You probably already know what is ocean acidification: as CO2 increases in the atmosphere due to fossil-fuel burning and deforestation by humans, around 25% of all that CO2 is taken up by the oceans. There, it interacts with seawater and forms carbonic acid, leading to a reduction in pH, an increase in acidification and an alteration of carbonate chemistry. The average surface pH of the ocean has already decreased by 0,1 since the Industrial Revolution, and a further 0,3-0,4-unit decrease is expected by the end of this century. It may seem like very little, but this means that acidity will double in the ocean by 2100.

Typically, when we think of ocean acidification we relate it to the bleaching of tropical corals or to decalcification and death of shellfish. But, have you ever stopped to think about how will ocean acidification affect human health and wellbeing around the globe? Today we wanted to bring you attention to a recent paper that discusses all the implications of ocean acidification for humans.

How can ocean acidification affect humans?

The most obvious way, in which ocean acidification will affect humans, is through a reduction in the quantity and the nutritional composition of seafood, and we are not only talking about the obvious impact on shellfish. For example, studies have shown negative direct effects of increased CO2 on the survival of eggs and early larval stages of some fish species. Indirect effects on fish can also be driven by changes in a food source, or by a change in usual places of shelter and feeding. But ocean acidification may also lead to a reduction of lipids and proteins in the fish, including the essential omega-3 fatty acids. Seafood is a fundamental protein intake for over 1 billion people worldwide, most of them in areas where the most vulnerable communities are found.

But ocean acidification can also affect the propagation of contaminants through the marine environment, changing their bioavailability and intensifying exposure and bioaccumulation. For example, mercury and some metals (such as aluminum, iron, lead or copper) are often more bioavailable in acidified aquatic habitats. It also modifies the abundance and chemical composition of harmful algal blooms, increasing shellfish toxicity. This effect has already been proved in Karenia brevis, a frequent visitor of Florida’s coasts, which already costs the tourism industry of the area around 2,5 million euros per month in economic loss.

Other ways in which ocean acidification affects human health is through an increase in respiratory issues, disruption of nature-based recreational activities, or loss of potential medical new resources. Read the full paper for a complete picture of things to come.

Research in this field is essential and urgent in order to understand the full scale and risks of ocean acidification to human health and wellbeing, and to anticipate and monitor such changes, adapting to them. Maybe by acknowledging the profound effect it will have on humanity, we may begin to take real action to reduce, if not stop, ocean acidification and climate change.