So you want to use plants to reduce CO₂ | Hacker News Reader

So you want to use plants to reduce CO₂

dynomight.net

123 pointssurprisetalk110 comments

Trees respire. They breath in and out. At night time, many trees emit more CO2.

And trees don't exist in isolation as these napkin calculation articles consider them (spherical cows and all that). Every single tree on earth relies on mycorrhizal fungi for the vast majority of its nutrients. Fungi break things down release CO2.

Most of our oxygen comes not from forest but from oceans (specifically from phytoplankton, algae, and photosynthetic bacteria). Between 50-80% of it in fact. Likewise, most of the CO2 that has been captured has been captured by the ocean not by forests. About 25-30% of all human emissions have been captured by the ocean.

Forests (and grasslands) are tremendously important for ecosystems and our health but I think this focus on CO2 and oxygen is simply misleading. If that's your concern you should really be focusing on the ocean. Which IMO is in an even more dire strait than our forests

If the ocean is the main hero there, why is the forest still important to our health?

Rainfall

And at least the forest soil has the same amount of carbon stored.

The ocean breathes in and out too. Very little carbon sinks down to the sea floor. The ocean does happen to absorb a lot of CO2, but that's from acidification rather than photosynthesis.

Yes agreed. But the organisms breath "out" much more oxygen than anything else. And yes ocean acidification is both what's driving a massive crisis and saving us from the full impacts of our CO2 output. It's not a pretty picture

You could induce artificial algea blooms. All that needs is iron and light + water soluble co2 and / or o2. If you are greedy you pump light down into the depths , go cubic instead of quadratic?

Intentional oceanic iron fertilization (OIF) is actually well-studied. Unfortunately it carries risks of ecological disruption and can lead to deoxygination (dead zones). Which would long-term hinder our ability to repeat this. It also often leads to methane and nitrous oxide emissions which are both very potent (though shorter lived) greenhouse gasses

> Most of our oxygen comes not from forest but from oceans (specifically from phytoplankton, algae, and photosynthetic bacteria). Between 50-80% of it in fact.

That fact checks out: about 70% of the earth's surface is covered by oceans. It follows that most photosynthesis, thus oxygen comes from oceans.

> Which IMO is in an even more dire strait than our forests

I think you are probably right, but could you kindly elaborate and provide more details? Very curious to hear your view and learn more.

https://science.nasa.gov/earth/explore/the-ocean-and-climate...

Has a pretty good overview. But in brief: Changes in biosphere due to heat and decreasing pH balance due to increased CO2 can leave species unable to adapt fast enough causing deaths.

It can also cause adaptations to go haywire like temperature dependent sex determination where the ratio of male to females in eggs is set by ambient temperatures, skewing breeding population gender too much in one direction.

My opinion is largely colored by the IPCC Ocean/Cryosphere report. I closely followed each IPCC report and this was by far the most "doomer" of the special reports released by the IPCC. Some highlights:

  - ocean acidification and deoxygination (imo the most alarming and underdiscussed doomsday scenarios of climate change): About 0.5 to 3.3% of dissolved oxygen had been lost between 1970 and 2010 which has led to the rapid expansion of Oxygen Minimum Zones ("dead zones"). Acidity has increased by 30 to 40% and at a clearly accelerating rate. That's 10 times faster acidification than at any other point in the last 300 million years
  - they estimated oceans had absorbed about 90% of "excess global heat" and their ability to absorb is slowing rapidly
  - up to 99% of permafrost could melt by 2100. Permafrost melting was completely unanalyzed in the 1.5C report due to lack of good data

https://www.ipcc.ch/srocc/

Forests on the other hand have shown surprising resilience. And, if they survive the impending destabilization, they might in the long term (I mean looong term) even benefit from increased CO2 concentrations as they historically have.

PS the IPCC reports are more accessible than people realize. Even the technical reports are often not much more difficult to parse than the policymaker reports meant for the general public. I'd quite recommend giving them a try

wholesale destruction of almost every biome. Overfishing (where 'fish' means anything that swims) with methods that destroy both the fish and the ecosystem-- have you ever considered what a trawler net destroys as it is dragged over the bottom of the seabed?

And now deep-sea mining.

