Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Arctic environment during an ancient bout of natural global warming

28.02.2011
Scientists are unravelling the environmental changes that took place around the Arctic during an exceptional episode of ancient global warming.

Newly published results from a high-resolution study of sediments collected on Spitsbergen represent a significant contribution to this endeavour. The study was led by Dr Ian Harding and Prof John Marshall of the University of Southampton’s School of Ocean and Earth Science (SOES), based at the National Oceanography Centre, Southampton.

Around 56 million years ago there was a period of global warming called the Paleocene–Eocene Thermal Maximum (PETM), during which global sea surface temperatures increased by approximately 5°C.

The warming of the oceans led to profound ecological changes, including the widespread extinction of many types of foraminifera, tiny single-celled organisms with distinctive shells. Plankton that had previously only prospered in tropical and subtropical waters migrated to higher latitudes. Similar changes occurred on the land, with many animals and plants extending their distributions towards the poles.

“Although environmental changes associated with the PETM at low- to mid-latitude settings and high southern latitudes are well documented, we know less about these changes at high northern latitudes,” explained Dr Harding.

Information about the Arctic environment during the PETM has come predominantly from sediment cores drilled from under the pack ice on the Lomonosov Ridge (~ 88°N) by the Integrated Ocean Drilling Program (IODP Site 302-4A). However, these cores do not span the entire PETM and therefore do not provide a complete picture.

“Information from other Arctic sites is needed for a better understanding of PETM environmental conditions, such data can then in turn be used in computer models which will improve our understanding not only of past climatic conditions but also enhance our ability to predict future perturbations,” said Dr Harding.

To help fill this knowledge gap, Dr Harding’s team turned to a site (~78 °N) on Spitsbergen in the high Arctic. Here, 2.5-kilometre-thick sediments span the critical period. During the PETM, the site would have been at around 75 °N, the difference in position being due to the slow movement of tectonic plates over millions of years.

Through analyses of plankton and the chemical and magnetic characteristics of the sediments, they were unambiguously able to identify a 15-metre succession of exposed sediment representing the approximately 170 thousand year PETM event.

At the base of the segment they found the preserved remains of the cyst-forming dinoflagellate Apectodinium augustum, a planktonic species diagnostic of the PETM across the globe. In fact, the species was already present in Spitsbergen before the shift in carbon isotope composition formally marking the onset of the PETM, suggesting that environment change was by then already well underway.

Along with data from other sites, their Arctic evidence suggests not only that sea level began to rise well before the formal onset of the PETM, but also that it peaked about 13,000 years into the period. At the same time, increased surface-water run-off from the land dampened water-column mixing and led to stratification, with an upper freshened layer that overlay denser, more saline seawater beneath.

By carefully comparing their results with those from IODP Site 302-4A to the north, they found evidence for regional differences in the environmental manifestations of the PETM in high northern latitudes. For example, the evidence from the IODP site suggests that the sunlit surface layer of the ocean was often depleted of oxygen, the results from Spitsbergen suggest that oxygen depletion was largely restricted to the bottom waters and sediments. In addition, they found that pollen from flowering plants was scarce, unlike at the IODP site, suggesting that conditions around the Spitsbergen Central Basin may not have been conducive to the growth of flowering plants during the PETM.

“Because this geologically short-lived event is represented by such an expanded section at Spitsbergen by comparison to other deep water sites, this locality has provided us with opportunities for further high-resolution studies of the PETM, which we are currently preparing for publication,” concluded Dr Harding.

The researchers are Ian Harding, Adam Charles , John Marshall, Heiko Pälike, Paul Wilson, Edward Jarvis, Robert Thorne, Emily Morris, Rebecca Moremon, Richard Pearce and Shir Akbari of SOES, and Andrew Roberts of the Australian National University, Canberra.

Preliminary field work was funded by The Millennium Atlas Company Limited, and a second expedition with other members of the palaeo-Arctic Climates and Environments (pACE) group was funded by the Worldwide Universities Network.

Publication:
Harding, I. C., Charles, A. J., Marshall, J. E. A., Pälike, H., Roberts, A. P., Wilson, P. A., Jarvis, E., Thorne, T., Morris, E., Moremon, R., Pearce, R. B. & Akbari, S. Sea-level and salinity fluctuations during the Paleocene–Eocene thermal maximum in Arctic Spitsbergen. Earth Planet. Sci. Lett. (2011).doi:10.1016/j.epsl.2010.12.043

Dr. Rory Howlett | EurekAlert!
Further information:
http://www.soton.ac.uk

More articles from Earth Sciences:

nachricht Large-Mouthed Fish Was Top Predator After Mass Extinction
26.07.2017 | Universität Zürich

nachricht Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds
25.07.2017 | University of Illinois at Urbana-Champaign

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

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

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>