To repair the damage we've inflicted on the planet, it's generally agreed that as well as reducing how much carbon we emit in the future, carbon dioxide will need to be removed from the atmosphere and stored somewhere else, permanently. The ocean is a pretty attractive destination.
Already the world's largest carbon sink, the ocean contains 50 times more CO2 than is currently in the atmosphere. And while a single wildfire could undo decades, if not centuries, of sequestration in a forest, carbon stored in the ocean is less at risk of what a rocket scientist might call a "rapid unplanned disassembly." As we look to remove billions of tons of historic emissions from the atmosphere, the sheer size of the ocean, covering 70% of the Earth's surface, comes in handy.