Is the ocean acidifying?

Tuesday, June 4, 2024
By John Mason

Acidification of oceans simply means a reduction in their pH outside of normal values.

The pH scale measures acidity and alkalinity of water-based solutions. It runs from 0 (highly acidic) through 7 (neutral) to 14 (highly alkaline). Any reduction in pH value, in the direction of 0, is acidification. The oceans acidify whenever they become less alkaline, regardless of whether their pH declines below 7.

A good analogy for acidification can be found with the way we talk about temperatures. If the pH of a solution shifts from 8.1 to 7.9, that is acidification, even though the solution remains slightly alkaline. In the same way, if the temperature rises from -40°C to -15°C, it has definitely warmed up, even though it's still freezing cold.

Since the Industrial Revolution, ocean pH has declined from 8.2 to 8.1 — a 30% increase in acidity.

This fact brief is responsive to conversations such as this one.
Smithsonian Ocean Ocean Acidification
Encyclopædia Britannica PH | Definition, Uses, & Facts
National Oceanic and Atmospheric Administration What is Ocean Acidification?
European Environment Agency Ocean acidification
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