Quote: Originally Posted by Extrafire
Here's the article I was referring to:Quote has been trimmed, See full post:
The BBC ran an article this week titled “Acid oceans ‘need urgent action‘” based on the premise: The world’s marine ecosystems risk being severely damaged by ocean acidification unless there are dramatic cuts in CO2 emissions, warn scientists.
This sounds very alarming, so being diligent researchers we should of course check the facts. The ocean currently has a pH of 8.1, which is alkaline not acid. In order to become acid, it would have to drop below 7.0. According to Wikipedia “Between 1751 and 1994 surface ocean pH is estimated to have decreased from approximately 8.179 to 8.104.” At that rate, it will take another 3,500 years for the ocean to become even slightly acid. One also has to wonder how they measured the pH of the ocean to 4 decimal places in 1751, since the idea of pH wasn’t introduced...
Yes, I've read this before. It's not very convincing, except for the loons over at WUWT.
Acidification doesn't mean something has to already be an acid. It describes the water chemistry just fine, it is becoming more acidic. After all, the pH scale is measuring the H+ ions in an aqueous solution, and as the pH drops, you have more H+ ions. Of course the pH scale is logarithmic, so the difference between 8.14 and 8.25 is about 28.8% (10^8.25/10^8.14=1.28). Second, there will be huge problems before the ocean ever becomes acidic. It's an equilibrium problem. Check out this graph, and look at the CO3 ion, the carbonate ion that is so important to marine ecosystems.
At a pH of 8.14, the ocean is already low in carbonate, though the surface waters are still saturated. You add more H2CO3, that's carbonic acid, and the finely tuned balance that exists in nature between carbonate and bicarbonate (HCO3) very soon will be unbalanced, the equilibrium shifts more towards bicarbonate, and you no longer have enough carbonate, even when the surface waters are saturated with it. There will be not enough carbonate for shellfish, corals, diatoms, etc. to build/maintain their exo-skeletons.
And in regards to measuring pH, how do you know what the temperature was say 500 million years ago? They use proxies. If you know how much carbon dioxide is in the air, you can use equilibrium and air-ocean exchanges to estimate.
This does indeed sound alarming, until you consider that corals became common in the oceans during the Ordovician Era (external - login to view) – nearly 500 million years ago – when atmospheric CO2 levels were about 10X greater than they are today. (One might also note in the graph below that there was an ice age during the late Ordovician and early Silurian with CO2 levels 10X higher than current levels, and the correlation between CO2 and temperature is essentially nil throughout the Phanerozoic.)
Except the Ordovician era didn't build up it's concentration in the atmosphere in less than two centuries. The deep ocean has time to mix when you have a building concentration over millions of years. When the ocean is well mixed, you don't have this problem. Our oceans today are not well mixed, and certainly would take millenia to come to an equilibrium if we stopped perturbing it today.
There seems to be no shortage of theories about how rising CO2 levels will destroy the planet, yet the geological record shows that life flourished for hundreds of millions of years with much higher CO2 levels and temperatures. This is a primary reason why there are so many skeptics in the geological community. At some point the theorists will have to start paying attention to empirical data.
Ahh, the classic idiotic reply. It's idiotic because it requires no thought, which is probably why the folks at WUWT liked it so much.
The shallow ocean corals that we have today evolved from deep sea corals. In the deep sea, where the waters essentially never mix with surface waters, the higher atmospheric carbon dioxide would not be as large a problem. It's only a problem when they move into shallow waters 40 million years ago, which happens when atmospheric carbon dioxide is less than 600 ppm.
If you really want to learn something, and aren't interested in just posting some crap you found that you think sounds smart, try reading these. I know you won't, but I'll post it here anyways. Maybe some others who stumble by this will want to learn what science is telling us.
Dynamic patterns and ecological impacts of declining
ocean pH in a high-resolution multi-year dataset (external - login to view)
Southern Ocean acidification: A tipping point
at 450-ppm atmospheric CO2 (external - login to view)
Imminent ocean acidification in the Arctic projected with the NCAR
global coupled carbon cycle-climate model (external - login to view)
Anthropogenic ocean acidification over
the twenty-first century and its impact on
calcifying organisms (external - login to view)
Last edited by Tonington; Jun 6th, 2009 at 12:20 PM..