Ocean acidification

Besides increases in temperatures, the world’s oceans also take up CO2, leading to a lowering of pH-levels in the water. This process is especially relevant to marine ecosystems and coral reefs, which are very sensitive to changes in ocean chemistry. Strong ocean acidification depresses metabolic rates in some organisms and reduces the ability of species to sequester calcium required for building shells and skeletons, or even leads to dissolving existing coral reef structures. We assess greenhouse-gas emission scenarios regarding the possibility to prevent the worst of the projected effects of ocean acidification.


Ocean systems are particularly vulnerable to climate change and are already heavily impacted today. This briefing provides an overview of the latest science including from the latest IPCC special reports on key risks for ocean systems including from sea-level rise, ocean acidification and impacts on marine and coastal ecosystems. The analysis underscores the need to limit warming below 1.5°C to limit impacts on ocean systems. It is clearer than ever that exceeding that warming level will fundamentally affect ocean systems and undermine any other attempts to protect them. Limiting warming to 1.5°C remains of paramount importance to safeguard the oceans.  


Science and policy to assist and support SIDSs and LDCs to negotiate a strong international climate regime, enabling low carbon development and supporting adaptation needs.