SEVENSEAS junior

Ocean Acidification Basics: How CO2 is Affecting Ocean

I keep seeing “ocean acidification” everywhere lately. Since I started at SEVENSEAS Media, this phrase pops up in a lot of articles I read, every research paper I skim through. Another science term, another thing to worry about, I thought.

Then I was mindlessly scrolling TikTok (doomscrolling even, please help me) last weekend when this cleaning video popped up. Someone was cleaning old jewelry by dropping it into white vinegar and the thing just started bubbling like crazy. The tarnish dissolved right off. I watched it three times because it was weirdly satisfying, but then I had this moment where I thought, wait. This is exactly what’s happening to the ocean.

So What Is It All About?

We all know about carbon emissions, right? Most of that CO2 goes into the air, but here’s what I didn’t know until recently: the ocean soaks up about 30% of it. Just absorbs it like a massive sponge.

When CO2 hits seawater, it turns into acid. Not like, burn-your-skin acid, but enough to change the ocean’s chemistry. And it’s happening fast.

Since 2007 (the year 1st generation of iPhone launched, crying elderly), our oceans have absorbed like 2.5 billion tons of CO2. I can’t even picture what that looks like, but researchers can measure it. Ocean surface waters have dropped from a pH of 8.2 to 8.1 since the industrial revolution began. That might sound tiny, but the pH scale is logarithmic, so this represents about a 30% increase in acidity in just over two centuries.

It’s certainly changing faster than most marine life can adapt.

Infographic explaining ocean acidification process from CO2 emissions to marine life impacts, showing how carbon dioxide creates carbonic acid in seawater — *Credit: https://ocean-acidification.com/ocean-acidification-infographic/*

Corals Are Screwed

Corals build their skeletons out of calcium carbonate. Same stuff that makes seashells. In acidic water, building with calcium carbonate becomes nearly impossible. It’s like trying to make cement in the rain.

Baby corals are getting hit the worst. They can’t even form their initial skeletons properly. As this is chemistry working against millions of years of evolution.

And it’s not just corals. There are these tiny sea snails called pteropods that are basically dissolving as they swim. Their shells get thinner and thinner until they just fall apart. These things are food for whales, and tons of other species. When they disappear, food chain kinda collapsed.

Dr. Nina Bednaršek at NOAA’s Pacific Marine Environmental Laboratory found that over half of pteropods collected along the U.S. West Coast already show severe shell dissolution. Attached is the photo of pteropods literally being eaten away alive by acid.

Two pteropod shells side by side showing healthy transparent shell versus damaged shell with visible dissolution from ocean acidification — Pteropods, or sea butterflies, are a vital food source for salmon and other commercially important fish. Shown here in laboratory conditions are (left) a pteropod that has lived for six days in normal waters and (right) a pteropod showing the effects of living in acidified water for the same time period. The white lines indicate shell dissolution and explain why ocean acidification is called “osteoporosis of the sea.” (Image credit: NOAA)

Hopeful Glimpse

Dr. Nina Bednaršek, who spends her time studying those dissolving sea snails. She works with fishing communities to help them understand what acidification means for their livelihoods. Her work in the Pacific Northwest shows that pteropod shell damage has doubled since pre-industrial times and could triple by 2050.

In Australia, Dr. Adriana Vergés at UNSW Sydney is working on coral refugia. Places where reefs have the best shot at surviving. Working with indigenous communities, and local governments. Everyone bringing different knowledge to figure out how to protect what’s left. Her research on climate refugia shows that some reef areas might stay 1°C cooler than surrounding waters well into the 2080s.

Some diving instructors I’ve read about now collect water samples during their regular trips. They know their reefs better than any satellite can see them. When they notice changes, they’re often the first to spot trouble.

What Actually Helps

We need to stop pumping so much CO2 into the air. But there’s other stuff that makes a difference too.

Ocean acidification gets worse when there’s other pollution in the water. Fertilizer runoff, sewage, that kind of thing. It all adds up. Beach cleanups actually matter. Supporting better wastewater treatment matters.

Some places are trying to add crushed limestone to coastal waters. Basically giving the ocean antacids. It sounds weird, but early results look promising.

Kelp forests and seagrass beds naturally buffer against acidification. They’re like the ocean’s kidneys, filtering and cleaning as they grow. Protecting and restoring these areas gives marine life more places to hide from the worst chemistry changes.

Even choosing sustainable seafood helps. When fish populations are healthy, the whole ecosystem works better at dealing with stress.

Reality Check

I’m not going to pretend this isn’t a massive problem. Ocean acidification is real, it’s happening now, and it’s going to get worse before it gets better.

But the ocean is also incredibly resilient when we give it a chance. Natural processes are constantly working to balance pH levels. Reduce the CO2 input, and chemistry can stabilize over time.

Marine life adapts in ways that blow my mind. Some boulder corals are already showing tolerance to more bleaching/acidic conditions. Some fish populations are shifting their ranges to find better water. Evolution doesn’t stop just because we’ve messed things up.

What gives me hope is the people I keep discovering through this work. From researchers spending months on boats collecting tiny samples to indigenous knowledge keepers sharing centuries of observations with marine biologists.

When I see those TikTok cleaning videos now, I think about chemistry. How the right conditions can dissolve years of buildup in minutes. But I also think about how, with different chemistry, that same process can work in reversibly to our favor. That’s what we should be working toward.