# The acid test

Here is a nice short film (~20 minutes) about ocean acidification, the “other carbon dioxide problem“, the reason geoengineering “solutions” like orbiting sun shades are not solutions.

It is only about one third doom and gloom, sandwiched between the natural beauty of what we have now in the beginning and some hopeful prospects for the future at the end.

I found it worth watching:

(thanks go to MT for posting it at his place.)

1. #1 maxwell
February 28, 2010

I’m confused. In the post you link to above, JPL found that pH changed by 0.1, but this video claims that ‘ocean acidity’ (they make no difference between shallow or deep waters as opposed to the JPL paper) has increased by 30%. A change from pH 8.2 to 8.1 is less than 1% change in pH, however. So where is the 30% number coming from? H+ concentrations?

2. #2 Doug Mackie
February 28, 2010

Yep.
(Though the numbers here are rounded and real values differ by location and other factors).

pH is a log scale.
Here an item in [square brackets] means concentration.

By definition [H3O+] = 10^(-pH)

At pH 8.1: [H3O+] = 10^(-8.1) = 7.9×10^-9
At pH 8.2: [H3O+] = 10^(-8.2) = 6.3 x10^-9

The absolute difference is:
(7.9×10^-9) – (6.3×10^-9) = 1.6×10^-9

The relative difference is:
(1.6×10^-9) / (6.3×10^-9) = 0.25 = 25%

3. #3 maxwell
February 28, 2010

…sorry, that’s a pH change of less than 2%, not 1%.

4. #4 maxwell
February 28, 2010

so if they are discussing H+ concentrations, a doubling of ‘acidity’ reduces the pH to just under 7.9 in specific areas.

How does a basic solution dissolve calcium carbonate?

5. #5 V. infernalis
February 28, 2010

Max,

Because different substances have different solubility/dissolution constants, none of which are dependent on the arbitrary division between an acidic and basic solution.

Calcium carbonate exists in equilibrium with bicarbonate ion and several other species, including aragonite and calcite. The equilibrium state of each species depends on the H+ ion concentration.

6. #6 maxwell
March 1, 2010

V.I., according to Wikipedia’s entry on carbonic acid, there is not an equilibrium between CO2 and carbonate ions. The fully protonated acid is in equilibrium with CO2. It seems rather weird to me to say the least. There is also a table of pH’s and the concentration of the different carbonate ions, but it only goes up to pH=7. At that point the carbonate ions have concentrations on the order of 10^-9 molar or less. How do such small concentration affect solid calcium carbonate in rather high concentrations in shells?

Here’s the wikipedia entry:

http://en.wikipedia.org/wiki/Carbonic_acid

7. #7 Peter of Sydney
March 1, 2010

Here we go – ocean acidification, the next big fraud. The oceans have often been absorbing and releasing far more CO2, and the slight rise of CO2 of recent times is essentially meaningless.

8. #8 skip
March 1, 2010

Hi Peter.

9. #9 Proper Gander
March 1, 2010

Very nice, but I’m disappointed that it didn’t mention the possible consequences of letting sulfate-reducing bacteria run wild with the Oceans’ biomass.

Has anyone seen any research on the pH we’d have to get to for significant HS blooms?

10. #10 Dappledwater
March 1, 2010

“The oceans have often been absorbing and releasing far more CO2, and the slight rise of CO2 of recent times is essentially meaningless.” – POS

Maybe not so meaningless:

http://e360.yale.edu/content/feature.msp?id=2241

“A new study says the seas are acidifying ten times faster today than 55 million years ago when a mass extinction of marine species occurred. And, the study concludes, current changes in ocean chemistry due to the burning of fossil fuels may portend a new wave of die-offs”

11. #11 mandas
July 6, 2010

There is an interesting and disturbing paper in the current edition of the Proceedings of the National Academy of Sciences of the USA, which examines the effects of increasing ocean acidification on the behaviour of some fish species. The link to the paper is here:

http://www.pnas.org/content/early/2010/06/24/1004519107.full.pdf

This is from the abstract:

“….we use a combination of laboratory and field-based experiments to show that levels of dissolved CO2 predicted to occur in the ocean this century alter the behavior of larval fish and dramatically decrease their survival during recruitment to adult populations. Altered behavior of larvae was detected at 700 ppm CO2, with many individuals becoming attracted to the smell of predators. At 850 ppm CO2, the ability to sense predators was completely impaired. Larvae exposed to elevated CO2 were more active and exhibited riskier behavior in natural coral-reef habitat. As a result, they had 5–9 times higher mortality from predation than current-day controls, with mortality increasing with CO2 concentration….”

These results are not based on modelling (for those of you who are of the mistaken belief that there is something wrong with using models). These results are based on actual trials under a variety of environmental conditions, and show concusively that under certain conditions, the behaviour of some species changes dramatically, such that they actually seek out their predators, with obvious consequences (although the behaviour of the predator has not been modelled, and would make an interesting experiment in itself).

12. #12 crakar24
July 6, 2010

So an increase of CO2 makes some fish think predators smell nice thats amazing. Do they explain how it does this or do they just show a correlation between fish smell and CO2 levels?