Saturday, October 25, 2008

Carbon Dioxide, Ocean Acidification And Global Warming

Here is another geological, or geochemical explanation of why slightly increasing levels of carbon dioxide are not going to destroy planet Earth. Are mankinds carbon dioxide emissions causing global warming and climate change? Impossible.

Not Enough CO2 in Fossil Fuels to Make Oceans Acidic: A Note from Professor Plimer
Posted by admin, October 24th, 2008 - under Opinion.Tags: ,
In response to a question concerning the likelihood of our oceans becoming acidic from global warming Ian Plimer, University of Adelaide, has replied:

THE oceans have remained alkaline during the Phanerozoic (last 540 million years) except for a very brief and poorly understood time 55 million years ago.

Rainwater (pH 5.6) reacts with the most common minerals on Earth (feldspars) to produce clays, this is an acid consuming reaction, alkali and alkaline earths are leached into the oceans (which is why we have saline oceans), silica is redeposited as cements in sediments, the reaction consumes acid and is accelerated by temperature (see below).

In the oceans, there is a buffering reaction between the sea floor basalts and sea water (see below). Sea water has a local and regional variation in pH (pH 7.8 to 8.3). It should be noted that pH is a log scale and that if we are to create acid oceans, then there is not enough CO2 in fossil fuels to create oceanic acidity because most of the planet’s CO2 is locked up in rocks.
When we run out of rocks on Earth or plate tectonics ceases, then we will have acid oceans.
In the Precambrian, it is these reactions that rapidly responded to huge changes in climate (-40 deg C to +50 deg C), large sea level changes (+ 600m to -640m) and rapid climate shifts over a few thousand years from ’snowball’ or ’slushball’ Earth to very hot conditions (e.g. Neoproterozoic cap carbonates that formed in water at ~50 deg C lie directly on glacial rocks). During these times, there were rapid changes in oceanic pH and CO2 was removed from the oceans as carbonate. It is from this time onwards (750 Ma) that life started to extract huge amounts of CO2 from the oceans, life has expanded and diversified and this process continues (which is why we have low CO2 today.

The history of CO2 and temperature shows that there is no correlation.
Ask your local warmer:
1. Why was CO2 15 times higher than now in the Ordovician-Silurian glaciation?

2. Why were both methane and CO2 higher than now in the Permian glaciation?

3. Why was CO2 5 times higher than now in the Cretaceous-Jurassic glaciation?

The process of removing CO2 from the atmosphere via the oceans has led to carbonate deposition (i.e. CO2 sequestration).

The atmosphere once had at least 25 times the current CO2 content, we are living at a time when CO2 is the lowest it has been for billions of years, we continue to remove CO2 via carbonate sedimentation from the oceans and the oceans continue to be buffered by water-rock reactions (as shown by Walker et al. 1981).

The literature on this subject is large yet the warmers chose to ignore this literature.
These feldspar and silicate buffering reactions are well understood, there is a huge amount of thermodynamic data on these reactions and they just happened to be omitted from argument by the warmers.

When ocean pH changes, the carbon species responds and in more acid oceans CO2 as a dissolved gas becomes more abundant.

Royer, D. L., Berner, R. A. and Park, J. 2007: Climate sensitivity constrained by CO2 concentrations over the past 420 million years. Nature 446: 530-532.
Bice, K. L., Huber, B. T. and Norris, R. D. 2003: Extreme polar warmth during the Cretaceous greenhouse? Paradox of Turonian ∂18O record at Deep Sea Drilling Project Site 511. Palaeoceanography 18:1-11.
Veizer, J., Godderis, Y. and Francois, L. M. 2000: Evidence for decoupling of atmospheric CO2 and global climate during the Phanerozoic eon. Nature 408: 698-701.
Donnadieu, Y., Pierehumbert, R., Jacob, R. and Fluteau, F. 2006: Cretaceous climate decoupled from CO2 evolution. Earth and Planetary Science Letters 248: 426-437.
Hay, W. W., Wold, C. N., Soeding, E. and Floegel, S. 2001: Evolution of sediment fluxes and ocean salinity. In: Geologic modeling and simulation: sedimentary systems (Eds Merriam, D. F. and Davis, J. C.),
Kluwer, 163-167.Knauth, L. P. 2005: Temperature and salinity history of the Precambrian ocean: implications for the course of microbial evolution. Palaeogeography, Palaeoclimatology, Palaeoecology 219: 53-69.
Rogers, J. J. W. 1996: A history of the continents in the past three billion years. Journal of Geology 104: 91-107.
Velbel, M. A. 1993: Temperature dependence of silicate weathering in nature: How strong a negative feedback on long-term accumulation of atmospheric CO2 and global greenhouse warming? Geology 21:1059-1061
Kump, L. R., Brantley, S. L. and Arthur, M. A. 2000: Chemical weathering, atmospheric CO2 and climate. Annual Review of Earth and Planetary Sciences 28: 611-667.
Gaillardet, J., Dupré, B., Louvat, P. and Allègre, C. J. 1999: Global silicate weathering and CO2 consumption rates deduced from the chemistry of large rivers. Chemical Geology 159: 3-30.
Berner, R. A., Lasagna, A. C. and Garrels, R. M. 1983: The carbonate-silicate geochemical cycle and its effect on atmospheric carbon dioxide over the past 100 million years. American Journal of Science 283: 641-683.
Raymo, M. E. and Ruddiman, W. F. 1992: Tectonic forcing of late Cenozoic climate. Nature 359: 117-122.Walker, J. C. B., Hays, P. B. and Kasting, J. F. 1981: A negative feedback mechanism for the long term stabilization of the Earth’s surface temperature. Journal of Geophysical Research 86: 9776-9782.
Berner, R. A. 1980: Global CO2 degassing and the carbon cycle: comment on ‘Cretaceous ocean crust at DSDP sites 417 and 418: carbon uptake from weathering vs loss by magmatic activity.” Geochimica et Cosmochimica Acta 54: 2889.
Schwartzman, D. W. and Volk, T. 1989: Biotic enhancement of weathering and the habitability of Earth. Nature 311: 45-47.
Berner, R. A. 1980: Global CO2 degassing and the carbon cycle: comment on ‘Cretaceous ocean crust at DSDP sites 417 and 418: carbon uptake from weathering vs loss by magmatic activity.” Geochimica et Cosmochimica Acta 54: 2889. CO2 + H2O = H2CO3 H2CO3 = H+ + HCO3- 2Ca2+ + 2HCO3- + KAl2AlSi3O10(OH)2 + 4H2O = 3Al3+ + K+ + 6SiO2 + 12H2O 2KAlSi3O8 + 2H+ + H2O = Al2Si2O5(OH)4 + 2K+ + 4SiO2 2NaAlSi3O8 + 2H+ + H2O = Al2Si2O5(OH)4 + 2K+ + 4SiO2 CaAl2Si2O8 + 2H+ + H2O = Al2Si2O5(OH)4 + Ca2+ KAl2AlSi3O10(OH)2 + 3Si(OH)4 + 10H+ = 3Al3+ + K+ + 6SiO2 + 12H2O CO2 + CaSiO3 = CaCO3 + SiO2 CO2 + FeSiO3 = FeCO3 + SiO2 CO2 + MgSiO3 = MgCO3 + SiO2
In the oceans, CO2 exists as dissolved gas (1%), HCO3- (93%) and CO32- (8%)

1 comment:

dissertation said...

well post, i was looking the same information to write global warming essay.