Arctic Ocean acidification a result of warmer climate: Research
Gothenburg, Sweden: Sea ice in the Arctic Ocean is melting as a result of climate change. According to a study published in the journal Science and co-authored by researchers from the University of Gothenburg, carbon dioxide intake increases and disrupts the aquatic food chain when the Arctic ocean loses its sea ice cover.
Researchers have been able to observe how the pH of the ocean north of Alaska and Siberia has dramatically reduced by comparing data from numerous Arctic missions. The Arctic Ocean has been becoming more acidic at a rate that is three to four times quicker than that of other oceans in recent decades.
This is due to the fact that seawater absorbs more carbon dioxide when it comes into direct contact with the atmosphere without the help of ice. The sea ice has historically prevented carbon dioxide from becoming saturated in the seawater around the North Pole.
"The time series of pH measurements made in the Arctic Ocean is long. The oldest are from an expedition in 1994 when the ice sheet was extensive and thick, and measurements were taken in the leads between the ice floes. On the expedition in 2014, the icebreaker Oden was able to travel in open water halfway from Siberia to the North Pole," says Leif Anderson, a researcher in marine chemistry at the University of Gothenburg and one of the authors of the study.
Acidification most significant in cold oceans
The pH scale, the measured acidification during the past 30 years is equivalent to around 0.1. If carbon dioxide levels in the atmosphere continue to rise at the same rate they are now, the researchers predict that the pH value will drop by another 0.3 by the turn of the century. The coldest oceans will be most affected. How much carbon dioxide can be dissolved in the ocean depends on the temperature of the water. Due to alterations in the chemistry of saltwater, more freshwater from melted sea ice also has a greater acidification effect by absorbing more carbon dioxide from the atmosphere.
Strong Pacific Ocean currents are pushing nutrient-rich water up to the northern oceans, and the Arctic's ice-free waters are experiencing a high rate of phytoplankton primary production throughout the long summer days. Because phytoplankton absorbs a lot of carbon dioxide during photosynthesis, the water is undersaturated with carbon dioxide as it travels further north under the polar ice. However, because there is less sea ice throughout the summer, the seas are getting more acidic as a result of the seawater's continued absorption of carbon dioxide.
Sea butterflies may be adversely affected
Marine life in the arctic oceans is already being affected by acidification, according to researchers.
"Phytoplankton, which takes up carbon dioxide, are benefiting from climate change. For other species, however, the news is not so good. Sea butterflies are a species of predatory sea snail that have shells of aragonite which they form from calcium and carbonate ions. We have measured lower and lower aragonite saturation levels of in the ocean from our expeditions," says Leif Anderson.
For many whales that often move up to the Arctic Ocean to graze and gain weight, sea butterflies are a crucial species and an essential staple meal. However, there may be less food in the pantry right now.
Polar seas are getting increasingly acidic due to a number of factors, including a decrease in sea ice cover and the warming of the high Arctic tundra. There is a significant release and transport of organic carbon into the Arctic rivers, where it breaks down into carbon dioxide and other compounds, lowering pH levels.
"All of these factors are consequences of climate change, and more open waters in the Arctic is amplifying their effects," says Leif Anderson.
