Usually the deep sea floor is chalky white in color. It's composed, to a large degree, of the mineral calcite (CaCO3) formed from the skeletons and shells of many planktonic organisms and corals. The seafloor plays a crucial role in controlling the degree of ocean acidification.
The dissolution of calcite counterbalances the acidity of the CO2, and in the process prevents seawater from becoming too acidic. But these days, at least in certain hotspots, for instance, the Northern Atlantic and the southern Oceans, the ocean's chalky bed is becoming more of a murky brown. As a result of human actions the level of CO2 in the water is so high, and the water is so acidic, that the calcite is simply being dissolved.
The McGill-led research team, consider that what they are seeing today is only an indication of the way that the ocean floor will most likely be affected in future. In future work, the researchers plan to look at how this deep ocean bed dissolution is likely to evolve over the coming centuries, under various potential future CO2 emission scenarios.