Pupil lesson
How does carbon move through the ocean?
Read, think and draw. Use paper or a document provided by your teacher. You do not need an account or to send personal details to KEO.
Read and wonder
Carbon is part of living things, air, water and rocks. The carbon cycle describes how it moves between these places. Carbon dioxide passes between the atmosphere and surface seawater. Some dissolves in the water.
Phytoplankton use sunlight and carbon dioxide to make food. Carbon then moves through food webs. Respiration and decomposition return some carbon to water or air. Some sinking material carries it deeper. Burning fossil fuels transfers stored carbon into the atmosphere quickly. The ocean absorbs some extra carbon dioxide, changing seawater chemistry.
Three things to know
- Carbon moves between stores.
- Surface water exchanges carbon dioxide with the air.
- Some sinking material carries carbon deeper.
- Atmospheric carbon dioxide
- Surface water and phytoplankton
- Food webs and some sinking material
Words to explore
- Carbon store
- A place where carbon is held.
- Phytoplankton
- Tiny drifting organisms, including algae, that use sunlight to make food.
Think it through
1. Name two carbon stores.
2. How can carbon enter an ocean food web?
3. Why is the ocean not an unlimited solution to fossil-fuel emissions?
Try it
Draw boxes for air, surface water, living things and deep water. Add labelled transfer arrows, including a return arrow.
Sources and credits
Lesson summary and activity prepared for Kids.Earth.Org. Factual sources checked 5 November 2026.