ASSOC PROF ABBY SMITH
When the oceans absorb carbon dioxide then they... it changes their chemistry a little. It drives a carbon cycle, which involves a series of fairly simple chemical equations, and it causes the pH [level] of the sea to go down. That means the sea becomes a little more acidic. Now, if we were only producing a little bit of carbon, then the ocean might only become a little more acidic and that would be OK, but we are producing enormous amounts of carbon, and the ocean is absorbing more carbon more quickly than it ever has ever in the past, and it is changing in terms of its pH very, very rapidly, and critters living in the water just can't adjust to that.