Researchers investigate increased ocean acidification

August 3, 2015 by Christopher Packham, Phys.org report
Credit: Tiago Fioreze / Wikipedia

The primary cause of global ocean acidification is the oceanic absorption of CO2 from the atmosphere. Although this absorption helps to mitigate some of the effects of anthropogenic climate change, it has resulted in a reduction of oceanic pH levels, with its own set of environmental consequences. Coral bleaching, algae loss, and decreasing oceanic oxygen levels are all attributable to the reduced pH of the oceans. Additionally, acidification poses a threat to human industry with projected declines in commercial fisheries, the breakdown of food webs, and a decline in tourism as ocean ecosystems and the natural environment suffer degradation. The current pace of acidification is greater and faster than at any time in the last 300 million years, and bears close scrutiny.

Because of the lack of data about basin-wide pH changes at varying depths, an international group of investigators conducted a study of decadal acidification in Atlantic Ocean water masses, and compared the results to existing climate models. They've published their conclusions in the Proceedings of the National Academy of Sciences.

Earth climate models project that in the last decade alone, ocean acidity has exceeded cyclic changes in historical analogs. The current study tracked pH levels across two decades and data collected from three cruises in 1993, 1994, and 2013. The observations correspond closely with the model predictions of pH changes in the near surface and upper waters. "For the first time, to our knowledge," the authors write, "our observations confirm the major role of mode and intermediate waters at the basin scale in the acidification of the ocean interior, which was also evidenced in the ."

The highest pH waters were found in South Atlantic Central Water and upper North Atlantic Central Water. The lowest pH (highest acidity) was found in the Antarctic Intermediate Water layer of the equatorial region. The researchers note that, although some degree of pH reduction is attributable to natural causes, all of the observed changes in surface water pH had anthropogenic origin, a finding that corresponds closely with climate modeling.

In mode waters and intermediate waters, natural components and anthropogenic inputs are of the same order of magnitude, "indicating that changes in ocean circulation and biological activity contributed significantly to pH variability in the subsurface waters of the Atlantic Ocean over this time period," the authors write.

Mode waters, vertically homogenous water masses caused by deep vertical winter convection, have a lower buffering capacity than surface waters because they have a lower temperature, and because their alkalinity-to-carbon ratios are lower, making them more sensitive to increases in oceanic carbon. Additionally, mode waters have greater exposure to the atmosphere than deeper water, enabling higher uptake of CO2 and consequently higher levels of acidity.

The authors conclude, "Based on projections of future increases in atmospheric CO2 and the associated penetration of (anthropogenic change) into intermediate and deep waters, the contribution of anthropogenic forcing to the acidification of subsurface waters will increase with time and eventually will exceed natural variability and trends."

Explore further: Naturally acidic waters of Puget Sound surround UW's Friday Harbor Labs

More information: "Decadal acidification in the water masses of the Atlantic Ocean." PNAS 2015 ; published ahead of print July 27, 2015, DOI: 10.1073/pnas.1504613112

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21 comments

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gkam
3.1 / 5 (16) Aug 03, 2015
Cue the Deniers, who have no real counter-argument to this.

What will their gripes be?
denglish
2.2 / 5 (13) Aug 03, 2015
Phys.org must be down on advertisement. "We need more hits, start another crap tossing contest!".

Cue the liberal troll, first out of the gate. How's the pathological lying going anyway?

Actually, the real truth about the ocean is that it isn't increasing in acidification, it is reducing in alkaline content.
neblina
4.2 / 5 (15) Aug 03, 2015
@denglish: so how is "reducing in alkaline content" different to "increasing in acidification"?
gkam
2.6 / 5 (10) Aug 03, 2015
neblina,
Some of these people are unable to admit error. It's an ego thing, even though they are just anonymous posters.
denglish
2.3 / 5 (9) Aug 03, 2015
The researchers note that, although some degree of pH reduction is attributable to natural causes, all of the observed changes in surface water pH had anthropogenic origin, a finding that corresponds closely with climate modeling.


"indicating that changes in ocean circulation and biological activity contributed significantly to pH variability in the subsurface waters of the Atlantic Ocean over this time period," the authors write.

Anyone see the contradiction? So, both AGW and natural factors are being called out.

Ok, its a start.

From the paper:
To avoid biases in Δ pHNat caused by water mass mixing, the ΔpHNat was corrected for these effects using changes in potential temperature (Δθ) in the water masses from 1993 to 2013.

Changes in potential temperature and not actual?

denglish
2.2 / 5 (10) Aug 03, 2015
From the paper:
"Our observations show that the anthropogenic and natural components had a similar magnitude in the MW–IW (Fig. 4A), indicating that changes in ocean circulation and biological activity contributed significantly to pH variability in the subsurface waters of the Atlantic Ocean over this time period."

So, natural causes "contributed significantly".

The paper goes on to describe an attempt to figure out how much AGW contributes using a model. A lot of uncertainty and dependence on variables being stable ensues.

So, using observations and models, the authors conclude that AGW Ph variability will overtake natural variability, but not yet.

Models are hard to trust, given the immense number of variables.

This was the first climate related academic paper I really studied, and I enjoyed it. In the end, humanity is still not guilty without a reasonable doubt, and therefore enacting policies that cripple us morally and economically are not justified.
gkam
2.8 / 5 (11) Aug 03, 2015
Yeah, . . "They're right, but I'm not changing".
Sigh
4.3 / 5 (12) Aug 03, 2015
denglish:
humanity is still not guilty without a reasonable doubt, and therefore enacting policies that cripple us morally and economically are not justified.
You might want to listen to an interview with Taleb on the relationship between uncertainty and reasons to take action: http://www.econta...las.html And in case you don't trust any source I give you, it's the EconTalk podcast, subtitled "Library of Economics and Liberty".
denglish
2.5 / 5 (11) Aug 03, 2015
Yeah, . . "They're right, but I'm not changing".

