Volcanic Carbon Dioxide

Abstract

A brief survey of the literature concerning volcanogenic carbon dioxide emission finds that estimates of subaerial emission totals fail to account for the diversity of volcanic emissions and are unprepared for individual outliers that dominate known volcanic emissions. Deepening the apparent mystery, there is no magic fingerprint with which to identify industrially produced CO₂ as volcanic CO₂ is isotopically identical. Molar ratios of O₂ consumed to CO₂ produced are likewise of little use because of the abundance of processes other than volcanic CO₂ emission and fossil fuel consumption that are, to date, unquantified. Furthermore, the discovery of a surprising number of submarine volcanoes underscores the underestimation of global volcanism and provides a loose basis for an estimate that explains ocean acidification in the absence of acidification of isolated water reservoirs such as aquariums as well as shedding much needed light on intensified polar spring melts and perhaps even providing an explanation for the rising atmospheric carbon dioxide levels observed last century.

 

Introduction: How Volcanoes make the Carbon Budget Holier than Thou

If we neglect to ask how the greenhouse effect of various gases is quantified in terms of real, measureable thermodynamic properties, the idea of anthropogenic global warming may well survive long enough for us to ask how the carbon budget establishes that observed increases in CO₂ (Keeling et al., 2005) could not be caused by anything other than human activity. Plimer (2001), Wishart (2009), and Plimer (2009) point out that an enormous and unmeasured amount of CO₂ degasses from volcanoes. This is not such a silly idea given that the source chemistry for lavas contains a surprising amount of carbon. The "solid earth", a term popular amongst climatologists, is a very silly misnomer. Flexible fragments of crust, ride upon a deeply convecting fluid aesthenosphere that tears these delicate plates apart at rift zones and crushes them together like the bonnet of a wrecked car at convergeance zones. Mountains rise out of fold belts resulting from the crumpling of plates, and where differences in plate bouyancy allow, one plate rides over another; forcing the other plate to follow the convection current into the aesthenosphere. The liquid aesthenosphere is the upper layer of the mantle and is a tremendously deep ocean of high temperature magmatic fluids, which continues to create new crust at rifting zones such as the mid oceanic ridges, and break down subducting crust; fractionating lighter volatile elements (those forming materials of a lower melting point) as they float up towards the surface to feed plate margin volcanoes, while melting down and reassimilating the remainder. Of course, no process is perfectly efficient, and a small proportion of volatiles enter the mantle. Wilson (1989) provides an excellent evidence-based introduction to plate tectonics.

 

The Importance of CO₂ in Volcanic Emissions

The importance of juvenile (erupted) volcanic CO₂ is due to the fact that carbon, and particularly carbon dioxide has a strong presence in mantle fluids, so much so that it is a more abundant volcanic gas than SO₂ (Wilson, p. 181; Perfit et al., 1980). According to Symonds et al. (1994) CO₂ is the second most abundantly emitted volcanic gas next to steam. Although you might imagine that there is no air in the mantle, the chemical conditions favour oxidation, and shortages of oxygen ions are rare enough to ensure a strong presence of CO₂ (Schneider & Eggler, 1986). Oxidation of subducted carbon sources such as kerogen, coal, petroleum, oil shales, carbonaceous shales, carbonates, etc. into CO₂ and H₂O makes volcanic CO₂ quite variable in back arc and continental margin volcanoes where these volatile gases can be surprisingly abundant (eg. Vulcano & Mount Etna). Subduction isn't the only way CO₂ enters magma. At continental rift zones, where an entire continent is being pulled apart by divergeant mantle convection, magma rising to fill the rift is enriched in CO₂ from deep mantle sources (Wilson, 1989, p. 333) and Oldoinyo Lengai is an example of a continental rift zone volcano. Oldoinyo Lengai has above average CO₂ outgassing at 2.64 megatons of CO₂ or 720 KtC per annum (Koepenick et al., 1996).

If volcanoes produce more CO₂ than industry when they are not erupting, then variations in volcanic activity may well explain the present rise in CO₂.

 

The Location of Co₂ Monitoring Station in regions enriched by volcanic CO₂

Volcanic CO₂ emission raises some serious doubts concerning the anthropogenic origins of the rising atmospheric CO₂ trend. In fact, the location of key CO₂ measuring stations in the vicinity of volcanoes may well result in the measurement of volcanogenic CO₂ rather than a representative sample of the Troposphere. For example, Cape Kumukahi is located in a volcanically active province in Eastern Hawaii while Mauna Loa Observatory is on Mauna Loa, an active volcano - both observatories within 50km of the highly active Kilauea and it's permanent 3.2 MtCO₂pa plume. Samoa is within 50 km of the active volcanoes Savai'i and/or Upolo, while Kermandec Island observatory is located within 10 km of the active Raoul Island volcano.

