Ocean acidification refers to the process of seawater pH decreasing (“increased acidity”) as the ocean absorbs CO2. As atmospheric CO2 levels have increased since pre-Industrial times (the mid-1700s), the oceans have absorbed approximately 30% of anthropogenically-produced CO2. As a consequence, ocean pH has dropped from 8.2 to 8.1. While this may not seem like a major change, the logarithmic scale of pH means that this change actually represents a 30% increase in acidity. Click here to read more.