The 0.1 drop in pH doesn't reflect the severity of the situation vis a vis ocean acidification. The ocean is a buffered system. This means that as you add more acid (read Carbon dioxide) certain ions in the water take up the acid and only allow the pH to drop slightly. The ocean is a multiply buffered system so when you have used up the ions which work at the top of the pH range, a little more acid will cause a sharp drop in pH to the level where the next ion takes up the work of keeping the pH stable. The corals, shells of various animals and calcarious oozes on the bottom of the sea fit somewhere into this buffering system so when their pH threshold is reached they will dissolve and keep the sea at another pH plateau. If we continue to add Carbon dioxide to the oceans, the pH will go down in a series of steps, each one more severe in terms of the productivity of the ocean than the previous one. We need some research by marine chemists to work out the fine details of this system to see how close we are to the first drop and where solid Calcium carbonate (read corals and shells) fits into the system.