Observatories located within active volcanic provinces are not the only problem. There is also the problem of pressure systems carrying volcanic plumes several hundred kilometers to station locations. For example, the observatory in New Zealand, located somewhere along the 41^st parallel, is within 250 km of Tanaki and the entire North Island active volcanic province. Low pressure system centres approaching and high pressure system centres departing the Cook Strait will displace volcanic plumes from the North island to the South Island. Then we have La Jolla, which is adjacent to the San Andreas back arc and within 160 km of the active volcano, Salton Buttes. Not only is La Jolla subject to the same kinds of weather modulated volcanic influence on measurements, but it is located at the focal point of a radial fault zone extending seaward from the San Andreas Fault. The implications of a radial fault zone are obvious, and I wouldn't live within 100 km of La Jolla even if I was given the house for free.

Another class of problem for monitoring stations plagues "Christmas Island", which is actually Kiribati Island (10º89'N, 105º38'E) where the Clipperton Fracture Zone (Taylor, 2006) crosses the Christmas Ridge and is nowhere near Christmas Island (10º89'N, 105º38'E; located on the other side of Australia, 10,000 km due west of Kiribati). Christmas Ridge is formed in a concentration of Pacific Seamounts. Extraordinary numbers of seamounts are volcanically active (Hillier et al., 2007), and active fracture zones also offer a preferred escape route for magmatic CO₂.

Amundsen Scott South Pole Station appears to be well separated by 1300 km from the volcanic lineation extending along Antarctica's Pacific Coast (From the Ross Shelf to the Antarctic Peninsula), However, Antarctic Volcanoes are not nearly as well mapped as those in more populated regions such as Japan. In any case the strong cirumpolar winds that delay mixing will inevitably concentrate Antarctica's volcanic CO₂ emissions over the Antarctic continent, including Amundsen Station. The same potential problem exists with the observatory at Alert in Northern Canada, and more importantly, inside the circumpolar wind zone along with the Arctic Rift and thousands of venting sea mounts along key parts of the Northwest Passage.

That leaves us with Point Barrow, arguably the only CO₂ monitoring station whose CO₂ measurements are unlikely to be influenced by volcanic emissions. However, the Canada Basin is also referred to as "the Hidden Ocean" because of poor access which consequently leaves us with very little information about the sea floor in this region. The high probability of active seamounts in the vicinity of Point Barrow has not been ruled out, and in view of the fact that the other observatories must experience significant skew due to volcanic CO₂, it would not be unreasonable to remain skeptical until this possibility has been ruled out.

This question of volcanic skew to CO₂ measurements has been raised a number of times, in addition to other more serious allegations (Bacastow, 1981; Jaworowski et al., 1992; Segalstad, 1996).

 

Calculated Estimates: Glorified Guesswork

Gerlach (1991) estimates volcanic CO₂ emissions total 55 MtCpa globally and evenly distributed between subaerial and submarine volcanism. Kerrick (2001) takes a grand total of 19 subaerial volcanoes, which on p. 568 is described as only 10% of "more than 100 subaerial volcanoes". It was interesting to observe that Kerrick (2001) leaves out some of the more notable volcanoes (eg. Laki, Tambora, Krakatoa, Mauna Loa, Pinatubo, El Chichon, Katmai, Vesuvius, Agung, Toba, etc.). Nevertheless, based on these assumptions Kerrick calculates 2.0-2.5 x 10¹² mol of annual CO₂ emissions from all subaerial volcanoes and understates the estimate on the assumption that the sample is from the most active demographic. This is in spite of the fact that eight of the world's ten most active volcanoes are omitted from Kerrick's study (Klyuchevskoy Karymsky, Shishaldin, Colima, Soufriere Hills, Pacaya, Santa Maria, Guagua Pichincha, & Mount Mayon). At 44.01g/mol, 2.0-2.5 x 10¹² mol of CO₂ amounts to a total of 24-30 MtCpa - less than 0.05% of total industrial emissions. My main criticism of Kerrick's guess is that it putatively covers only 10% of a highly variable phenomenon on land, and with the cursorary dismissal of mid oceanic ridge emissions, ignores all other forms of submarine volcanism altogether. If we take the Smithsonian list of 1500 active subaerial volcanoes worldwide, Kerrick's 10% is reduced to 1.3%.

