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Comment by philwelch | Hacker News Reader

> Co2 levels and its impact on our cognitive capacity

This is junk science.

The CO2 level of the open atmosphere is ~400 ppm. The CO2 level aboard a nuclear submarine can range between ~2000-10000 ppm. 10000 ppm is enough to cause sleep disturbances and headaches, and we're less sure about the range between 5000-10000, but we're talking orders of magnitude away before we start seeing issues among people who engage in cognitively challenging work on a daily basis. The CO2 levels aboard the ISS are usually a bit lower--they try to keep it under 5000 ppm--but the astronauts there are even more closely monitored for medical issues and also have to perform cognitively challenging work. These are over extended periods of time between 3-9 months.

If the CO2 concentration of the Earth's atmosphere went up 10x, you'd have much bigger problems than the cognitive effects of CO2 exposure.

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You'll notice CO2 levels at 1000 ppm. The air will feel "stuffy," you'll feel lethargic, and feel like going outside. This is the primary reason why meetings at work are so stultifying. There's just too much CO2 in the room for anyone to think clearly. Just carry a CO2 meter around and measure it yourself. Once you're aware of it, the feeling is impossible to miss.

If the CO2 level of the atmosphere doubles, we are still going to have bigger problems to solve.

> Just carry a CO2 meter around and measure it yourself. Once you're aware of it, the feeling is impossible to miss.

Sounds like a combination of confirmation bias and psychosomatic placebo effect to me. Plus you’re assuming a specific correlation between subjective minor discomfort and cognitive performance.

I would posit that the level of CO2 you need to cause detectable society wide problems is probably lower than the level that makes a room actively uncomfortable to be in.

There's a reason why we already have universal colloquial language to describe a room with too much CO2, "stuffy," "getting some fresh air to clear your head." We all know this stuff intuitively, we've experienced it directly our whole lives.

You can posit whatever you like, but I don't see any evidence.

Edit to reply to ninja edit:

> There's a reason why we already have universal colloquial language to describe a room with too much CO2, "stuffy" "getting some fresh air to clear your head." We all know this stuff intuitively, we've experienced it directly our whole lives.

First off, you're going back to the perception of minor discomfort to defend the claim that CO2 levels that aren't even high enough to cause minor discomfort are high enough to cause "detectable society wide problems". This strikes me as incoherent and evasive. Secondly, you're assuming that the minor discomfort of being in a "stuffy" room is entirely caused by CO2 concentration. (In my personal experience, body and food odors are the main sources of discomfort when I'm in a poorly ventilated space.) And thirdly, you're assuming that this discomfort necessarily causes poor cognitive performance.

CO2 will be elevated in a stuffy room, but that's not actually what you're noticing. It's humidity and VOCs.

If CO2 was actually high enough to be a problem, the first symptoms would be an increase in heart rate and rate of respiration. Kinda the opposite of lethargy.

No, it really isn't. Plant conservatories never feel stuffy even though the humidity is high, and the same room with fewer people in it doesn't feel stuffy either.

I am very interested in this because there appear to be studies with conflicting conclusions (e.g., https://ehp.niehs.nih.gov/doi/10.1289/ehp.1510037 says 1,000 ppm causes cognitive decline). This has made me want to run some experiments.

> there appear to be studies with conflicting conclusions

So far, conflicting conclusions are more common throughout much of recent climate science than any of us like. The basic lab bench physics behind CO2 is obviously very well-understood but long-term global climate (as opposed to regional, seasonal weather) is a 'wickedly' hard problem.

Modeling future global climate shifts over years and decades is hard because Earth's climate is a highly-complex, dynamically coupled system with thousands of interacting variables and possible feedbacks. Then extrapolating the output of those models to estimate significant changes to health, agriculture and extreme weather event severity and frequency requires making assumptions which are not nearly as well-understood. Then trying to adapt those estimates to further estimate the relative benefits, costs and impacts of myriad regulatory, economic and behavioral policy proposals is the kind of thing which would cause my favorite stats prof to say "It's fine... that's why god made error bars".

That is a good argument for discontinuing putting more carbon into the atmosphere until we understand it better.

Even doubling would already have an impact. The fact that astronauts can operate a few weeks in extreme conditions doesn't prove anything. I'm not talking about top of the line engineers/scientists working at 70% capacity for a few weeks, I'm talking about long term human scale average decline of cognitive capacity which would get worse over generations

We see no slowing down in the rate of co2 production and according to many studies we might reach 1000ppm or more by the end of the century.

Anyways, I'm not saying each of these are the end of humanity, I'm just saying that "it's going to be 2c more so whatever" isn't the whole picture

> The fact that astronauts can operate a few weeks in extreme conditions doesn't prove anything.

Astronauts stay on the ISS for six months at a time, not “a few weeks”.

What is 6 months on a human evolution scale? Not much

What does evolution have to do with any of this?

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