Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

Research Team Advances Knowledge of Antarctica's Climate History

11.08.2008
North Dakota State University researchers, Fargo, are among the leaders of a group of National Science Foundation-funded scientists who have discovered the last traces of tundra on the interior of Antarctica before temperatures began a relentless drop millions of years ago.

The collaboration’s research, which resulted in a major advance in the understanding of Antarctica’s climatic history, appears in the Aug. 4 issue of the Proceedings of the National Academy of Sciences.

The international team of scientists headed up by NDSU geoscientists Allan Ashworth and Adam Lewis and David Marchant, an earth scientist at Boston University, combined evidence from glacial geology, paleoecology, dating of volcanic ashes and computer modeling, to report a major climate change centered on 14 million years ago. The three scientists often spend months living in tents in the Transantarctic Mountains’ Dry Valleys doing their research.

They have documented the timing and magnitude of the continent’s shift from warm, temperate glaciers and fringing tundra to polar glaciers and polar tundra. “The contrast couldn’t be more striking,” Marchant said. “It is like comparing Tierra del Fuego today with the surface of Mars—and this transition took place over a geologically short interval of roughly 200,000 years.”

According to Lewis, the discovery of lake deposits with perfectly preserved fossils of mosses, diatoms and ostracods is particularly exciting to scientists. “They are the first to be found even though scientific expeditions have been visiting the Dry Valleys since their discovery during the first Scott expedition in 1902-03,” said Lewis.

For Ashworth, the fossils are a paleoecological treasure trove. He notes that some ancient species of diatoms and mosses are indistinguishable from the ones today, which occur throughout the world except Antarctica.

“To be able to identify living species amongst the fossils is phenomenal. To think that modern counterparts have survived 14 million years on Earth without any significant changes in the details of their appearances is striking,” said Ashworth, the principal paleoecologist in the research. “It must mean that these organisms are so well-adapted to their habitats that in spite of repeated climate changes and isolation of populations for millions of years, they have not become extinct but have survived.”

The fossil finds and dating of volcanic ash show that roughly 14.1 million years ago, the area was home to tundra, “wet” glaciers typical of those of the mountains of Tierra Del Fuego in the high southern latitudes and seasonally ice-free lakes. The beds of the long-gone lakes contain layers of sediments where dying plants and insects accumulated and were preserved.

The mean summertime temperatures would have dropped in that period by as much as 8 degrees Celsius. On average, the summertime temperatures in the Dry Valleys 14.1 million years ago would have been as much as 17 degrees warmer than the present-day average.

According to Lewis, the freshness of the crystals and glass in the volcanic ash and the preservation of cellular detail in the fossils indicate they have been permanently frozen since 13.9 million years ago.

The research conclusion suggests that even when global atmospheric temperatures were warmer than they are now, as occurred 3.5 million years ago during the Pliocene Epoch, and as might occur in the near future as a consequence of global warming, there was no significant melting of the East Antarctic ice sheet inland of the Dry Valleys. According to Ashworth, if this conclusion stands the test of time, it suggests a very robust ice sheet in this sector of Antarctica, and emphasizes the complex and non-uniform response of Antarctica’s ice sheets to global change.

He adds, "The huge uncertainties regarding the inherently unstable marine-based West Antarctic ice sheet, however, make all predictions about the future based on past behavior educated guesses at best.”

The National Science Foundation, in its role as the manager of the United States Antarctic Program, supported the work of Ashworth, Lewis and Marchant as well as United States researchers from Lamont-Doherty Earth Observatory, Ohio State University and the University of Montana.

The work of the research team in the field also appears in the documentary “Ice People” by Emmy-award-winning director Anne Aghion. The film will be screened in science museums throughout Australia during the month of August and will air on SBS Australian Television on August 24. Ice People received support from the National Science Foundation’s Antarctic Artists and Writers Program. It has been screened at international film festivals in New York, San Francisco and Jerusalem and is scheduled to air on the Sundance Channel in 2009.

For more information about the study:
http://www.ndsu.nodak.edu/instruct/ashworth/Boreas/index.htm
Proceedings of the National Academy of Sciences
http://www.pnas.org/content/105/31/10676

Steven Bergeson | Newswise Science News
Further information:
http://www.ndsu.nodak.edu/
http://www.ndsu.nodak.edu/instruct/ashworth/Boreas/index.htm
http://www.icepeople.com

More articles from Earth Sciences:

nachricht Sea ice extent sinks to record lows at both poles
23.03.2017 | NASA/Goddard Space Flight Center

nachricht Less radiation in inner Van Allen belt than previously believed
21.03.2017 | DOE/Los Alamos National Laboratory

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fliegende Intensivstationen: Ultraschallgeräte in Rettungshubschraubern können Leben retten

Etwa 21 Millionen Menschen treffen jährlich in deutschen Notaufnahmen ein. Im Kampf zwischen Leben und Tod zählt für diese Patienten jede Minute. Wenn sie schon kurz nach dem Unfall zielgerichtet behandelt werden können, verbessern sich ihre Überlebenschancen erheblich. Damit Notfallmediziner in solchen Fällen schnell die richtige Diagnose stellen können, kommen in den Rettungshubschraubern der DRF Luftrettung und zunehmend auch in Notarzteinsatzfahrzeugen mobile Ultraschallgeräte zum Einsatz. Experten der Deutschen Gesellschaft für Ultraschall in der Medizin e.V. (DEGUM) schulen die Notärzte und Rettungsassistenten.

Mit mobilen Ultraschallgeräten können Notärzte beispielsweise innere Blutungen direkt am Unfallort identifizieren und sie bei Bedarf auch für Untersuchungen im...

Im Focus: Gigantische Magnetfelder im Universum

Astronomen aus Bonn und Tautenburg in Thüringen beobachteten mit dem 100-m-Radioteleskop Effelsberg Galaxienhaufen, das sind Ansammlungen von Sternsystemen, heißem Gas und geladenen Teilchen. An den Rändern dieser Galaxienhaufen fanden sie außergewöhnlich geordnete Magnetfelder, die sich über viele Millionen Lichtjahre erstrecken. Sie stellen die größten bekannten Magnetfelder im Universum dar.

Die Ergebnisse werden am 22. März in der Fachzeitschrift „Astronomy & Astrophysics“ veröffentlicht.

Galaxienhaufen sind die größten gravitativ gebundenen Strukturen im Universum, mit einer Ausdehnung von etwa zehn Millionen Lichtjahren. Im Vergleich dazu ist...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Auf der Spur des linearen Ubiquitins

Eine neue Methode ermöglicht es, den Geheimcode linearer Ubiquitin-Ketten zu entschlüsseln. Forscher der Goethe-Universität berichten darüber in der aktuellen Ausgabe von "nature methods", zusammen mit Partnern der Universität Tübingen, der Queen Mary University und des Francis Crick Institute in London.

Ubiquitin ist ein kleines Molekül, das im Körper an andere Proteine angehängt wird und so deren Funktion kontrollieren und verändern kann. Die Anheftung...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Lebenswichtige Lebensmittelchemie

23.03.2017 | Veranstaltungen

Die „Panama Papers“ aus Programmierersicht

22.03.2017 | Veranstaltungen

Über Raum, Zeit und Materie

22.03.2017 | Veranstaltungen

 
VideoLinks
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Besser lernen dank Zink?

23.03.2017 | Biowissenschaften Chemie

Lebenswichtige Lebensmittelchemie

23.03.2017 | Veranstaltungsnachrichten

Innenraum-Ortung für dynamische Umgebungen

23.03.2017 | Architektur Bauwesen