The subsequent finding of Werner & Brantley (2003) is hardly surprising. The Yellowstone volcanic province produces 6-7 x 10¹² mol of annual CO₂ (72-84 MtCpa), which is about three times more CO₂ than the total subaerial volcanic emission of Kerrick (2001) and Gerlach (1991). It just goes to show that consensus is political, not scientific. Need I point out that volcanic systems are diverse and unpredictable and cannot be statistically second-guessed for the same reason that lottery numbers cannot be statistically second-guessed - as the findings of Werner & Brantley so spectacularly demonstrate.

According to Batiza (1982), Pacific mid-plate seamounts number betwen 22,000 and 55,000 with 2,000 active. None of the more than 2,000 active submarine volcanoes have been discussed in Kerrick (2001). Furthermore, Kerrick (2001) justifies the omission of mid oceanic ridge emissions by claiming that mid oceanic ridges discharge less CO₂ than is consumed by mid oceanic ridge hydrothermal carbonate systems. In point of an interesting of fact, CO₂ escapes carbonate formation in these hydrothermal vent systems in such quantities that, under special conditions, it accumulates in submarine lakes of liquid CO₂ (Sakai, 1990; Lupton et al., 2006; Inagaki et al., 2006). Although these lakes are prevented from escaping directly to the surface or into solution in the ocean, there is nothing to prevent superheated CO₂ that fails to condense from dissolving into the seawater or otherwise making its way to the surface. It is a fact that a significant amount of mid oceanic ridge emissions are not sequestered by hydrothermal processes; a fact which is neglected by Kerrick (2001), who contends that mid oceanic ridges may be a net sink for CO₂. This may well sound reasonable except for the rather small detail that seawater in the vicinity of hydrothermal vent systems is saturated with CO₂ (Sakai, 1990) and as seawater elsewhere is not saturated with CO₂, it stands to reason that this saturation is sourced to the hydrothermal vent system. If the vent system consumed more CO₂ than it emitted, the seawater in the vicinity of hydrothermal vent systems would be CO₂ depleted.

Morner & Etiope (2002) published a somewhat more representative estimate of subaerial volcanogenic CO₂ output based on a more comprehensive selection and found as a bare minimum that subaerial volcanogenic CO₂ emission is on the order of 163MtCpa. Morner & etiope (2002) also provide a much better explanation of how CO₂ is cycled through the mantle and the lithosphere.

 

Abusing Doctor Suess: Pulling the Cat out of the Hat

So far, the evidence presents the rather tantalising implication that volcanogenic CO₂ emission is a significant if not dominant contributor to atmospheric CO₂ levels. The next logical step for those trying to prove that the CO₂ rise is anthropogenic is to find a signature to fingerprint anthropogenic CO₂ as seperate from all other sources of CO₂. The research of one Hans Suess into the contamination of ¹⁴C dates by variations in normal atmospheric ¹⁴C was seized upon because fossil fuels, being too old to contain measurable amounts of this cosmogenic isotope, will deplete atmospheric concentrations of ¹⁴C when burned. In Cleveland & Morris (2006, p. 427) Hans Suess and the Suess Effect, used to account for contamination of radiocarbon dates by recent phenomena, are given the following entries:

Suess, Hans   1909-1993, U.S Chemist who developed an improved method of carbon-14 dating and used it to document that the burning of fossil fuels had a profound influence on the earth's stocks and flows of carbon. (Fossil fuels are so ancient that they contain no C-14.)

Suess Effect   Climate Change. a relative change in the ratio of C-14/C or C-13/C for a carbon pool reservoir; this indicates the addition of fossil fuel CO₂ to the atmosphere.

This is hardly surprising given that this kind of assumption has quite some history in the literature. According to Tans et al (1979):

THE dilution of the atmospheric ¹⁴CO₂ concentration by large amounts of fossil-fuel derived CO₂ which do not contain any ¹⁴C is commonly called the Suess effect. Its magnitude can be calculated with the same geochemical models as the global carbon cycle that also predict the future rise of atmospheric CO₂ to be caused by the combustion of fossil fuels.

Keeling (1979) concurs with a bizarre emphasis on "formulating models rather than surveying and interpreting data". This reflects the rather general attitude amongst anthropogenic global warming proponents that the Suess Effect fingerprints the rising atmospheric carbon dioxide as the exclusive product of fossil fuel combustion. Does such a narrow interpretation concur with the original author's idea? Suess (1955), who first proposes the idea that fossil fuels may contaminate the carbon isotope reservoir with adverse effects on carbon dating methods, estimates that fossil fuel CO₂ accounted for less than 1% of carbon isotope reservoir contamination. In other words, Suess acknowledged that other sources of contamination played a much larger role, but authors with a political agenda ignored this rather important point. Moreover, insistent on correcting the "misleading" arguments of Durkin (2007) in their 2007 glossy handout, Climate Change Controversies: a simple guide, the Royal Society gets its name plastered to this evident faux pas:

In contrast to this natural process, we know that the recent steep increase in the level of carbon dioxide – some 30 per cent in the last 100 years – is not the result of natural factors. This is because, by chemical analysis, we can tell that the majority of this carbon dioxide has come from the burning of fossil fuels.

