Summit County Citizens Voice

Cycle of dust, phytoplankton and climate change studied

Scientists have long known that atmospheric dust plays a big role in climate cycles. This image from the NASA Earth Observatory website shows what's most likely Saharan dust over the Mediterranean, and recent study shows that dust blowing into the Southern Ocean was part of past climate shifts on a global scale.

By Summit Voice

SUMMIT COUNTY — A study of dust deposition in the Southern Ocean going back 4 million years  shows a close link between high levels of dust in the Antarctic Ocean and  low concentrations of CO2 in the atmosphere, which, in turn, are linked with deep glaciations typical of Earth’s recent history.

The study, by a group of scientists led by researchers from the Universitat Autònoma de Barcelona and the Swiss Federal Institute of Technology, indicates that the dust probably played a key role in fertilizing microscopic algae of the Southern Ocean, emphasizing its role as a CO2 sink. These microorganisms grow by absorbing atmospheric CO2. When they die, they sink, releasing carbon into the depths of the ocean.

The research was published in the journal Nature. It provides evidence of the close relationship between the maximum contributions of dust to the Southern Ocean and climate changes occurring in the most intense glaciation periods of the Pleistocene period, some 1.25 million years ago. Data confirms the role of iron in the increase in phytoplankton levels during glacial periods, intensifying the function of this ocean as a CO2 sink.

Dust, formed by particles of soil, plants and other materials, affects the climate by altering the energy balance of the atmosphere and provides iron and other micronutrients necessary to marine organisms.

Scientists considered that dust fluxes deposited by the wind into the Antarctic Ocean increased during glacial periods and that iron fertilization may have stimulated marine productivity, contributing significantly to the CO2 reduction in the atmosphere during the most recent Pleistocene glacial periods (in the past 800,000 years). 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 — the longest and most detailed up to date on the Southern Ocean — reveal a sharp increase in dust and iron inputs during the Climate Transition of the Middle Pleistocene Epoch (1,250,000 years ago) when 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.

The research will help 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.

Some current climate change discussions include the possibility of trying to adjust the Earth’s climate system by fertilizing the Southern Ocean with iron to increase CO2 absorption by phyoplankton.

“Although our data indicates that this process occurred naturally during glacial periods, we must take into account that ocean circulation was completely different to what it is now, and this made the role of iron fertilization more efficient in capturing carbon dioxide from the atmosphere. There are also several unknown aspects of what could happen to marine ecosystems if iron were artificially added in large quantities, and therefore its commercial application continues to be unviable at the moment”, the researchers concluded.

Filed under: climate and weather, Environment, global warming, Summit County news Tagged: | atmospheric dust-climate link, Autonomous University of Barcelona, climate, ETH Zurich, global warming, Southern Ocean carbon sink, Summit County News