The ocean has absorbed a significant portion carbon dioxide emissions from human activities, decreasing the pH of the water and leading to a suite of chemical changes collectively known as ocean acidification. The long-term consequences of ocean acidification are uncertain, but they are expected to affect many ecosystems and the services they provide to society. Ocean Acidification: A National Strategy to Meet the Challenges of a Changing Ocean reviews the current state of knowledge, explores gaps in understanding, and identifies several key findings.