Suffice it to point out the fact that isotopic analysis is not chemical analysis, moreover would I go so far as to suggest that the same basin sediment kerogen (the carbon source for oil) in addition, no doubt, to some petroleum reservoirs have been subducted and are the major source for volcanic CO₂ emissions at continental margins. Due to the fact that the subduction zone is where crustal material enters the mantle, subducted carbon reservoirs would represent the youngest magmatic source of CO₂. Given the confirmed presence of carbon and particularly CO₂ enriched fluids in magma and lava (Wilson, 1989), one may well ask if it would not be so irrational to suppose that volcanogenic carbon released at continental margins (closest to the subduction zone) is very old; far too old in fact to contain any measureable amount of ¹⁴C. Mantle carbon and CO₂ is vastly older still, as longer lived cosmogenic isotopes such as ¹⁰Be can be used to confirm the speed of mantle convection. In fact, Clark & fritz (1997) document that there is no volcanic emission of ¹⁴C.

This bears on a peculiar twist in the use and abuse of the Suess Effect. The process of photosynthesis favours the assimilation of ¹²C into plant tissue during growth, which has the consequence of enriching the atmosphere with ¹³CO₂ (Furquhar et al., 1989). This is used to differentiate between terrestrial and oceanic CO₂ sources (Keeling et al., 2005). Moreover, plant based fossil fuel derivatives are therefore considered to be ¹³C depleted. Following this line of logic, fossil fuel emissions should be ¹³CO₂ depleted as well. In fact, the Keeling (1979) article expands its internal definition of the Suess Effect to include this observation, once again to the exclusion of volcanic influence. Continental margin and back arc volcanoes also source their carbon from the ¹³C depleted mantle. Thus we can expect most continental margin and back arc volcanic emissions to be ¹³CO₂ depleted, just like fossil fuel emissions. As it turns out, there are many examples of ¹³C depleted back arc and margin setting volcanic emissions (eg. Giggenbach et al., 1991; Sano et al., 1995).

Although many significant carbonates are not ¹³C depleted, they are eventually subducted along with organic carbon sources depleted in ¹³C while plants continue to enrich the atmosphere in ¹³C. The consequence is that with time, the mantle also becomes ¹³C depleted. This too is solidly confirmed by a number of studies of deep mantle rocks (Deines et al., 1987; Catigny et al., 1997; Zheng et al., 1998; Puustinen & Karhu, 1999; Ishikawa & Marayuma, 2001; Statchel & Harris, 2009). As a consequence of ¹³C depletion in the atmosphere, ¹²C is enriched in the atmosphere. Fossil fuel emissions of CO₂ are not the only ¹³C depleted sources that enrich the atmosphere in ¹²C. Volcanic CO₂ emissions, being ¹³C depleted also enrich the atmosphere in ¹²C. This makes the CO₂ emissions of volcanic origin isotopically identical to those of fossil fuel emissions. It is therefore unsurprising to find that Segalstad (1998) points out that 96% of atmospheric CO₂ is isotopically indistinguishable from volcanic degassing. So much for the Royal Society's "chemical analysis", whatever anytical method that is supposed to be! If you believe we know enough about volcanic gas compositions to distinguish them chemically from fossil fuel combustion, you have indeed been mislead. As we shall see, the number of active volcanoes is unknown, never mind a tally of gas signatures belonging to every active volcano. We have barely scratched the surface and as such, there is no magic fingerprint that can distinguish betwen anthropogenic and volcanogenic sources of CO₂.

