Scientists find unexpected carbon sink on Antarctic seafloor

In a rare piece of good news on climate change, a paper in the journal Current Biology suggests that the loss of sea ice over Antarctic waters in some areas has led to the increased growth of creatures living on the seafloor that are acting as an important and unexpected carbon sink.

Arctic forests and new algal blooms where ice shelves disintegrated are know to work, to some extent, against climate change.

Scientists now say, based on studies of West Antarctic bryozoans – organisms sometimes referred to as “moss animals” – that other organisms living on the seafloor “could be more important than both” when it comes to accumulating and burying carbon.

“We’ve found that a significant area of the planet – more than three million square kilometres – is a considerable carbon sink and, more importantly, a negative feedback on climate change,” says David Barnes of the British Antarctic Survey (BAS). 

Antarctica has not experienced a net loss of sea ice in the way the Arctic has, but ice has melted over continental shelves  and formed over deeper waters.

In the new study, Barnes and his colleagues collected specimens across West Antarctic seas and used high-resolution images to calculate the density of life on the seabed.

The data, collected over more than 20 years, reveals strong increases in annual production of shelf seabed carbon in the bodies of West Antarctic bryozoans.

The researchers calculate that growth of the bryozoans has nearly doubled, and they are taking in the equivalent amount of carbon to about 50,000 hectares of tropical rainforest.

“The forests you can see are important with respect to the carbon cycle and climate change, but two-thirds of our planet is ocean, and below it the life you can’t see is also very important in climate responses as well,” Barnes says.