Ocean Acidification: pH and the Ocean's Balance

The Big Question

What happens to sea animals when ocean water changes?

What Is Happening?

People burn fuel for cars and homes. This makes a gas called carbon dioxide.

Some carbon dioxide goes into the sky. Some goes into the ocean.

Carbon dioxide is an "acid gas." It makes ocean water more acidic. Acidic means less basic. We use pH to measure this.

What Is pH?

pH tells us if something is an acid or a base.

The pH scale goes from 0 to 14.

• 0 is the strongest acid. Acids often taste sour. They can hurt if you touch them.
• 14 is the strongest base. Bases feel slippery. They can break down fat and oil.
• 7 is in the middle. It is not an acid or a base. We call it neutral.

Everyday Things and pH

Many foods and things at home are acids or bases!

• Lemon is very acidic.
• Milk is a little acidic.
• Water is neutral.
• Baking soda is a little basic.
• Bleach is very basic.

The Ocean's pH

The ocean is special. It is home to many sea creatures.

One hundred years ago, the ocean's pH was 8.1.

Today, the ocean's pH is 8.0.

That seems like a tiny change. But it is a big deal!

Why a Small Change Matters

Our blood has a pH too. Healthy blood pH is 7.4.

If blood pH drops just a little, to 7.35, people can feel sick. They may get headaches. They may feel confused or very tired.

Scientists think ocean animals feel sick too, when ocean pH drops just a little.

For example, clownfish (like Nemo!) may get confused. They might swim toward danger instead of away from it.

What Causes This Change?

Carbon dioxide comes from things like:

• Driving cars, boats, trains, and planes
• Using electricity in our homes
• Cutting down trees (trees hold carbon dioxide and keep it out of the ocean)

What Can We Do?

We can help lower carbon dioxide!

Here are some easy ways:

• Turn off lights when you leave a room
• Unplug chargers and machines you are not using
• Walk, bike, or ride the bus when you can

Communities can help too! Towns can use less energy. They can build better bike paths and buses.

Remember

The ocean and our bodies are alike. Both need the right pH balance to stay healthy.

A small change in pH can make a big difference — for us, and for sea animals too.