Exploring the evolution of Earth’s habitability regulated by oxygen cycle


Research News


As an essential material for the survival and reproduction of almost all aerobic organisms, oxygen is closely related to the formation and development of complex organisms. A recent review provides a systematic overview of the latest advances in the oxygen cycle at different spatial and temporal scales and the important role that oxygen plays in shaping our current habitable Earth.

Professor Jianping Huang from Lanzhou University is the corresponding author of the review entitled “The oxygen cycle and a habitable Earth”, which is the cover article of the 64(4) of SCIENCE CHINA Earth Sciences in 2021.

Based on summarizing the latest research results of predecessors, the authors of this paper propose a coupling model of the five spheres of the earth system with the oxygen cycle as the core, and clarify the link role of the oxygen cycle in it. In this paper, the authors comprehensively summarized the changes of oxygen cycle and its effect on the habitability of the earth on multiple time scales including modern and geological time, and prospected the future development trend of oxygen cycle research.

“We take O2 for granted because it is just there and we breathe it all the time, yet it took billions of years before there was enough of it to keep animals like us alive.” Professor Jianping Huang of Lanzhou University, the corresponding author of the paper, points out, “These processes involve the interaction of various spheres of the Earth system, which are complex interdisciplinary issues with multiple temporal and spatial scales.” In this paper, the authors illustrate how the key biochemical processes in the oxygen cycle tie together the various spheres of the Earth system through feedback and interaction. “A habitable Earth gradually formed during the long evolution of the oxygen cycle.”

The effects of current human activities on the oxygen cycle and biodiversity are also discussed. “Four of the five large-scale species extinctions that have occurred in the history of the earth are related to the lack of oxygen,” Professor Huang concluded, “At present, under the compulsion of human activities, our planet is experiencing a large-scale oxygen reduction, with the ocean deoxygenation as a representative. The oxygen cycle of the Earth system is gradually out of balance, which is very worrying.”

Studies of the oxygen cycle cover a wide span of timescales from daily to geologic scales. The oxygen cycles of different timescales dominate the control of atmospheric O2 over the corresponding timescales. However, a distinct boundary that divides the long-term and short-term oxygen cycles has yet to be established, and the complex interactions between the short-term and long-term processes remain unclear. Since the earth system is a highly non-linear and strongly coupled system, a minor perturbation can have the potential to cause a series of dramatic changes. “It is a top priority to connect the short-term and long-term oxygen cycles under a comparable timescale rather than separating them. Effective multidisciplinary cooperation among the subdisciplines of Earth sciences (geology, oceanography, atmospheric sciences, paleobiology, etc.), and social sciences should be promoted to reveal the hidden mechanisms that control the trajectory of the Earth system and how the trajectory may influence the future of human beings.” said Prof. Huang. Fortunately, efforts have been made to reverse the decline of atmospheric O2. In China, the Green Great Wall, which was designed to mitigate desertification and expand forests has achieved overall success in past decades. Reductions in carbon emission and its related O2 consumption have been achieved in some major cities around the world.

This study has far-reaching scientific significance and important reference value for understanding the potential link between the oxygen cycle and the biodiversity in geological history and exploring the historical evolution and future of the Earth’s habitability.


This work was supported by the National Natural Science Foundation of China (Grant No. 41888101, 41521004 & 41991231), and the China University Research Talents Recruitment Program (111 Projects, Grant No. B13045).

See the article: Huang J, Liu X, He Y, Shen S, Hou Z, Li S, Li C, Yao L, Huang J. 2021. The oxygen cycle and a habitable Earth. Science China Earth Sciences, 64(4): 511-529,

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April 4, 2021 2:37 am

WTF is the anthroposhere

Another con job to get us to worry about the O2 we breathe as well as the CO2 we exhale

Reply to  Enthalpy
April 4, 2021 2:45 am

I know – the anthroposhere is the bubble of hot air around inner city lefties

Charles Higley
Reply to  Enthalpy
April 4, 2021 7:20 am

350 millions ears ago, there was a mass extinction, but Focusing on O2 is simplistic. During the preceding 250 million years, CO2 dropped from 7000 ppm to about 200-300, which is where we were 50 years ago. Photosynthetic processes would have suffered greatly and O2 wold decrease. C4 plants finally evolved that were more able to take up low concentrations of CO2.

