Sunday, March 4, 2012

Yes!....The Oceans Are Getting Ever More Acidic!

Some 6 weeks ago in his regular Weekend WSJ column, 'Mind and Matter', Matt Ridley opined that all the kerfuffle concerning the oceans becoming ever more acidic (pH being dangerously lowered even below 6.9) was a mere "storm in a teacup" and mostly exaggerated. Like all naysayers, the tactic Ridley used to cast doubt was that there was too much "variation" - and hence one could not be sure what specific pH level applied to any one area of the ocean, including those where human regularly fish or rely on.

The variation aspect is valid, but over-hyped by Ridley. It's somewhat like saying 'Well, we don't know how much hail will fall on any particular area it's no big deal to be fretting over it since the average is low". But the point is, given the right cells in storm clouds, regions expecting hail often see major damage we can often attest here in Colo. And just because ALL areas don't receive the same size hail (say golfball v. baseball) doesn't mean all areas escape! In the same way, because some remote areas of the oceans may have relatively normal pH values, that doesn't mean organisms in the oceans where the pH has been lowered aren't affected or that we can claim "no harm, no foul".

Now the evidence has been reinforced that not only is the acidity of Earth's oceans the greatest since the dawn of the Industrial revolution, but in the past 300 million years! Indeed, according to new research our oceans may be acidifying faster than at any point during the last 300 million years due to industrial emissions, endangering marine life from oysters and reefs to sea-going salmon. And we won't even mention the phytoplankton which generate so much of the planet's oxygen!

The scientists from Columbia University, which led the research. have found surging levels of carbon dioxide in the atmosphere that forced down the pH of the ocean by overall 0.1 mean unit in the last century. This is 10 times faster than the closest historical comparison from 56 million years ago. It's deadly serious because - like the margins for ushering in a runaway greenhouse effect, the margins of safety for acidic oceans are extremely low. Hence, one can't tell by the small magnitude of numerical pH that the increment change is nothing to fret over.

As noted in earlier blogs: the seas absorb CO2 from the atmosphere, forming carbonic acid. The particular chemical reaction is:

H2O + CO2 -> H2 CO3

The lower the pH level in the seas ('7' is neutral pH), the more acidic they are. This is also worrisome because mass extinctions of marine creatures in the past have been linked to instances of ocean acidification. Thus the current incremental change could also threaten important species. This according to Baerbel Hoenisch, the paleoceanographer at Columbia who was lead author of the paper that appeared in the journal Science. As he noted:

If industrial carbon emissions continue at the current pace, we may lose organisms we care about — coral reefs, oysters, salmon,”

Meanwhile, the UN’s Intergovernmental Panel on Climate Change has said ocean pH may fall another 0.3 units this century, according to Columbia.

This could easily bring us into the pH ~ 6.5 range which would be catastrophic, at the same time that we're on the cusp of the runaway Greenhouse effect with temperature increases of nearly 6C since the Industrial Revolution onset.

The closest period change to the current pace occurred during the Paleocene-Eocene Thermal Maximum about 56 million years ago, when a doubling of the atmospheric concentration of carbon dioxide may have pushed pH levels down by 0.45 units over 20,000 years, according to the Columbia researchers.

Fossil records of the time indicate as many as half of all species of seabed-dwelling single-celled creatures called benthic foraminifers became extinct, suggesting species higher up the food chain may also have died out, they said.

The Columbia scientists used fossil records including the preservation of calcium carbonate in ocean sediments and the concentrations of various elements to reconstruct past ocean conditions. Two other mass extinctions about 200 million years and 252 million years ago may also be linked to acidification, though there’s less fossil evidence, according to the study.

A major concern issuing from the research is the future projected impact on the balance of ocean carbonate chemistry. This is no small thing! As observed by the authors of the article,''Progress Made in Study of Ocean’s Calcium Carbonate Budget’ (Eos Transactions of the AGU , Vol. 83, No. 34), from August 20, 2002:

"Future decreases in sea water pH (and CO3(-2)) concentration will decrease the saturation state of the waters with respect to Ca CO3”.

This means that spillover effects become much more likely, as the saturation threshold is lowered, with masses of CO2 released additionally into the atmosphere. Melting ice from glaciers, etc. will then surely reduce further the sea water pH and accelerate the release of CO2 from the oceans ultimately triggering catastrophic release of CO2 from sedimentary carbonates, representing the largest reservoir of carbon on Earth.

In terms of the most recent work, researchers based in the United States, Britain, Netherlands, Germany and Spain contributed to the study, funded by the U.S. National Science Foundation.

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