The ocean around New Zealand is getting more acidic, RNZ reveals, potentially causing widespread harm to marine life. Ocean acidity has increased by 30% over the last 250 years, with a rise of 8.6% between 1998 and 2020. Caused by the ocean absorbing carbon dioxide from the air, acidity can dissolve the shells of pāua, mussels and other kaimoana. Acidification may also cause widespread harm to ecosystems.