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By Charles Rhodes, P. Eng., Ph.D.

About 56 million years ago, at the commencement of the Paleocene Eocene Thermal Maximum (PETM), there was large scale combustion of nearly all the biomass and exposed fossil fuels on Earth's surface which triggered both atmospheric thermal runaway and warm state trapping. The corresponding increased atmospheric carbon dioxide (CO2) concentration and consequent melting of ice raised Earth's average surface temperature by about 17 degrees C for about 200,000 years. The result was a global extinction of all large animals and complete melting of the polar ice caps.

For the last two centuries mankind has used combustion of fossil fuels as a prime energy source. This combustion converts fossil carbon into atmospheric CO2. The consequent increase in the atmospheric CO2 concentration from the pre-industrial revolution norm of 280 ppmv to the present 400 ppmv has been about 43%. However, most of the fossil CO2 produced by man kind has been absorbed by the oceans via conversion of insoluble marine metal carbonate rock (limestone) into water soluble metal and bicarbonate ions.

The atmospheric methane (CH4) concentration today is 2.5 times higher than before the industrial revolution. Methane spontaneously oxidizes to form more atmospheric CO2. If the present trends continue the atmospheric CO2 concentration will approximately double during this century.

Historically the solar power absorbed by the Earth and the infrared power emitted by the Earth were in approximate balance. The injection of transient CO2 into the atmosphere by combustion of fossil fuels reduces infrared radiation emission by the Earth and hence causes net heat accumulation which in turn causes gradual ocean warming.

As the average ocean temperature rises CO2 comes out of ocean solution which increases the atmospheric CO2 concentration. As a consequence Earth's surface temperature rises.

As Earth's surface and cloud temperatures rise past 273.15 K there is a step decrease in the planetary albedo which causes about a 14 degrees K (14 degrees C) step increase in the steady state atmospheric emission temperature as viewed from outer space. The corresponding 17 degree C step increase in Earth surface temperature at sea level heats the oceans causing additional release of dissolved CO2.

The flux of CO2 into the atmosphere from the oceans due to ocean warming adds to the flux of CO2 into the atmosphere due to combustion of fossil fuels, resulting in a rapid increase in the atmospheric CO2 concentration and hence further ocean warming. This positive feedback driven ocean warming and consequent ocean CO2 emission process continues until new steady state conditions are reached.

The 17 degree C increase in average Earth surface temperature is beyond the adaption capability of most plants and large animal species and hence will cause a major life form extinction. It is of paramount importance that man kind do all necessary to prevent this extinction. Preventing this extinction requires an immediate major reduction in world fossil fuel consumption, particularly by the industrialized countries.

Major energy infrastructure is often financed over a 60 year period and is relied upon for funding pensions and life insurance. Quite apart from the disruption to the transportation, heating, chemical and metal industries consider what will happen to life insurance and old age retirement funding as fossil fuel production is forced to cease. The financial reality is that smooth closure of fossil fuel production is at least a 60 year process. However, an equally blunt reality is that if fossil fuel consumption continues within 15 years Earth will be on the threshold of thermal runaway. At that point concerns about pensions and life insurance will be academic.

In late 2016 we are at a sustained nonequilibrium atmospheric CO2 concentration of over 400 ppmv. The exponential decay time constant of the non-equilibrium portion of the CO2 concentration is over 40 years. Based on experimental data we can reasonably project thermal runaway commencing at an atmospheric CO2 concentration of about 433 ppmv.

Since 1959 the rate of rise of the atmospheric CO2 concentration has almost tripled. In 2013 the atmospheric CO2 concentration rose at about 2.66 ppmv per year. Over the next 15 years the atmospheric CO2 concentration could easily rise at an average of 2 ppmv / year. Hence the atmospheric CO2 concentration will likely reach 433 ppmv, the calculated onset of thermal runaway.

Practical experience has demonstrated that it is unrealistic to assume no increase in fossil fuel consumption by persons in the third world. Third world people have the same aspirations as ourselves and are demanding their share of energy related benefits now. Hence we must be realistic regarding future fossil fuel consumption projections. In order to have any hope of preventing thermal runaway developed nations must immediately cease consumption of fossil fuels. For Ontario to meet this requirement at the projected rate of population increase the installed nuclear power capacity must be increased about 6 fold over a 50 year period.

No other course of action is sustainable. Wind energy is environmentally more desirable, but due to the geography of Ontario it is simply not affordable. The advocates of wind power failed to properly consider the costs of storing wind energy and transmitting wind energy from remote northern generation sites to southern load centers.