I little known aspect of our planet is that it is not in a balance. Ionic deposition processes in the oceans are constantly trying to precipitate CaCO3 (calcium carbonate) and, thus, constantly trying to draw down atmospheric CO2. It is only from the huge quantities of CO2 released by volcanic activity that the planet does not not succumb to this process.

In warm waters, CaCO3 precitipitates quite easily, which is how coral reefs cement themselves together. Since Earth spent most of those 250 million years, much warmer than now, deposition was a given and CO2 decreasing. See the T vs. CO2 of Geocarb IV.

Steve Case
April 4, 2021 2:40 am

All words, no numbers.

John Tillman
Reply to  Steve Case
April 4, 2021 5:27 am

Even the words are wrong. China’s Green Great Wall hasn’t fought desertification. Its massive release of CO2 from burning coal has. Pure CCP propaganda.

Reply to  John Tillman
April 4, 2021 4:04 pm

Every word coming out of China is written by or for the CCP. This paper is CCP propaganda, trying to claim that its tree-planting will save Earth’s oxygen.

I suspect that we can see here the next scare campaign, for when the CO2 scare campaign runs out of steam. We thought it would be ocean acidification, but if it’s oxygen then China begins with a head start.

April 4, 2021 2:47 am

I noticed that rise and fall of co2 levels every year due to apparently the Northern spring and summer growing season is almost equal. If the growing season drew down 33% more Co2 then co2 levels would stop growing – Net Zero would be reached. I don’t really want the CO2 to stop growing (the plants are loving the extra CO2 NASA says) but the green shirts, the ecofascist socialists who currently control the world won’t let us live in peace, and are threatening to choke us off unless co2 stops growing. Wouldn’t it be simpler, cheap and faster and better for the environment than covering it with more of man’s crap in the form of inefficient wind turbines and solar panels, to enhance nature that extra 33%? In the way we already help nature by building artificial reefs and irrigation projects, we could fertilize the oceans with the little bit of iron and other nutrients that the oceans are starving for so the plankton can grow, as well as projects around the world to bring life back to the deserts – which will reduce pressure on the wildlife reserve areas that are being encroached upon. Probably makes too much sense for any greens out there to grab the idea and run with it.

Charles Higley
Reply to  PCman999
April 4, 2021 7:26 am

we could fertilize the oceans with the little bit of iron and other nutrients that the oceans are starving for so the plankton can grow,”

We do not know enough to do this kind of thing. The primary productivity and food webs evolved around them might, or probably, or surely, be affected by fertilizing odd parts of the oceans. The results are more likely to be bad for the existing food webs, as added fertility would attract, move, or artificially augment populations from their normal habitats. We are clearly unable to know the consequences. It sounds good but is clearly not realistic.

Reply to  Charles Higley
April 6, 2021 2:24 pm

“We do not know enough to do this kind of thing. The primary productivity and food webs evolved around them might, or probably, or surely, be affected by fertilizing”

You could say exactly the same thing about modern farming. Or, in my case, fishery enhancement. Luddite thinking.

Peta of Newark
April 4, 2021 3:35 am

Only a few millennia late to the party.
So much for all our contemporary crises & emergencies then hey-ho ha. ha. ha.

But, credit where ii could, might, may be, is projected, possibly be due, state-of-the-art model says, maybe the Good People Of China actually discovered these things.
Bless him he has made another.
Some folks will assert that there are 5 elements – the 5th one being ‘space’
As in, ‘room to move around’, not Outer Space.

Anyway, Outer Space is choked up with Sputniks, only mad people would go there, OR, those who imagine themselves to be vastly important.
So important in fact as to be The Most Important Thing since Important Things first ever became Important
Those being contemporary politicians and their ever grovelling & fawning ‘servants’
Muppets calling themselves, not just Climate, Scientists.

