Not Just Land, the Ocean is in Trouble Too... A Looming 'Vicious Cycle' [The Signal/XR]

[Anchor]

Just like the land, which gets hotter every summer, the ocean is also heating up. The ocean has played a role in slowing down the pace of climate change by absorbing carbon dioxide from the atmosphere. However, a forecast suggests it will become increasingly difficult for the ocean to perform this role.

Reporter Seo Donggyun brings us the report as part of the year-long climate change project, "The Signal."

[Reporter]

Sweltering heatwaves and extreme heat are not just happening on land.

This summer, fish in aquaculture farms have died off in succession. Looking at sea surface temperatures around South Korea over the past month, they were about 1.5 degrees Celsius higher than average.

The ocean's seasons usually arrive a season late, but water temperatures in some sea areas, including Jeju, have already exceeded 30 degrees Celsius (86 degrees Fahrenheit).

The impact of high water temperatures does not stop there.

The ocean absorbs about 30 percent of the carbon dioxide emitted by humans.

However, as climate change warms the water, warm water becomes lighter, which slows down the vertical movement of seawater mixing up and down.

Slower circulation means that the amount of carbon dioxide dissolved into the surface of the sea decreases accordingly.

Carbon dioxide absorption also decreases through another pathway.

Let us look at it from the perspective of phytoplankton.

Plankton, which perform photosynthesis, live by feeding on nutrients rising from the deep sea. When circulation weakens, nutrients decrease, and when nutrients decrease, photosynthetic activity also weakens.

Photosynthesis is, after all, the process of using light to convert carbon dioxide into nutrients and oxygen.

If photosynthesis by phytoplankton in the ocean decreases, the amount of carbon dioxide absorbed from the atmosphere inevitably decreases as well.

Of course, if seawater circulation slows down, carbon dioxide already dissolved may remain trapped inside the ocean for a longer period.

However, the impact of the ocean failing to newly absorb carbon dioxide outweighs this containment effect, ultimately resulting in a greater increase of carbon dioxide in the atmosphere than now.

Overseas researchers have analyzed that if climate change and high water temperatures continue, carbon dioxide concentrations could rise by about 16 percent by around the year 2500.

[Samar Khatiwala / Professor, Faculty of Core Research, Waseda University: We developed a calculation method that allows for a close analysis of the carbon cycle, and the calculation results showed that by the year 2500, the concentration of carbon dioxide would increase by about 16 percent, or 270 ppm.]

Higher carbon dioxide concentrations intensify global warming, which in turn raises ocean temperatures again, repeating a vicious cycle that accelerates climate change.

(Video Editing: Lee So-young, Design: Hwang Se-yeon, Producer: Kim Do-gyun, Han Seung-ho, XR: Lee Jun-ho, Jeon Yu-geun, Choi Jae-young)
※ Please note: This article was translated by AI and may contain errors.