From 1910 until the 1930s there was not much said about anthropogenic global warming. A few scientists were concerned about it in some of their writings, but not much research or investigation was done. Knut Ångström's experiment which showed that CO2 infrared radiation absorption was saturated by current levels of CO2 in the atmosphere was widely accepted, and it was widely believed that any excess CO2 would be absorbed by the oceans.
But some relevant work was done about the atmosphere and geochemistry---the most interesting contributions being made by Vladimir Vernadsky
Vladimir Vernadsky (1863-1945) was a sort of dreamy person in his writings, and seems to have had a thick layering of pagan naturalism in his beliefs. Perhaps his non-Christian viewpoints were a factor in surviving the Stalin purges. With his thick goatee, dreamy manner, belief in naturalism, and slightly odd mannerisms he in some way resembled a druid or a sweet grandfather. However he had to have had prodigious political skills to survive the Stalinist purges that decimated so much of the Russian science establishment. Stalin seemed to prefer scientists who thought outside the box, and more specifically had viewpoints similar to his own. In most cases, Stalin's viewpoint was dreadful--his embrace of Trofin Lysenko set back Soviet agriculture by 30 years.
Vernadsky was different---although dreamy, his science was valid. And he made many original contributions to geochemistry, biogeochemistry (both fields he practically invented) and radiogeology (in which he was one of several scientists who developed the field)
Vernadsky wrote his wife in 1888:
...to collect facts for their own sake, as many now gather facts, without a program, without a question to answer or a purpose is not interesting. However, there is a task which someday those chemical reactions which took place at various points on earth; these reactions take place according to laws which are known to us, but which, we are allowed to think, are closely tied to general changes which the earth has undergone by the earth with the general laws of celestial mechanics. I believe there is hidden here still more to discover when one considers the complexity of chemical elements and the regularity of their occurrence in groups...
One of the things that puzzled him was how the Earth has an atmosphere of nitrogen and oxygen. Both are reactive gases and should not be present in more than trace amounts. A century ago (and until the 1960s in the west) it was believed that oxygen in the atmosphere resulted from the splitting of water molecules (H2O) by ultraviolet radiation---the heavier oxygen would remain in the atmosphere and the hydrogen would escape to space. Some believed that was the reason for so many shallow seas in the Cretaceous Period--the Earth was slowly, but surely, drying out. This belief had several difficulties---it was obvious that the Triassic and Permian periods had plenty of dry land and deserts, to say nothing of earlier periods.
It is surprising that this belief held on so long in the west---the final nail in the coffin was an experiment aboard Apollo 17 which looked at the atmosphere of the Earth and proved that hydrogen was not escaping at anything close to what had been believed---enough to lower the volumes of the oceans only an inch in a hundred million years. And definitely not supply Earth with much oxygen!
Vernadsky proved that the absorption of oxygen by chemical weathering was far to rapid to permit oxygen to accumulate in the atmosphere, even using a much more generous estimate of water dissociation.
It is said that oxygen results from plant photosynthesis. That is where our atmospheric oxygen comes from, but it is not so simple. Plants excrete oxygen, but animals, fungi and many single-cell organisms consume it. It's a giant closed loop. And this was why it was believed that oxygen had to result from dissociation of water--oxygen had to be continually introduced into the cycle.
Vernadsky proposed that what was really going on was carbon sequestration Plankton in the sea would release oxygen into the atmosphere, and when they died their bodies would sink to the abyssal plains, where their remaining carbon would be effectively removed from the biosphere. To a lesser extent, he also held that burial of surface plants and heating and compressing them would convert them to coal, with the carbon sequestered as coal beds.
Both of these are correct, although the oceanic sequestration of carbon is far more important. But not in a way that Vernadsky envisioned.
A flaw in Vernadsky's hypothesis is that most of the oceans are really biological deserts. Ocean fauna and flora live exuberantly in continental zones, where rivers bring in minerals and organic material, and in a few places where upwelling brings in water rich in oxygen. But most places in the ocean--the surface waters are almost devoid of life--not much plankton to sink. Vernadsky used assumptions for carbon sequestration that were far too high, and proposed that more carbon was ultimately returned to the biosphere than in reality.
What actually happens is more interesting. And weird. Carbon sequestration does produce our surplus of oxygen--but it needs another mechanism. It needs continental drift.
Continental drift was in the air, with the famous hypothesis of Alfred Wegener, but was not considered valid by most of the scientific community. Through subduction, carbon laid on the ocean floor is transported deep into the earth, removing it from the biological cycle. This means that surplus oxygen remains. Vernadsky was correct, but his figures were way off. He assumed that large amounts of carbon were continually sinking down to the sea floor with most returning to the biosphere eventually. In reality, a little carbon is sinking, but what is sinking is removed from the biosphere far more efficiently.
