How Climate Change Affects Ocean Acidification — Reading Comprehension

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This comprehensive science passage explores how climate change impacts ocean acidification and why this process is important for the health of our oceans. Designed for grades 6-8 and aligned with NGSS standards, students learn how increased carbon dioxide (CO2) from human activities leads to changes in ocean chemistry, making seawater more acidic. Key concepts such as the carbon cycle, pH scale, and effects on marine organisms like corals and shellfish are explained with clear definitions and real-life examples. The passage includes a glossary of important science terms, a Spanish translation, a multiple-choice quiz, and writing prompts to encourage deeper thinking. This resource is perfect for classrooms seeking interactive, audio-integrated content to build science literacy, vocabulary, and critical thinking skills related to environmental science and climate change.

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A visual representation of the process of ocean acidification. — When the ocean becomes more acidic, it affects the entire marine food web.

Climate change is causing many changes on Earth, including rising temperatures and shifting weather patterns. One important effect of climate change is called ocean acidification. This is a process that makes the ocean more acidic, which can harm ocean life.

When people burn fossil fuels like coal, oil, and gas, they release a gas called carbon dioxide (CO2) into the air. Some of this CO2 stays in the atmosphere, trapping heat and causing global warming. But about 30% of this CO2 is absorbed by the ocean. When CO2 mixes with seawater, it forms a weak acid called carbonic acid. This process lowers the pH of the ocean, making it more acidic.

The pH scale measures how acidic or basic a substance is. Pure water has a pH of 7, which is neutral. Numbers lower than 7 mean the water is acidic, and numbers higher than 7 mean it is basic. Before the Industrial Revolution, the ocean’s average pH was about 8.2. Now, because of extra CO2, the pH has dropped to about 8.1. This may not seem like a big change, but even small drops in pH can make it harder for some sea creatures to survive.

Many marine animals, such as corals, oysters, and plankton, build their shells or skeletons out of a mineral called calcium carbonate. When the ocean becomes more acidic, it is harder for these animals to make their shells strong. Their shells can even begin to dissolve. This affects the entire marine food web because many animals depend on these tiny creatures for food.

For example, coral reefs are home to thousands of species. If corals cannot build their skeletons, entire reef ecosystems can be damaged. In some places, oyster farms have had trouble growing young oysters because the water is too acidic. Scientists are studying ways to reduce CO2 emissions and protect ocean life, such as using renewable energy and planting more trees to absorb CO2.

Interesting Fact: Some types of plankton, called coccolithophores, make tiny shells that help remove CO2 from the atmosphere. Ocean acidification can affect how well they do this important job!

What gas causes ocean acidification?

Carbon dioxide (CO2)OxygenNitrogenHydrogen

What does pH measure?

Acidity or basicityTemperatureSalinitySize

What do corals use to build skeletons?

Calcium carbonateIronSaltSilicon

Why is ocean acidification harmful to oysters?

Shells can't form wellWater is too saltyNo food availableOcean too cold

Lower pH makes it easier for shells to form.

TrueFalse

What is one way to reduce CO2?

Plant more treesBurn more coalDump trashUse more plastic