What about oxygen levels?

[LRC1962]

A question has come to mind. Statement of facts. CO2 levels rising at alarming rates. Forests and plant growing areas getting lost at alarming rates (although saw one argument that hey wouldn't count anyway as they are basically carbon neutral as very little gets buried. Oxygen producing ocean plankton down by alarming rates usually blamed on acidification. The higher pollutants count gets in the atmosphere the more oxygen needed for body to counteract the effects. Given all that what are the actual oxygen levels, how fast are they failing and at what point do things get to be a health hazard to humans?
By doing a search oxygen has come up on occasion, but usually in context of a consequence of a previous statement, or an one off observation, and not as a line of inquiry. This is by no meas a scientific study and probably pathetic at best, but is an attempt at showing our grand CO2 experiment maybe has other very dangerous implications to us as individuals.
I have found a variety of articles that deal somewhat with the problem, but it seems to be a subject that is not studied that much, very difficult to get good numbers historically and generally am left with the impression that It is something that after the advent of photosynthesizing critters has always been there and always will be. Not only that is that in different places I saw they talked in terms of PPM, % , showing a decline but starting point was 0.
Maybe it is nothing to be worried about, but still think it would have some relevance in todays world.
In no particular order, but giving some indication as to subject.
With forest resources--"the lungs of the Earth"-- under attack in many regions, some have raised concerns about the planet's oxygen supply. A leading geochemist assesses these claims and finds that we can probably breathe easy, this does not talk at all about deletion of ocean lungs.
O2 Dropping Faster than CO2 Rising
Scripps O2 Global Oxygen Measurements.

The changes are too small to have an impact on human health, but are of interest to the study of climate change and carbon dioxide.

Statement maybe true at this point, but as we has no reference points to look at historically, we do not have a good idea where we have fallen fron and how fast it is happening. Wikipedia does have a chart, but that was debunked as its main source was based on bubbles trapped in amber. The problem came when it was found amber exchanges the gas in the bubble with outside air every 1,000 yrs or so.
Acid Seas Threaten Creatures That Supply Half the World's Oxygen
Smothered oceans: Extreme oxygen loss in oceans accompanied past global climate change
Full research article.
Paleoceanographic Insights on Recent Oxygen Minimum Zone Expansion: Lessons for Modern Oceanography
Ocean’s most oxygen-deprived zones to shrink under climate change Issue I have is that you can not necessarily extrapolate conclusion to the whole ocean as you can with acidification on shelled creatures.
On a different problem and I will not vouch for accuracy Why are Millions of Sea Creatures Dying off the Pacific Coast Fukushima seems to be have major consequences and from everything I have gathered their troubles are getting much worse as time goes on and not better. Another experiment that could have long ranging impacts on a lot of the earth. One warning as what is occurring on several news sites now, those sliding popups are a major pain.
Granted this has no direct bearing on arctic sea ice, I see it as another consequence of CO2 rising which does have a direct impact on sea ice.

[pikaia]

For every 1 ppm that CO2 increases, oxygen decreases by 1 ppm. But the atmosphere contains 210,000 ppm of oxygen, so a change of even 1000 ppm of CO2 would have a negligible effect on oxygen levels.

[crandles]

Oxygen at 20.946% of air and declining at 19 'per meg'.

This corresponds to losing 19 O2 molecules out of every 1 million O2

That seems to be about 4ppm of the atmosphere around twice as fast as CO2 is increasing. I didn't realise it was that much faster than CO2 is rising but it is still blamed on fossel fuel burning. I can imagine some extra nitrogen, sulphur ... being oxidized by ff burning but twice as fast seems quite high. Maybe something else is going on?

Anyway 1000 years of oxygen declining by 4ppm would reduce O2 to 20.548% of air. This is about 98.1% of current levels. I make this as about equivalent to living at 154m above sea level rather than at sea level. Highest village is at 3.6km above sea level; certainly does have problems now let alone with that much reduction of oxygen. Fossil fuel burning is unlikely to continue for 1000 years, so I am not inclined to see it as a major problem - rate is such that evolution may be able to keep up and/or loss of use of land above 3.5km high at a very slow rate is not a huge loss of useful land i.e. not at all like large number of cities at 1m above sea level worrying about sea level rise.

[folke_kelm]

If you count molecules, you have to consider tat burning oil is not burning coal, and burning coal is not only burning carbon either.
Burning oil is burning carbohydrates, Methane CH4 is consuming exactly2 molecules of oxygen for one atome carbon.
So, nothing strange with oxygen decreasing faster than CO2 climbs.
Then consider that roughly half of the CO2 is absorbed by the ocean, so, now it is strage that Oxygen is not declinig faster ;-)

[wili]

The oxygen reservoir is enormous.

Not that we shouldn't care that we are drawing it down.

But even if all photosynthesis stopped and we continued burning ffs at current or higher rates, it would take thousands of years to use up all the O2.

So, not the most immediate threat, but not, imho, something to completely dismiss either.