This has interesting implications for life requiring the presence of free oxygen, our animal life, on other planets.
All modeling now shows that without continental drift and subduction, there is no way for carbon to be sequestered in amounts sufficient to generate much free oxygen. Continental drift requires the presence of enough radioactivity in the core of the Earth to keep the interior of the planet hot enough for continental drift to occur.
A curious feature of our solar system is that we are not in an 'average' solar system. Our solar system is anomalously high in metals--about 25%-30% higher than other stars like our own in our region. There has been evidence for a long time that our solar nebula formed from the residue and interaction of several supernova explosions, which created lots of heavy elements, including radioactive elements.
Models of planetary development show that if the Earth had 25% fewer radioactive materials in its core there would not be enough heat generated to drive plate tectonics after 2-3 billion years. Which means that carbon sequestration could not take place, and oxygen could not accumulate. Even if photosynthetic organisms developed that released oxygen, it would not accumulate enough to support animal respiration--oxygen would stay below 1%-2%.
Earth life developed quickly after the Late Heavy Bombardment, but for reasons not well understood remained mostly single celled for the next three billion years, not increasing much in complexity. If life on other planets follows a similar course, by the time complex animal life began to try to develop, it would be too late--plate tectonics would have shut down. Carbon could not be sequestered, oxygen could not accumulate, and animal life based on oxygen respiration could not develop.
Of course other forms of life based on other elements and chemical pathways are possible--not using oxygen, and perhaps motile 'animals' analogous to ourselves could develop. It is very difficult to imagine a large motile 'plantimal' generating enough oxygen to support its metabolic needs.
Surveys of our region of the galaxy show that among stars of near solar mass, not one star in a thousand approaches our own in its heavy metal content. (Stars near the center of the galaxy have higher metal contents, but are subject to far more stellar instabilities, nearby nova explosions, and perturbations that could wipe out or set back complex life).
This information, developed over the past 20 years, is one of the keystones of the Rare Earth Hypothesis, and I believe one of the strongest elements of it. The Rare Earth Hypothesis says that while simple celled life may be quite common, complex animal life may be very rare. And a reason why the galaxy is not all colonized by aliens by now.
There is a way around this---what if life, instead of pausing at the single-cell level, had just kept evolving to more complex forms and large animals and plants appeared within a few hundred million years? Then plate tectonics would not have stopped yet and complex oxygen-metabolizing animal life could have developed.
The reason(s) why Earth's life 'paused' in its complexity for 3 billion years are not well understood as yet. It may be that most life bearing planets evolve more quickly to complex forms---or it may be that the progression to complex forms is very difficult, very unlikely, and that we are an outlier in how rapidly it occurred.
Back to the atmosphere:
Another question for Vernadsky is why does the Earth have nitrogen in its atmosphere? Most people, if they think about it at all, consider nitrogen to be an inert element. But it isn't, not really. Nitrogen is not reactive the way oxygen is, but it does react with lightning flashes (which produce nitrogen compounds vital for plant life) and with some minerals. The basic stable form for nitrogen is as nitrite ions in the oceans. This was much easier---nitrogen fixing bacteria release lots of ammonia---which is also released in plant decomposition, the breakdown of urea, and to a limited extent, in animal decomposition. 4 NH3 + 3 O2 molecules results in 6 water molecules + 2 molecules of nitrogen (N2). There are other more complicated pathways in a carbon dioxide and methane atmosphere, before oxygen was a major part of the atmosphere, but they do work to liberate nitrogen gas (while creating a lot of cyanides and other compounds)
Ammonia does react with oxygen fairy rapidly and is produced in large amounts---Vernadsky was able to demonstrate that the amount of ammonia produced by biological processes would reduce the oxygen content by 1% of the atmosphere of the Earth every 20,000 years (from 21% to 20% and so on) This reduction of the oxygen content of the atmosphere, a continuous biological drain, made the dissociation hypothesis for oxygen even more untenable.
Nitrogen stays in the atmosphere because while it is not completely inert, it is not very reactive. It has a long residence time in the atmosphere before it is zapped by lightning or incorporated in microbes. It does react with some minerals and becomes part of their chemical structure, but not often or in large amounts. Nitrogen is believed to be the only element on the Earth for which the majority of it is contained within the atmosphere.
[This is not certain however. Argon is created by the decay of potassium-40 deep in the Earth. Although argon is an inert gas and very reluctant to form compounds, it does remain in rocks fairly well and does not diffuse to the surface quickly. It is believed that most argon has remained in the Earth.]
Vernadsky had demonstrated that the atmosphere of the earth is a biological construct.
