Interview with Mr. Tomohiko Tsunoda, Senior Research Fellow at the Ocean Policy Research Institute, Sasakawa Peace Foundation on ocean warming and acidification

What is ocean acidification and why is it occurring?

Mr. Tsunoda: In short, ocean acidification is the process whereby carbon dioxide dissolves in the ocean and makes the water more acidic. Seawater is normally slightly alkaline on the pH scale, but as more carbon dioxide is dissolved in the oceans, the pH moves toward neutrality, or in other words, becomes more acidic. The more carbon dioxide in the air, the more carbon dioxide dissolves into the sea. Ocean acidification, like global warming, is caused by the carbon dioxide that is produced by human activities.
 
What are the effects of ocean acidification?

Mr. Tsunoda: When seawater becomes more acidic, the number of carbonate ions in the water goes down. This creates a problem for organisms that have a shell or a skeleton made of calcium carbonate.
 
For example, between 2005 and 2009, ocean acidification on the west coast of the United States caused problems for oyster farming. In the Arctic Ocean and elsewhere, there are concerns about the decrease in the number of organisms with calcium carbonate shells and the subsequent effects on the marine life that feeds on those organisms. When the natural food chain breaks down, it eventually reaches human beings at the top of the chain, but it’s difficult to predict the nature of these effects or how far reaching they will be.
 
Item 3 of Sustainable Development Goal 14, which was announced in 2015, relates to ocean acidification. OPRI has been conducting research on acidification since 2015, and we’ve found that ocean acidification is a complex issue.

What makes these issues so complex?
 
Mr. Tsunoda: Ocean issues, acidification included, rarely occur in isolation, and often involve several interconnected factors. The problems that occur also vary from region to region. For example, in coastal areas, eutrophication (a process that leads to excessive growth of algae or other plants) due to human activities can cause ocean acidification. This also reduces the amount of dissolved oxygen in the water in a process called deoxygenation.
 
There is also a pattern occurring on the western coasts of continents around the world, wherein coastal fisheries are negatively impacted by so-called anoxic water masses, which contain low levels of oxygen, rising to the ocean surface. Unfortunately, this upwelling of anoxic water is occurring at the same time as acidification, which is a double blow to the fishing industry.
 
Additionally, in the frigid seas near the North and South Poles, ocean acidification has become more pronounced than anywhere else in the world due to the fact that carbon dioxide dissolves more easily in cold water.

That does sound like a complex situation.
 
Mr. Tsunoda: Absolutely. Ocean acidification is a complex phenomenon, making it difficult to explain not only to the general public but also to the government officials who are in a position to make policy decisions. In addition, the measures that need to be taken to address the problem will vary from region to region.
 
If a problem and its causes are clear, it is easy to take action. For example, in the case of the hole in the ozone layer, the relationship between emissions of chlorofluorocarbon gases and the hole in the ozone layer was easy to understand and scientifically proven. As a result, the Montreal Protocol was drawn up, the use of chlorofluorocarbons was banned, and we are now seeing reports that the ozone layer is likely recovering.

It seems that the complexity of the acidification problem is one of main factors preventing us from taking steps to address the issue.
 
Mr. Tsunoda: It's difficult to see the whole picture when a problem is so complex. Making matters worse, we don't yet have enough basic monitoring data and scientific studies on the subject.

Article 4 of the Basic Act on Ocean Policy has a section entitled “Improvement of Scientific Knowledge of the Oceans.” It states: “In consideration of the fact that scientific knowledge of the oceans is indispensable for the proper development and use of the oceans and conservation of the marine environment, while many scientifically unsolved fields remain with regard to the oceans, the scientific knowledge of the oceans shall be improved."
 
The United Nations has designated 2021-2030 as the “United Nations Decade of Ocean Science for Sustainable Development.” I hope that scientific research on the oceans will continue and that solutions will become possible through innovations in science and technology.

So we require solutions based on scientific data.
 
Mr. Tsunoda: That's right. In order to take effective measures, we have to think scientifically and holistically about the situation regarding the oceans and the various problems we face. Some time ago, I noticed that there was not much useful reference information in Japanese about the marine crisis. That's why we launched the Marine Crisis Watch website. Our goal now is to use the website to provide a regular stream of scientific information and data on complex marine issues in Japanese to communicate these ideas in a way that is easy for people to understand.
 
In order to broaden public awareness of ocean acidification, we also created a Japanese dubbed version of the British clay animation “The Other CO2 Problem” in collaboration with Kanagawa Prefectural Marine Science High School. Little by little, we are working to let the public know about the complex issues related to ocean warming and acidification with the hope that they will be reflected in policies down the line.