Oh hello Professor Jianping Huang from Lanzhou University, how did you know we were talking about you in this dead end part of the world? ##

Lemme guess, a paranoid media/government allied to legions of peeping toms, computers and Sputniks told you, didn’t it?

## Wonderz: If it’s round, how can it have an end? Maybe Earth is flat after all. Science, politics and most of the population are certainly ‘flat’ nowadays, thanks everyone to eating sugar, booze and cannabis.
Only the Really Important People ‘know’ different and they’re all Miles High (extremely low in actuality) on the drugs just mentioned)
Away with the Sputniks???
ha ha, how many Sputniks can dance on a pin?
(I didn’t just ask that, I really didn’t)

Hmmmm, not easy is it.
Ask that Austrian girl WW2 veteran in the u-tube we were pointed to recently, she’ll tell you about ‘not easy’ living in a land of well-intentioned while mendacious zombies
Professor Jianping, are you still listening? have yo nothing important to be doing?
Like, telling everyone how important you are.

Last edited 9 days ago by Peta of Newark
Reply to  Peta of Newark
April 4, 2021 10:20 am

Some folks will assert that there are 5 elements – the 5th one being ‘space’

I humbly and eagerly ask for a short explanation, link, reference. This has real and immediate relevance to research I am doing for a movie on Tetragrammotron.
I sincerely hope you answer…

Ron Long
April 4, 2021 3:38 am

The history of oxygen on earth is interesting, and geologists utilize the biggest step-change as the marker from the Archean Eon to the Precambrian. This change occurred about 2.5 billion years ago, and was caused by, or associated with, oxygen becoming more common in the earths atmosphere. The appearence of oxygen fixed a lot of available iron in iron formations, which eventually became the source of most of mined iron. What promoted the advancement in the atmosphere? Appears to be primitive algae like life forms in the oceans that breathed in CO2 and breathed out oxygen. We’re related to pond scum? Some of us still are.

John Tillman
Reply to  Ron Long
April 4, 2021 5:24 am

Proterozoic Eon. All eons before the Cambrian Period of the present Phanerozoic Eon are Precambrian, ie the Hadean, Archaean and Proterozoic.

Cyanobacteria. Algae are eukaryotes which have incorporated cyanobacteria as chloroplasts. They used to be called blue-green algae, but aren’t. They are indeed slimy however.

Yup. Cyanobacteria produced the oxygen via photosynthesis which precipitated out the red bands of iron deposits. This led to the Oygen Catastrophe, the first great mass extinction, wiping out most anaerobic organisms. Too bad it didn’t get botulism microbes. Unless you’re fighting wrinkles.

Last edited 9 days ago by John Tillman
Reply to  Ron Long
April 4, 2021 6:54 am

The Denver Museum of Nature and Science states in on of it’s exhibits that the first mass extinction even occurred as O2 levels hit 1%.
Although essential for widespread life as we’ve experienced it, there is a trade off.

Ken Towe
Reply to  Ron Long
April 5, 2021 6:34 pm

That “step change” called the GOE is totally wrong for several reasons, but the largest is the fact that if cyanobacterial oxygen was used up by the oxidation of ferrous iron to create red BIFs then the organic matter they created would have to have been left behind. It is not there.The same oxygen cannot be used twice.There is very little organic carbon in Archean rocks. The second problem is that prior to the evolution of photosynthesis there would have been no protection for early life, esp, DNA, from the young Sun’s enhanced UV radiation.The answer to that is the photodissociation of water vapor in the stratosphere with the loss of light hydrogen to space leaving oxygen to form ozone.

April 4, 2021 4:00 am

“Fortunately, efforts have been made to reverse the decline of atmospheric O2.“

So, now we’re running low on Oxygen because we burn fossil fuels?


Joseph Zorzin
April 4, 2021 4:48 am

Forests produce oxygen. Cutting down millions of acres of forests to install wind and solar “farms” will result in less oxygen.

April 4, 2021 4:58 am

” …. yet it took billions of years before there was enough of it to keep animals like us alive.””