Vernadsky's work was published in 1926 as The Biosphere, a word he did not invent, but did not have a real meaning until his book. Vernadsky described the Earth not as layers of rock with water and air above, but a construct in which life (biogeochemical processes) takes the premier role. In his book, he describes the Earth as covered by an almost continuous surface of biological matter--life--whose chemical activity created the present atmosphere which blankets the earth, and had profound effects on the geology of the earth, extending to its interior.
This view has had some surprising confirmations---there are strong indications that without life and photosynthesis that the small amount of photosynthesis 2.5 billion years ago created the ozone layer (which does not require large amounts of oxygen), which thereby warmed the stratosphere, which kept the stratosphere from mixing with lower moist layers of the Earth (the troposphere), sealing moisture in and keeping dissociation of water from drying the Earth. That greenhouse effect may have saved our oceans (the sun was 30-40% fainter 4 billion years ago and has been slowly brightening and warming, more than doubling ultraviolet emissions. It seems that before 2.5 billion years ago, ultraviolet emissions from the sun were not enough to dissociate much water, and about 2.5 billion years ago an ozone layer formed from the traces of oxygen released by photosynthesis, warming the stratosphere, stopping mixing with the troposphere, which became a separate atmospheric layer, trapping moisture in the troposphere) Without oceans of water pressing down on the seafloor rock and permeating them, plate tectonics might not exist. (Water seems to be vital for plate tectonics--rocks without water seem to be much stiffer in experiments in the lab, and Venus, similar in size and composition does not have plate tectonics. So without life, water would have dissociated with hydrogen irretrievably lost, and with the loss of the oceans, plate tectonics would have stopped, and making complex life impossible, in a sort of fortuitous feedback)
Vernadsky had many accomplishments, including the establishment of the first academy of science in the Soviet Union (the National Academy of Sciences of Ukraine)
Vernadsky's work, being Soviet, was largely unknown in the west until the 1960s, when James Lovelock read The Biosphere and realized that much of what it said made sense. Lovelock's citations of Vernadsky's work created a great deal of interest in Vernadsky's research and hypothesis, and, with modifications, much of Vernadsky's work has been proven largely correct, or at least in the right direction.
Vernadsky however had a distinct New-Agy, mystical side. He believed that we are entering the third great epoch of the Earth--the first being the geosphere, when the Earth was a geological construct solely, to the biosphere, during which life began altering the planet and changed the Earth in ways that increased its suitability for life (an anticipation of the Gaia Hypothesis). Vernadsky postulated in 1936 that the Earth was entering a third epoch: the Noösphere. This New-Agy concept is about the Earth entering the age of thought, in which the human mind would be the driving force behind the reshaping of the Earth, perhaps evolving towards a group mind. The Earth will become what our thoughts make of it. \
Vernadsky had some oddball ideas. He believed in telepathy and other forms of psionics--not necessarily that they were an important factor now, but would be an 'emergent property' of human thought as people became more interconnected. (Vernadsky did not used the term 'emergent property' but the concept is clearly in his work)
Vernadsky as I have said was a 'dreamy' person. He frequently would lost attention to what others were saying, and have a blank expression on his face--daydreaming--even when in an animated conversation with one other person---and have to be brought back to reality with a hand on the shoulder. He took long walks in woods, collecting mushrooms, or wandering around gardens, with a blank look on his face. He was always kindly to children--young children nearby would snap him out of his daydream state and he would give them flowers with a smile on his face. In his gardens, he resembled a gnome. He certainly resembled a shaman or druid.
It is difficult to imagine how he became a premier part of the Stalin/Soviet scientific establishment. The picture of a dreamy, mystical scientist somehow jars with Stalinism. It also jars with the concept we have of a 'serious' scientist today. But he did first rate geochemical work, and his work in radiometric dating makes him one of the founding fathers of that science.
Another jarring juxtaposition with his dreamy, mystical demeanor was his strong advocacy for Soviet nuclear development including the atom bomb. Vernadsky apparently wrote a letter to Stalin very much like the famous letter Einstein wrote to President Roosevelt urging that the Soviet Union develop the atom bomb. I have not been able to find this letter or much about it, but the letter is spoken of frequently in my sources on Vernadsky.
Here is a picture of Vladimir Vernadsky.
This entry has been another diversion from global warming---but I still think it is relevant. Vernadsky, 40 years before western scientists took the idea seriously, showed that the atmosphere is a biological construct. He demonstrated that oxygen, nitrogen, and carbon cycle through the atmosphere, and that it is largely controlled by biological processes. During the 1910s and 1920s there was practically no work on anthropogenic global warming, and Vernadsky is an interesting character, so I thought his insights worth sharing.