Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Changing climate: how dust changed the face of the earth

24.01.2014
The journal Science publishes results from a Polarstern expedition in the mostly unexplored South Pacific

In spring 2010, the research icebreaker Polarstern returned from the South Pacific with a scientific treasure - ocean sediments from a previously almost unexplored part of the South Polar Sea.


Eine Staubfahne weht von Australien aus in Richtung Südwestpazifik (Tasmanische See). Die meisten staubhaltigen Stürme reichen heute nicht über die Südostspitze Neuseelands hinaus in den Südozean. Aktuelle Sedimentdaten zeigen jedoch, dass der Staubeintrag in den pazifischen Teil des Südozeans in verganenen Eiszeiten wesentlich höher war. Graphik: Verändert NASA Visible Earth (http://visibleearth.nasa.gov/view.php?id=69212)

What looks like an inconspicuous sample of mud to a layman is, to geological history researchers, a valuable archive from which they can reconstruct the climatic history of the polar areas over many years of analysis. This, in turn, is of fundamental importance for understanding global climatic development.

With the help of the unique sediment cores from the Southern Ocean, it is now possible to provide complete evidence of how dust has had a major influence on the natural exchange between cold and warm periods in the southern hemisphere. An international research team under the management of the Alfred Wegener Institute in Bremerhaven was able to prove that dust infiltrations there were 2 to 3 times higher during all the ice ages in the last million years than in the warm phases in climatic history.

"High large-area dust supply can have an effect on the climate for two major reasons", explained Dr. Frank Lamy, geoscientist at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, about the findings. "Trace substances such as iron, which are essential for life, can be incorporated into the ocean through dust. This stimulates biological production and increases the sea's capacity to bind carbon.

The result is that the greenhouse gas carbon dioxide is taken out of the atmosphere. In the atmosphere itself, dust reflects the sun's radiation and purely due to this it reduces the heat input into the Earth's system. Both effects lead to the fact that the Earth cools down."

Lamy is the main author of the study which will be published in the renowned Science journal on 24th January 2014. Other participants included geochemist Gisela Winckler from the US Lamont-Doherty Earth Observatory and the Bremen Centre for Marine Environmental Sciences MARUM.

The influence of dust supply on the climate changes between ice ages and warm periods has long been suspected. Climatic researchers always found particularly high dust content containing iron when the earth was going through an ice age, both in Antarctic ice cores and in sediment cores from the Atlantic part of the Southern Ocean. However, up to now there was no data available for the Pacific section, which covers 50% of the Southern Ocean.

"We can now close this central gap" is how Lamy underlines the importance of the new study. "The result is that we are now finding the same patterns in the South Pacific that we found in cores from the South Atlantic and the Antarctic ice. Therefore, the increased dust input was a phenomenon affecting the southern hemisphere during colder periods. This means that they now have to be considered differently when assessing the complex mechanisms which control natural climate changes."

What sounds almost incidental in Lamy's words is something of considerable relevance for research. This is because up to now many scientists were convinced that dust supply to the Pacific area could not have been higher during the ice ages than during warmer periods of the Earth's climate history. Where could larger dust quantities in this area of the Earth's oceans come from? Up to now, South Patagonia was suspected as a geological dust source since it is the only landmass in the Southern Ocean, intruding into it like a huge finger. However, since the wind predominating in this part of the world comes from the West, any dust particles in the air originating from South America mostly drift towards the Atlantic. For this reason, data from the South Pacific has been on scientists' wishlists for a long time.

However, the Pacific section of the Southern Ocean has remained something of a "terra incognita" for researchers despite modern technology. It is considered to be one of the most remote parts of the world's oceans. "The region is influenced by extreme storms and swells in which wave heights of 10 m or more are not uncommon. The area is also complicated from logistic point of view due to the huge distance between larger harbours" is how AWI scientist Dr. Rainer Gersonde, co-author and at the time leader of the Polarstern expedition, explains the extraordinary challenges faced by the research voyage. The Polarstern made a voyage of 10,000 nautical miles or 18,500 km through this particularly inhospitable part of the Antarctic Ocean in order to obtain high quality and sufficiently long sediment cores.

The question is, however, where did the historic dust freight towards the South Pacific come from, and why did the phases of increased input take place at all? Frank Lamy believes that one of the causes is the relocation or extension of the exceptionally strong wind belts prevalent in this region towards the Equator. The entire Southern Ocean is notorious amongst sailors for its powerful westerly winds - the "Roaring Forties" and the "Furious Fifties". It is considered to be one of the windiest regions in the world. The scientists' theory is that a relocation or extension of this powerful westerly wind belt towards the North could have caused the extended dry areas on the Australian continent to be influenced by stronger wind erosion. The result was higher dust infiltration into the Pacific Ocean - with the consequences described above. On top of this, New Zealand was an additional dust source. The extended glaciation of the mountains there during the ice age provided considerable quantities of fine-grained material which was then blown far out into the South Pacific by the winds.

"Our investigations have now proved without a doubt that colder periods in the southern hemisphere over a period of 1 million years always and almost everywhere coincided, , with lower carbon dioxide content in the atmosphere and higher dust supply from the air. The climatic history of the Earth was, therefore, written in dust."

Notes for Editors:

Original title: “Increased Dust Deposition in the Pacific Southern Ocean During Glacial Periods” F. Lamy et al., "Science", 24 January 2014 (DOI: 10.1126/science.1245424). You can find print-quality images and a video at http://www.awi.de/index.php?id=7066&L=1.

Your contacts at the Alfred Wegener Institute are Dr. Frank Lamy, tel. +49 471 4831- 2124 (e-mail: Frank.Lamy@awi.de) and Ralf Röchert, Department of Communications and Media Relations, tel. +49 471 4831-1680 (e-mail: medien@awi.de).

Follow the Alfred Wegener Institute on Twitter and Facebook to receive up-to-date news and information about everyday life at the Institute.

The Alfred Wegener Institute researches in the Arctic, the Antarctic and oceans in the central and high latitudes. It coordinates polar research in Germany and provides important infrastructure such as the research icebreaker Polarstern and stations in the Arctic and Antarctic for the international science community. The Alfred Wegener Institute is one of the 18 research centres belonging to the Helmholtz Association, which is Germany's largest scientific organisation.

Ralf Röchert | idw
Further information:
http://www.awi.de

More articles from Earth Sciences:

nachricht Icebergs: Mathematical model calculates the collapse of shelf ice
24.08.2017 | Technische Universität Kaiserslautern

nachricht Improved monitoring of coral reefs with the HyperDiver
24.08.2017 | Max-Planck-Institut für marine Mikrobiologie

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Scientists discover species of dolphin that existed along South Carolina coast

24.08.2017 | Life Sciences

The science of fluoride flipping

24.08.2017 | Life Sciences

Optimizing therapy planning for cancers of the liver

24.08.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>