Poster's note : obliquely relevant to OIF and open ocean storage of supercritical CO2
https://phys.org/news/2018-02-scientists-theory-role-south-pacific.html Scientists verify theory of the role of the South Pacific in natural atmospheric CO2 fluctuationsFebruary 22, 2018 Alfred Wegener Institute [image: Scientists verify theory of the role of the South Pacific in natural atmospheric CO2 fluctuations] <https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/2018/5a8ea90e459c4.jpg> View from RV Polarstern while collecting sediment samples used in the study by Basak et al. Credit: Dr. Katharina Pahnke A team led by geochemist Dr. Katharina Pahnke from Oldenburg has discovered important evidence that the rise in atmospheric carbon dioxide levels at the end of the last ice age was triggered by changes in the Antarctic Ocean. The researchers from the University of Oldenburg's Institute for Chemistry and Biology of the Marine Environment (ICBM), the Max Planck Institute for Marine Microbiology in Bremen and the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) were able to demonstrate that the deep South Pacific was strongly stratified during the last ice age, and could thus have facilitated long-term, deep-sea storage of the greenhouse gas carbon dioxide (CO2). The study, which has now been published in the academic journal *Science*, also indicates that in the course of the warming following the end of the last ice age the mixing of the deep water masses increased, releasing stored CO2 and enhancing global warming. The Southern Ocean plays an important role in climate events because CO2 can be absorbed from the atmosphere into the ocean <https://phys.org/tags/ocean/>. When increased amounts of dust are deposited in the seawater, microscopic algae multiply because the iron contained in the dust acts as a fertilizer. When these single celled algae die, they sink to the ocean floor, taking the sequestered carbon dioxide with them. To ensure long-term removal of the CO2 from the atmosphere, however, it must be stored in stable conditions in deep water <https://phys.org/tags/water/> over long periods of time. In order to find out how water masses in the deep South Pacific have developed over the last 30,000 years, the team recovered sediment cores from water depths of between 3,000 and more than 4,000 metres during an expedition of the research vessel "Polarstern" to the South Pacific. The geochemists Dr. Chandranath Basak and Dr. Henning Fröllje of the ICBM, the two main authors of the study, extracted tiny teeth and other skeletal debris of fossil fish from the sediment to analyse their content of isotopes of the rare earth metal neodymium. "Neodymium is particularly useful for identifying water masses of different origin," said Pahnke, the head of the Max Planck Research Group for Marine Isotope Geochemistry based at the ICBM and the Max Planck Institute for Marine Microbiology in Bremen, explaining that each layer of water has its own characteristic neodymium signature. The isotope ratios of this element vary depending on which ocean basin the water comes from. For instance, the coldest and therefore deepest water mass in the Southern Pacific forms on the continental shelf of Antarctica and carries a distinct neodymium signature. Overlying this mass is a layer that combines water from the North Atlantic, the South Pacific and the North Pacific and hence is marked by a different signature. Using fish debris in deep-sea sediments, the researchers were able to trace the variations in neodymium concentrations at different depths over the course of time. The result: at the peak of the last ice age approximately 20,000 years ago, the neodymium signature of samples taken from depths below 4,000 metres was significantly lower than at lower depths. "The only explanation for such a pronounced difference is that there was no mixing of the water masses at that time," said Fröllje, who currently works at the University of Bremen. He and his colleagues concluded from this that the deep waters were strongly stratified during the glacial period. As the climate in the southern hemisphere <https://phys.org/tags/southern+hemisphere/> grew warmer towards the end of the last ice age around 18,000 years ago, the stratification of the water masses <https://phys.org/tags/water+masses/> was broken up and neodymium values at different depths converged. "There was probably more mixing because the density of the water decreased as a result of the warming," Pahnke explained. This then led to the release of the carbon dioxide stored in deep waters. For some time now climate researchers have been speculating on why fluctuations in atmospheric CO2 levels followed the same pattern as temperature in the southern hemisphere whereas the temperature in the north at times ran counter to these fluctuations. One theory is that certain processes in the