The downside is that a second study shows that,
the sink effect is now changing ocean chemistry. The resulting change has slowed growth of plankton, corrals, and other invertebrates that serve as the most basic level of the ocean food chain.
This is a real problem for a couple reasons. The scary thing is that the effects of destruction to the marine world are easier to ignore than melting ice caps, creeping temperature increases, and irregular weather patterns.
The second reason this is a real problem is that carbon dioxide is an acidic gas. This means that the natural pH levels are dropping. This could make it more difficult for shelled animals to produce shells. It makes algae less capable of growing. Also the corrals are not able to grow which destroys a part of the ecosystem.