Forests do net sequester carbon. But if you want to really sock away the carbon you harvest the trees and pyrolize it. It will give you energy (heat) you can use and elemental carbon (biochar). You could bury that a few feet under or innoculate it with microorganisms and work it into fields. Carbon in that form will sit in the soil for hundreds of years. Thousands or millions if you bury it.

I mean technically we already do this: renewable plantation timber is a widespread operation (also why I get kind of annoyed at YouTubers talking about how great the timber is in old homes - yes it's great because it was logged from 50 year old old growth forests and now they're all gone because we cut them down).

You can just buy engineered wood products that are much stronger than any old growth lumber. My family lake house built in 1970 has three gluelam trusss beams that support the roof. There are even better engineered wood products available these days.

> Carbon in that form will sit in the soil for hundreds of years. Thousands or millions if you bury it.

And what is the scale that global climate change works on?

Trees do jack shit for carbon on the scale that is important.

50 tons per acre, over 35 years (to grow the trees to a harvestable age) with an expectation that you can capture ~25-40% of that in long term storage via pyrolizing it.

The US alone has ~1 billion acres of forest land and could produce a lot more if needed. Over 35 years, we could remove 50 billion tons * 25-40%. Basically enough to offset a years worth of emissions during those years.

It's not enough, but it would be a significant amount of carbon removed. Combined with other efforts, we could put a lot of carbon back in the soil.

“I couldn’t live with so many trees. They suck up all the oxygen.”

it looks like i'm guilty of having never really thought and done some research about this and i'm a bit ashamed to admit i fell in this trap and used to think forests and trees are the most important pieces in the system.

I don't get why media has been fixating so much on trees and forests (Amazonia!) without even mentioning ocean's role in this.

Click bait sells, therefore outrage sells. And how do you film an ocean absorbing(or not) CO2.

But you can film people cutting trees, and protests, and you can blame companies.

And the average person won't understand much about the chemistry of the oceans, the average person can barely read.

(UN literacy numbers are the equiv of a grade 6 reading capability. And again, average grade 6, not bright students).

Probably because you can plant more trees but not more ocean.

Forests and grasslands are critical for the climate because of the carbon they lock away. So long as the plants stay alive, they store carbon in the cellulose structures of roots and stems.

Conserving these ecosystems is less about their daily respiration and more about keeping existing carbon out of the atmosphere. It's a defensive strategy. Not "carbon capture" per se but more "avoid loosing the carbon we've already captured". We're interested in the sink, not the flow.

Of course when the plant dies and decomposes or burns up, it all goes back. Long term, it's almost exactly net zero. The ONLY way to use plants for long term carbon sequestration is to make sure that plant matter gets treated or literally buried so that aerobic microbes and fungi can't break it down.

This is true but I have to admit I despise the reductionism inherent in arguments for valuing forests in this way. There are so many important ecosystem services played by forests and "wildlife" that is missed when focusing solely on carbon sink capacity. Not to mention the rights of nature itself to exist.

We would be dealing with so many more diseases if it weren't for vultures, opossums, etc. Our soils would not have the capacity to hold top soil if it wasn't for the critical microclimates plant roots create for mycorrhizal fungi. Landslides, floods, and desertification would all simultaneously be more common. Biodiversity would plummet leading to even more fragile ecosystems. Rainfall would be reduced while flooding increases. Temperatures would rise and food systems of humans and more-than-humans would collapse.

I just think the carbon sink capacity of forests and grasslands are a minor point compared to everything else they do for us

Good point. I didn't mean to imply that carbon was the only value. The "services" provided by these ecosystems are incalculable.

The myopic focus on carbon is an easy trap to fall into; it's the quantifiable part of the system. In this world, that which gets measured gets managed.

I would hope we'd conserve these ecosystems because of a deeply-held spiritual connection to life. Or at least a realization of the value they provide to humanity by simply existing. But carbon remains the objective metric by which conservation interacts with the financial market.

(Author here) I've added the word "indoor" to the title, which will hopefully make it harder to miss that this is not about climate change or carbon sequestration.

As somebody who works on carbon dioxide removal at planetary scale, I was excited about your article about indoor air… but nearly every comment here seems to want to talk about the changing climate!

I don't want to stop anyone from debating the merits of using plants for carbon sequestration. But the ones explaining why my article did such a bad job of explaining those merits are kind of eye-opening, yes.

