Oceans in Crisis - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 185

Acid Oceans
For a long time, the fact that the oceans are absorbing a good deal of
the carbon dioxide that we pump out into the atmosphere was seen
as an unmitigated benefit. After all, the more that there is stored in the
oceans, the less that remains in the atmosphere to trap heat and warm
the Earth. And there is the 45,000 billion tonnes of carbon that is
stored in the ocean in one form or another—bound within organic
matter, or as carbonate and bicarbonate molecules, or simply as dis-
solved molecules of carbon dioxide. This is an amount that is vastly
greater than the ~550 billion tonnes of carbon that were stored in the
atmosphere before humans took a hand in the process, and the 800
billion tonnes that the atmosphere holds today. A little more would
not make much difference, surely?
There have even been ideas of compressing carbon dioxide from
power stations and pumping it down to the deep ocean floors. There,
at the near-freezing temperatures and high pressures of that realm,
the compressed carbon dioxide would stay as a dense liquid for a long
time, hugging the ocean floor and only slowly being dissolved into
the waters above. Only a few obscure deep-sea organisms would suf-
fer, it was said, while the rest of us would benefit. In recent years,
though, people have gone quiet about this idea.
In hindsight, the idea that dissolving more carbon dioxide in the
oceans may have a dark side was extraordinarily late in being widely
realized. From the late 1970s, oceanographers raised concerns over
possible unpleasant unintended consequences of humanity's giant
experiment with carbon dioxide. The chemistry was, after all, straight-
forward—or at least moderately straightforward. The carbon dioxide
dissolved into the oceans will combine with water to form carbonic
acid, which releases the business end of its acid nature—hydrogen
ions—into the water. The pH drops, changing the balance of the