In the 200-plus years since the industrial revolution began, the concentration of carbon dioxide (CO2) in the atmosphere has increased due to humans burning fossil fuels (such as car emissions) and changing the way land is used (such as deforestation). During this time, the pH of surface ocean waters has fallen by 0.1 pH units. The pH scale, like the Richter scale, is logarithmic, so this change represents approximately a 30 percent increase in acidity.
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The ocean absorbs about 30% of the CO2 that is released in the atmosphere, and as levels of atmospheric CO2 increase, so do the levels in the ocean. When CO2 is absorbed by seawater, a series of chemical reactions occur resulting in the increased concentration of hydrogen ions. This increase causes the seawater to become more acidic and causes carbonate ions to be relatively less abundant.
Carbonate ions are an important building block of structures such as sea shells and coral skeletons. Decreases in carbonate ions can make building and maintaining shells and other calcium carbonate structures difficult for calcifying organisms such as oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. The pteropod, or "sea butterfly," is a tiny sea creature about the size of a small pea. Pteropods are eaten by organisms ranging in size from tiny krill to whales and are a major food source for North Pacific juvenile salmon. When pteropod shells were placed in sea water with pH and carbonate levels projected for the year 2100, the shells slowly dissolved after 45 days. Researchers have already discovered severe levels of pteropod shell dissolution offsite link in the Southern Ocean, which encircles Antarctica. Pteropods are small organisms, but imagine the impact if they were to disappear from the marine ecosystem!
Changes in ocean chemistry can affect the behavior of non-calcifying organisms as well. The ability of certain fish, like pollockoffsite link, to detect predators is decreased in more acidic waters. Recent studies have shown that decreased pH levels also affect the ability of larval clownfishoffsite link to locate suitable habitat. When subjected to lower pH levels, the larval clownfish lost their chemosensory ability to distinguish between their favored and protective anemone habitat among the reefs and unfavorable habitats like mangroves. Additionally, greater acidity impairs their ability to distinguish between the "smell" of their own species and that of predators. These two factors create an increased risk of predation. When these organisms are at risk, the entire food web may also be at risk. Ocean acidification is expected to impact many ocean species to varying degrees. While some species will be harmed by ocean acidification, photosynthetic algae and seagrasses may benefit from higher CO2 conditions in the ocean, as they require CO2 to live just like plants on land.
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https://www.noaa.gov/education/resource-collections/ocean-coasts-education-resources/ocean-acidification
Of course the oceans are major food suppliers for much of human society.
Congratulations to our presumptive Democratic nominee, Joe Biden!
If I were to vote in a presidential
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