At the present time there is nothing in Canadian federal or provincial government policies that addresses the thermal runaway problem. If this matter is not promptly addressed the atmospheric CO2 concentration will rise out of control and there will be a global extinction due to thermal runaway.

Injection of sufficient non-equilibrium CO2 into the Earth's atmosphere via combustion of fossil fuels will trigger a transition from the atmospheric "cool" state to the "warm" state.

As the ocean temperature rises a portion of the dissolved bicarbonate (HCO3)- ions in the oceans will combine with dissolved metal ions and liberate CO2 gas. This CO2 gas emission by the ocean will accelerate the transition from the "cool" state to the "warm" state.

The consequent reduction in infrared energy emission by the Earth will cause heat retention that will completely melt all land borne glaciers, including the Greenland and Antarctic glaciers. As a result of both glacier melting and thermal expansion of the oceans the average sea level will rise about 80 m.

The present densely populated coastal and river delta areas of the Earth will be inundated by the oceans. During the summer months those land areas not inundated will have insufficient fresh water for intense agriculture. The combination of drought, starvation and high temperatures will drive all large animal species, including humans, into extinction.

While the Earth is in the "warm" state ice cannot form, so ice ages cannot occur.

If humans are so foolish as to continue to burn fossil fuels while the Earth is in its "warm" state the quantity of carbon in the ocean-atmosphere pool will gradually increase until after several centuries the Earth is trapped in the warm state. Meanwhile the polar ice caps will melt raising the sea level about 80 m.

The time frame for recovery from warm state trapping via natural processes that remove the excess carbon from the ocean-atmosphere pool and store it in fossil fuels and metal carbonate rocks, is several hundred thousand years.

An early sign of atmospheric warming is melting of mountain snow/ice packs that in the past were relied upon by farmers to provide fresh water for aquifer recharging and for agricultural irrigation during the summer months.

An early sign of ocean warming is melting of the polar floating ice pack.

Addition of CO2 to the atmosphere reduces radiative energy transfer through the Earth's atmosphere from low altitudes to higher altitudes. Instead energy transfer from low altitudes to high altitudes increasingly occurs via atmospheric convection, which produces more violent hurricanes, tornados and similar storms. In recent years violent storm damage has systematically increased.

Most humans have little awareness of average sea level. Most ocean front properties routinely experience a daily sea level change of about 5 m due to normal tides caused by the Earth-Moon gravitational interaction. Ocean front land owners have no easy way of precisely monitoring the average ocean level. Their prime concern is the position of the extreme high tide mark.

Random co-incidence of a normal high tide, a sun-moon-Earth alignment, a low atmospheric pressure due to a local storm center and an on-shore wind causes an extreme high tide. Such an extreme high tide can cause immense property damage in low elevation areas. An example was the extreme high tide that occurred during the landfall of "Super Storm Sandy" in 2012, which caused flood related damage in the US states of New York and New Jersey in excess of $70 billion. Another example was hurricane Katrina in 2005 during which an extreme high tide caused property damage in New Orleans and along the adjacent Gulf Coast in excess of $100 billion.

In recent years sudden extreme rainfall has caused billions of dollars of damage in the Canadian cities of Calgary and Toronto.

Extraordinarily dry conditions caused billions of dollars in fire damage at Fort McMurray in Alberta.

As the atmospheric CO2 concentration increases the frequency and severity of extreme weather events will increase gradually rendering existing coastal areas uninhabitable. During the summer months continental interior areas that previously relied on snowpack fed rivers will have insufficient fresh water for intense agriculture and for fire control. The resulting combination of loss of arable land, drought, starvation, high temperatures and fires will drive many life forms into extinction.

The time remaining until thermal runaway is triggered is barely sufficient for building one generation of nuclear reactors. There is almost no public comprehension of this reality.

Due to mankind's present dependence on fossil fuels, absent immediate world wide implementation of an effective fossil carbon tax, it will likely be impossible to prevent thermal runaway from occurring. The problem is aggravated by fossil fuel producers and their lackeys who are encouraging continued large scale use of fossil fuels under the guise of balancing solar and wind generation. The present low price of natural gas in North America in combination no effective fossil carbon tax is financially preventing conversion from fossil fuels to nuclear power and renewable energy.

