The acidity of a substance relates to the proportion of free hydrogen ions (H+) it contains. Acidity is measured on a logarithmic scale. Even a small decrease in pH of ocean water can cause a large increase in hydrogen ions and acidity. This increase can have grave effects on marine ecosystems. For the last 300 million years, the average pH of the oceans has been 8.2. Today, the average pH is 8.1. Using the hydrogen ion concentrations, what is the percent increase in acidity of the ocean in the past compared to today?