What does acidification mean?
Acidification is the process by which a substance or environment becomes more acidic — that is, its pH falls. The term is most prominent in environmental science, where 'ocean acidification' describes the drop in seawater pH caused when oceans absorb atmospheric carbon dioxide, threatening corals, shellfish, and other calcifying organisms. It also applies to freshwater lakes damaged by acid rain and to agricultural soils degraded by fertilizers or acid deposition. Beyond ecology, chemists and food scientists use acidification for any conversion toward an acidic state, such as souring milk or fermenting foods. The word derives from Latin roots: 'acidus' (sour) combined with the suffix '-fication', indicating a making or causing. Formal and technical in register, acidification almost always carries negative connotations, signaling chemical imbalance and harm. Its rise in public usage since the late twentieth century reflects growing awareness of human-driven changes to the planet's chemistry, making it essential vocabulary in climate and environmental discussion.
nounThe process of becoming acidic or of converting something into an acid; in environmental science, especially the reduction in pH of oceans, lakes, and soils caused by the absorption of carbon dioxide or by acid deposition.
- The process by which an environment or substance becomes more acidic, especially the lowering of pH in oceans and freshwater bodies due to absorbed carbon dioxide.
- The reduction in soil pH caused by acid rain, fertilizer use, or natural leaching, affecting agriculture and ecosystems.
- In chemistry and food science more broadly, any conversion of a substance into an acid or acid-like state.
"Ocean acidification threatens shell-forming marine life as seawater absorbs rising levels of atmospheric carbon dioxide."
"Scientists warn that continued ocean acidification could devastate coral reefs within decades."
"Decades of heavy nitrogen fertilizer use accelerated the acidification of farmland across the region."
Rarely pluralized; the singular is standard even when discussing multiple instances, which are usually referred to individually (e.g., 'ocean acidification and soil acidification').
"The report catalogued regional acidifications across several affected watersheds."
Since the Industrial Revolution, the oceans have absorbed roughly a quarter of humanity's carbon dioxide emissions — making their surface waters about 30% more acidic.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of acidification
Acidification comes from the Latin 'acidus', meaning sour or sharp, combined with '-fication', from Latin 'facere' (to make), via the verb 'acidify'. The underlying adjective 'acid' entered English from French 'acide', itself from Latin 'acidus'. The noun formed alongside related terms such as 'acidification' processes described in nineteenth-century chemistry, though it gained widespread currency only in the late twentieth century as scientists documented falling ocean and soil pH. It shares its root with cognates such as 'acidity', 'acidic', and 'acidulate'.
Related word forms
How acidification is actually used
A formal, scientific term used chiefly in environmental science, chemistry, and policy discussions. It carries strongly negative connotations in ecological contexts, where it signals environmental damage. The phrase 'ocean acidification' has become so established since the early 2000s that it often functions as a fixed term in climate discourse.
Easily confused with acidification
Acidosis is a medical condition of excess acid in body fluids, whereas acidification is the general process of something becoming more acidic, most often applied to environments like oceans and soils.