Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Southern glaciers grow out of step with North

04.05.2009
New dating technique points to differences over 7,000 years

The vast majority of the world’s glaciers are retreating as the planet gets warmer. But a few, including ones south of the equator, in South America and New Zealand, are inching forward.

A new study in the journal Science puts this enigma in perspective; for the last 7,000 years New Zealand’s largest glaciers have often moved out of step with glaciers in the northern hemisphere, pointing to strong regional variations in climate.

Conventional wisdom holds that climate during the era of human civilization has been relatively stable, but the new study is the latest to challenge this view, by showing that New Zealand's glaciers have gone through rapid periods of growth and decline during the current interglacial period known as the Holocene.

"New Zealand's mountain glaciers have fluctuated frequently over the last 7,000 years and glacial advances have become slightly smaller through time," said lead author Joerg Schaefer, a geochemist at Columbia University's Lamont-Doherty Earth Observatory. "This pattern differs in important ways from the northern hemisphere glaciers. The door is open now towards a global map of Holocene glacier fluctuations and how climate variations during this period impacted human civilizations."

Glaciers are extremely sensitive to changes in temperature and snowfall, which makes them well suited for studying past climate. This archive has been largely untapped, however, because of the difficulty in assigning precise ages to glacier fluctuations.

One way to measure glacial fluxes is by studying the moraines, or rock deposits that glaciers often leave behind at their maximum points of advance. However, until now the methods of dating such moraines, including radiocarbon dating of organic matter, could be off by hundreds of years. By refining the analysis of a method called cosmogenic dating, Schaefer and his colleagues were able for the first time to assign precise ages to young Holocene moraines. They did this by measuring minute levels of the chemical isotope beryllium 10 in the rocks, which is produced when cosmic rays strike rock surfaces, and builds up over time. The researchers were thus able to pinpoint exactly when glaciers in New Zealand's Southern Alps began to recede, exposing the rocks to the cosmic rays.

From the results, they constructed a glacial timeline for the past 7,000 years and compared it against historic records from the Swiss Alps and other places north of the equator.

They found that the glaciers around Mount Cook, New Zealand's highest peak, reached their largest extent in the past 7,000 years about 6,500 years ago, when the Swiss Alps and Scandinavia were relatively warm. That's about 6,000 years before northern glaciers hit their Holocene peak during the Little Ice Age, between 1300 and 1860 AD.

That finding was a surprise to some scientists who assumed that the northern cold phase happened globally. The record in New Zealand shows other disparities that point to regional climate variations in both hemispheres, including glacial peaks during classic northern warm intervals such as the Medieval Warm Period and the Roman Age Optimum.

The new chemical and analytical protocols developed in Schaefer's cosmogenic dating lab is expected to allow scientists to accurately date glacier fluctuations throughout the Holocene, rounding out the climate picture on the continents.

"With this measure we can go to almost any mountain range on earth and date the moraines in front of the glaciers and produce a similar chronology," said coauthor George Denton, a glaciologist who is a senior professor at the University of Maine and an adjunct scientist at Lamont-Doherty.

Overall, glaciers around the world have been declining since about 1860, with the exception of a brief advance in Switzerland in the 1980s, New Zealand in the late 1970s through today, and a few other places. Changes in wind and sea surface temperatures are thought to be causing these regional fluctuations. Currently in a wet phase, New Zealand is expected to swing back to a warmer, drier phase in the next few years, causing the glaciers to retreat once again.

"The application of this technique should allow for much more accurate reconstructions of glacial advances worldwide," says Paul Filmer, program director for the National Science Foundation (NSF)'s Division of Earth Sciences, which helped fund the study. "This would provide more constraints to allow us to make our climate models more accurate."

The study also received funding from the Comer Science and Education Foundation and the New Zealand Foundation for Research, Science and Technology.

The other researchers involved in the study were: Michael Kaplan and Roseanne Schwartz, also of Lamont-Doherty; Aaron Putnam, University of Maine; Robert Finkel, University of California, Berkeley; David Barrell, GNS Science, New Zealand; Bjorn Anderson, University of Oslo; Andrew Mackintosh, Victoria University of Wellington, New Zealand; Trevor Chinn, Alpine and Polar Processes Consultancy, New Zealand; Christian Schluchter, University of Bern, Switzerland.

Copies of the paper, "High-Frequency Holocene Glacier Fluctuations in New Zealand Differ from the Northern Signature," are available from the authors or from Science: 202-326-6440 or scipak@aaas.org.

Scientist contacts:

Joerg Schaefer, schaefer@ldeo.columbia.edu, Ph: 845-365-8756
George Denton, gdenton@maine.edu, Ph: 207-581-2193
Robert Finkel, rfinkel@berkeley.edu, Cell: 510-520-1738
More information: Kim Martineau, Science Writer, Lamont-Doherty Earth Observatory, kmartine@ei.columbia.edu, Ph: 845-365-8708, Cell: 518-221-6890

The Earth Institute at Columbia University mobilizes the sciences, education and public policy to achieve a sustainable earth. Through interdisciplinary research among more than 500 scientists in diverse fields, the Institute is adding to the knowledge necessary for addressing the challenges of the 21st century and beyond. With over two dozen associated degree curricula and a vibrant fellowship program, the Earth Institute is educating new leaders to become professionals and scholars in the growing field of sustainable development. We work alongside governments, businesses, nonprofit organizations and individuals to devise innovative strategies to protect the future of our planet.

Lamont-Doherty Earth Observatory, a member of The Earth Institute at Columbia University, is one of the world's leading research centers seeking fundamental knowledge about the origin, evolution and future of the natural world. More than 300 research scientists study the planet from its deepest interior to the outer reaches of its atmosphere, on every continent and in every ocean. From global climate change to earthquakes, volcanoes, nonrenewable resources, environmental hazards and beyond, Observatory scientists provide a rational basis for the difficult choices facing humankind in the planet's stewardship.

Kim Martineau | EurekAlert!
Further information:
http://www.ei.columbia.edu

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

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

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>