Question

How are human activities disturbing carbon dioxide levels and affecting marine life?

Answer 1

I think the answer is Increased carbon dioxide levels have made the oceans more acidic. 

Answer 2

The right answer is Increased carbon dioxide levels have made the oceans more acidic.

The acidification of the ocean is the gradual decrease of the pH of the oceans. It was estimated that from 1751 to 2004, the pH of the ocean's surface waters decreased from 8.25 to 8.14. This is the "other problem" of increasing anthropogenic carbon dioxide (CO2) emissions into the atmosphere.