[nicibiene]

Just had a view in IPCC 2013 and found a plot regarding negative O2 developement. Pretty steep downwards curve...

If someone is interested-original plots and original datas are to find here:
http://scrippso2.ucsd.edu/plots

[gerontocrat]

Wikipedia:- Diatomic oxygen gas constitutes 20.8% of the Earth's atmosphere. As compounds including oxides, the element makes up almost half of the Earth's crust.

Apparently the 20.8% equates to 21,000 ppm [/s] (cf CO2 407 ppm). It will see me out, anyway.

CORRECTION

209,460 Parts Per Million by Volume (ppmV)

[gerontocrat]

Hullo nicibiene,

In my post above I suggest that atmospheric oxygen depletion relative to CO2 ppm increase is a minor distraction. (See table below)

But oxygen levels in the oceans, lakes, rivers and streams is much more of a critical parameter affecting the health of the biosphere. The article below is a good intro to the subject.
http://www.fondriest.com/environmental-measurements/parameters/water-quality/dissolved-oxygen/#8

The oceans are in bad shape, and discussed in this forum under :
Consequences / Re: Climate change, the ocean, agriculture, and FOOD

Numerous articles on the subject, e.g.
Climate Change Is Suffocating Large Parts of the Ocean - Latest Stories
https://news.nationalgeographic.com/2018/01/climate-change-suffocating-low-oxygen-zones-ocean/

[nicibiene]

Yes, gerontocrat, I know about the sad circumstances in the ocean... in the end all oxygen based life functions via physics and chemistry. We have the mechanism of diffusion-respiration of insects, birds, fishes is adapted to certain CO2 and O2 levels. All of the exchange depends on partial pressure of the gases and the temperature. Human takes out 5% of the oxygen content while breathing. Higher CO2 concentration in air means higher CO2 level in the blood-all is limited by physics.

The question I ask myself about insects for instance: they have no lungs, animals with lungs increase frequency and depht of breath when we are suffering of low oxygen or higher CO2 levels. Could insects adapt? What is the minimum/maximum humans need for health?

If there is solved less oxygen in the oceans due to higher water temperatures, it should be in the air-but it is not... more growth of plant biomass due to higher CO2 (that takes place to a certain level -when there is enough water) should produce more oxygen... but it decreases faster than CO2 grows. 

Dropping water oxygen level is the first step to a "nice" down spiral of oxygen based life... I know ocean is the most important source of our planets breathable oxygen.

[gerontocrat]

The question I ask myself about insects for instance: they have no lungs, animals with lungs increase frequency and depht of breath when we are suffering of low oxygen or higher CO2 levels. Could insects adapt? What is the minimum/maximum humans need for health?

Dropping water oxygen level is the first step to a "nice" down spiral of oxygen based life... I know ocean is the most important source of our planets breathable oxygen.

Kenyans and Ethiopians are famous for being the kings of long-distance running. They grow up on high plateaus - as a result they have greater lung capacity and better respiratory systems. As usual, humans are the no #1 adaptable species.

Altitude                 Oxygen %   Altitude Category / Example
0 ft              0 m   20.9 %   Low   Boston, MA
1,000 ft   305 m   20.1 %   Low   
2,000 ft   610 m   19.4 %   Low   
3,000 ft   914 m   18.6 %   Medium   
4,000 ft   1,219 m   17.9 %   Medium   
5,000 ft   1,524 m   17.3 %   Medium   Boulder, CO
6,000 ft   1,829 m   16.6 %   Medium   Mt. Washington

Insects - you triggered an old memory - giant dragonflies in Carboniferous times and I found this site ; http://forces.si.edu/atmosphere/02_02_06.html

The Age of Oxygen (400 million to 290 million years ago)
As plants became firmly established on land, life once again had a major effect on Earth’s atmosphere during the Carboniferous Period. Oxygen made up 20 percent of the atmosphere—about today’s level—around 350 million years ago, and it rose to as much as 35 percent over the next 50 million years.

and this site:-

http://discovermagazine.com/1995/sep/insectsoftheoxyg567

In the swampy forests of the Carboniferous Period, 360 to 286 million years ago, dragonflies with two-and-a-half-foot wingspans darted among the giant ferns. Mayflies grew to canary size. Cockroaches appeared suddenly (as cockroaches do) for the first time. The number of insect families increased from 1 or 2 to more than 100 during the Carboniferous, and many of the insects were huge, and no one has been able to say exactly why. Jeffrey Graham, a researcher at the Scripps Institution of Oceanography, has been pondering the problem since childhood. I remember seeing models of giant dragonflies as a child and wondering how they could fly, Graham recalls. Now Graham, zoologist Carl Gans of the University of Michigan, and their colleagues think they have an answer. The flight of the giant dragonfly, they say, along with the whole Carboniferous insect explosion, may have been made possible by an oxygen-rich atmosphere.

