Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Scripps O2 Global Oxygen Measurements

scrippso2.ucsd.edu

Post reply on HN
Print view View original

11–20 of 27 posts

Re: Scripps O2 Global Oxygen Measurements

#11

Post by ccn0p »

cgugino wrote: post #7
leptoniscool wrote: post #5

Earlier quoted context omitted.

That's a 0.0019% decrease, not very significant is it?

Not today, but the trend is worrying, especially if the rate increases. What will this look like in 50 years? 1,000?

am i missing something? this is right in the FAQ:

``` Should we be concerned that the atmospheric oxygen supply is declining?

This point was addressed in an article by Broecker (Science, Vol. 168, 1537-1538, 1970). Although written many years ago, the basic point made by the article remains valid. The maximum potential loss of O2 from fuel burning, when fossil fuel reserves (mostly coal) are exhausted is only a few percent of the atmospheric burden. Since even this loss will take many centuries to materialize, it's hard to see this as high on the list of possible environmental concerns. ```

Re: Scripps O2 Global Oxygen Measurements

#12

Post by noduerme »

CameronNemo wrote: post #4
mmastrac wrote: post #3

Losing O2 isn't a huge deal as humans - it's the outsized effect of replacing O2 with CO2. O2 is 20% of the air, N2 is 78%. CO2 lives in that last little bit and, given its miniscule contribution to composition, has a far outsized effect.

Losing O2 has an effect on cognition.

TIL that pulse oxymeters can read over 95% in the presence of carbon monoxide poisoning.

https://pubmed.ncbi.nlm.nih.gov/8037391/

Re: Scripps O2 Global Oxygen Measurements

#13

Post by kadoban »

CameronNemo wrote: post #4
mmastrac wrote: post #3

Losing O2 isn't a huge deal as humans - it's the outsized effect of replacing O2 with CO2. O2 is 20% of the air, N2 is 78%. CO2 lives in that last little bit and, given its miniscule contribution to composition, has a far outsized effect.

Losing O2 has an effect on cognition.

This amount? I really doubt it.

Re: Scripps O2 Global Oxygen Measurements

#14

Post by ljf »

booi wrote: post #10
bioinformatics wrote: post #9

Earlier quoted context omitted.

50 * 0.0019% = 0.00095 1000 * 0.0019% = 1.9%

Previous commenter said if the loss accelerates. Larger and larger changes each year would be more than worrisome.

I agree, we should consider that further oxygen loss could come from long burning wild fires etc, should the environment lend itself to a higher propensity to them. This could both burn oxygen and remove plants that would therefore not create and replace oxygen (in the short terms at least).

I am sure there are some weird feedback loops we are going to see in the next century or two, that aren't yet considered an issue.

Re: Scripps O2 Global Oxygen Measurements

#16

Post by caymanjim »

People have a lot of misconceptions about atmospheric oxygen. There is a lot of it. If every photosynthetic organism on the planet died, it would still take tens of thousands of years before we had to worry about an appreciable reduction in breathable oxygen levels. We're not going to run out of it unless literally every oxygen-producing organism on the planet dies (trees don't even matter; they could all die and we'd be fine forever). If all plants and phytoplankton die, we'll starve to death and won't have to worry about oxygen levels.

Re: Scripps O2 Global Oxygen Measurements

#17

Post by slavik81 »

noduerme wrote: post #12
CameronNemo wrote: post #4

Earlier quoted context omitted.

Losing O2 has an effect on cognition.

TIL that pulse oxymeters can read over 95% in the presence of carbon monoxide poisoning. https://pubmed.ncbi.nlm.nih.gov/8037391/

However, the point of that study is that the oxygen levels are not 95%. The pulse oxymeter is wrong, and that study is about determining how wrong it is.

The abstract basically says you can subtract the blood carbon monoxide level from the pulse oxymeter's reported blood oxygen level to find the actual blood oxygen level. (They were a bit more precise than that, but it was very nearly one-to-one.)

A pulse oxymeter measures oxygen levels indirectly. It works by checking the colour of your blood. I suppose that the colour of carbon-monoxide poisoned blood must be similar to that of oxygenated blood. Perhaps because carbon monoxide attaches to blood cells in a similar way to pure oxygen.

Re: Scripps O2 Global Oxygen Measurements

#18

Post by noduerme »

slavik81 wrote: post #17
noduerme wrote: post #12

Earlier quoted context omitted.

TIL that pulse oxymeters can read over 95% in the presence of carbon monoxide poisoning. https://pubmed.ncbi.nlm.nih.gov/8037391/

However, the point of that study is that the oxygen levels are not 95%. The pulse oxymeter is wrong, and that study is about determining how wrong it is. The abstract basically says you can subtract the blood carbon monoxide level from the pulse oxymeter's reported blood oxygen level to find the actual blood oxygen level. (They were a bit more precise than that, but it was very nearly one-to-one.) A pulse oxymeter me…

Right - I get it. It can read over 95% in the absence of oxygen if carboxyhemoglobin tricks it out. I thought this might explain why during the pandemic, I could get a pulse ox reading of 85%, then smoke a cigarette and make the little bastard stop beeping.

Re: Scripps O2 Global Oxygen Measurements

#19

Post by beowulfey »

slavik81 wrote: post #17
noduerme wrote: post #12

Earlier quoted context omitted.

TIL that pulse oxymeters can read over 95% in the presence of carbon monoxide poisoning. https://pubmed.ncbi.nlm.nih.gov/8037391/

However, the point of that study is that the oxygen levels are not 95%. The pulse oxymeter is wrong, and that study is about determining how wrong it is. The abstract basically says you can subtract the blood carbon monoxide level from the pulse oxymeter's reported blood oxygen level to find the actual blood oxygen level. (They were a bit more precise than that, but it was very nearly one-to-one.) A pulse oxymeter me…

Yes this is correct. Heme binds to CO in the same way it binds to O2–the iron is oxidized and has the same color.

This is also the source of carbon monoxide toxicity, as it binds to CO tighter than O2.

Re: Scripps O2 Global Oxygen Measurements

#20

Post by roenxi »

booi wrote: post #10
bioinformatics wrote: post #9

Earlier quoted context omitted.

50 * 0.0019% = 0.00095 1000 * 0.0019% = 1.9%

Previous commenter said if the loss accelerates. Larger and larger changes each year would be more than worrisome.

We're quite likely to start running out of fossil fuels in the next few decades. It is unlikely that the loss will accelerate.
Post reply on HN