The Southern Ocean is home to a diverse and rich community of marine life which thrives in an environment dominated by glaciers and strong currents. Antarctic waters cover around 10% of the global ocean and are home to almost 10,000 unique polar species. Due to the impact of climate change in this region, securing vital protection for the Southern Ocean has never been more urgent.
Threat in Marine Biodiversity
By the end of the century, the acidity of the coastal waters in Antarctica could double, threatening penguins, whales, and hundreds of other species which inhabit the Southern Ocean. This was the finding of a new research entitled "Severe 21st-century ocean acidification in Antarctic Marine Protected Areas", conducted by experts from the University of Colorado Boulder.
Led by INSTAAR research scientist Cara Nissen, the researchers used a computer model to simulate how the seawater surrounding Antarctica would change in the 21st century. It was projected that by 2100, the upper 650 feet (200 meters) of the Southern Ocean could see over 100% increase in acidity compared with 1990s levels.
This situation would also be severe if the world fails to cut emissions. According to CU Boulder's Institute of Arctic and Alpine Research (INSTAAR) interim director Nicole Lovenduski, the results of their study are critical for our understanding of the future evolution of marine ecosystem health.
The Southern Ocean surrounding Antarctica is particularly prone to acidification, partly because colder water absorbs more CO2. Meanwhile, ocean currents in the regions also contribute to the relatively acidic water conditions. Nissen further noted that the impact of acidification is not just on the top layer of the ocean, since it can affect the entire water column of the coastal Southern Ocean.
The team also investigated the conditions that are specific in Antarctica's marine protected areas (MPAs) where human activities are restricted to protect biodiversity. There are currently two MPAs in the Southern Ocean which covers about 12% of the water in the area. The team's model showed that both adopted and proposed MPAs would likely experience significant acidification by the end of the century.
The study serves as a reminder that the dynamic coastal seas in Antarctica are also themselves capable of rapid change. It also suggests that our planet could only avoid severe ocean acidification of the Southern Ocean if CO2 emissions are cut quickly and aggressively.
What is Ocean Acidification?
Ocean acidification refers to the process by which seawater becomes more acidic when excess carbon dioxide is absorbed from the atmosphere. This phenomenon has affected not only the entire world's oceans, but also coastal estuaries and waterways.
The oceans play a crucial role as a buffer against climate change by absorbing 25% of the carbon dioxide emitted worldwide. For more than 200 years, the concentration of carbon dioxide in the atmosphere has increased because of extensive land usage and burning of fossil fuels. As more CO2 dissolves in the oceans, the seawater gets more acidic.
Increasing acidity of the ocean affects many ocean species, especially those that make hard shells and skeletons by combining calcium and carbonate from seawater. With increased ocean acidification, the available carbonate ions bond with excess hydrogen. This results in fewer carbonate ions available for calcifying creatures to build and maintain their shells, skeletons, and other structures. If the pH level of the ocean continues to get lower, the shells and skeletons of these animals can begin to dissolve.
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