Meridional overturning circulation conveys fast acidification to the deep Atlantic Ocean posing a severe threat to cold-water coral habitats.

Increasing atmospheric carbon dioxide concentrations are increasing the acidity of the oceans and reducing carbonate-ion concentrations, making it difficult for corals to maintain their calcium carbonate skeletons. This paper reports a roughly 40 per cent reduction in the transport of carbonate ions to the deep North Atlantic ocean since preindustrial times, with implications for cold-water coral habitats. The authors suggest that a further doubling of the concentration of anthropogenic carbon dioxide in the atmosphere could reduce the transport of carbonate ions to corals below 1,000 metres to a quarter of its preindustrial levels, potentially posing a severe threat to these habitats.

https://www.nature.com/articles/nature25493