Melting glaciers might be making ocean water more acidic, an unexpected finding that’s given scientists new cause for concern. A new study published yesterday in the journal Nature Climate Change suggests surprising ways that climate change is drastically altering the water chemistry in deep seas—a process that may happen faster than researchers anticipated.
(From Scientific American/ By Chelsea Harvey) — The threat of ocean acidification has drawn increasing attention in recent years. The ocean absorbs a substantial amount of the carbon dioxide that humans emit into the atmosphere—and when carbon dioxide goes into the sea, a chemical reaction occurs that causes the water to become more acidic. That’s a big concern for marine biologists, as research suggests that the decreasing pH levels could disrupt the ability of corals, mollusks and other marine organisms to build the hard outer shells they need to survive.
Because humans are still emitting about 40 billion tons of carbon dioxide into the atmosphere each year, ocean absorption of greenhouse gases from the air remains the primary concern about acidification. This process mainly affects the water close to the surface, where the gases are actually being absorbed.
But as the new research points out, dead plants and animals also release carbon dioxide as they drift to the bottom of the sea and decompose. Deep ocean currents can help to move the carbon dioxide throughout the water so it doesn’t sit in one place. But some scientists believe that certain effects of climate change—including the influx of cold, fresh water from melting glaciers, or an increase in the heat absorption as sea ice disappears and exposes the water to the sun—may eventually disrupt these currents or cause them to slow down.
Now, the new study’s authors suggest this process could speed up the acidification of the deep seas. In fact, their new research suggests this process may already be occurring in the Sea of Japan, a 380,000-square-mile body of water between Japan, North and South Korea, and Russia.
Like the open ocean, the Sea of Japan contains special currents that carry water from the surface down to the bottom of the ocean, a kind of mixing process known as “overturning circulation.” (The same process occurs on a much larger scale in the open ocean, where huge currents act as a kind of conveyor belt carrying warm water from the equator to the poles and vice versa.) But over the past decade…
Read the full article here: https://www.scientificamerican.com/article/melting-ice-could-mess-up-deep-sea-chemistry/