Carbonic acid is frequently created by the dissolution of atmospheric CO, into water. This is the main cause of the acidification of large bodies of water. Over the last 100 years, the pH of the oceans has gone from 8.2 to 8.1. However the pH of the oceans may decrease even further to 7.8 in the NEXT 100 years. To a layperson that may not sound so bad therefore they might say: Well it is just a decrease of 0.4, explain why this decrease is much worse than it sounds.