Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study finds unprecedented warmth in Arctic

24.10.2013
The heat is on, at least in the Arctic.

Average summer temperatures in the Eastern Canadian Arctic during the last 100 years are higher now than during any century in the past 44,000 years and perhaps as long ago as 120,000 years, newfound evidence indicates.


Gifford Miller collects long-dead tundra plants exposed by melting of an Arctic ice cap on Baffin Island, Canada. Using radiocarbon dating of plants from the Eastern Canadian Arctic, he and his colleagues have found that average summertime temperatures in the region are currently higher than at any time in the past 44,000 years. Credit: Gifford Miller


As ice caps today recede, like this one nicknamed Sputnik, they expose dead plants killed long ago when the ice cap formed and then preserved ever since by the ice. By carbon-dating the organic material, scientists can determine when the plants lived, thousands of years ago, and infer the average temperatures back then that allowed the plants to thrive. Credit: Gifford Miller

The new research offers the first direct evidence that the present warmth in the Eastern Canadian Arctic exceeds the peak warmth there in the Early Holocene, when solar energy reaching the Northern Hemisphere in summer was roughly 9 percent greater than today, said Gifford Miller of the University of Colorado, Boulder (CU-Boulder), who led the study. The Holocene is a geological epoch that began after Earth’s last glacial period ended roughly 11,700 years ago and which continues today.

Miller and his colleagues used dead moss clumps emerging from receding ice caps on Baffin Island as tiny clocks. At four different ice caps, radiocarbon dates show the mosses had not been exposed to the elements since at least 44,000 to 51,000 years ago.

Since radiocarbon dating is only accurate to about 50,000 years and because Earth’s geological record shows it was in a glaciation stage prior to that time, the indications are that Canadian Arctic temperatures today have not been matched or exceeded for roughly 120,000 years, Miller said.

“The key piece here is just how unprecedented the warming of Arctic Canada is,” said Miller, a geological sciences professor and a fellow at the university’s Institute of Arctic and Alpine Research. “This study really says the warming we are seeing is outside any kind of known natural variability, and it has to be due to increased greenhouse gases in the atmosphere.”

A paper on the subject appeared online Oct. 21 in Geophysical Research Letters, a journal of the American Geophysical Union.

Miller and his colleagues compiled the age distribution of 145 radiocarbon-dated plants in the highlands of Baffin Island that were exposed by ice recession during the year they were collected by the researchers. All samples collected were within 1 meter of the ice caps, which are generally receding by 2 to 3 meters a year. “The oldest radiocarbon dates were a total shock to me,” said Miller.

Located just east of Greenland, the 508,000 square-kilometer (196,000-square-mile) Baffin Island is the fifth largest island in the world. Most of it lies above the Arctic Circle. Many of the ice caps on the highlands of Baffin Island rest on relatively flat terrain, usually frozen to their beds. “Where the ice is cold and thin, it doesn’t flow, so the ancient landscape on which they formed is preserved pretty much intact,” said Miller.

Ice melted by Arctic warming exposed dead plants
As ice caps today recede, like this one nicknamed Sputnik, they expose dead plants killed long ago when the ice cap formed and then preserved ever since by the ice. By carbon-dating the organic material, scientists can determine when the plants lived, thousands of years ago, and infer the average temperatures back then that allowed the plants to thrive. Credit: Gifford Miller

To reconstruct the past climate of Baffin Island beyond the limit of radiocarbon dating, Miller and his team used data from ice cores previously retrieved by international teams from the nearby Greenland Ice Sheet.

The ice cores showed that the youngest time interval from which summer temperatures in the Arctic were plausibly as warm as today is about 120,000 years ago, near the end of the last interglacial period. “We suggest this is the most likely age of these samples,” said Miller.

The new study also showed summer temperatures cooled in the Canadian Arctic by about 2.8 degrees Celsius (5 degrees Fahrenheit) from roughly 5,000 years ago to about 100 years ago – a period that included the Little Ice Age from 1275 to about 1900.

“Although the Arctic has been warming since about 1900, the most significant warming in the Baffin Island region didn’t really start until the 1970s,” said Miller. “And it is really in the past 20 years that the warming signal from that region has been just stunning. All of Baffin Island is melting, and we expect all of the ice caps to eventually disappear, even if there is no additional warming.”

Temperatures across the Arctic have been rising substantially in recent decades as a result of the buildup of greenhouse gases in Earth’s atmosphere. Studies by CU-Boulder researchers in Greenland indicate temperatures on the ice sheet have climbed 3.9 degrees Celsius (7 degrees Fahrenheit) since 1991.

Co-authors on the new study include CU-Boulder Senior Research Associate Scott Lehman, former CU-Boulder doctoral student and now Prescott College Professor Kurt Refsnider, University of California Irvine researcher John Southon and University of Wisconsin, Madison Research Associate Yafang Zhong. The National Science Foundation provided the primary funding for the study.

AGU Contact:
Thomas Sumner
+1 (202) 777-7516
tsumner@agu.org
University of Colorado Boulder Contact:
Jim Scott, CU-Boulder media relations
+1 (720) 381-9479
jim.scott@colorado.edu
Notes for Journalists
Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this early view article by clicking on this link: http://onlinelibrary.wiley.com/doi/10.1002/2013GL057188/abstract

Or, you may order a copy of the final paper by emailing your request to Thomas Sumner at tsumner@agu.org. Please provide your name, the name of your publication, and your phone number.

Neither the paper nor this press release is under embargo.

Title

“Unprecedented recent summer warmth in Arctic Canada”

Gifford H. Miller, Scott J. Lehman, and Kurt A. Refsnider
Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA;
John R. Southon
Earth System Science Dept., University of California Irvine, Irvine, USA;
Yafang Zhong
Center for Climatic Research, University of Wisconsin, Madison, WI, USA.
Contact information for the authors:
Gifford H. Miller, Cell Phone: +1 (303) 990-2071, Office Phone: + 1 (303) 492-6962, Email: gmiller@colorado.edu

Thomas Sumner | American Geophysical Union
Further information:
http://www.agu.org
http://news.agu.org/press-release/new-study-finds-unprecedented-warmth-in-arctic/

More articles from Earth Sciences:

nachricht In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>