Ocean Acidification: How Rising CO2 Is Changing Our Seas

When you think of climate change, you probably picture rising temperatures or melting ice. But there’s another quiet disaster happening right under the surface: ocean acidification, the process by which seawater becomes more acidic as it absorbs excess carbon dioxide from the atmosphere. Also known as marine acidification, it’s not just a chemical shift—it’s a threat to the entire food web in the ocean. Every day, the ocean soaks up about 30% of the CO2 we pump into the air. That sounds helpful, right? But that CO2 reacts with seawater to form carbonic acid, lowering the water’s pH. Since the Industrial Revolution, ocean pH has dropped by 0.1 units. That might sound small, but it’s a 30% increase in acidity. And it’s happening faster than at any time in the last 66 million years.

This isn’t just about water chemistry. It directly impacts coral reefs, vibrant underwater ecosystems that support nearly a quarter of all marine species. Corals rely on calcium carbonate to build their skeletons, but acidic water makes it harder for them to do it. In places like the Great Barrier Reef, bleaching events are worsening because corals are already stressed from acidification. Then there’s shellfish, including oysters, clams, and plankton like pteropods that form the base of the marine food chain. Their shells dissolve in more acidic water. That’s not just bad for them—it’s bad for fish, seabirds, and even humans who depend on seafood for protein.

And it’s not just happening far out at sea. Coastal communities in India, from Kerala to Odisha, are already seeing impacts on local fisheries. Small-scale fishermen report fewer catches of shellfish. Aquaculture farms are struggling with larval mortality in hatcheries. This isn’t a future problem—it’s happening now. The science is clear: if we keep burning fossil fuels at today’s rate, ocean pH could drop another 0.3 to 0.4 units by 2100. That would make the ocean more acidic than it’s been in millions of years.

What you’ll find here aren’t just abstract studies or alarmist headlines. These are real reports from Indian scientists, field observations from coastal researchers, and breakdowns of how this invisible change is reshaping marine life—and what’s being done to fight it. From lab experiments on plankton to policy proposals for reducing emissions, this collection gives you the facts without the fluff.