Yes indeed, as all of it there became instantly H2O before, and none left for
animals, which had not evolved yet.

Amazing, how long can live and what discoveries animals can come up with if enough oxygen there!

Rod Evans
April 4, 2021 5:04 am

Are the China scientist not aware the April1st fun day ends at 12.00 hrs on April 1st?

Reply to  Rod Evans
April 4, 2021 5:16 am

That was the “official stand” for April 1st fun day,
like, there in 69 is fun, but in 96 not so much…
Though, that wash before the discovery of Oxygen cycle by animals. 🙂

April 4, 2021 5:14 am

“At present, under the compulsion of human activities, our planet is experiencing a large-scale oxygen reduction, with the ocean deoxygenation as a representative.”

What on Earth is this guy talking about??????
Did I miss something? Is the Oxygen level in the atmosphere dropping?

We used to have a rule in science:
Any theory which is contradicted by prior observation is Dead On Arrival. DOA.

I do think his theory of “large-scale oxygen reduction” is DOA.

Reply to  TonyL
April 4, 2021 6:11 am

Is this information relevant to the oxygen reduction fears?


John Tillman
Reply to  Sommer
April 4, 2021 7:20 am

CNN doesn’t know where Wuhan is. It’s not in NE China, even if you free Uyghuristan and Tibet from the PRC.

Reply to  Sommer
April 4, 2021 8:28 am

Very strange.
The CNN article does not mention Oxygen depletion at all. In fact, the term “oxygen” does not appear even once in the entire article. I fail to see the connection between a routine article about Chinese air polution and this alleged global oxygen depletion.

Charles Higley
Reply to  TonyL
April 4, 2021 7:34 am

Hubris is a wonderful thing. A paper came out recently that pointed out that atmospheric CO2 is largely derived from volcanic activity all over the planet. Indeed, much of this activity is under the oceans where the dissolved CO2 might take 100s of years to reach the surface. One large volcano can emit as much CO2 in 2–4 days as human emit in a year. And we want to control every aspect of everyone’s life to pretend to fight natural processes that they claim are guilty of.

R Grubb
April 4, 2021 6:42 am

“Effective multidisciplinary cooperation among the subdisciplines of Earth sciences (geology, oceanography, atmospheric sciences, paleobiology, etc.), and social sciences…”

Social Sciences? Ah, yes. One must remember to always include the proctors of the party line, the Fact Checka, in any and all scientific research.

April 4, 2021 6:43 am

This has taken some time to get some traction.

Back in 2008 we were warned…

The oxygen crisis

The rise in carbon dioxide emissions is big news. It is prompting action to reverse global warming. But little or no attention is being paid to the long-term fall in oxygen concentrations and its knock-on effects.

Compared to prehistoric times, the level of oxygen in the earth’s atmosphere has declined by over a third and in polluted cities the decline may be more than 50%. This change in the makeup of the air we breathe has potentially serious implications for our health. Indeed, it could ultimately threaten the survival of human life on earth, according to Roddy Newman, who is drafting a new book, The Oxygen Crisis.

Yes it is from The Guardian

The oxygen crisis | Greenhouse gas emissions | The Guardian

Only it’s no more convincing now than it was 13 years ago.

Last edited 9 days ago by fretslider
Rick Kargaard
April 4, 2021 7:15 am

There is a particular mindset amongst humans that earth’s biosphere is near perfect in balance. Alarmist see it as a very fragile balance easily upset by human activity. Sceptics see it as a very robust and self correcting balance.
Careful analysis of what we know would indicate that there has never been a balance but rather a sort of evolution from one state to another. Significant change appears to be the norm with tipping points a constant occurrence but often with effects barely noticeable over less than several million years.
We likely are significant enough to affect some change but the results are also likely to be miniscule, fleeting, and with many unknowns. Eventually, no trace of our efforts or existence will remain.
This all may seem fatalistic but could be better described as acceptance. Change will happen despite the best efforts of alarmists or sceptics.
Several generations in the future even this past will be largely forgotten and if homo sapiens still exist they will likely see their environment as normal and seek to avoid climate change. All the while, many will seek to enforce social change, perhaps using a changing climate as an excuse.

