Retreat of glaciers locks up carbon

Phytoplankton are flourishing in areas of open water left exposed by  Antarctic melting  – and are acting as a carbon sink.

As blooms die back, the phytoplankton sinks to the sea-bed where it can store carbon for thousands or millions of years. Scientists from the British Antarctic Survey (BAS) now estimate that this new natural ‘sink’ is taking around 3.5 million tonnes of carbon from the ocean and atmosphere each year – equivalent to 12.8 million tonnes of CO2.

“Although this is a small amount of carbon compared to global emissions of greenhouse gases in the atmosphere it is nevertheless an important discovery,” says Professor Lloyd Peck of the BAS. “It shows nature’s ability to thrive in the face of adversity.” 

The team compared records of coastal glacial retreat with records of the amount of chlorophyll in the ocean.

They found that over the past 50 years, melting ice has opened up at least 24,000km2 of new open water, which has been colonised by carbon-absorbing phytoplankton.

According to the authors, this new bloom is the second largest factor acting against climate change so far discovered on Earth – the largest being new forest growth in the Arctic.

Professor Peck said: “Elsewhere in the world, human activity is undermining the ability of oceans and marine ecosystems to capture and store carbon. At present, there is little change in ice shelves and coastal glaciers away from the Antarctic Peninsula, but if more Antarctic ice is lost as a result of climate change, then these new blooms have the potential to be a significant biological sink for carbon.”

The research appears in Global Change Biology.