A new study, conducted by scientists from the University of Sheffield and led by Professor Grant Bigg, has added to the growing body of research focusing on global warming and the carbon cycle. According to the findings, the storage of up to 20% of the carbon in the Southern Ocean is due to huge icebergs. The paper is published in Nature Geoscience.
Carbon is locked into the sea – carbon sequestration – thanks to a combination of biological and chemical processes in which phytoplankton growth plays a critical role. These organisms use up carbon dioxide, thereby sequestrating carbon on a long-term basis, thus slowing down global warming.
The Southern Ocean is an important component in the global carbon cycle: it accounts for around 10 % of the ocean’s total carbon storage.
The team from University of Sheffield has found giant icebergs melting into iron- and nutrient-rich water that boosts the growth of the phytoplankton. They made their discovery when analysing ocean colour through satellite images of huge icebergs (at least 18 km in length) situated in the Southern Ocean to find indications of the production of phytoplankton. The scientists observed great phytoplankton productivity (at unusually high levels) at locations hundreds of kilometres from the icebergs. Furthermore, these activities would last for at least one month following the passage of the iceberg. Professor Bigg, therefore, concluded that giant icebergs might have a major role in the carbon cycle pertaining to the Southern Ocean.
It was previously suggested that icebergs would account for ocean fertilisation, contributing only to a small extent to the uptake of carbon in the form of carbon dioxide by phytoplankton. But, the new research shows that melting icebergs lead to as much as 20% of carbon locked into the Southern Ocean. Therefore, giant icebergs might slow down global warming to a greater extent than would have been thought.