 

The Rise and Fall of Oxygen

Manning et al., (1999) find, as an average at La Jolla, that 1.3 mol of O₂ are consumed for every mol of CO₂ produced. They point out that if all atmospheric CO₂ was produced by the combustion of fossil fuels, this result would be 1.44 mol of O₂ are consumed for every mol of CO₂ produced. Cellular respiration as a simplified reaction is as follows:

C₆H₁₂O₆ (aq) + 6 O₂ (g) → 6 CO₂ (g) + 6 H₂O

Photosynthesis does not throw out the balance of cellular respiration following the same molar ratios of CO₂ and O₂ in play:

6 CO₂ (g) + 6 H₂O → C₆H₁₂O₆ (aq) + 6 O₂ (g)

As you can see, the net effect of respiration is to lower the number of mols of O₂ consumed for every mol of CO₂ produced with no skew introduced by photosynthetic consumption of CO₂. Volcanoes, once again ignored by Manning et al (1999), produce CO₂ freely without any observable O₂ consumption in passive emission (although active emissions may well consume significant amounts of O₂, the mystery of the loss of half the atmosphere's oxygen 250 million years also remains unsolved - see Berner et al, 2003). Although we can't clearly identify exactly what amount of atmospheric O₂ is consumed for every mol of volcanogenic CO₂ released to the atmosphere, we can say that volcanogenic emissions reduce this ratio towards a figure substantially less than unity. The argument is therefore made that because we don't see a significantly lower ratio, volcanogenic CO₂ cannot possibly be very much. However this neglects common oxidation reactions that consume O₂ without producing any CO₂. For example:

4 FeSiO₃ + 2 O₂ + 2 H₂O → 4 FeO(OH) + 4 SiO₂

Weathering and the successive oxidation of elements like iron from minerals such as pyroxenes and amphiboles are a major example of how oxygen is consumed without producing carbon dioxide, because carbon is not the only element on the planet that preferentialy combines with oxygen. Such reactions drive the number of mol of O₂ consumed per mol of CO₂ produced higher. As you can see, it is not only fossil fuels that drive this ratio in this direction, and it is a simpler matter to more comprehensively measure volcanic CO₂ output to determine whether volcanoes are indeed a significant CO₂ contributor.

 

Those Mysteriously Fuming Oceans of Acid

Archer (2009, pp. 114-124) describes the chemistry of CO₂ acidification of seawater and proposes that ocean acidification will stress marine fisheries and may cause the destruction of coral reefs. However, it remains a mystery as to why, if atmospheric CO₂ is acidifying the oceans, it is not acidifying inland water reservoirs - particularly fresh water reservoirs in lakes, dams, ponds, billabongs, swimming pools, and aquariums that are not formed as part of a volcanic province (Eg. The Blue Lake in the crater of Mount Gambier is acidifying due to volcanogenic CO₂ input - which shows that Mount Gambier is not quite so dormant as you may have been lead to believe). In fact, the lack of aquarium acidification is well known in the industry that supplies the pumps which aerate the water. Unexpectedly, there is no demand for for any filtering equipment to remove the carbon dioxide from air pumped into aquarium water. If it is really true that the oceans are acidifying at the present time, then given that isolated water reservoirs and aquariums are not acidifying, the source cannot be common to both. This would exclude atmospheric carbon dioxide as a potential source of oceanic acidification.

 

Plimer Strikes Again: 139,000 Intraplate Volcanos Leaking CO₂ into the Ocean

Until reading Hillier & Watts (2007), I would have estimated that the oceans, occupying twice the surface area of land, would have twice the number of volcanoes. Given the update of Werner & Brantley (2003), which raises the estimate of subaerial volcanogenic CO₂ from 27±3 MtCpa to 105±9 MtCpa, this would seem to imply roughly 200 MtCpa from submarine volcanogenic CO₂ and brings the total estimate of lithospheric CO₂ in line with the bare minimum determined by Morner & Etiope (2002). Plimer (2001), and Plimer (2009) maintains that the amount of CO₂ from volcanoes is enormous, and without estimating an amount suggests that it dwarfs anthropogenic contributions. If we take the updated estimate, correct the conservative bias, and extend to submarine environments we still wind up with a figure around 1.575 GtCpa for total passive volcanic emissions (excluding imponderables such as mid oceanic ridge emissions) and that is still only 20% of the 7.8 GtCpa attributed to anthropogenic CO₂ emissions. As it turns out, there is alot more to the distribution of volcanoes across different tectonic settings, and Plimer (2009) omits the rather small detail of a 2007 paper presenting primary evidence that underpins his claim in spectacular fashion.

Hillier & watts (2007) surveyed 201,055 submarine volcanoes estimating a total of 3,477,403 submarine volcanoes exist worldwide. According to the observations of Batiza (1982), at least 4% of seamounts are active. We can expect a higher precentage in the case of the Hillier & Watts (2007) count because it includes smaller, younger seamounts; a higher proportion of which will be active. Nevertheless, in the spirit of caution, I estimate 139,096 active submarine volcanoes worldwide. If we are to assume that Kilauea is a typical mid oceanic plate volcano, with a typical mid oceanic emission of 870 KtCpa (Kerrick, 2001), then we might estimate a total submarine volcanogenic CO₂ output of 121 GtCpa. Even using the Kerrick (2001) and Gerlach (1991) assumption that we've only noticed the biggest to curb our estimate accordingly, we still have 24.2 GtCpa of submarine volcanic origin. This would certainly go some way to explain a mysterious acidification of the oceans that is as yet not observed in reservoirs isolated from volcanic input.

