Chapter 17, Key Finding 1

Rising carbon dioxide (CO₂) has decreased seawater pH at long-term observing stations around the world, including in the open ocean north of Oahu, Hawai‘i; near Alaska’s Aleutian Islands; on the Gulf of Maine shore; and on Gray’s Reef in the southeastern United States. This ocean acidification process has already affected some marine species and altered fundamental ecosystem processes, and further effects are likely (high confidence, likely).