Additional CO2 in water near Antarctic Peninsula | Polarjournal

The western side of the Antarctic Peninsula is one of the regions of the world most affected by climate change. Warmer water is causing glaciers to melt more here than in other places on Earth. Sea ice formation has also changed as a result in recent decades, more sea ice had formed, the so-called Antarctic paradox. Now, U.S. researchers have found that these changes have also created a positive aspect. The upper water masses in coastal areas have absorbed moreCO2 than previously thought due to increased algae production.

The study, which was overseen by Professor Oscar Schofield of Rutgers University in New Brunswick, and was conducted by Michael Brown, his doctoral doctoral student, examined oceanographic data sets from the past 25 years. “In order to understand how climate change will affect carbon dioxide uptake of the Southern Ocean, particularly in coastal areas such as the Antarctic Peninsula, is enormously important for better better understanding on a global scale,” explains lead author Michael Brown. Because the oceans in general and the Southern Ocean in particular are the largest CO2 sinks worldwide. And this is related, among other things, to the temperature: The lower the water temperature, the higher the ability, to absorb gases. The scientists in the study found that theCO2 uptake at the water surface along the western side of the Antarctic Peninsula is related to the stability of the uppermost water layer and to the amount and species composition of the phytoplankton, the algae. The carbon dioxide is absorbed by the algae through photosynthesis and can thus no longer enter the atmosphere. When the phytoplankton subsequently dies, it sinks to the seabed and thus theCO2remains bound for a long time. The moreCO2 is captured, the more is removed from the atmosphere (up to a limit). The whole process is also influenced by the species composition and other physical factors.

Plant plankton is highly dependent on sea ice formation. Due to climate change, the amount of sea ice will decrease, according to scientific predictions. As a result,CO2 absorption will also decrease. (Photo: Dr Michael Wenger)

According to the researchers, between 1993 and 2017, the sea ice dynamics had changed along the western side of the peninsula. This stabilized the upper layer of the ocean. This in turn led to a larger amount of algae and to a shift in species composition. The scientists found that this was accompanied by a fivefold increase inCO2 uptake in the summer. The researchers found a significant regional difference between the north of the peninsula and the south, which until recently was less affected by climate change. In the latter area, the increases inCO2 uptake were greatest, as this is also where stability was was the strongest. But here, too, the wind has changed in the meantime. Higher Water temperatures have already been measured. The researchers suspect that the stability will decrease in the coming decades, because here too the sea ice is receding. When a critical minimum value has been reached, winds will mix the water masses more strongly. This can reduce the absorption and thus more CO2 remains in the atmosphere again and reinforces the cycle… and with it the melting of the ice masses in the Antarctica.

Already, the northern part of the water masses on the Antarctic Peninsula is no longer so strongly protected by sea ice. Wind and waves have led to greater mixing of the layers and reduced CO2 uptake. (Photo: Dr Michael Wenger)

Source: Rutgers University New Brunswick

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