Worse than just the direct acidification: if we're already seeing the increase in surface temperatures that we are, with oceans absorbing more carbon than we thought, what happens when ocean sequestration decreases? It will do that nonlinearly, we just don't know exactly when.

(It's expected that when the pH of the Southern Ocean gets past a threshold, phytoplankton (with carbonate shells) will start to be replaced by algae (without). Dead phytoplankton falling to the ocean floor is a major component of carbon sequestration by the oceans.)

It suggests that we could pass a threshold and be in for a world of hurt very soon.

On the contrary. If ocean uptake is larger than previously thought and the pH has only decreased from 8.1 to 8.0 it shows large resiliance. But the 0.1 decrease should be questioned because of uncertainty in measurement. Measuring ocean pH can be considered impossible since the oceans is on average 3000m deep and measurements in history should be questioned. Also, acidification happens below ph7. A reduction from 8.1 to 8.0 is neutralization, not acidification. Sea creatures (including corals) have been shown in experiments to tolerate larger pH-drops well.

I initially read the headline as good news - less CO2 in the atmosphere - but I forgot about ocean acidification. Thanks the the heads up.