863319
- taeric 2y ago
  Thanks for linking that! Will be hunting a bit for any recent takes on these studies. I'm finding I can't really tell any difference in mood/alertness/whatever despite what my sensor thing reports. To the point that I don't know why I bother keeping this thing in the office.
  - dzhiurgis 2y ago
    Same here, but I do love fresh air in my home.
    - taeric 2y ago
      It is only in my office that the values get high. Rest of the house is fine. My suspicion is these devices just can't really tell you much about how localized the readings are. And comparing a number for a large room to a converted closet is not at all meaningful.

robxorb 2y ago

How did we measure CO2 accurately pre-industry? Isn't the rise of industry kind of coincident with the ability to measure gases accurately? And if the trend as accuracy increased was up, wouldn't it suggest initial underestimates? Or is there some reliable way we can measure in retrospect?

leptons 2y ago
Sometimes air gets trapped in unusual places. When these types of things are found, that air can be tested with modern equipment. "Ancient air pockets changing the history of Earth’s oxygen" https://www.sciencedaily.com/releases/2016/08/160822174234.htm https://www.sciencedaily.com/releases/2016/08/160822174234.h...
- robxorb 2y ago
  Thanks, though that study makes no mention of CO2, and concerns instead oxygen from 500m, to 1b years ago, which seems a little far off to be applicable to the order of the around one hundred and fifty years ago being asked about. Have I missed something?
  - leptons 2y ago
    My comment only explains how it's done. I'm sure you can understand that the article I mentioned was just an example. If you're looking for a specific CO2 measurement from air captured exactly one hundred and fifty years ago, I'll leave you to Google that yourself.
    - robxorb 2y ago
      Well, here's the only solid thing with referenced figures that came up. Chart on page one is quite the ride, as I'd have expected for early science: https://21sci-tech.com/Subscriptions/Spring%202008%20ONLINE/CO2_chemical.pdf https://21sci-tech.com/Subscriptions/Spring%202008%20ONLINE/... Everything else I found was unfortunately hand-wavy "scientific consensus says" and the ubiquitous "280ppm" coupled with "pre-industrial" repeated again without reference, nor apparent empirical basis. Not convincing, which for "the science is settled" I'd expect a bit of a higher standard.

gpm 2y ago

CO2 levels are increasing at ~3ppm/year*. In 40 years we're looking at roughly 120ppm. Noticeable but not "we're all going to have headaches and covid" numbers. I mean we might all have headaches and covid, but not directly because of CO2 at outdoor concentrations. * 2.8ppm in 2022-2023, the rate at which CO2 is increasing is very slowly increasing but it's close enough to constant for rough calculations, especially after rounding up to 3.

genman 2y ago
The rate is increasing, it is not constant. It used to be 1ppm per year. So it will be not 120ppm extra, it will be more. It might appear not much but when you consider indoor air then when currently room stayed below the recommended CO2 limit, it maybe now be above of it or you need more air changes that will require more energy (to move air and to condition it). And while 120ppm in 40 years might appear not a lot then you should also consider that 40 years is actually very short time - in 120 years it will be about twice as today - there would be no fresh air anymore.
- aeternum 2y ago
  Earth CO2 concentrations during the Triassic were 6000ppm.
  - seadan83 2y ago
    Perhaps not that high. Regardless, entering that period was marked by a mass extinction.* This source [0] states it well: "The end-Permian mass extinction, the largest biological crisis in Earth history, is currently understood in the context of Siberian Traps volcanism introducing large quantities of greenhouse gases to the atmosphere, culminating in the Early Triassic hothouse. In our study, the late Permian and Early Triassic atmospheric CO2 history was reconstructed by applying the paleosol pCO2 barometer. Atmospheric pCO2 shows an approximate 4× increase from mean concentrations of 412–919 ppmv in the late Permian (Changhsingian) to maximum levels between 2181 and 2610 ppmv in the Early Triassic (late Griesbachian)." [0] https://pubs.geoscienceworld.org/gsa/geology/article/50/6/650/612995/Five-million-years-of-high-atmospheric-CO2-in-the https://pubs.geoscienceworld.org/gsa/geology/article/50/6/65... * looks like we can quibble on 2k ppm or 5k ppm, the salient part is the global mass extinction part. Whether that was a correlation or caused by CO2 is not defined, at any rate it is not really speaking to a very habitable earth for humans.