If guesses of this order are anywhere near the ballpark, then we can take it that either what has beeen absorbing all this extra CO₂ is not absorbing as much or there has been some variation to volcanic output over the past 500 years of so. Both are normal assmuptions given the variable state of the natural environment, and considering that vegetation consumed something on the order of 38GtCpa more in 1850 than today (see my Deforestation article for the quick and dirty calculation), it is hardly surprising that we were missing a large natural CO₂ source in the carbon budget. The other disturbing possibility is that both Werner et al (2000) and Werner & Brantley (2003) are correct with the implication that volcanogenic CO₂ emissions are increasing rapidly. This certainly would explain steadily rising CO₂ observed at stations in regions most affected by volcanic emissions, it would explain the recent increase in ocean acidification, and further it would explain the more intense Spring melting centred on the Pacific Coast of Antarctica and along the Gakkel Ridge under the Arctic ice cap.

 

Conclusion: Three Million Volcanoes "Can't be Wrong"

Irrespective that other authors may neglect to allow for volcanogenic CO₂, volcanoes represent an enormous CO₂ source that is mostly submarine, and this is strongly supported by the isolation of water acidification to only those seas, oceans and reservoirs with direct volcanic input. Furthermore, volcanic activity beneath both ice caps and localised to the regions of most intense melting has demonstrated an obvious cause of stronger Spring melts at the Poles. The NorthWest Passage was evidently opened up by powerful volcanic activity under the Arctic Ice along the Gakkel Ridge (Sohn et al., 2008; Reves-Sohn et al., 2008), while West Antarctic melting (as opposed to thickening of ice throughout the rest of Antarctica) can be explained by recent volcanic activity beneath the ice (Corr & Vaughan, 2008). Moreover, there are simply too many volcanoes to deny that the atmospheric concentration of the most erupted gas next to water is predominantly controlled by the balance or lack thereof between volcanic activity and photosynthesis.

 

Bibliography

Bacastow, R., 1981, "Numerical evaluation of the evasion factor" In: B. Bolin [Editor]: Carbon cycle modelling (SCOPE 16). John Wiley & Sons, pp. 95-101

Batiza, R., 1982, "Abundances, distribution and sizes of volcanoes in the Pacific Ocean and implications for the origin of non-hotspot volcanoes", Earh & Planetary Science Letters, Vol. 60, pp. 195-206

Berner, R. A., Beerling, D. J., Dudley, R., Robinson, J. M., & Wildman Jr., R. A., 2003, "Phanerozoic Atmospheric Oxygen", Annual Review of Earth and Planetary Sciences, Vol. 31, pp. 105-134.

Catigny, P., Boyd, S. R., Harris, J. W., & Javoy, M., 1997, "Nitrogen Isotopes in Peridotitic Diamonds from Fuxian, China: the Mantle Signature", Terra NovaVol. 9, pp. 175-179

Clark, I., & Fritz, P., 1997, Environmental Isotopes in Hydrogeology, Lewis Publishers, Boca Raton

Cleveland, C. J., & Morris, C., 2006, Dictionary of Energy, ISBN13: 978-8-1312-0536-5

Corr, H. F. J., & Vaughan, D. G., 2008, "A recent volcanic eruption beneath the West Antarctic ice sheet", Nature Geoscience, Vol. 1, pp. 122-125

Deines, P. Harris, J. W., & Gurney, J. J., 1987, "Carbon isotopic composition, nitrogen content and inclusion composition of diamonds from Roberts Victor kimberlite, South Africa: Evidence for 13C depletion in the mantle", Geochimica et Cosmochimica Acta, Vol. 51, pp. 1227-1243

Farquhar, G. D., Ehleringer, J. R., & Hubick, K. T., 1989. "Carbon isotope discrimination and photosynthesis", Annual Review Plant Physiology and Molecular Biology, Vol. 40, pp. 503–537

Gerlach, T. M., 1991, "Present-day CO₂ emissions from volcanoes", Eos, Transactions, American Geophysical Union, Vol. 72, pp. 249-255.