Same here, I wonder if there’s some missing conversation in the hacker news community about climate. Seems like some people really wanna talk about it even off topic.

I get to spend plenty of time working on climate already, so I was particularly interested in the indoor air pieces. Someone below suggested there’s a ventilation system alternative. I wonder what you could do with a little miniaturized direct air capture machine. Probably crazy energy inefficient and whatnot, but maybe a cool experiment.

Long ago I ordered an indoor algae system from a couple of CMU PhDs. It is very cool, it looks cool and has a nice water flow backgroundy sound, the algae grows quickly, allegedly doing the co2 consumption equivalent of 20 houseplants. Space efficient! But immaterial relative to human co2 production.

If it was circa 2010 I think I remember those guys. It was partly for people who wanted fresh algae smoothies? How big a tank do you need to remove 1 kg of CO2 per day…

Did you consider the alternative calculation of how many plants you need to grow to feed yourself? A few thousand potatoes growing simultaneously might do it.

That would overestimate the number you need to remove excess exhaled CO2, since you could throw out the parts you can't eat rather than letting them decay and release CO2 indoors.

It's an interesting article overall, but this assertion:

> Carbon dioxide is bad for cognition.

is dubious and unsupported by science. As I point out downthread, we have extensive experience with very high-CO2 environments-- at levels regularly exceeding ten or twenty times current atmospheric levels-- and as yet little good evidence of uncompensated cognitive effects.

Beyond that, modern humans live much of our lives in moderately elevated CO2 with no apparent ill effect. Without deliberate ventilation, any enclosed space like a bedroom or classroom will rapidly achieve elevated CO2 levels, often into the thousand ppm range. Again, we have lots of data, and little of it points to a practical cognitive effect.

The US Navy maintain an informal goal to keep levels on board submarines to below 8000 ppm, loosely informed by what little evidence they have of its effects on crew performance. That's twenty times the current atmospheric levels. In practice, CO2 levels often go over 10,000 ppm, which apparently still doesn't cause them much concern.

There's definitely quite a lot of scientific support, e.g. see this review paper: https://doi.org/10.1016/j.envint.2018.08.059

I'm open to the possibility that this is wrong, but as far as I can tell, the conventional scientific view is that high-CO2 environments are somewhat bad (although not catastrophic, even at 8000 ppm).

This looks like a good review, and it definitely pertains to your effort here. Although the authors play up the positivity of their conclusions a bit (which is useful if they want to continue the research), they are also honest about the limitations of the material they cite. Many positive correlations are cited, but nearly every paragraph is laden with caveats. Here are a few pulled at random:

> However, the relationship between CO2 concentrations and upper respiratory symptoms in this study was no longer statistically significant after adjusting for the number of people in the office

> A 100 ppm increase in CO2 concentration (range, 549–1318 ppm) was positively correlated with non-specific symptoms including headache and dizziness (107 participants from 11 oﬃces) although the correlation was not significant

> Several epidemiological studies indicate a relationship between low-level exposure to CO2 and BRSs. However, BRS is possibly inﬂuenced by other comorbid indoor pollutants, including artificial volatile organic compounds (VOCs) brought into buildings or occupant-generated pollutant

> CO2 concentration at 5000 ppm had no eﬀect on acute health symptoms (respiratory, visual and skin-related, headache, and sensory) and performance in cognitive tests (Zhang et al., 2016).

> the relationship between low-level exposure to CO2 and the reported symptoms remain inconsistent between studies

> A relationship between low-level exposure to CO2 and BRSs is therefore very complicated to prove and strength of the evidence is very limited.

My biggest issue with all of this is that we have a ton of data from very high-CO2 environments going back decades, and still very little clear evidence of negative effects. If high CO2 concentration imposes significant cognitive costs for which the human body cannot compensate after some period of time, it seems like that signal should have become clear by now.

I've withdrawn this claim, which I believe was overstated. Thank you for following up!

OK, so we can’t use plants.

What are the options, then?

In my apartment I’m running 2 AirGradients. One in the bedroom and one in the main room.

Awesome little devices, btw. They monitor temp, humidity, CO2, TVOC, and various particulate matter metrics. They expose prometheus metrics for scraping, and can be configured through a REST API to never phone home. I’ve got grafana alerts set up to push notifications to my phone when things get to “bad” ranges.

