In combination with warming of the ocean waters which is already occurring, this acidification will kill off most corals and most other creatures which make carbonate shells and exoskeletons.
In addition to wide scale species extinctions, when the ocean waters become saturated with CO2, the ocean will no longer absorb more CO2 than it releases. When that happens the rate of increase of CO2 concentration in the atmosphere will itself increase - very significantly.
There is much more can be said about this.
I believe however there is a method by which we may overcome the very real problem of ocean acidification and in the process create enormous ecological, economical and social benefits.
Other upwelling situations are:
Note, smaller systems can be built using pipes suspended from buoys. Where a non-return valve is fitted - preferably to the bottom of such pipes - wave action raising and lowering the buoys relative to the average sea level will cause water to be drawn up to the surface. This has been demonstrated to work and the expected increase of phytoplankton occurs.
Note also that if enough such upwellings are created in ocean areas where hurricanes/ taiphoons/ tropical cyclones arise and/or pass through, it should be possible to decrease their ferocity. This has the potential to save many thousands of lives in the future as global warming causes the breeding of ever greater tropical storms!