Acidification Beneath The Waves

As carbon emissions climb, the world's oceans absorb more carbon dioxide, putting coral reefs, shellfish, and entire marine ecosystems at risk, calling for urgent mitigation efforts

- AARATI KRISHNA

s the world grapples with the visible impacts of climate change — melting glaciers, rising sea levels, and extreme weather — an equally urgent, but less visible threat is unfolding beneath the ocean's surface. Ocean acidification, often referred to as the "evil twin" of global warming, is a chemical shift in the seas driven by the same carbon emissions altering climate. It is quietly, but profoundly changing marine ecosystems, threatening food security, economies, and biodiversity. Unlike many environmental crises that are localized, ocean acidification is global, affecting every corner of the world's oceans and touching countless lives.

The root cause of ocean acidification is excess atmospheric carbon dioxide. When fossil fuels like coal, oil, and natural gas are burned, CO2 is released into the atmosphere, 30% of which is absorbed by the ocean. While this might seem like a natural climate buffer, it comes with a hidden cost.

Once in seawater, CO2 reacts to form carbonic acid. This acid dissociates, releasing hydrogen ions and lowering the pH of the ocean. The resulting increase in acidity depletes carbonate ions — an essential building block for organisms that rely on calcium carbonate to form shells and skeletons. As pH levels drop, these organisms face increasing difficulty in maintaining their structures, weakening the very foundation of marine food chains.

Vulnerable marine life The consequences of ocean acidification are already visible in many coastal regions. In the Pacific Northwest of the United States, oyster hatcheries have experienced mass die-offs due to acidic seawater preventing larvae from forming shells. Clams, mussels, and corals, creatures that form the structural backbone of marine ecosystems, are suffering similar fates.