Anyway, the big issue is that the only way I’ve found to clear CO2 and TVOC is to open windows. However, windows open means increased humidity and particulate matter, even with air purifiers running aggressively. Also, opening windows at night kind of sucks for obvious reasons. In the summer it also sucks to lose that cool air.

I found these devices you put in your window, sort of like window fans, that can open/close airflow completely, but they don’t fit in my side-opening windows.

The only other thing I can think of is some kind of home automation with a little gadget that cracks the window until the metrics are back in an acceptable range. My AC unit unfortunately does not have a mode where it takes air from outside. I know some things like this exist for opening blinds, etc, but haven’t gone down that rabbit hole yet.

Anyone find a good way to solve this problem?

Challenging in an apartment setting, but the state of the art here is an Energy Recovery Ventilator (ERV) installed in your home to continuously refresh the air.

"Residential CO2 scrubber" seems like the sort of gadget eccentric rich people would buy, sort of a distributed DAC system.

Honestly this seems like a super long-shot but at least semi-plausible avenue for putting DAC on the sort of learning curve that took lithium batteries from "high-end camcorder" to utility-scale storage.

What does DAC stand for in this context? My brain is stuck on Digital-Analog Converter and I'm pretty sure we aren't talking about using those, but if so I'm even more fascinated by this discussion

I'm guessing: https://en.wikipedia.org/wiki/Direct_air_capture

That said, it seems intrinsically wrong-headed to me, a kind of trojan-horse technology for getting everyone else to spend money cleaning up the mess the polluter keeps spilling out into the commons.

Every dollar spent trying to extract low-concentration CO2 from ambient atmosphere is probably better-spent trying to grab it from a high-concentration source (e.g. exhaust, smokestacks) before it gets diluted.

NASA is working on it: https://www.nasa.gov/spacecraft-oxygen-recovery-scor/

If it wasn't an apartment and you could cut holes in the wall, I would say a ductless HRV.

I don't really understand this. First of all, you can just weigh the plant, and tell how much CO2 it has captured, right?

Second of all, what does it matter how much CO2 I produce? What's harmful is the additional CO2 that goes into the atmosphere for burning fossil fuels. All other CO2 is just in the same cycle that's been happening for ever.

EDIT: My child comment is dead and vouching doesn't resurrect it, but now the post makes sense, thanks for the clarification.

> what does it matter how much CO2 I produce

Because the author of the piece is worried about the CO2 levels in their home, not about global warming. (well maybe they are worried about global warming too, but that's not what this is about)

You can sequester carbon with plants, but you can't let them decay or it will release it back into the environment (it's called the "carbon cycle" of a reason).

A startup has solved this problem the following way (for example): grow microalgae near a very dry desert, and bury it in trenches. It never decays and thus never releases CO2 due to lack of water.

Basically, we'd have to permanently stick it back underground again.

To me, this is great that demonstrates how ridiculous carbon capture and storage is. I just can't imagine us paying to do something like this at scale, when we have a much more straightforward alternative: Stop burning fossil fuels, and use clean energy instead. Right? Like why even both going through the effort of carbon capture, when we're still going to have to stop burning fossil fuels anyways, in order to fix the climate?

We'll have to do both I imagine by the time we realize it's too late.

If you can find a way to get other people to stop burning carbon, let us know.

I know that sounds dismissive but I mean it. There's no magic wand.

Exactly. Getting other people to behave a certain way is different from a team going off and doing something, like marine cloud brightening to raise the Earth's albedo.

Think of it like a battery. We pour sunlight into the plant at one end and then we take this gasoline from the other side of the battery and burn it. The end-result is that we have full fuel cycle powered by the Sun.

This kind of battery is useful. All human hearts together produce about the same power in beating as a Falcon 9 in the final stage but you can't use hearts like that.

Carbon capture is already done at scale because CO2 is commercially valuable.

The proposed carbon storage is permanent in the form of carbonates. This is a variant of the Solvay process used to make washing powder.

Chalk cliffs were once the shells of sea creatures. That's a whole load of sequestered carbon right there.

I was under the impression that commercial CO₂ was produced by mining chalk.

Yes, lime kilns use the reverse process -- heating chalk to drive off the CO2.

