premise: Ocean acidification is the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of carbon dioxide (CO2 ) from the atmosphere.
hypothesis: Ocean acidification occurs when excess carbon dioxide in the atmosphere causes the oceans to become acidic.
hypothesis_graph_structure: Ocean acidification<>occurs<>when excess carbon dioxide in the atmosphere causes the oceans to become acidic$$$excess carbon dioxide in the atmosphere<>causes<>the oceans to become acidic$$$the oceans<>to become<>acidic