This acidification makes it difficult for calcifying organisms - coral, snails and oysters and other mollusks, and more - to build shells and skeletons sturdy enough for them to survive.
The elevated atmospheric CO2 also has raised the acidity of the oceans, which affects the ability of coral and mollusks such as oysters to build shells and skeletons.
In 2006-2007, Mr. Poles said his company, which builds shells of single-family homes and apartment buildings, was framing 120 units a week, but now 20 to 30 units is a busy week.
"Japanese tend to be insular and build shells around themselves," said Kimio Yamamoto, 71, a retired Japanese engineer who has become a familiar face at Homi's Japanese-Brazilian-run fitness club.
Extra acid impedes certain marine creatures' synthesis of calcium carbonate, which they need to build shells and skeletons.
Researchers have known for some time that high CO2 concentrations in water can affect the ability of shellfish and crustaceans to build shells and skeletons.
Not long ago, for instance, many researchers feared that most shell-building organisms, such as oysters, crabs, and shrimp, might not be able to withstand more acidic waters, which can dissolve the calcium carbonate used to build shells.
If the aragonite saturation state falls below 1.5, some organisms such as oyster larvae are unable to harvest enough aragonite to build shells during the first days of their lives, and they typically succumb quickly.
When carbon dioxide dissolves in the sea, it becomes an acid, and corrosive waters make it hard for creatures like oysters, mussels, and coral to build shells.
This would have further reduced the sunlight reaching the Earth's surface and then precipitated as acid rain, killing vegetation, plankton, and organisms that build shells from calcium carbonate (coccolithophores and molluscs).
