Ocean's becoming more acidic? I think not!

[Elite Engineer]

With increased CO2 output in the atmosphere, there is talk that the oceans will/are becoming more acidic via carbonic acid

 

(note: only talking about CO2, not other pollutants). However, if the Earth is getting warmer, and the ice caps are melting, in

 

the near future, won't that decrease the oceans acidity or at least keep it constant, due to the fact that gases are MORE

 

soluble in colder conditions rather than warmer/ hotter condition?

 

 

~ee

[CaptainPanic]

The solubility of CO2 in water is indeed a function of temperature. However, 1 or 2 degrees difference is not going to decrease the solubility by more than a few percent. Even if we have a temperature increase of 5 degrees (which is huge - hurricanes would become insane), as you can see in the graph below, the CO2 solubility would drop by approximately 20%.

 

(source)

The increase in atmospheric CO2 was approx. 22% in the last 50 years. Since the amount of CO2 in water is roughly linearly dependent on the amount of CO2 in the air, we can conclude that the increase in atmospheric CO2 has a greater effect on the CO2 dissolved in the oceans than the increase in water temperature.

 

Having said that, modeling the pH of the oceans is ridiculously difficult. It is influenced by CO2, which is in equilibrium with carbonic acid, which in turn is in equilibrium with its (bi)carbonates, which are also in equilibrium with everything else in the oceans that affect the pH, including all marine life and a lot of the sediments and rocks... sooooo, it's a pretty complicated model, and it is very difficult (if not impossible) to really predict what will happen. It is yet another case of: "Do we want to risk jumping into the unknown, or shall we try to prevent the unknown from happening?". When asked "what is the worst that could happen?", we must answer that we don't really know.

[studiot]

 

Having said that, modeling the pH of the oceans is ridiculously difficult. It is influenced by CO2, which is in equilibrium with carbonic acid, which in turn is in equilibrium with its (bi)carbonates, which are also in equilibrium with everything else in the oceans that affect the pH, including all marine life and a lot of the sediments and rocks... sooooo, it's a pretty complicated model, and it is very difficult (if not impossible) to really predict what will happen. It is yet another case of: "Do we want to risk jumping into the unknown, or shall we try to prevent the unknown from happening?". When asked "

", we must answer that we don't really know.

 

 

 

Yes indeed it is complicated.

 

Further considering the solubility of an atmosphere of pure carbon dioxide above pure water is very different from the solubility of the same gas in the open ocean.

 

There is substantial discussion of the chemistry here, along with some calculations.

 

http://www.physicsforums.com/showthread.php?t=398208

[swansont]

My reaction as an experimentalist is that you could just go and measure the pH of the ocean

 

http://www.epa.gov/climatechange/science/indicators/oceans/acidity.html

[studiot]

 

My reaction as an experimentalist is that you could just go and measure the pH of the ocean

 

http://www.epa.gov/c...ns/acidity.html

 

 

What is the statistical provenance of this data?

[swansont]

 

What is the statistical provenance of this data?

 

The sources are given at the link. If you click on "larger image" there's a more complete list.

[CaptainPanic]

My reaction as an experimentalist is that you could just go and measure the pH of the ocean

 

http://www.epa.gov/climatechange/science/indicators/oceans/acidity.html

 

Obviously. Why model when you can measure? Measurements lead to certainty, while models only lead to uncertainties and endless discussions.

 

But today we cannot measure the pH of the ocean which will occur in 2035 when the CO2 concentration is predicted to reach a certain percentage - we have to wait until it is 2035. But we want to predict today how bad it's gonna be. You could set up experiments or models to simulate it, or extrapolate it from other data... and then you run into all the issues I mentioned.

[swansont]

 

Obviously. Why model when you can measure? Measurements lead to certainty, while models only lead to uncertainties and endless discussions.

 

But today we cannot measure the pH of the ocean which will occur in 2035 when the CO2 concentration is predicted to reach a certain percentage - we have to wait until it is 2035. But we want to predict today how bad it's gonna be. You could set up experiments or models to simulate it, or extrapolate it from other data... and then you run into all the issues I mentioned.

 

I agree — you want to be able to predict what will happen, so you need models. But the title of the thread is one for which empirical data is just the ticket. Is the ocean becoming more acidic? Yes, it is. We have the data to show it. For that specific question, the models are moot. "I think not" can go see the egress.

[studiot]

 

We have the data to show it.