Southern Ocean played an important role. "With our analyses we have for the first time provided concrete evidence supporting the theory that there is a connection between the CO2 fluctuations and stratification in the Southern Ocean," said co-author of the study Dr. Frank Lamy of the AWI in Bremerhaven. The current study supports the hypothesis that the warming of the southern hemisphere broke up stable stratification in the Antarctic Ocean, resulting in the release of the carbon dioxide <https://phys.org/tags/carbon+dioxide/>that was stored in these waters. *More information:* "Break-up of last glacial deep stratification in the South Pacific", Chandranath Basak, Henning Fröllje, Frank Lamy, Rainer Gersonde, Verena Benz, Robert F. Anderson, Mario Molina-Kescher, Katharina Pahnke, *Science*, 23 February 2018, DOI: 10.1126/science.aao2473 <http://dx.doi.org/10.1126/science.aao2473> http://science.sciencemag.org/cgi/doi/10.1126/science.aao2473 *Provided by:* Alfred Wegener Institute Recommended for you Self-assembling peptides and the fight against obesity and diabetes <https://m.phys.org/news/2018-02-self-assembling-peptides-obesity-diabetes.html?utm_source=related&utm_medium=link&utm_campaign=horz> Google Assistant adds more languages in global push <https://m.phys.org/news/2018-02-google-languages-global.html?utm_source=related&utm_medium=link&utm_campaign=horz> New method could help quantify untapped natural gas reservoirs <https://m.phys.org/news/2018-02-method-quantify-untapped-natural-gas.html?utm_source=related&utm_medium=link&utm_campaign=horz> Researchers discover novel exciton interactions in carbon nanotubes <https://m.phys.org/news/2018-02-exciton-interactions-carbon-nanotubes.html?utm_source=related&utm_medium=link&utm_campaign=horz> Stretchable health sensor could improve monitoring of chronic conditions <https://m.phys.org/news/2018-02-stretchable-health-sensor-chronic-conditions.html?utm_source=related&utm_medium=link&utm_campaign=horz> Walking crystals may lead to new field of crystal robotics <https://m.phys.org/news/2018-02-crystals-field-crystal-robotics.html?utm_source=related&utm_medium=link&utm_campaign=horz> First nanoscale look at how lithium ions navigate a molecular maze to reach battery electrode <https://m.phys.org/news/2018-02-nanoscale-lithium-ions-molecular-maze.html?utm_source=related&utm_medium=link&utm_campaign=horz> Clay print from seal may be first ever extra-biblical reference to the prophet Isaiah <https://m.phys.org/news/2018-02-clay-extra-biblical-prophet-isaiah.html?utm_source=related&utm_medium=link&utm_campaign=horz> Researchers film bacteria using melee combat to steal antibiotic resistance genes <https://m.phys.org/news/2018-02-bacteria-melee-combat-antibiotic-resistance.html?utm_source=related&utm_medium=link&utm_campaign=horz> Scientists find frustration in battery materials <https://m.phys.org/news/2018-02-scientists-frustration-battery-materials.html?utm_source=related&utm_medium=link&utm_campaign=horz> Explore further - Researchers solve one of the great scientific mysteries of the ice ages May 13, 2016 An international team of researchers headed by scientists from the Alfred Wegener Institute has gained new insights into the carbon dioxide exchange between ocean and atmosphere, thus making a significant contribution to ... <https://m.phys.org/news/2016-05-great-scientific-mysteries-ice-ages.html> - Rapid climate change and the role of the Southern Ocean Apr 08, 2013 Scientists from Cardiff University and the University of Barcelona have discovered new clues about past rapid climate change. <https://m.phys.org/news/2013-04-rapid-climate-role-southern-ocean.html> - Study gives clues about carbon dioxide patterns at end of Ice Age Oct 25, 2010 (PhysOrg.com) -- New University of Florida research puts to rest the mystery of where old carbon was stored during the last glacial period. 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They found that sea water mixes dramatically as it rushes over undersea mountains ... <https://m.phys.org/news/2013-09-undersea-mountains-crucial-piece-climate.html> - Oxygen depletion in the upper waters of the Southern Ocean during glacial periods Mar 31, 2016 Research published this week by an international team of scientists, including the British Antarctic Survey, provides new insights into how carbon dioxide changed in the oceans surrounding Antarctica during glacial periods. <https://m.phys.org/news/2016-03-oxygen-depletion-upper-southern-ocean.html> Subscribe for important news alerts? Try - <https://m.phys.org/> - <https://m.phys.org/news/2018-02-scientists-theory-role-south-pacific.html#share> 154 - <https://m.phys.org/comments/438508868/>0 - <https://m.phys.org/news/2018-02-scientists-theory-role-south-pacific.html#redirect> -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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