Just popping in here to say that the IPCC has no model for a stable climate that doesn’t involve removing many billion tons of carbon dioxide alongside complete decarbonization, so unfortunately simply stopping emissions at this point isn’t enough. Some level of carbon dioxide removal is required to maintain a stable climate.

You don't necessarily have to bury the plants to sequester the carbon. A lot of oceanic carbon just sinks to the bottom and is eventually covered over, especially near estuaries that spew silt.

The BBC did this in their 2012 documentary mini-series "How to Grow a Planet" with Iain Stewart. It was a lovely series; I highly recommend it.

OK, this was fun.

But I think the real problem is that we’re pushing carbon into the atmosphere that has hitherto been sequestered for upwards of millions of years deep underground and under the oceans. I.e., nothing that’s been a part of a plant, or involved in any ecosystem, on the surface or underwater for a very long time.

Do we even have enough land on the planet to grow enough plants to sequester all this additional carbon? If we reforested the whole earth, would that be enough (and over what time period)? Can enough plants grow in the oceans without turning them all into a giant algal bloom?

I don’t know but I certainly would like to see the maths that answers those questions.

Or… you could go outside?

But the analysis rests on 0 ventilation, which doesn’t work at all.

I think the main thing to keep in mind is plants really aren’t industrial carbon sinks. They were never evolved to be. Their biological functions are about growing and thriving, and the soil they grow in are net carbon producers.

In a broad open system, they are net carbon sinks over the long term. But any analysis in a closed system is bound to fail, you don’t even need numbers to know intuitively this won’t work.

Crack open a window. Run a fan. Have plants because they have many benefits. Reducing CO2 around you meaningfully isn’t one of them.

Outside it's not much better it's 430 ppm. Supposedly that's not enough to impact cognition.

What if the plants were algae?

Here's a real world* example:

https://www.youtube.com/watch?v=AAbyUaLN2QA

*youtuber

I did some of the napkin math on algae a couple years ago... The fun realization is that the physical carbon has to go somewhere. So if we're trying to sequester the average american's 14 tons a year of carbon or whatever it is these days, that means you're going to have at least 14 tons of dead algae to deal with. (And a lot more weight if the algae isn't dehydrated.). That's a lot of dead algae, which demonstrates the difficulty of the problem...

In other news, have you considered ditching your car and becoming a vegetarian? Not emitting the carbon in the first place is much easier!

Related tangent: I recently bought an inexpensive consumer CO2 monitor for under $40. It confirmed my suspicion about air quality in my home office; after a few hours, levels rise above 1000ppm unless I leave a window partway open. Mid-afternoon mental fog cleared right up.

I find it especially a problem at night. Started out leaving the window open in the bedroom, but that lets in noise and wind. Current solution is leave the bedroom door open and have a window cracked open in another room. It seems to work out really well as measured by my CO2 monitor.

I mentioned this elsewhere here, but a friend told me that it’s not only CO2 that leads to that mental fog, but it’s also the VOCs in the air too. All that gets cleared out by having an open window.

Of course, do it with vats of plant cells in floating oceanic CO2 factories. Not in your living room.

Or, just let the oceans recover, let the mollusks return to the bays and shores, let them do their efficient thing.

This guy actually built an algae farm to test how much you need to breathe. https://youtu.be/AAbyUaLN2QA

The grow lights are only needed at night.

You can leverage a sunny window for free.

I would have liked a more how many plants can do it, rather than the its impossible route.

AI says a snake plant and spider plant can produce oxygen night & day. Now assume I live in a tiny hovel (kinda true) how many plants do I need for "net oxygen surplus" (?)

Apparently, AI says, high yield crops of say wheat under intense LEDs or Spirulina make for optimal oxygen producers.

So 15 m^2 of spirulina in an aquaponics garden with intense led fixtures to supplement natural light might do it.

I can’t find a single credential or scientific qualification of merit of the author and yet their commentary spans many topics, including cancer.

I’ll pass. The About page is not very helpful either. It says very little about the author except this:

> Like most people, I use AI “for research”, but I impose fairly strict limits to make sure I don’t use AI “for writing”.

I have had the same impulse to reduce CO2 to about half(Close to pre-industrial levels 200 to 280 ppm). Of course my first thought was CO2 scrubbing by chemical means, plants are obviously silly. But was convinced not to pursue given the fact that

1. Cognitive decline starts above 600 ppm according to air quality studies.

2. Levels below 200 ppm are actually dangerous.

> Cognitive decline starts above 600 ppm according to air quality studies.

