Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stagnation in the South Pacific Explains Natural CO2 Fluctuations

23.02.2018

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 Southern Ocean. The researchers 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 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. When increased amounts of dust are deposited in the seawater, microscopic algae multiply because the iron contained in the dust acts as a fertilizer.


Neodymium isotopes in fish debris showed that the water in the South Pacific was stratified during the last ice age.

Katharina Pahnke/Universität Oldenburg


Katharina Pahnke opens a sediment core from the South Pacific.

Katharina Pahnke/Universität Oldenburg

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 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 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) 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.

Nedymium Signature in Fish Debris

"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.

Global Warming broke up Stratification

As the climate in the southern hemisphere grew warmer towards the end of the last ice age around 18,000 years ago, the stratification of the 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 that was stored in these waters.

Contact: Katharina Pahnke, Phone: *49-441-798-3328, Email: k.pahnke@icbm.de or kpahnke@mpi-bremen.de

Weitere Informationen:

http://www.sciencemag.org/
https://uol.de/presse/mit/
https://www.icbm.de/mig/

Dr. Corinna Dahm-Brey | idw - Informationsdienst Wissenschaft

More articles from Earth Sciences:

nachricht A promising target in the quest for a 1-million-year-old Antarctic ice core
24.05.2018 | University of Washington

nachricht Tropical Peat Swamps: Restoration of Endangered Carbon Reservoirs
24.05.2018 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

12th COMPAMED Spring Convention: Innovative manufacturing processes of modern implants

28.05.2018 | Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

 
Latest News

International Workshop Sees Central Role for Solar in Transforming the World Energy Economy

28.05.2018 | Seminars Workshops

Cognitive Power Electronics 4.0 is gaining momentum

28.05.2018 | Trade Fair News

Organic light-emitting diodes become brighter and more durable

28.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>