One of the more serious threats now facing all life on this planet has crept up almost unnoticed
…
Our collective indifference to the oceans may go some way towards explaining how one of the more serious threats now facing all life on this planet has crept up almost unnoticed. And that is ocean acidification.
Human activity over the last two centuries has pumped an estimated 1,000 billion tonnes of CO2 into the atmosphere. This is the “greenhouse” gas that is implicated in global warming.
We have, however, been extremely fortunate that around half of this extra load of CO2 has been reabsorbed from the atmosphere and dissolved into the world’s oceans as carbonic acid. Were this not the case, temperatures would have risen far more sharply than the one degree or so of average warming that has occurred so far.
However, our good fortune has been at a heavy price for the oceans. This vast influx of additional carbon has altered the basic chemistry of the world’s oceans, making them more acidic in the process.
Surface ocean acidity has increased by 30 per cent in the 200 years or so since we started burning fossil fuels on an industrial scale, with half of this increase occurring in just the last 30 years. Experts now project that ocean acidity will have doubled by 2050.
…
John Gibbons, IRISHTIMES.com, 19 March 2009. Full article.
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
In the oceans, there is a buffering reaction between the sea floor basalts and sea water. 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 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.