According to an older, small study of short duration (Mendell and Fisk at LBNL), the results of which are heavily disputed. Since 600 ppm isn't too much higher than the current level of 400+ ppm, this study is the one most commonly cherry-picked in order to instill fear in people that climate change is getting ready to damage our brains.

Just for comparison, the CO2 composition of exhaled breath is around 40,000 ppm (~4%), which is the reason that it's totally normal for CO2 concentrations in enclosed spaces like bedrooms and classrooms to reach several thousand ppm. CO2 levels in submarines average well over ten times atmospheric, and routinely reach well over 10,000 ppm.

In none of these situations have researchers found a clear and convincing long-term impact on cognitive performance. Short term yes, but our bodies and brains adapt. Some compensations appear incomplete, but others are possibly sufficient to incur health benefits from high CO2 concentrations. Notably, high CO2 levels cause blood vessels to dilate, increasing the flow of oxygen to tissues including the brain. There is in fact ongoing research into medical therapies using concentrated CO2.

As far as I am aware astronauts that were experiencing concentrations above 3000 ppm for presumably weeks to months reported mental viscosity(brain fog) and headaches.

A definite global health concern is the increase in blood bicarbonate levels which chronically impact available calcium and phosphorus levels.

Additionally the higher CO2 levels increase plant growth which impacts the plants mineral absorption, there are less naturally occurring micronutrients in our crops than there used to be just 20 years ago.

These things are far from apocalyptic but have to be taken into account going forward when updating existing food enrichment programs.

I believe you are conflating hyperbaric oxygen treatment with CO2. I could not find references to concentrated CO2 treatments. While exhaled air is about 4% CO2, breathing air with CO2 at these concentrations is immediately dangerous.

Additionally I do not believe that has been any study comparing relative cognitive performance of continuously operating in different low concentration environments, all studies focus on short term, high concentrations and for obvious practical reasons treat the atmospheric level as the baseline.

As far as we know operating in pre-industrial levels of CO2 280ppm improves, deteriorates or has no effect on cognition compared to modern levels.

> astronauts... reported mental viscosity(brain fog) and headaches

I can think of plenty of excellent reasons the environment in the space station would lead to physiological issues. Sleep disturbance, stress, restrictions on diet and exercise, and the many severe effects of microgravity all come to mind. Again, you have to ignore humanity's extensive experience with other high-CO2 environments like submarines in order to believe that it's a significant factor compared to those other stressors.

> A definite global health concern is the increase in blood bicarbonate levels

It's hardy definite. It's another junk-science "study" out of Australia that took two epidemiological trends (bicarbonate level and mineral levels in blood over 20 years) and tried to interpret correlation as causation. You can use this kind of data-dredging to propose correlation between all kinds of unrelated trends. I'm seeing headlines blaming climate change for the obesity epidemic, for example, and you can be sure there's a junk science study behind every headline. In this case, I'm aware of no evidence from well-controlled studies (i.e., actual science) showing a causal chain from moderately elevated CO2 to physiological mineral deficiencies in real life. Again, we have lots of long-term data from high-CO2 environments like submarines. Show me some numbers.

> higher CO2 levels increase plant growth which impacts the plants mineral absorption, there are less naturally occurring micronutrients in our crops than there used to be just 20 years ago.

More questionable headline-generating studies. Yes, isolated increases in CO2 can cause carbohydrate dilution and subsequent changes in water usage and mineral uptake, but it also universally increases plant growth, and in many plants it increases production of other phytochemical nutrients. This is an extremely complex topic, and it's reductive to the point of absurdity to blame atmospheric CO2 for trends that are overwhelmingly influenced by soil depletion, water usage, and chemical fertilization.

Think about this logically: A substantial portion of our fruits and vegetables are grown in greenhouses. In the Netherlands-- the world's second-largest food exporter-- over one-fifth of produce is grown in greenhouses. Almost all modern greenhouses employ carbon dioxide enrichment, typically doubling the level of the atmosphere. If there's a brewing crisis of CO2-induced nutrient deficiency, don't you think the climate alarmists would be warning us about greenhouses? The fact that they aren't should tell you something.

