Climate change indicators in the United States – ocean acidity

Posted on EPOCA: 07 Jun 2012

This indicator shows acidity levels in the ocean, which are strongly affected by the amount of carbon dioxide in the water.

Key Points

  • Measurements made over the last few decades have demonstrated that ocean carbon dioxide levels have risen, accompanied by an increase in acidity (that is, a decrease in pH) (see Figure 1).
  • Modeling suggests that over the last few centuries, ocean acidity has increased globally (meaning pH has decreased), most notably in the Atlantic (see Figure 2).
  • Direct observations show that pH levels fluctuate more frequently in some areas of the ocean than in others. 3 More measurements are needed to better understand the links between these natural fluctuations and long-term changes in ocean acidity.




US Environmental Protection Agency (EPA). Web page.