5 ms·

> 250-400ppm Normal background concentration in outdoor ambient air So we’d expect this site to be nearer 250 given its ideal location away from humans and ind

> 250-400ppm Normal background concentration in outdoor ambient air So we’d expect this site to be nearer 250 given its ideal location away from humans and industry?

twobitshifter 5y ago
Since it’s located on a barren volcano at a high altitude I would say there is less oxygen in the air than at sea level. The air there should also be less affected by nearby emissions. They also have stats on the ratio of O2 to N2, which has been falling over the same period. People argue that plants will produce more oxygen to make up for the new CO2 in the air, but here we see that combustion is winning out. https://gml.noaa.gov/obop/mlo/programs/coop/scripps/o2/o2.html https://gml.noaa.gov/obop/mlo/programs/coop/scripps/o2/o2.ht...
- CraigJPerry 5y ago
  CO2 ppm should reduce with altitude though right? E.g. if we saw 250ppm at sea level, we’d expect to see around 3% reduction in ppm counts per 1000 ft altitude. This observatory is at 11,000ft so we’d expect 250ppm sea level to give us 82ppm not >400
  - lutorm 5y ago
    No, the "parts" in ppm reduce, but the "millions" does, too. It's a ratio. (There might be a tiny effect due to the fact that CO2 is heavier than air, so as you go up you might expect the CO2 to mostly have settled against the bottom of the atmosphere. I suspect as long as you're in the troposphere, there's sufficient mixing to make it uniform, though.)
    - CraigJPerry 5y ago
      Yeah you’re right https://www.researchgate.net/figure/In-situ-CO2-concentrations-versus-altitude-measured-by-the-DOE-Cessna-aircraft-with-an_fig12_227619523 https://www.researchgate.net/figure/In-situ-CO2-concentratio...
    - mturmon 5y ago
      This is correct. CO2 is well-mixed, both laterally and vertically. Mauna Loa observatory is at about 4200 meters, or 0.6 atmospheres. At that atmospheric height, CO2 should generally be within ~10ppm of the concentration anywhere above the atmospheric boundary layer (BL). Below the BL, CO2 can be trapped by topography or temperature inversions, or in general, not be as well-mixed vertically. The height of the BL varies with time and location but generally that's a few hundred meters. Well above 0.6 atmospheres -- say, 0.2 atmospheres, or > 12km up -- the CO2 concentration in ppm can decrease noticeably more.
dmurray 5y ago
The ground there sporadically goes on fire, completely naturally. So it might not be an "ideal" location for atmospheric purity.
sbierwagen 5y ago
Mauna Loa has never recorded co2 as low as 250ppm. Started at 315ppm in the 50s: https://www.noaa.gov/sites/default/files/legacy/image/2019/Jun/co2_data_mlo.jpg https://www.noaa.gov/sites/default/files/legacy/image/2019/J...
- koheripbal 5y ago
  I have a CO2 monitor, and with all the windows open the range is ~400-430. There is very little variation globally. 250 is not a reading you can find anywhere on earth anymore. CO2 diffuses very very quickly so global readings are very close to the global average.
Buttons840 5y ago
CO2 levels vary by season, lowest in spring, highest in fall. Cause plants breath it in during sprint and exhale it out in fall (I don't remember if this is correct, or just my own misguided idea).
- nwallin 5y ago
  > CO2 levels vary by season, lowest in spring, highest in fall. Read the article. Look at the chart. The seasonal fluctuations are much, much less significant than the rising trend. > Cause plants breath it in during sprint and exhale it out in fall (I don't remember if this is correct, or just my own misguided idea). Plants absorb CO2 to grow, making leaves, branches, plant material and whatnot. In the fall, leaves fall off trees, grasses die, and are metabolized by fungi and bacteria, releasing CO2.
  - Buttons840 5y ago
    I don't know why were speaking as though we disagree about something. I agree with everything you said. I have my own CO2 meter inside, which I watch with some curiosity. I've observed that CO2 levels vary far more where my sensor is located, inside in an urban environment, and I was surprised to see that the CO2 levels are so steady elsewhere. [1] measured CO2 levels in an outdoor urban environments and found that sometimes the CO2 levels were about 20 times what they were at other times, 16 units vs 0.8 units. I say this as a curious observation, not as an attempt to argue against anything you said. [1] http://www.co2science.org/subject/u/summaries/urbanco2dome.php http://www.co2science.org/subject/u/summaries/urbanco2dome.p...

