Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 


Research Team Advances Knowledge of Antarctica's Climate History

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:
Proceedings of the National Academy of Sciences

Steven Bergeson | Newswise Science News
Further information:

More articles from Earth Sciences:

nachricht Earth's magnetic field is not about to flip
25.11.2015 | The Earth Institute at Columbia University

nachricht Autumn gales again drive salt into the Baltic: Third Major Baltic Inflow within 1.5 years.
25.11.2015 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Klimawandel: Forscher weisen dramatische Veränderung in den 1980er Jahren nach

Ende der 1980er Jahre erlebte die Erde eine dramatische Klimaveränderung. Sie umfasste die Tiefen der Ozeane ebenso wie die obere Atmosphäre und reichte vom Nord- bis zum Südpol. Ausgelöst durch den Ausbruch des Vulkans El Chichón in Mexico 1982 und verstärkt durch menschliches Handeln folgte daraus die größte Temperaturverschiebung der letzten 1.000 Jahre. Erstmals nachgewiesen hat dies ein internationales Forscherteam um Prof. Philip C. Reid von der Plymouth University und der Sir Alister Hardy Foundation for Ocean Science (UK). Die Ergebnisse wurden kürzlich in der Fachzeitschrift „Global Change Biology“ veröffentlicht.

Abrupte Klimaveränderungen haben oft dramatische Folgen für unseren Planeten. Dennoch sind sie in ihrer Art, ihrem Ausmaß und in ihrer Wirkungsweise meist nur...

Im Focus: Climate study finds evidence of global shift in the 1980s

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...

Im Focus: Innovative Photovoltaik – vom Labor an die Fassade

Fraunhofer ISE demonstriert neue Zell- und Modultechnologien an der Außenfassade eines Laborgebäudes

Das Fraunhofer-Institut für Solare Energiesysteme ISE hat die Außenfassade eines seiner Laborgebäude mit 70 Photovoltaik-Modulen ausgerüstet. Die Module...

Im Focus: Innovative Photovoltaics – from the Lab to the Façade

Fraunhofer ISE Demonstrates New Cell and Module Technologies on its Outer Building Façade

The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...

Im Focus: Follow Me: Forscher der Jacobs University steuern Unterwasser-Roboter erstmals durch Zeichensprache

Normalerweise werden Unterwasser-Roboter über lange Kabel von Booten oder von Land aus gesteuert. Forschern der Jacobs University in Bremen ist nun ein Durchbruch in der Mensch-Maschine-Kommunikation gelungen: Erstmals konnten sie einen Unterwasser-Roboter mit Hilfe von Gesten navigieren. Eine spezielle Kamera half dabei, die Zeichensprache in Befehle umzusetzen. Die Feldtests fanden im Rahmen des EU-geförderten Projektes CADDY „Cognitive Autonomous Diving buddy“ statt.

Archäologische Untersuchungen im Ozean und vergleichbare komplexe Forschungsprojekte unter Wasser sind auf die Unterstützung von Robotern angewiesen, um in...

Alle Focus-News des Innovations-reports >>>



im innovations-report
in Kooperation mit academics

Konzepte nutzergerechter Fahrerarbeitsplatzgestaltung

26.11.2015 | Veranstaltungen

Versammelter Sachverstand: Fachleute des Mess- und Eichwesens treffen sich in der PTB

26.11.2015 | Veranstaltungen

Fraunhofer-Kongress »Urban Futures«: 2 Tage in der Stadt der Zukunft

25.11.2015 | Veranstaltungen

Weitere VideoLinks >>>
Aktuelle Beiträge

Alles unter Kontrolle – Energieautarke RFID-Transponder in der Logistik

26.11.2015 | Verkehr Logistik

Konzepte nutzergerechter Fahrerarbeitsplatzgestaltung

26.11.2015 | Veranstaltungsnachrichten

Versammelter Sachverstand: Fachleute des Mess- und Eichwesens treffen sich in der PTB

26.11.2015 | Veranstaltungsnachrichten