John Rudesill

Peter Kelemen at Columbia, U https://www.google.com/search?q=peter+kelemen&rlz=1C1EODB_enUS524US526&sxsrf=ALeKk03xRQOAbgzpjnmkXiCjUw126vFN3w:1619977006555&tbm=isch&source=iu&ictx=1&fir=re5Qdxc_CvfhUM%252C4pYuc3xYN_yGQM%252C_&vet=1&usg=AI4_-kS8kWwcz5LkYZ5gzL1PohM5ZOiYqg&sa=X&ved=2ahUKEwiF9JPQxKvwAhUjEFkFHUtNCS8Q9QF6BAgNEAE#imgrc=re5Qdxc_CvfhUM is doing fascinating work in the deserts of Oman where enormous deposits of alkaline silicate rocks are exposed and directly interact with the CO2 in the air despite the arid environment. Reaction rates when water is provided accelerate dramatically. The rock that is exposed in this location is normally found well below the surface where CO2 could be pumped down into the strata with some water and reacted forming silica and carbonate minerals.

I am sure that he gets support from fossil fuel interests for obvious reasons, but it is not hidden. The amount of this exposed rock in Oman alone is huge. There are several videos to sample. I tried to contact him by email back in November to learn more, but he did not respond. He seems to be pretty straight forward in his videos.

Geologically speaking there is enough of these minerals on the planet to soak up every last molecule of CO2 possible from fossil fuels and bio mass many times over if contact is facilitated. It also suggest that the large deposits of alkaline silicates may have been carbonates that were converted by geologic heat events to the alkaline silicates. If we were really crazy we could take atmospheric CO2 to zero and keep it there. It would be a barren planet, but no more CO2 green house effect.

The Oman surface feature of ophiolite
https://en.wikipedia.org/wiki/Ophiolite#:~:text=An%20ophiolite%20is%20a%20section,texture%20of%20some%20of%20them. contains the CO2 reactive silicates in the serpentinite family https://en.wikipedia.org/wiki/Serpentinite. Note that the chemistry that forms these hydrated silicates from the anhydrous precursors produces H2 inorganically from water. It can generate locally very significant heat that powers hydrothermal vents in the ocean bottom. The H2 can reduce carbonates and sulfates providing building blocks and energy for biology in the anoxic depths.

John Rudesill

Charles Rhodes

Hello John:
You have several times asserted that there is enough of this potentially CO2 absorbing basalt rock to absorb all the present CO2. If that is the case I ask myself why the planet Venus has such an enormous amount of CO2 in its atmosphere? Is it the case that above a certain critical average temperature this CO2 absorption process reverses direction?

If one heats carbonate rock sufficiently it releases CO2. Is it possible that the average temperature of surface rocks in Oman is already above this threshold temperature? I presume that the threshold temperature is different for different carbonate compounds. It will also vary with the atmospheric CO2 concentration. I am wondering if the high CO2 content of Venus' atmosphere is explained by the high surface temperature, which prevents carbonate rock formation. If that is the case, what happened in Earth's history to cool Earth's surface for long enough to allow enough carbonate rock formation to reduce the average temperature sufficiently to allow photosynthesis to commence?

For example, did Earth previously exist in a much larger diameter orbit? If not how did the carbonate rocks come about? It appears to me that if there is enough CO2 in the atmosphere Earth's surface temperature will be locked high like on Venus so that carbonate rocks simply cannot form.

Can one carry this line of reasoning back to the PETM? Is it possible that the high CO2 concentration during the PETM was due to decomposition of a significant fraction of the exposed surface carbonate rock? The average temperature swings were supposedly not that big, but most of the average temperature is determined by the ocean. Suppose that the dry land surface got really hot for a relatively brief period of time, perhaps due to a passing star. The exposed limestone would emit CO2 which would create a runaway atmospheric heating situation. It would take many years for that CO2 to be absorbed by the oceans and then form carbonate rock within the ocean. Ultimately the atmospheric CO2 concentration would diminish enough via ocean absorption that the dry land surface temperature would drop enough for land based biological processes to take over.

This explanation of the PETM makes more quantitative sense to me than simple burning of exposed hydrocarbon matter. It also explains the reason for the dense CO2 atmosphere on Venus.

Maybe the same argument applies in reverse on Mars. If it is cold enough a larger fraction of the CO2 is trapped by surface rock leading to less atmospheric CO2 and hence less heating. Once the Mars surface temperature is too cold for photosynthesis there will be no free oxygen. Hence the CO2 concentration on the surface of Mars displaces oxygen that would otherwise exist.

If this theory makes sense the conditions for life on Earth are in large measure set by the temperature dependence of metal oxide plus CO2 versus metal carbonate formation. If humans add more CO2 to the atmosphere by burning fossil fuels and thus increasing the average temperature the atmospheric CO2 concentration will be amplified by decomposition of exposed carbonate rock. At some point this process will run away as happened during the PETM.

Until we better understand the temperature dependence of the metal oxide plus CO2 versus metal carbonate equilibrium chemical reactions I would be very cautious about believing IPCC projections. My concern is that the situation might be a lot worse than projected by the IPCC. My concern is that while basalt may be effective its exposed surface area is very small compared to more common limestone, so even a small increase in average exposed limestone temperature may completely outweigh the beneficial effect of the basalt.

