Explain how carbon dioxide dissolved in the oceans as the atmosphere changed.

As the Earth's atmosphere evolved, the levels of carbon dioxide decreased due to its dissolution in the oceans. This process occurred as the oceans formed from condensed water vapour, allowing carbon dioxide to react with water and form carbonic acid, which further contributed to the reduction of atmospheric carbon dioxide levels.

A strong answer should directly address the approved learning objective to explain that carbon dioxide dissolved in the oceans as the atmosphere changed. This question belongs to How carbon dioxide decreased within The composition and evolution of the Earth's atmosphere, so the response should use that exact curriculum context rather than a generic statement. The answer is correct when it names the key idea, explains the link to carbon dioxide, and keeps the wording specific to AQA GCSE revision.