Deacidification of Our Oceans

When CO2 in the atmosphere is absorbed into the oceans it dissolves and becomes carbonic acid, which reacts with the water and increases the acidity.  In the last 150 years we’ve increased our CO2 emissions to a level higher than they ever have been. The result is the marine ecosystem is changing rapidly, more rapidly than the last major change 56 million years ago, and as such, the goods and services the oceans provide us simply will not be available. Nearly eighty percent of the earth is covered by oceans, which are the foundation of the food webs that we rely on on land and sea.

If we stopped all CO2 emissions of today, we would still have acidification from the atmosphere to the oceans going on for decades. We know we cannot stop using hydrocarbons, so we have to engineer our way out of this and fast. We have been performing the largest experiment in the history of man and now we need to try a different experiment, to reverse the trends. The technologies that exist needs to be put to use, their performance and acceptance will increase. We face dire consequences if action is not taken immediately.

This video is a simple explanation of how acidification impacts the food web:

The Economist (full article here), states describes the possible scenario of life in these increased acidic oceans:

[The reason] That [acidification] matters, because many creatures which live in the ocean have shells or skeletons made of stuff that dissolves in acid. The more acidic the sea, the harder they have to work to keep their shells and skeletons intact. On the other hand, oceanic plants, cyanobacteria and algae, which use CO2 for photosynthesis, might rather like a world where more of that gas is dissolved in the water they live in—a gain, rather than a loss, to ocean productivity.

While this might appear to have a silver lining, for photosynthesis based life, they point out:

Oceanic acidity levels appear now to be rising ten times as fast as they did at the end of the Palaeocene. Some Earth scientists think the planet is entering, as it did 56m years ago, a new epoch—the Anthropocene. Though the end of the Palaeocene was an extreme example, it is characteristic of such transitions for the pattern of life to change quickly. Which species will suffer and which will benefit in this particular transition remains to be seen

So we are faced with a rapidly increasing acid level, as the chart below shows:

Arogonite Saturation State forecast 2100

Patchier data that go back further suggest there has been a 26% rise in oceanic acidity since the beginning of the industrial revolution, 250 years ago. Projections made by assuming that carbon-dioxide emissions will continue to increase in line with expected economic growth indicate this figure will be 170% by 2100.

The variable people most worry about is called omega. This is a number that describes how threatening acidification is to seashells and skeletons. Lots of these are made of calcium carbonate, which comes in two crystalline forms: calcite and aragonite. Many critters, especially reef-forming corals and free-swimming molluscs (and most molluscs are free-swimming as larvae), prefer aragonite for their shells and skeletons. Unfortunately, this is more sensitive to acidity than calcite is.

The chart below, shows regular, direct measures of the amount of CO2 in the air date to the 1950s. Those of the oceans’ acidity began only in the late 1980s (see chart). Since it started, that acidity has risen from pH 8.11 to pH 8.06 (on the pH scale, lower numbers mean more acid). This may not sound much, but pH is a logarithmic scale. A fall of one pH point is thus a tenfold rise in acidity, and this fall of 0.05 points in just over three decades is a rise in acidity of 12%.

Relationship between CO2 in the atmosphere and acidity of the oceans

Relationship between CO2 in the atmosphere and acidity of the oceans

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

To see how the acidity up-welling in the Pacific Northwest, watch this Youtube video about the Taylor Shellfish Farms:

“The ocean is so acidic that it is dissolving the shells of our baby oysters,” says Diani Taylor of Taylor Shellfish Farms in Shelton, Washington. She and her cousin Brittany are fifth-generation oyster farmers, and are grappling with ocean waters that are more acidic and corrosive than their fathers, grandfathers, and great-grandfathers knew.

This “ocean acidification” is one planetary response to humans’ burning of fossil fuels, which releases carbon dioxide that is absorbed by the oceans. According to the National Climate Assessment, oceans currently absorb about a quarter of human-caused carbon dioxide emissions to the atmosphere, leading to ocean acidification that will alter marine ecosystems in dramatic yet uncertain ways.

Livermore scientists develop CO2 sequestration technique that produces ‘supergreen’ hydrogen fuel, offsets ocean acidification

Lawrence Livermore scientists have discovered and demonstrated a new technique to remove and store atmospheric carbon dioxide while generating carbon-negative hydrogen and producing alkalinity, which can be used to offset ocean acidification.

The team demonstrated, at a laboratory scale, a system that uses the acidity normally produced in saline water electrolysis to accelerate silicate mineral dissolution while producing hydrogen fuel and other gases. The resulting electrolyte solution was shown to be significantly elevated in hydroxide concentration that in turn proved strongly absorptive and retentive of atmospheric CO2.

Further, the researchers suggest that the carbonate and bicarbonate produced in the process could be used to mitigate ongoing ocean acidification, similar to how an Alka Seltzer neutralizes excess acid in the stomach.

“We not only found a way to remove and store carbon dioxide from the atmosphere while producing valuable H2, we also suggest that we can help save marine ecosystems with this new technique,” said Greg Rau, an LLNL visiting scientist, senior scientist at UC Santa Cruz and lead author of a paper appearing this week (May 27) in the Proceedings of the National Academy of Sciences.

Click here to read the Lawrence Livermore article on a development that produces hydrogen and an alkaline product which can lower the acidity in the oceans.