Study Reveals Giant Icebergs Help Slow Down Global Warming

Professor Grant Bigg and his team from the University of Sheffield’s Department of Geography have conducted pioneering research on giant icebergs and high levels of phytoplankton growth, and the subsequental decrease in global warming.

Giant icebergs are responsible for storing up to 20 per cent of carbon in the Southern Ocean, a new study has found.

The melting water from the icebergs contained iron and other nutrients, which was realized to be useful in supporting the increase in phytoplankton growth. This phenomenon is known as carbon sequestration, and aids in long-term storing of atmospheric carbon dioxide for long periods of time, which, helps in slowing down global warming.

The researchers examined 175 satellite images of ocean color, an indicator of phytoplankton productivity on the surface of the ocean, from a selection of icebergs which were at least 18 km in length, and on the Southern Ocean. The images, taken between 2003 and 2013, revealed an increase in phytoplankton growth, which has a direct influence on the storage of carbon in the ocean, extends hundreds of kilometers from the giant icebergs, and remains intact for about a month after the icebergs have moved.

This new analysis reveals that giant icebergs may play a major role in the Southern Ocean carbon cycle. We detected substantially enhanced chlorophyll levels, typically over a radius of at least 4-10 times the iceberg’s length. The evidence suggests that assuming carbon export increases by a factor of five-10 over the area of influence and up to a fifth of the Southern Ocean’s downward carbon flux originates with giant iceberg fertilization. If giant iceberg calving increases this century as expected, this negative feedback on the carbon cycle may become more important than we previously thought.

Professor Grant Bigg

The Southern Ocean plays a significant role in the carbon cycle worldwide. It is accountable for an estimated 10 per cent of the total carbon sequestration in the ocean through a blend of chemical and biologically driven processes, this includes phytoplankton growth.

Former studies have considered that ocean fertilization from icebergs do not greatly affect the phytoplankton’s uptake of carbon dioxide. Though this current research shows that the melting water from icebergs is accountable for nearly 20 per cent of the carbon concealed in the Southern Ocean.

This research paper was published in the January issue of Nature Geoscience.

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