carbon-budget.geologist-1011.netVolcanic Carbon Dioxide

eMail directory . Software . Web Design . Geologist Consulting Geologist | Home | About me | Contact me | Site Map | Privacy | Security | Standards | Legal | Timothy Casey B.Sc.(Hons.): Consulting Geologist . Not so Apologetic . Deforestation . Climate . Greenhouse Effect . Volcanic CO 2 . Volcanic CFCs . Expanding Earth . Palaeomagnetism . The Age of the Earth . Fossil Record. Science . Pseudoscience . Genesis . Interpretation . Movies and Books. Most Misquoted Timothy Casey B.Sc. (Hons.) Consulting Geologist Uploaded ISO:2009-Oct-25 Revision 3 ISO:2014-Jun-07 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 of total volcanogenic CO 2 emission, there is no magic fingerprint with which to identify industrially produced CO 2 as there is insufficient data to distinguish the effects of volcanic CO 2 from fossil fuel CO 2 in the atmosphere. Molar ratios of O 2 consumed to CO 2 produced are, moreover, of little use due to the abundance of processes (eg. weathering, corrosion, etc) other than volcanic CO 2 emission and fossil fuel consumption that are, to date, unquantified. Furthermore, the discovery of a surprising number of submarine volcanoes highlights the underestimation of global volcanism and provides a loose basis for an estimate that may partly explain ocean acidification and rising atmospheric carbon dioxide levels observed last century, as well as shedding much needed light on intensified polar spring melts. Based on this brief literature survey, we may conclude that volcanic CO 2 emissions are much higher than previously estimated, and as volcanic CO 2 contributions are effectively indistinguishable from industrial CO 2 contributions, we cannot glibly assume that the increase of atmospheric CO 2 is exclusively anthropogenic. 1.0 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, measurable 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 CO 2 (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 CO 2 degases from volcanoes. This is not such a silly idea given that the source chemistry for lavas contains a surprising amount of carbon dioxide. Along with H 2 O, CO 2 is one of the lightest volatiles (materials of relatively low melting point), found in the mantle (Wilson, 1989). The fluid nature of the aesthenosphere, or upper mantle of the earth, ensures that lighter volatiles are fractionated, buoyed towards the surface, and either extruded or outgassed into the atmosphere via volcanoes and faults. The "solid earth", a term popular amongst climatologists, is a deceptive misnomer as the aesthenosphere is a deeply convecting fluid upon which flexible sheets of crust (i.e. plates) float. This deeply convecting fluid tears these delicate plates apart at rift zones and crushes them together like the bonnet of a wrecked car at convergence zones. Mountains rise out of fold belts resulting from the crumpling of plates, and where differences in plate buoyancy allow, one plate rides over another, forcing the other plate to follow the convection current into the aesthenosphere. Furthermore, this liquid aesthenosphere, which continues to create new crust at rifting zones such as the mid oceanic ridges, melts down subducting crust as the residue of this crust is drawn deeper into the mantle. While volatiles trapped in the remaining crustal residue are ultimately assimilated into the mantle, lighter volatiles from the crustal melt are fractionated and float up towards the surface to feed plate margin volcanoes. Volatiles, such as CO 2 , are more prone to outgassing at the surface via tectonic and volcanic activity because of the fluid nature of the earth. 1.1 The Importance of CO 2 in Volcanic Emissions The importance of juvenile (erupted and passively emitted) volcanic CO 2 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 SO 2 (Wilson, p. 181; Perfit et al., 1980). According to Symonds et al. (1994) CO 2 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 CO 2 (Schneider & Eggler, 1986). Oxidation of subducted carbon sources such as kerogen, coal, petroleum, oil shales, carbonaceous shales, carbonates, etc. into CO 2 and H 2 O makes volcanic CO 2 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 CO 2 enters magma. At continental rift zones, where an entire continent is being pulled apart by divergent mantle convection, magma rising to fill the rift is enriched in CO 2 from deep mantle sources (Wilson, 1989, p. 333). Oldoinyo Lengai is an example of a continental rift zone volcano, which has above average CO 2 outgassing at 2.64 megatons of CO 2 or 720 KtC per annum (Koepenick et al., 1996). If volcanoes produce more CO 2 than industry when they are not erupting, then variations in volcanic activity may go a long way towards explaining the present rise in CO 2 . 1.2 The Location of CO 2 Monitoring Station in regions enriched by volcanic CO 2 Volcanic CO 2 emission raises some serious doubts concerning the anthropogenic origins of the rising atmospheric CO 2 trend. In fact, the location of key CO 2 measuring stations (Keeling et al., 2005; Monroe, 2007) in the vicinity of volcanoes and other CO 2 sources may well result in the measurement of magmatic CO 2 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 its permanent 3.2 MtCO 2 pa 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. Another class of problem for monitoring stations plagues "Christmas Island", which is actually Kiribati Island (02º00’N, 157º20’W) where the Clipperton Fracture Zone (Taylor, 2006) crosses the Christmas Ridge and is nowhere near Christmas Island (10º29’S, 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 & Watts, 2007). Moreover, active fracture zones also offer a preferred escape route for magmatic CO 2 , as this CO 2 also finds its way into aquifers (eg. Giggenbach et al., 1991), which can be cut by fracture zones that consequently provide a path to the surface (Morner & Etiope, 2002). This may raise...