Giggenback, W. F., Sano, Y., & Schmincke, H. U., 1991, "CO₂-rich gases from Lakes Nyos and Monoun, Cameroon; Laacher See, Germany; Dieng, Indonesia, and Mt. Gambier, Australia—variations on a common theme", Journal of Volcanology and Geothermal Research, Vol. 45, pp. 311-323.

Hillier, J. K., & Watts, A. B., 2007, "Global distribution of seamounts from ship-track bathymetry data", Geophysical. Research. Letters, Vol. 34, L13304, doi:10.1029/2007GL029874

Inagaki, F., Kuypers, M. M. M., Tsunogai, U., Ishibashi, J. i., Nakamura, K. i., Treude, T., Ohkubo, S., Nakaseama, M., Gena, K., Chiba, H., Hirayama, H., Nunoura, T., Takai, K., Jørgensen, B. B., Horikoshi, K., & Boetius, A., 2006, "Microbial community in a sediment-hosted CO2 lake of the southern Okinawa Trough hydrothermal system", Proceedings of the National Academy of Sciences of the United States of America, Vol. 103, pp. 14164-14169

Ishikawa, A., & Maruyama, S., 2001, "Compositional Variability of the Roberts Victor Eclogites: Evidence for Mantle Metasomatism Involving Diamond Destruction", UHPM Workshop 2001 at Waseda University Tokyo Institute of Technology, Faculty of Science, Department of Earth & Planetary Sciences

Jaworowski, Z., Segalstad, T.V. & Hisdal, V., 1992, Atmospheric CO₂ and global warming: a critical review; 2nd revised edition. Norsk Polarinstitutt, Meddelelser [Norwegian Polar Institute, Memoirs] 119

Keeling, C. D., 1979, "The Suess Effect: ¹³Carbon-¹⁴Carbon Interrelations", Environment International, Vol. 2, pp. 229-300

Keeling, C. D., Piper, S. C., Bacastow, R. B., Wahlen, M., Whorf, T. P., Heimann, M., & Meijer, H. A., 2005, "Atmospheric CO₂ and ¹³CO₂ exchange with the terrestrial biosphere and oceans from 1978 to 2000: observations and carbon cycle implications", in J. T. Ehleringer et al., [Editors], A history of atmospheric CO2 and its effects on plants, animals, and ecosystems, Springer

Kerrick, D. M., 2001, "Present and Past Nonanthropogenic CO2 Degassing From the Solid Earth", Reviews of Geophysics, Vol. 39, pp. 565-586

Koepenick, K. W., Brantley, S. L., Thompson, M. L., Rowe, G. L., Nyblade, A. A., & Moshy, C., 1996, "Volatile emissions from the crater and flank of Oldoinyo Lengai volcano, Tanzania", Journal of Geophysical Research, Vol. 101(B6), pp. 13,819–13,830

Lupton, J., Butterfield, D., Lilley, M., Evans, L., Nakamura, K., Chadwick Jr., W., Resing, J., Embley, R., Olson, E., Proskurowski, G., Baker, E., de Ronde, C., Roe, K., Greene, R., Lebon, G., & Young, C., 2006, "Submarine venting of liquid carbon dioxide on a Mariana Arc volcano", Geochemistry Geophysics Geosystems: an electronic journal of the earth sciences, Vol. 7, Q08007, doi:10.1029/2005GC001152

Manning, A. C., Keeling, R., F., & Severinghaus, J. P., 1999, "Precise atmospheric oxygen measurements with a paramagnetic oxygen analyzer", Global Biogeochemical Cycles, Vol. 13, pp. 1107-1117

Morner N. A., Etiope, G, 2002, "Carbon degassing from the lithosphere", Global and Planetary Change, Vol. 33, pp. 185-203

Perfit, M. R., Gust, D. A., Bence, A. E., Arculus, R. J., & Taylor, S. R., 1980, "Chemical characteristics of island arc basalts: implications for mantle sources", Chemical Geology, Vol. 30, pp. 227-256.

Plimer, I. R., 2001, a short history of planet earth, 250 pp., ISBN13: 978-0-7333-1004-0

Plimer, I. R., 2009, Heaven and Earth: Global Warming, the Missing Science, 503 pp., ISBN13: 978-1-9214-2114-3

Puustinen, K., & Karhu, J.A., 1999 "Geological Survey of Finland, Current Research 1997-1998", in S.Autio, [Editor], Geological Survey of Finland, Special Papers, Vol. 27, pp. 39-41

