I found this study interesting. I thought it might be good to think about how human activity changes the planet. Yes, there is a measurable degree of uncertainty to the time frame, but it is a measurable certainty that atmospheric O2 is currently decreasing. We don’t seem to think of O2 as a consumable resource and take the air we breathe as an unchanging constant.
Below is the abstract. To add some context to the time frame in the abstract of 3,600 years the pyramids are roughly 4,500 years old, and this is about the same time or a bit earlier that writing systems were developed. I realize these are long time frames when compared to the human life span. What do you say we just keep kicking the can done the road.
There are a number of other studies on the causes such as deforestation, ocean dead zones, forest fires, and burning fossil fuels. If you care to look for them. I saw a report that the oceans have lost about 2% of their O2. For every carbon atom to become CO2 it takes two oxygen atoms. The reason we currently have about 21% of the atmosphere made up of oxygen is because life came up with photosynthesis.
Abstract
There has been a clear decline in the volume of oxygen in Earth’s atmosphere over the past 20 years. Although the magnitude of this decrease appears small compared to the amount of oxygen in the atmosphere, it is difficult to predict how this process may evolve, due to the brevity of the collected records. A recently proposed model predicts a non-linear decay, which would result in an increasingly rapid fall-off in atmospheric oxygen concentration, with potentially devastating consequences for human health. We discuss the impact that global deoxygenation, over hundreds of generations, might have on human physiology. Exploring the changes between different native high-altitude populations provides a paradigm of how humans might tolerate worsening hypoxia over time. Using this model of atmospheric change, we predict that humans may continue to survive in an unprotected atmosphere for ~3600 years. Accordingly, without dramatic changes to the way in which we interact with our planet, humans may lose their dominance on Earth during the next few millennia.
The solution may just be as simple as fewer humans. Everybody should endeavor to stop air conditioning homes. I never had one in my home and never will.
So if matter can neither be created of destroyed at atomic levels how can there be “less” oxygen? Breaking of the Oxygen molecules into atoms? How’d that happen?
A “study” that shows movement of oxygen might be of value.
But showing “less” means it had to disappear or be broken down into atomic particles.
So…where’d it go? Into the dirt? Into the water?
Off planet?
(just watch…the "answer’ will be to convince some people give up some additions rights and liberties. What-cha-wanna-bet)
It is being attached to carbon atoms when all life metabolizes nutrients and you breath out CO2. When your steel knife rust it is oxidized by O2 or when combustion takes place O2 attaches to free carbon. This is simple chemistry. This O2 comes from the atmosphere and is produced only by green plants and algae. They strip it off of CO2. On a molecular level it doesn’t disappear. O2 is highly reactive and doesn’t exist long as such. Before bluegreen algae developed photosynthesis the atmosphere didn’t have a free O2 component. When it was being strip from CO2 by the first organisms that could do photosynthesis it caused the great oxidation of planetary iron. Think how much it took to make red rocks and red clay. It is called by science the “Great Oxidation Event” and happened between 2.5 and 2.2 billion years ago. So, until the majority of exposed iron was oxidized the atmosphere and water held little free O2. Once it could accumulate in the environment It caused a mass extinction as it was toxic to most of the existing microorganisms. Most of life now requires O2 for their metabolism.
What we have that allows for O2 in the atmosphere is caused by a balance of natural phenomena. The balance of nature and the web of life is being changed by our activities which among other consequences is changing the atmospheric equilibrium. It can also be changed by natural means such as desertification or extreme vulcanism. Algae in the Oceans produce about half of the atmospheric O2. Nutrient runoff is creating dead zones in the Ocean. The BP oil spill has created a large benthic dead zone in the Gulf. These things add up over time.
Basically, you reduce the amount of plant life you reduce O2, or if you increase the uptake of O2 you reduce what is available. At the moment it is decreasing annually by a small amount. 3,600 years gives us some “breathing room” (Pun intended) so don’t get too bent out of shape. I had wondered about the O2 levels and came across this paper. It is something to think about. It always amazes me how little science is of interest to some. As a trained biologist and wildlife ecologist it is a passion for me. All fields of science, I find interesting. Knowlege is a true treasure.
Thankfully oxygen and hydrogen are also strongly attractive, or we wouldn’t be able to paddle. The point I am trying to make is O2 doesn’t stick around because it wants to stick to other elements. Only because plants can unstick it from CO2 is it part of the atmosphere.
Incidentally demographic studies suggest the world population is on track to be declining by the end of this century. This may present a problem for the growth economy concept. Of course, we don’t really know where the AI revolution will lead us. We live in interesting times to say the least.
In the famous words of ScupperFrank… Paddle On!
When you burn something it takes O2 out of the air and combines it with carbon. We are producing 35 billion tons of CO2 a year. O2 is most of that weight.
Half the CO2 is being absorbed by the ocean, turning it into carbonic acid. Although it is slowly making the ocean acidic now, It will eventually eat thru the entire carbonate / bicarbonate buffer and acidity will skyrocket. At that point coral will go extinct. I’m more concerned with that than lack of oxygen.
I considered bring ocean acidification into the discussion as it also applies to the algae and other ocean life forms. here are a couple of informative links.