It was plants on land that made the planet oxygen rich (and then trapped so much CO2 in the ground that the earth cooled)

The oceans are an oxygen deposit, not an oxygen generator, methinks

[nicibiene]

The oceans are an oxygen deposit, not an oxygen generator, methinks

Im afraid that is not the fact.
http://earthsky.org/earth/how-much-do-oceans-add-to-worlds-oxygen
http://www.nationalgeographic.org/activity/save-the-plankton-breathe-freely/

I read a book about ocean biology and chemistry of Stefan Rahmstorf: Phytoplancton you find in cold waters is very sensitive regarding temperature changes. If temperature increases they imigrate to lower, colder waterlevels. But that is limited by light they need for photosynthesis.  Too warm water means a steep decay in phytoplankton- exactly that is the problem.... phytoplankton also works as a biological carbon pump that drews CO2 as CaCO3 particles down to ocean ground. That mechanism gets disrupted by acidification additionally. 

https://www.nasa.gov/feature/goddard/nasa-study-shows-oceanic-phytoplankton-declines-in-northern-hemisphere

[gerontocrat]

The oceans are an oxygen deposit, not an oxygen generator, methinks

Im afraid that is not the fact.
http://earthsky.org/earth/how-much-do-oceans-add-to-worlds-oxygen
http://www.nationalgeographic.org/activity/save-the-plankton-breathe-freely/

I read a book about ocean biology and chemistry of Stefan Rahmstorf: Phytoplancton you find in cold waters is very sensitive regarding temperature changes. If temperature increases they imigrate to lower, colder waterlevels. But that is limited by light they need for photosynthesis.  Too warm water means a steep decay in phytoplankton- exactly that is the problem.... phytoplankton also works as a biological carbon pump that drews CO2 as CaCO3 particles down to ocean ground. That mechanism gets disrupted by acidification additionally. 

https://www.nasa.gov/feature/goddard/nasa-study-shows-oceanic-phytoplankton-declines-in-northern-hemisphere

Thanks for the info - always good to know a bit more. BUT, he said, is it not true that it is land plants that are the main source of O² production? I read somewhere that most of the ocean is very much a desert. In the South Pacific, where I worked for two glorious years, the Tuna only came (together with the big predators) when the cold current arrived with it's load of oxygen. Most of the year, game fishing was pretty hopeless.

Phytoplankton reduction through warming of cold waters is obviously a major threat to the entire ocean-based food chain on which hundreds of millions of humans depend as a major food source, as is over-fishing of krill. But it is not a threat to O² levels in the atmosphere?

Climate - too many connections to too many issues. I've got information overload. How can anybody keep hold of the big picture with so many inter-twined variables?

[vox_mundi]

Deep Ocean Oxygen Levels May Be More Susceptible to Climate Change than Expected
https://phys.org/news/2020-02-deep-ocean-oxygen-susceptible-climate.html

Much more oxygen than previously thought is transported deep into the ocean interior through a 'trap door" in the Labrador Sea that some researchers say could be closing as a result of climate change.

... Researchers measured the transfer of gases, including oxygen and carbon dioxide, from the atmosphere to depths as great as two kilometres. The oxygen taken up by the ocean over a year in the Labrador Sea was 10 times larger than typically estimated. Large numbers of air bubbles, injected during violent, winter storms, were responsible for the difference.

The higher oxygen supply also implies higher-than-expected demand for oxygen by deep-sea ecosystems.

The Labrador Sea is one of only a handful of locations worldwide, where the atmosphere and deep ocean connect, directly. A 'trap door' to the deep ocean opens there for a few months each winter, when surface water becomes cold and dense enough to sink into and mix with deep, oxygen-deficient waters.

"While bubble-mediated gas transfer has been recognized for decades, our measurements show how critically important it is when the 'trap door' is open and a vast volume of oxygen-deficient deep ocean water is exposed to the atmosphere," says Dariia Atamanchuk, a research associate in Dalhousie's Department of Oceanography and lead author of the study.

The deep ocean waters then flow out of the Labrador Sea, supplying life-supporting oxygen to a vast area of the ocean, worldwide.

"We refer to the Labrador Sea as one of the lungs of the deep ocean and the deep circulation as being like its blood stream," says Dr. Atamanchuk. "Oxygen taken up from the atmosphere in the Labrador Sea may ultimately support respiration of organisms living tens of thousands of kilometers away, including fish living in the deep Pacific or Indian oceans."

Model-based projections have suggested that the Labrador Sea's 'trap door' might be closing, due to the delivery of increasing amounts of fresh water from melting ice on Greenland and the rapidly changing Arctic.

"More fresh water means lower density and shallower mixing, and that would cause the ocean's breathing to, literally, become shallower," says Doug Wallace, a professor of Oceanography at Dalhousie and initiator of the study.

Dr. Atamanchuk adds that the effect of a similar 'trap door' closure off Antarctica may already have been felt in the deep South Atlantic Ocean, which has recorded high and difficult-to-explain levels of deoxygenation over the past 50 years.

D. Atamanchuk et al. Rapid transfer of oxygen to the deep ocean mediated by bubbles, Nature Geoscience (2020).