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This is an archive article published on September 2, 2011

Dust in Southern Ocean has driven climate over millions of years: study

Dust is formed by various Earth surface processes and provides micronutrients to marine organisms.

Researchers from the Universitat Autònoma de Barcelona (UAB) and the Swiss Federal Institute of Technology (ETH Zürich) have shown a close relation between contributions of dust to the Southern Ocean and intense periods of climate change during the Pleistocene,some 1.25 million years ago.

Dust is formed by various Earth surface processes and provides micronutrients,especially iron,to marine organisms.

Scientists believe that this process increased during glacial periods,suggesting iron fertilization could have increased marine productivity,reducing CO2 in the atmosphere during the last million years of glacial periods.

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However,the magnitude of these effects and their role in the evolution of the climate system had remained unclear.

Records of the period studied in this research work reveal a sharp increase in dust and iron inputs during the Climate Transition of the Middle Pleistocene Epoch (1,250,000 years ago) in which fluxes tripled.

This transition marked a global climate change with the beginning of glacial periods lasting 100,000 years,in comparison to the gradual intensification of glacial cycles occurring in the three million years immediately before,when periods lasted 41,000 years.

Researchers,who quantified dust and iron fluxes deposited in the Antarctic Ocean during the past 4 million years,say the dust might have played a key role in fertilising microscopic algae in the Southern Ocean,emphasising its role as a CO2 sink.

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The study also offers new clues on the causes behind the most intense glaciations of the Pleistocene Epoch,particularly on how interactions between dust with oceanic biology influence CO2 and the climate.

It also allows scientists to understand how future changes in atmospheric circulation and the superficial biology of oceans can make the Antarctic Ocean change the efficiency with which it captures and removes carbon dioxide from the atmosphere.

The study is published in Nature.

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