We do not normally think about the temperature dependence of the partial pressure of CO2 over limestone but maybe we should. Our lives might depend upon it. Surely this is not a difficult experiment to perform. Put a chunk of limestone in a vacuum chamber and exhaust the air. Isolate the vacuum pump. Monitor the partial pressure of CO2. Now gradually heat the limestone and see how temperature affects the partial pressure of CO2. The temperature may need to be cycled a few times due to water of hydration in the rock. There is a tricky balance between:
CaO + H2O = Ca(OH)2
CaO + CO2 = CaCO3.

These same reactions repeat for the other common metals. There are temperature and CO2 concentration dependent equilibria.

Only a small average temperature change may have severe consequences on the equilibrium atmospheric CO2 concentration.

Charles Rhodes

John Rudesill

Thank you for the thought provoking reply. The thermo chemistry governing this mess is that carbonates of Ca and Mg have a higher heat/free energy of formation than do the silicates. That reaction can be reversed by sufficient heat and the fact that CO2 is volatile compared to SiO2. There will be a zone deep in the earth where the pressure is high enough to inhibit even prevent the release of CO2 even if the temperature is high enough to start to reverse the reaction equilibrium. Things get very complicated beyond that. It will take some time to process your remaining questions. Some of your questions may change based on what I just wrote. I find the reaction shown in the one link that releases H2 fascinating. That H2 will reform water for instance if it reduces CO2. The reduced carbon can go all the way to methane over time if there is enough ferrous Fe present. Incidentally, rust is the common FT (Fischer-Tropsch catalyst!) The red rock strata are ferric which is the oxidation product of ferrous iron. FT runs at about 350 C depending on pressures and the exact catalysts. SIgnificant amounts of HC's could have been formed from abiogenic chemistry.

Venus is its own mystery we'll leave that for later. Back to earth. The inner and outer cores of the earth are metallic while the layers leading on up to the surface tend to be well oxidized consisting of oxides, silicates, and carbonates. On whole the earth's make up is reducing, there is insufficient oxygen to fully oxidize all of the reduced core atoms. The earth thus has a net tendency to donate electrons to space though the core is far more reducing than the upper layers and the surface. This creates a charge polarity between the core and the surface. Whether or not there is a charge flow of electrons from the core to the surface is an interesting question. Or does it act more like a spherical capacitor with a spherical dielectric?

Limestone CaCO3 is thermally stable up to around 900 C above which CO2 begins to volatize leaving CaO as the solid product. CO2 is thermally stable up to 2130 C unless chemical reducing agents are present. At temperatures above 100-150 C CO2 pumped down into an aquifer permeating a strata of Ca, Mg silicates would react vigorously creating more heat further accelerating the reaction. If 1st, order the reaction rate doubles for every 10 C increase in temperature provided there are minimal diffusion limitations.

The proto earth likely had no free O2 in the atmosphere. It probably had a very high CO2 level compared to later eras with biology. Due to high temperatures no liquid water could exist on the surface only in the cooled upper atmosphere and perhaps deep in the mantle under extreme pressure. One half life of 40-K would knock down radiation heat from that source as well as reduce the random pockets of fission as the 235-U levels dropped in half from the enriched levels that earth started with compared to today.

When earth had cooled enough for liquid water to persist on the surface, the possibility for carbonates to form from the gaseous CO2 reacting with solid alkaline silicates increased. The opportunity for water mediated proto life forms to appear was at hand. It follows that CO2 levels would begin to decrease at this time and oxygen levels would eventually begin to rise as photosynthetic organisms started to proliferate.

When water molecules are irradiated in the upper atmosphere they are decomposed creating free O atoms that can compliment any O released by photosynthesis. Venus may not have ever had the chance to cool to the point water could condense before the water vapor was lost to space dooming Venus to be a hot place.

In answer to your primary questions, I don't think small changes in temperature at or near the surface of the earth will change the stability of dry meal carbonates. Higher surface temperatures with water present will increase the rate of solid carbonate formation from contacted alkaline silicates. When water is in the mix, the situation get interesting and complicated fast because this includes the biological players in carbonate disposition. Kelemen is working to understand this better. He favors deep aquifer injection of CO2 to form solid carbonates. I concur that the thermodynamics are favorable on a geologic time frame. I think we should try to get him to talk to us and answer questions. He is very busy though.

Best regards
John Rudesill

Apart from the May 2, 2021 email exchange this web page last updated October 31, 2016.

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