Eli5: How exactly does the acidification of the ocean influence corals in their growth?

Question

I dont understand the underlying chemical processes.

In: 3

Answer 1

This is not really ELI5, but this as simple as I can make it:

Corals form calcium carbonate (CaCO3) from the ions in the water (Ca^(2+) and CO3^(2-)). This is one of their fundamental building blocks.

The carbonate ions (CO3^(2-)) form an equilibrium in the water: HCO3^(-) <-> H^(+) and CO3^(2-)

This reaction can go both ways, but if the water because more and more acidic (H^(+) added), the reaction will flow more and more to the left to compensate. This means there will be less CO3^(2-) in the water and more HCO3^(-). The corals thus need to filter more water to get the required C03^(2-)-ions to grow, this takes more time and energy and therefore they grow slower.