Actually, saying anthromorphic CO2 is “only” 2.5% of the ocean carbon is like saying one beverage is 97.5% alcohol and another is 100% alcohol. You can’t easily tell the difference in effect between them when compared to drinking pure water.

Grab a bushel of oranges and try the math for the “long term potential”.

Basically, the ocean is a giant acid-base buffer. It’s many other things as well, but since we’re talking about CO₂, the buffer is what’s relevant.

For those who have forgotten their high-school chemistry, buffers have some very strange properties, in particular their ability to absorb large amounts of acid (or base) with minimal change in pH – up to a point. Once that point is reached, a small addition of acid (or base) “blows the buffer” and a dramatic change in pH happens. To graph it, it looks something like this: (let’s see how my ASCII art turns out…)

  |
  |                    
  |                    
  |    \
p |     \
H |      \
  |       `---------,
  |                  \
  |                   \
  |
  +---------------------------
           add acid --->

(digression: this whole acid-base buffer thing is why we can eat tomatoes without dying from a messed-up pH)

Exactly how “long” that flat part is depends on a lot of factors, including how much buffer is dissolved in solution.

The buffer in the case of CO₂ in the oceans is actually a multiple buffer:

C0₂ + H₂O <–> HCO₃^- + H⁺
HCO₃^- <–> CO₃^2- + H⁺

Which means as you add more CO₂, the first reaction’s equilibrium shifts a bit to the right and more HCO₃^- is produced, which shifts the second reaction’s equilibrium a bit to the right and more CO₃^2- is produced.

However, as mentioned at the end of the article, this isn’t the end of the story. Some marine life uses calcium carbonate (CaCO₃) in its shell. (Recognize that carbonate ion?)

As both of the above equations shift right, more acid (H⁺) is produced. CaCO₃ dissolves in acidic solution, and neutralizes the acid via the exact reverse of the second equation above. So in a sense, it’s a triple buffer, if you don’t mind killing marine animals whose lives depend on those CaCO₃ shells.

Also, despite all the buffering, the level of CO₂ dissolved in the ocean does increase, and excess dissolved CO₂ causes dissolved-oxygen-breathing fish distress much as it causes us free-oxygen-breathing critters distress when the free CO₂ level rises.

Because the ocean is such a huge buffer, it’s taken a long time before we’ve noticed the effects of all the CO₂ we’ve been pumping out. I hope we can smarten up and stop expecting the world to clean up after us, because it’s only got so much capacity…

The proportion of man-made to natural CO₂ in the atmosphere is ~50%. The increase in CO₂ is easily measurable, partially because the atmosphere is so well mixed. in fact, a graph of data available since 1958 shows a small annual oscillation superimposed on a dramatic linear increase.

It’s an interesting article, but something that the activist environmentalists might use to decry the mysteriously inconclusive global warming. Strange, but I just read somewhere that in the past 100 years the sun has gotten slighter hotter — meaning it (more than the industrialized nations) is warming the Earth.

The interesting conclusion of the article — that “the effects of decreased calcification in microscopic algae and animals could alter marine food webs and, combined with other changes in salinity, temperature and upwelled nutrients, could substantially alter the diversity and productivity of the ocean” — is expressed in non-definitive terms. In other words, this study doesn’t know exactlty what might be happening or what might happen to the ocean’s flora and fauna.

jon

And it’s 118 billion metric tons…

Direct Estimates of the Oceanic Inventory of Anthropogenic Carbon
Scott C. Doney and Christopher L. Sabine

The anthropogenic carbon inventory approach requires high quality measurements of DIC and associated hydrographic properties in order to remove the large background and natural variability in ocean carbon. Typical DIC concentrations range from 1800 to 2400 mmol/kg, and the surface seasonal cycle is often as large as 100 mmol/kg. By comparison, the total anthropogenic signal in surface water for the 1990s is roughly 40-50 mmol/kg (Figure 1), dropping off rapidly with depth to 5-10 mmol/kg at the base of the main thermocline. By standardizing analytical techniques and developing new standards or Certified Reference Materials for DIC, the WOCE/JGOFS Global CO2 Survey team was able to improve dramatically the shipboard accuracy (2 mmol/kg) and precision (1 mmol/kg) to levels where the detection of the anthropogenic signal (estimated error 5-10 mmol/kg) became feasible.

Besides, how else is anybody gonna learn about Brix cups, one of the great inventions of the early 20th Century?