It's common for people to filter on the latest fear-mongering headlines. Maybe these things are true, but "studies" like these that appear in corporate media headlines can't tell us one way or the other.

> I could not find references to concentrated CO2 treatments

It's a young field of research to be sure, but it took me about five seconds to find a bunch of recent papers. Here's the first result google gave me:

https://pmc.ncbi.nlm.nih.gov/articles/PMC11763298/ | Effects of Carbon Dioxide Therapy on Skin Wound Healing

I am noticing a pattern where studies are dismissed as junk based on preformed opinions, specifically about "climate alarmists" you should consider why you are so quick to dismiss the majority of the research in indoor air quality.

There is one notable study about submariners that did not find impairment in one simulation, the consensus about it is selection bias and training. Submariners are not the average population, both in terms of general fitness and in terms of self selecting, people who can't cope or perform in the high CO2 environment quit or fail. The finding of other studies is brain fog not total incompetence.

> https://pmc.ncbi.nlm.nih.gov/articles/PMC11763298/ | Effects of Carbon Dioxide Therapy on Skin Wound Healing

That's cool, a bit of nuance though the studies are discussing applying CO2 directly at afflicted tissue not through breathing.

No, I pointed out specific flaws in those papers. You're just pretending that I'm dismissing them out of hand so you don't have to read them yourself.

Once again, the Australian study that's the source of your original assertion was very small (n=4 in each study group) and very short term (only a few hours of study time). And the paper about bicarbonate levels is a great example of data dredging, where coincident trends are implied to be causative with no further support.

I'm not saying the conclusions are wrong. They could both be right. I'm just saying that their methods are too poor to draw any useful conclusions.

> people who can't cope or perform in the high CO2 environment quit or fail

So here you are dismissing evidence out of hand by pretending not to understand it. Even if submariners are selected based on CO2 tolerance (which is silly), it wouldn't matter. The point is that the US Navy has had a large population to study for long periods of time in highly controlled environments. The same men can be examined before, during, and after exposure to very high concentrations of CO2, while other environmental variables are held constant, and the navies of multiple countries have data from many such populations over decades. That's what produces useful data, in contrast to that tiny, short Australian study you seem to be attached to.

Bamboo it is.

> Real plants do photosynthesis through a physical process

(nit) it is more accurate to call this a biological process, or chemical process

Saying "physical process" makes me think of inclined planes, free-body diagrams, and EM fields.

It's all physics at the bottom. Nature doesn't have APIs.

Yes, except parent is correct. Physcial and chemical mean very different and specific things in this context.

Calling photosynthesis a physical reaction is flatly incorrect no matter how you want to look at it. It is a physics reaction, sure, but "physical reaction" specifically means a Newtonian mechanical, reversible process at the macro scale.

A "chemical reaction" specifically means a (trivially) irreversible quantum/atomic reaction involving chemical bonds at the atomic/molecular scale.

> but "physical reaction" specifically means a Newtonian mechanical, reversible process at the macro scale.

Or friction.

Ok yeah, that’s fair. I missed the distinction.

The vast interior of the world's oceans are a nutrient desert. It has been proposed to grow algae by spreading silt, the same way that Saharan winds do.

I’ve always wanted to jam on how to create an indoor carbon dioxide removal system. (I think that’s what this article is about but perhaps it’s indirectly about the changing climate)

1 kg per day of material adds up fast but that assumes zero ventilation. If I simply wanted a system to keep my office below 500 ppm all day, I wonder how much material that would produce.

Anyone ever build a little carbon dioxide zapping system for indoor air quality? I’ve also heard that indoor CO2 isn’t actually all that bad but it’s VOCs that are what make me feel sluggish.

I think what you really want is an Energy Recovery Ventilator. It cycles in fresh air and uses an intercooler to limit the heat and humidity loss.

That’s cool. Is that something that you’ve built or installed?

Even if that is a better solution, I am personally curious about an indoor carbon dioxide zapper, since what I work on is carbon dioxide removal at planetary scale.

I haven't installed one yet, but plan to in my house. I'll probably end up buying an assembly, but they seem pretty spendy for what is really a very cheap BOM.

4.6 kg is easily dwarfed by just one of the trees on my lot.

I do like the math though. Gonna be very useful for space colonization

Or you make like old times and use the sun: build sky windows, green houses and indoor winter gardens.