Reves-Sohn, R., Willis, C., Humphris, S., Shank, T., Singh, H., Edmonds, H., Nakamura, K., Schlindwein, V., Soule, S., 2008, "Explosive volcanism on the ultraslow-spreading Gakkel Ridge, Arctic Ocean", Geophysical Research Abstracts, Vol. 10, EGU2008-A-02442, SRef-ID: 1607-7962/gra/EGU2008-A-02442, EGU General Assembly

Sakai, H., Gamo, T., Kim, E. S., Tsutsumi, M., Tanaka, T., Ishibashi, J., Wakita, H., Yamano, M., & Oomori, T., 1990, "Venting of Carbon Dioxide-Rich Fluid and Hydrate Formation in Mid-Okinawa Trough Backarc Basin", Science, v. 248, pp. 1093-1096

Sano, Y., Gamo, T., Notsu, K., & Wakita, H., 1995, "Secular variations of carbon and helium isotopes at Izu-Oshima Volcano, Japan", Journal of Volcanology and Geothermal Research, Vol. 64, pp. 83-94

Schneider, M. E., & Eggler, D. H., 1986, "Fluids in Equilibrium with Peridotite Minerals: Implications for Mantle Metasomatism", Geochimica et Cosmochimica Acta, Vol. 50, pp. 711-724

Segalstad, T.V., 1996, "The distribution of CO₂ between atmosphere, hydrosphere, and lithosphere; minimal influence from anthropogenic CO₂ on the global "Greenhouse Effect". In J. Emsley [Editor]: The Global Warming Debate; The report of the European Science and Environment Forum Bourne Press, Ltd., Bournemouth, Dorset, UK, pp. 41-50.

Segalstad, T. V., 1998, "Carbon cycle modelling and the residence time of natural and anthropogenic atmospheric CO2: on the construction of the "Greenhouse Effect Global Warming" dogma.", in R. Bate [Editor]: Global Warming: The Continuing Debate, European Science and Environment Forum (ESEF), Cambridge, England, pp. 184-219, ISBN10: 0-9527-7342-2

Sohn, R. A., Willis, C., Humphris, S., Shank, T. M., Singh, H., Edmonds, H. N., Kunz, C., Hedman, U., Helmke, E., Jakuba, M., Liljebladh, B., Linder, J., Murphy, C., Nakamura, K., Sato, T., Schlindwein, V., Stranne, C., Tausenfreund, M., Upchurch, L., Winsor, P., Jakobsson, M., & Soule, A., 2008 "Explosive volcanism on the ultraslow-spreading Gakkel ridge, Arctic Ocean", Nature, Vol. 453, pp. 1236-1238

Statchel, T., & Harris, J. W., 2009, "Formation of diamond in the Earth's mantle", Journal of Physics: Condensed Matter, Vol. 21, 364206, doi: 10.1088/0953-8984/21/36/364206

Suess, H. E., 1955, "Radiocarbon Concentration in Modern Wood", Science, Vol. 122, pp. 415-417

Symonds, R. B., Rose, w. I., Bluth, G., & Gerlach, T. M., 1994, "Volcanic gas studies: methods, results, and applications", in M. R. Carroll & J. R. Holloway [Editors], Volatiles in Magmas: Mineralogical Society of America Reviews in Mineralogy, Vol. 30, pp. 1-66

Tans, p. P., de Jong, A. F. M., &Mook, W. G., 1979, "Natural atmospheric ¹⁴C variation and the Suess effect"Nature, Vol. 280, pp. 826-828

Taylor, B., 2006, "The single largest oceanic plateau: Ontong Java–Manihiki–Hikurangi", Earth and Planetary Science Letters, Vol. 241, pp. 372-380.

Werner, C., Brantley, S. L., & Boomer, K., 2000"CO₂ emissions related to the Yellowstone volcanic system: Statistical sampling, total degassing, and transport mechanisms", Journal of Geophysical Research, Vol. 105(B5), pp. 10,831–10,846

Werner, C., & Brantley, C., 2003, "CO₂ Emissions from the Yellowstone Volcanic System", Geochemistry Geophysics Geosystems: an electronic journal of the earth sciences, Vol. 4, 1061, doi:10.1029/2002GC000473

Wilson, M., 1989, Igneous Petrogenenis: A Global Tectonic Approach., ISBN13:978-0-4125-3310-5

Wishart, I., 2009, Air Con: The Seriously Inconvenient Truth about Global Warming, ISBN13: 978-0-9582-4014-7

Zheng, Y.-f, Gong, B., Fu, B., Li, Y., 1998, "Extreme ¹³C depletion in ultrahigh pressure eclogites from the Dabie and Sulu terranes in China", Mineralogical Magazine, vol. 62A, pp. 1698-1699; DOI: 10.1180/minmag.1998.62A.3.223