An international team of researchers have sounded alarm bells about the changing chemistry of the western region of the Arctic Ocean after finding it to be three to four times more acidic than other ocean waters.
There is a correlation between the rate of melting ice in the region and the rate of ocean acidification, which threatens the survival of plants, shellfish, coral reefs and other marine life.
The data from more than two decades is included in the new study.
If not sooner, scientists have predicted that the sea ice in this region will be gone by the year 2050. The ocean's chemistry will grow more acidic as a result of the sea-ice retreat each summer.
The diverse population of sea creatures, plants and other living things depend on a healthy ocean to survive. Crabs live in a shell made of calcium carbonate in the ocean. Fish and sea birds rely on plankton and plants for food, while polar bears rely on healthy fish populations for food.
Many of the planet's inhabitants are affected by the acidification of these distant waters.
A quick course on how acidic or alkaline a liquid is is the first thing to do. Pure water is neutral with a pH of 7 and can be characterized by its pH level. All levels below 7 are acidic and all levels above 7 are basic or alkaline. On the acidic side, examples include battery acid, gastric acid, black coffee, and milk. Blood, baking soda, ammonia, and drain cleaner are moving towards basic. The sea water has a pH value of 8.1.
Cai, the Mary A.S. Lighthipe Professor in the School of Marine Science and Policy in the University of Delaware's College of Earth, Ocean and Environment, has published significant research on the changing chemistry of the planet's oceans and this month completed a cruise from Nova Scotia Four areas of study are included: the East Coast, the Gulf of Mexico, the Pacific Coast and the Alaska/arctic region.
A recent voyage to collect data in the Chukchi Sea and Canada Basin was done by a researcher from the University of Delaware.
Di Qi is the first author on the publication. Scientists from Seattle, Sweden, Russia, and six other Chinese sites collaborated on the publication.
Cai said you cannot just go by yourself. Collecting long-term data over a large area in the remote ocean is very important. In the past few years, we have collaborated with Japanese scientists, as it has become harder to access the water in the northern part of the planet. European scientists participate.
When they first looked at the data together, they were confused. The water was more acidic than ocean waters elsewhere.
That was stunningly beautiful. Why was it occurring?
The increased melt of sea ice is a prime suspect.
During the summer season, the sea ice has melted in some areas. Cai said that that began to change in the 1980's. The ice melt has advanced into the deep basin in the north.
The melting ice was thought to provide a carbon sink, where carbon dioxide from the atmosphere would be sucked into the cold, carbon-hungry waters that had been hidden under the ice. The cold water would hold more carbon dioxide than the warm water would and it might help to offset the effects of increased carbon dioxide in the atmosphere.
The ice had melted beyond the Chukchi Sea, all the way to the Canada Basin, when Cai first looked at the ocean in 2008. The fresh meltwater didn't mix into deeper waters, which would have hurt the carbon dioxide in the water. The surface water soaked up the carbon dioxide until it reached the same levels as in the atmosphere. The result was reported in a paper.
They knew that changing the pH level of the waters would change their chemistry and make them less resistant to acidification. What amount? How quickly? It took another decade for them to collect enough data to come up with a conclusion.
Analyzing data from 1994 to 2020 was the first time such a long-term perspective was possible.
Sea-ice melt is the key mechanism to explain the rapid pH decrease because it changes the physics and chemistry of the surface water.
The data so far show the effects of climate change, but more research is needed to better predict future changes.
He said that if all of the multiple-year ice is replaced with first-year ice, there will be lower alkalinity and lower buffer capacity. In the summer, we think all of the ice will go away. Papers are predicting that will happen by the year 2030. The summer acidification will be strong if we follow the trend for 20 more years.
It's not known what will happen to the creatures and plants that depend on healthy ocean waters.
What will this do to the biology there? Cai wanted to know. This is important because of that.
More information: Di Qi et al, Climate change drives rapid decadal acidification in the Arctic Ocean from 1994 to 2020, Science (2022). DOI: 10.1126/science.abo0383 Journal information: Science
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