Reducing population is part of the global plan. My gas and electric bill budget plan was $171 a month for over 15 years. In 2015. I started an addition on my house, upgrade the rest of my wndows and insulation to improve efficiency. The utility bill continued unchanged until it recently dropped to $164 for several months, as I reduced energy consumptiin. Over the past three months, the bill increased to $191, $223, and now $235. I can afford that, but I wonder who is going to pay the utility bills for the immigrants who left everything, payed $10k to a cartel to help them cross the border. I think I am paying for those who are not.
Anyone serious about climate can make. A big dent by turning off the home air conditioner. It might makes a big difference - I don’t have one, so I don’t know what kind of savings you’d realize. I often go a week without driving the car, and go two weeks between grass cutting.
Atmospheric oxygen refers to O2, i.e. diatomic oxygen. As others have mentioned, both combustion and oxidation will combine diatomic oxygen with other elements.
I’m almost embarrassed to write this post…
This article is ludicrous. What are its main points?
First sentence in their paper: "There has been a clear decline in the volume of oxygen in Earth’s atmosphere "
This the first tell that they don’t understand what they are discussing–and that anyone who supposedly “peer-reviewed” this paper didn’t either understand it either. What they mean is that the Earth’s atmosphere is losing oxygen content. Anybody that has taken a high school chemistry course ought to be able to tell you the difference between the volume of a gas (space occupied) and its content (number of molecules).
Look at their first graph: “Figure 1”. This shows that the percentage of O2 in the atmosphere peaked at 30% approximately 100M years ago. Well, 100M years ago was the Cretaceous period. T. rex still stalked the earth. Human beings would not appear for about another 98M years, and by then global O2 percentage in the atmosphere was already down near its current range–and has been basically stable since.
Those of you who paid attention to my first comment will correctly note that I shouldn’t equate “percentage” of a gas in a gaseous mix (i.e., the atmosphere) with the “content” of a gas. Gold star to you! However, we have no reason to believe that massive proportions of the atmosphere as a whole have been lost in that time period (the earth retains its atmosphere due to gravity), so in this case “percentage” can serve as an rough proxy for “content”.
Bottom line: whatever geophysical forces are driving this decrease in oxygen content in the atmosphere have NOTHING to do with human beings causing them
They say the following, "Earth’s atmosphere, like most biological systems… " Sorry, the earth’s atmosphere is not a biological system–it’s a geophysical system. Do biological activities affect it? Yes, at the margins in small amounts. Geophysical, non-biological processes affect it far, far more. Their failure to grasp this leads to what the well-known author Michael Crichton called the “wet streets cause rain” mistake that you read in many publications
They conflate two very different types of data–the type of long term geophysical data that informs their first graph (Fig 1) with about 35 years of recent global measurements (a pittance), and use this conflation to conclude that we’ve got about 4000 years to zero O2 in the atmosphere. I don’t know whether we have one year to zero O2 or one billion years to get there, but you can’t figure that out with this kind of data and no comprehension of the underlying processes driving atmospheric O2 content.
Their conclusion: human beings can’t survive without oxygen. No kidding. You need scientific credentials to know that? Which brings up the question of their background: the authors are 3 medical scientists and a mathematician. It’s not surprising that they don’t even understand the right questions to ask.
Losing content = losing volume. The atmosphere is under pressure. Take away a mole of O2 molecules and other molecules will fill the volume they occupy.
Every forest that people clear stops adding O2 to the atmosphere and stops removing CO2 from the atmosphere. Any time we burn anything, we remove O2 from the atmosphere and bond it to carbon, releasing some of it into the atmosphere as CO2 and other hydrocarbon gases. Oxidation of metals (e.g. rust) and minerals (ash) also removes some free oxygen.
There is no mystery or voodoo to this. The atmosphere contains an amount of free oxygen (O2) molecules. If you remove oxygen molecules from this amount, the amount goes down. Various biological processes that affect atmospheric oxygen had reached some balance resulting in O2 levels remaining stable for a while. These data just show we’re out of balance now. The CO2 trend is the opposite because the same thing is causing both.
losing content = losing volume. The atmosphere is under pressure. Take away a mole of O2 molecules and other molecules will fill the volume they occupy.
True in principle, false in practice. Fossil fuel burning doesn’t simply remove atoms from atmospheric gas, it substitutes (1 for 1) a CO2 atom for an O2 atom. Number of gas molecules, pressure, & volume stay unchanged. The proportions of O2 and CO2 change, so the content of either, at a volume of the same pressure, is what’s changing.
Various biological processes that affect atmospheric oxygen had reached some balance resulting in O2 levels remaining stable for a while. These data just show we’re out of balance now. The CO2 trend is the opposite because the same thing is causing both.
Again, this is true but basically irrelevant if you look at the magnitude of the effects. The data these authors themselves cite show that atmospheric O2 dropped over 30% in the 98M years before humans showed up, after rising for a long time before that. The global CO2 data shows a rise in atmospheric CO2 % from 0.028% to 0.042%; atmospheric O2 is about 20.8%. The change in O2 cause by human activity, at most (remember, 1:1, O2 to CO2) isn’t even a rounding error (approx. 0.018%) for atmospheric O2 concentration/content.
I stand by my point: much larger geophysical forces dwarf whatever people are doing. We are a lot more insignificant than we like to think we are.