 

But do we?

 

There is an awful lot of ocean, compared to the size of our sampling.

Edited August 13, 2014 by studiot

[CaptainPanic]

 

But do we?

 

There is an awful lot of ocean, compared to the size of our sampling.

 

According to wikipedia, there are 40 countries with oceanographic research institutes / universities ^(*), some of which have multiple institutes. If all these institutes again have people taking samples (by boat or along the coast), and we observe a trend, then yes we can say that the ocean is becoming more acidic.

 

Some of these institutes sail the oceans with large vessels to take lots of samples too.

 

Obviously, we cannot exclude that there are small areas where the opposite is happening... but there is enough data for a general trend.

 

(*) Wikipedia sometimes surprises me... they have a list of all oceanographic research institutes and programs. Wow!

[studiot]

 

but there is enough data for a general trend.

 

Then there is enough data to prove it statistically, without generalised hand waving.

 

BTW I am not saying the pH is going up or down or remaining the same.

 

I am asking for some statistical evaluation of the error in any claim.

 

Why do people find this unreasonable for a subject linked to GW, but a requirement for any other scientific claim?

Edited August 13, 2014 by studiot

[swansont]

 

But do we?

 

There is an awful lot of ocean, compared to the size of our sampling.

 

That's a different issue than saying we have data that shows pH dropping.

[studiot]

 

That's a different issue than saying we have data that shows pH dropping.

 

 

I didn't say that you did

 

However I am rather concerned at the apparent oscillation of the 'acidity of the ocean' with amplitude greater than the total variation over the timescale.

[Iota]

The solubility of CO2 in water is indeed a function of temperature. However, 1 or 2 degrees difference is not going to decrease the solubility by more than a few percent. Even if we have a temperature increase of 5 degrees (which is huge - hurricanes would become insane), as you can see in the graph below, the CO2 solubility would drop by approximately 20%.

 

(source)

The increase in atmospheric CO2 was approx. 22% in the last 50 years. Since the amount of CO2 in water is roughly linearly dependent on the amount of CO2 in the air, we can conclude that the increase in atmospheric CO2 has a greater effect on the CO2 dissolved in the oceans than the increase in water temperature.

 

Having said that, modeling the pH of the oceans is ridiculously difficult. It is influenced by CO2, which is in equilibrium with carbonic acid, which in turn is in equilibrium with its (bi)carbonates, which are also in equilibrium with everything else in the oceans that affect the pH, including all marine life and a lot of the sediments and rocks... sooooo, it's a pretty complicated model, and it is very difficult (if not impossible) to really predict what will happen. It is yet another case of: "Do we want to risk jumping into the unknown, or shall we try to prevent the unknown from happening?". When asked "what is the worst that could happen?", we must answer that we don't really know.

 

This is the key information. The fact that throughout Earth's history there's been occurrences of increased CO2 in the atmosphere leading to decreased ocean pH (usually on a more severe scale caused by mass volcanic eruptions etc. given), but there's no reason to doubt the occurrence of this phenomenon.

 

 

With increased CO2 output in the atmosphere, there is talk that the oceans will/are becoming more acidic via carbonic acid

 

(note: only talking about CO2, not other pollutants). However, if the Earth is getting warmer, and the ice caps are melting, in

 

the near future, won't that decrease the oceans acidity or at least keep it constant, due to the fact that gases are MORE

 

soluble in colder conditions rather than warmer/ hotter condition?

 

 

~ee

 

Seeing as trends of a drop in pH in various oceans Worldwide is being observed as pointed out by swansont, it should be clear that the melting of the icecaps isn't countering the CO2 rise. Besides that, there is CO2 trapped in the ice caps, so when they melt, more CO2 is released into the atmosphere.

Edited August 13, 2014 by Iota

[swansont]

 

I didn't say that you did

 

However I am rather concerned at the apparent oscillation of the 'acidity of the ocean' with amplitude greater than the total variation over the timescale.

 

I had said we have the data and you asked "do we?" Yes, we do.

 

Yes, error bars should be included but variation and noise aren't the same thing. It's possible error bars aren't included because they'd be too small. AFAIK measuring pH to a few hundredths is quite possible, and if you make enough measurements the resulting uncertainty could be the thickness of the line on the graph.

[studiot]

Well I just wasted a good while preparing a diagram with comments, facts and figures, when the site froze on me.

Edited August 13, 2014 by studiot