Rising carbon dioxide levels are not just warming the planet. The ocean absorbs a large share of atmospheric CO2, which shifts seawater chemistry and makes it more acidic. Marine biologist Christopher Cornwall from Victoria University explains how that process, called ocean acidification, makes it harder for abalone, calcareous seaweeds, and other marine organisms to build and keep the calcium carbonate structures they rely on. The RNZ article also covers two extra pressures on ocean ecosystems: marine heatwaves and coastal darkening, where sediment blocks sunlight and disrupts photosynthesis in marine plants and algae. Cornwall says cutting greenhouse gas emissions is the main solution, with habitat restoration and better management of marine ecosystems as supporting measures. The story is useful background for anyone tracking climate impacts on fisheries, coastal economies, or ocean-based carbon projects.