> 250-400ppm Normal background concentration in outdoor ambient air So we’d expect this site to be nearer 250 given its ideal location away from humans and industry?

twobitshifter 5y ago

Since it’s located on a barren volcano at a high altitude I would say there is less oxygen in the air than at sea level. The air there should also be less affected by nearby emissions. They also have stats on the ratio of O2 to N2, which has been falling over the same period. People argue that plants will produce more oxygen to make up for the new CO2 in the air, but here we see that combustion is winning out. https://gml.noaa.gov/obop/mlo/programs/coop/scripps/o2/o2.html https://gml.noaa.gov/obop/mlo/programs/coop/scripps/o2/o2.ht...

CraigJPerry 5y ago
CO2 ppm should reduce with altitude though right? E.g. if we saw 250ppm at sea level, we’d expect to see around 3% reduction in ppm counts per 1000 ft altitude. This observatory is at 11,000ft so we’d expect 250ppm sea level to give us 82ppm not >400
- lutorm 5y ago
  No, the "parts" in ppm reduce, but the "millions" does, too. It's a ratio. (There might be a tiny effect due to the fact that CO2 is heavier than air, so as you go up you might expect the CO2 to mostly have settled against the bottom of the atmosphere. I suspect as long as you're in the troposphere, there's sufficient mixing to make it uniform, though.)
  - CraigJPerry 5y ago
    Yeah you’re right https://www.researchgate.net/figure/In-situ-CO2-concentrations-versus-altitude-measured-by-the-DOE-Cessna-aircraft-with-an_fig12_227619523 https://www.researchgate.net/figure/In-situ-CO2-concentratio...
  - mturmon 5y ago
    This is correct. CO2 is well-mixed, both laterally and vertically. Mauna Loa observatory is at about 4200 meters, or 0.6 atmospheres. At that atmospheric height, CO2 should generally be within ~10ppm of the concentration anywhere above the atmospheric boundary layer (BL). Below the BL, CO2 can be trapped by topography or temperature inversions, or in general, not be as well-mixed vertically. The height of the BL varies with time and location but generally that's a few hundred meters. Well above 0.6 atmospheres -- say, 0.2 atmospheres, or > 12km up -- the CO2 concentration in ppm can decrease noticeably more.

dmurray 5y ago

The ground there sporadically goes on fire, completely naturally. So it might not be an "ideal" location for atmospheric purity.

sbierwagen 5y ago

Mauna Loa has never recorded co2 as low as 250ppm. Started at 315ppm in the 50s: https://www.noaa.gov/sites/default/files/legacy/image/2019/Jun/co2_data_mlo.jpg https://www.noaa.gov/sites/default/files/legacy/image/2019/J...

koheripbal 5y ago
I have a CO2 monitor, and with all the windows open the range is ~400-430. There is very little variation globally. 250 is not a reading you can find anywhere on earth anymore. CO2 diffuses very very quickly so global readings are very close to the global average.

Buttons840 5y ago

CO2 levels vary by season, lowest in spring, highest in fall. Cause plants breath it in during sprint and exhale it out in fall (I don't remember if this is correct, or just my own misguided idea).

nwallin 5y ago
> CO2 levels vary by season, lowest in spring, highest in fall. Read the article. Look at the chart. The seasonal fluctuations are much, much less significant than the rising trend. > Cause plants breath it in during sprint and exhale it out in fall (I don't remember if this is correct, or just my own misguided idea). Plants absorb CO2 to grow, making leaves, branches, plant material and whatnot. In the fall, leaves fall off trees, grasses die, and are metabolized by fungi and bacteria, releasing CO2.
- Buttons840 5y ago
  I don't know why were speaking as though we disagree about something. I agree with everything you said. I have my own CO2 meter inside, which I watch with some curiosity. I've observed that CO2 levels vary far more where my sensor is located, inside in an urban environment, and I was surprised to see that the CO2 levels are so steady elsewhere. [1] measured CO2 levels in an outdoor urban environments and found that sometimes the CO2 levels were about 20 times what they were at other times, 16 units vs 0.8 units. I say this as a curious observation, not as an attempt to argue against anything you said. [1] http://www.co2science.org/subject/u/summaries/urbanco2dome.php http://www.co2science.org/subject/u/summaries/urbanco2dome.p...