Read it again. Humanity has been acquitted.

For being a Master's Degree, you are showing a very low reading comprehension level.

The results of the paper, while commendable for using observation (which result in nature being the primary driver of Ocean Ph levels), fall back on models and certain conditions of variability to achieve an AGW dominating presence.

We know that models predicting the earth's temperature as a result of AGW have been falsified. Therefore, models which attempt to factor huge number of variables on a subject as poorly understood as ocean acidification, are suspect until observations prove them; making a decision to act out against society very poor.
Sigh
4.6 / 5 (11) Aug 03, 2015
The researchers note that, although some degree of pH reduction is attributable to natural causes, all of the observed changes in SURFACE WATER pH had anthropogenic origin, a finding that corresponds closely with climate modeling.


"indicating that changes in ocean circulation and biological activity contributed significantly to pH variability in the SUBSURFACE WATERS of the Atlantic Ocean over this time period," the authors write.

Anyone see the contradiction?

Seeing that your quotes appear to refer to different bodies of water (see capitalised phrases), not yet. Have I missed something?
denglish
2 / 5 (8) Aug 03, 2015
Seeing that your quotes appear to refer to different bodies of water (see capitalised phrases), not yet. Have I missed something?

I thought the same thing, so I read the paper. that's how I came up with the other paraphrasing and (my) verdict.

You might want to listen to an interview with Taleb on the relationship between uncertainty and reasons to take action

Philosophy, no?
There has been an uptick in a deadly disease in the world. Still within normal variability that we've observed over the years, but its really important to make sure you don't have it. Can we cut off your arm to make sure you're healthy? :-)
TheGhostofOtto1923
3.7 / 5 (6) Aug 03, 2015
What will their gripes be?
Well the big one is that youre a fraud and a liar.
neblina,
Some of these people are unable to admit error. It's an ego thing, even though they are just anonymous posters
Gkam/george kamburoff actually makes up his own mistakes like the one about dried manure, which he didnt know isnt called 'volatile solids', is a major constituent of pollution in the 'high air, wherever that is.

It is at the bottom of the list below miscellaneous.

George has dropped dozens and dozens of such lies since he showed up here.

This poster is a pathological liar.

Beware.
Sigh
4 / 5 (8) Aug 03, 2015
You might want to listen to an interview with Taleb on the relationship between uncertainty and reasons to take action

Philosophy, no?

Statistics.
denglish
2 / 5 (8) Aug 03, 2015
You might want to listen to an interview with Taleb on the relationship between uncertainty and reasons to take action

Philosophy, no?

Statistics.

Ok, I think the request to cut off your arm still stands. :-)
Steve 200mph Cruiz
4.2 / 5 (10) Aug 03, 2015
Denglish,
That is quite audacious of you to claim that fighting climate change is a morally corrupt proposition.

Last time I checked, gluttony is a sin. If we actually followed the 10 commandments, we wouldn't be in this situation in the first place.

What do you derive the notion of morality from? What does it mean to be a good person to you?
denglish
2.3 / 5 (6) Aug 03, 2015
That is quite audacious of you to claim that fighting climate change is a morally corrupt proposition.

You'll have to point out where I said that. Oh, you're talking about my reference to ClimateGate and the enactment of taxes in order to fill slush funds. Neither of those two things fight climate change, supposing its "fightable" anyway, which it isn't.

If we actually followed the 10 commandments, we wouldn't be in this situation in the first place.

?

What do you derive the notion of morality from? What does it mean to be a good person to you?

?

Holy attack of the red-herrings Batman! Guys, stay on topic!

Steve 200mph Cruiz
4.6 / 5 (9) Aug 03, 2015
humanity is still not guilty without a reasonable doubt, and therefore enacting policies that cripple us morally and economically are not justified.


How do you know we can't fight climate change?
Remember the hole in the ozone? We don't talk about it anymore because we fixed it man.

If you say something on an anonymous science board, you better be able to back it up. I was never indoctrinated into the libertarian mindset, I don't give a crap at all about any "scoop" Fox news comes up with, cable television is for idiots
denglish
2.1 / 5 (7) Aug 03, 2015
How do you know we can't fight climate change?

Because we aren't creating it.

If you say something on an anonymous science board, you better be able to back it up.

See above.

I was never indoctrinated into the libertarian mindset, I don't give a crap at all about any "scoop" Fox news comes up with, cable television is for idiots

That's nice.

leetennant
5 / 5 (9) Aug 04, 2015
Phys.org must be down on advertisement. "We need more hits, start another crap tossing contest!".

Cue the liberal troll, first out of the gate. How's the pathological lying going anyway?

Actually, the real truth about the ocean is that it isn't increasing in acidification, it is reducing in alkaline content.


I'm not getting fatter! I'm just getting less thin! Phew, that's a relief.
animah
5 / 5 (8) Aug 04, 2015
This was the first climate related academic paper I really studied

Yet you cast all these peremptory verdicts (your word), starting with this priceless pearl:

the real truth about the ocean is that it isn't increasing in acidification, it is reducing in alkaline content.

Then you're surprised you have zero credibility? Here's a hint: You sound like a child.
Sigh
5 / 5 (6) Aug 04, 2015
Ok, I think the request to cut off your arm still stands. :-)
First you need to back it up by an explanation of how your scenario is analogous to Taleb's argument. Second you need to show that the policies to limit ocean acidification would "cripple us morally and economically", which is the bit I take to be cutting off my arm in your analogy.

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