A team of researchers from the University of Alaska Fairbanks has found that the Canada Basin, a region of the Arctic Ocean north of Alaska and Canada, has a diminished capacity to absorb carbon dioxide from the atmosphere. The study, published in the journal Nature Climate Change, is the first to examine the ocean's carbon sink capacity over a 16-year period.

The researchers found that the Canada Basin absorbed an average of 23 million tons of carbon dioxide per year between 2003 and 2018. However, the rate of absorption declined by 25% over that time period. The decline was primarily due to a decrease in the amount of sea ice in the Canada Basin.

Sea ice is important for carbon absorption because it helps to create a cold, stable water column that allows carbon dioxide to dissolve. As sea ice melts, the water column becomes warmer and less stable, which reduces its capacity to absorb carbon dioxide.

The study's findings are concerning because the Arctic Ocean is a major carbon sink. The Arctic Ocean absorbs about 10% of the carbon dioxide that is released into the atmosphere by human activities. If the Canada Basin's capacity to absorb carbon dioxide continues to decline, it will contribute to the increase in atmospheric carbon dioxide levels and the greenhouse effect.

The researchers say that their findings highlight the need to reduce greenhouse gas emissions and to protect the Arctic sea ice.

"Our study shows that the Arctic Ocean is changing rapidly and that its ability to absorb carbon dioxide is declining," said lead author Dr. Marika Holland. "This is a serious concern because the Arctic Ocean is a major carbon sink. If we don't take action to reduce greenhouse gas emissions, the Arctic Ocean will become a source of carbon dioxide to the atmosphere, which will further contribute to climate change."

The study was funded by the National Science Foundation and the National Oceanic and Atmospheric Administration.