I figure answers to these questions are probably available online. Why discuss them here specifically?

Always seemed like algae or cyanobacteria are the only real nature based options that could be scaled up.

How is it that 132.5 watts is 3 light bulbs but 918 watts is 765 light bulbs? Is there a typo?

It might not be clearly worded, but 132.5 watts is the power used by 2 incandescent light bulbs, whereas 918 watts is the power present in the light produced by 765 light bulbs. The factor of 50 comes from the fact that incandescent lightbulbs are only ~2% efficient at turning power into light.

That one final number is all one needs as a reply for "but they help a little".

Get an HRV/ERV if you can't open a window.

Another way of looking at this is that--while it doesn't have to be edible--you have to grow plant matter inside your house at a rate equivalent to what everyone in there consumes as food.

Even if you found like an algae or something that converted CO2, light, and water into fat, 2400 kCal would be ~300g per person, per day, or not too short of a normal package of butter.

no, we are useing solar PV to eliminate the excess carbon bieng added to the atmosphere, and plants, rocks, and many other natural processes will return CO² levels to a more moderate level.

Getting CO2 back to preindustrial levels by natural processes may take 100,000 years, IIRC. There will be some drawdown, but the ocean surface waters will become more saturated with carbon and that will stall. Over a longer time scale, CO2 will be pumped down into the deeper ocean. The true drawdown will require mineralization and precipitation as calcium carbonate, a slow process. The fossil fuel CO2 emitted each year corresponds to the calcium added to the ocean by erosion over about 100 years.

Article is not about global atmospheric or climate phenomena, nor civilization scale industrial processes. It's about the CO^2 levels in your room due to your breathing.

oh no!

realy?

but since I live in a drafty farmhouse up on a windy hill beside the ocean, my room air and the atmosphere as whole have very similar compositions, and I will continue to treat conversations about both, the same as well.

> plants, rocks, and many other natural processes will return CO² levels to a more moderate level.

No... How can you be this delusional? This is cult like behavior: something will fix it somehow, eventually, don't ask about details

This seems trivial: if you could add enough plants to your room to reduce CO2, we could easily do the same thing at planet-scale and global warming wouldn't be an issue.

Sadly I am a bit hopeless about climate change. Even if every person on earth dropped everything and started making biochar to be buried it would not sequester enough carbon to make a difference.

It's going to be ok.

This article isn't about climate change. It's about using houseplants to absorb the CO2 you exhale in your house.

Hi! I work a lot with carbon dioxide removal systems. If every person on Earth dropped everything and started making biochar, it would definitely make a huge difference. Yes, we add a lot of carbon dioxide to the air of a year, but it’s doable to remove it. Humanity has taken on much bigger challenges before and succeeded. Now that’s not to say that it’s likely. I think it’s entirely unlikely that we avert the worst impacts of climate change unless something big changes. Thankfully, we get to choose what to work on every day, and I get to choose to work on that alongside inspiring people. (and yes, this isn’t what the article is about, but it seems like it’s what everyone is responding to)

> Humanity has taken on much bigger challenges before and succeeded.

Feel free to list them, we're basically reverse terra forming ourselves out of existence at that point, I don't think we've done anything even remotely close to that scale in such time frame

During World War II, the United States spent 40% of its GDP on the war. So we can spend big on things when we decide to.

That would be the equivalent of $12 trillion per year today, and we would clean up the climate in a jiffy with that. It would be a huge opportunity for job creation, manufacturing, innovation. It’s wild as a society we’ve convinced ourselves that stabilizing the climate is a cost instead of a massive opportunity.

> During World War II, the United States spent 40% of its GDP on the war. So we can spend big on things when we decide to.

The United States wasn’t the only one spending that much on war, that’s why we were able to do so. What incentive do countries have to spend money on carbon capture? Any money spent on that is money not being invested in generating more wealth, so there is zero incentive to move first, you’ll just fall behind and become economically and potentially physically vulnerable.

If we could convince all major powers to all spend money on carbon capture, it would work great. That’s a simple ask but an almost impossible thing to negotiate.

Otherwise, there’s no incentive to act first, there’s actually great incentive to not act first.

I desperately wish the world could work together on this problem, but I don’t see why we would given the situation.

Agreed! My point is that it’s possible financially, but yes the incentives are messy.

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