Reply to  Rick Kargaard
April 4, 2021 12:04 pm

Each moment in time is unique. As such, so is the position of the earth in relation to the universe. Anyone who thinks that there can possibly be a “balance” between past events and the unknown future is simply deluding themselves.

Rick Kargaard
Reply to  Doonman
April 4, 2021 7:45 pm

Yes, a headlong rush from oblivion to oblivion would be a better description of our reality.

April 4, 2021 10:01 am

So earths oxygen levels continue it’s long decline of about 0.7% over the last 800,000 years despite the greening of the earth due to increased CO2 levels! Miniscule in the larger scheme of things and yet someone has to start ringing alarm bells? Earth’s Atmospheric Oxygen Levels Continue Long Slide | Live Science

Reply to  rah
April 4, 2021 1:36 pm

So, small decrease in O2 = trivial

Small increase in CO2 = catastrophic

Steve Z
April 5, 2021 8:13 am

[QUOTE FROM ARTICLE] “In China, the Green Great Wall, which was designed to mitigate desertification and expand forests has achieved overall success in past decades. Reductions in carbon emission and its related O2 consumption have been achieved in some major cities around the world.”

China’s CO2 emissions (and oxygen consumption) has been increasing faster than any other country in the world, so that China has been the LEAST “successful” country in fighting oxygen depletion. Forests are expanding, but mostly in Europe and the USA. China is trying to take credit for improvements made elsewhere.

For every mole of CO2 produced by combustion of a fossil fuel, one mole of oxygen is consumed, so that if the CO2 concentration has increased from 280 ppm to 410 ppm (or 0.028% to 0.041%) since the start of the Industrial Revolution, the oxygen concentration would have decreased by 0.013 mol% (unless it was replenished by increased photosynthesis). Still, from a base point of 20.9 mol%, losing 0.062% of the total oxygen in 200 years isn’t really a catastrophe.

Photosynthesis also releases one mole of oxygen per mole CO2 consumed, so that when the CO2 removal rate by photosynthesis catches up to the CO2 emission rate by combustion, the oxygen concentration should also be stabilized.

Ken Towe
Reply to  Steve Z
April 5, 2021 6:55 pm

The early Earth’s atmosphere was plentiful in CO2 and low in oxygen. Today it is the reverse. The percentage ratio of oxygen to CO2 is now ~525 to one. All that CO2 was buried as organic carbon (fossil fuels) but most of it is in limestones, bio-carbonates. The rest is in the atmosphere and oceans and the biological standing crop.For humans to think they can duplicate that burial by any CCS technology in the amounts needed to affect the Earth’s climate is a pipe dream, and an expensive one at that.

Mike Dubrasich
April 5, 2021 8:56 am

“Reductions in carbon emission and its related O2 consumption have been achieved in some major cities around the world.”

CO2 doesn’t consume O2; it produces it. Every molecule of O2 in the air was once atmospheric CO2. CO2 is the fundamental building block of O2. Without CO2 (and photosynthesis) there would be no O2 to breathe. Everyone would asphyxiate. Total extinction of all plants and animals. Bye bye. The End of Life as we know it. The Carbocalypse. No CO2 = Termination of Planet Earth.

This is actual solid FACT. 99.99% of all scientists and pseudo-scientists agree. Without atmospheric CO2 this planet would be a dead planet. No life at all. The fools who have declared CO2 to be a pollutant are not just wrong; they are galactically wrong and are endangering Life Itself. I don’t care what religion you are, or if you have none, or what political party you ascribe to, the insane crazy anti-CO2 nutballs are threatening to erase All Life forever. That’s bad stuff, people. RESIST — you must resist! Now and always.

Ken Towe
Reply to  Mike Dubrasich
April 6, 2021 6:56 am

Photosynthesis creates organic matter and free oxygen from CO2 and water. Aerobic respiration is the exact opposite. The oxygen is used to recycle the organic matter back to CO2 and water. The only way that oxygen can build up in the atmosphere is for the organic carbon to be buried, permanently.

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