Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Revolutionary new findings about the history of trees and climate in Scandinavia

07.03.2002


Scientists at Umeå University in Sweden are putting forward an entirely new picture of climate change and the first immigration of trees following the last Ice Age. Research shows that 8,000-14,000 years ago the climate was considerably warmer than was previously thought. When it was at its warmest 9,000-10,000 years ago, the timberline was 500 m higher than today, and leafy trees grew in the mountains. The spruce immigrated considerably earlier that was assumed until now, and it probably came from the west, not the east. What’s more, research provides some support for the hypothesis that humankind has affected the climate in more recent times. Deciduous trees are again being spotted in mountain terrain!



The project combines in a unique way a long-term historical perspective with more contemporary events. For example, the reasons for the ever warmer climate of the last hundred years are being analyzed. “This research adds strength to the suspicion that the warmer climate may be related to the influence of human activity on the environment,” says Professor Leif Kullman, who heads this comprehensive physical geographical research project at the Department of Ecology and Environmental Science at Umeå University.

The spruce came from the west


High mountain peaks, like Åreskutan, thawed free as early as 14,000 years ago, which is 4,000-5,000 years earlier than earlier studies have indicated. After that, tree species like the mountain birch, pine, and spruce rapidly immigrated to these extremely high levels. Everything indicates that the climate was substantially warmer than today. One especially sensational finding is that the spruce appeared in the mountain chain more than 11,000 years ago. It has previously been taken for granted that the spruce came in from the east (from Russia) 3,000-4,000 years ago. The new discoveries show that the spruce was not only established earlier but also that it came from the west. Perhaps the trees ‘hibernated’ through the Ice Age on the emerged sea floor southwest of Norway.

Some 8,000-9,000 years ago, the tree flora of the mountains comprised previously unknown species for these regions, such as the Siberian larch, oak, lime, elm, hazel, and alder. The latter five are leafy trees that prefer an entirely different and warmer climate than that of today.

Changes in the timberline indicate climatic changes

The long-term trends of the climate have been reconstructed by analyzing changes in the timberline. The highest timberline and the warmest summers occurred about 9,500 years ago. At that time trees grew more than 500 m higher up the mountain slopes compared with today’s conditions. Subsequently there was incremental cooling up to the end of the 19th century. The timberline was then lower and the bare slopes greater than ever before.

Support for the greenhouse effect?
About 100 years ago there was a unique reversal of the trend. The climate suddenly became considerably warmer, and the timberline climbs 100-150 m during the following 100 years. The mountain forests were revitalized, and deciduous trees even started to appear on the mountain fringe. The project has managed to evaluate the ever warmer climate of the 20th century and the higher and higher elevation of the timberline. “Our present warm climate stands out as unique, at least in regard to the last 3,500 years, exceeding the natural variations that might be expected in the climate. We may be looking at one of the most concrete proofs that humans have started to affect the earth’s climate and ecosystem,” says Leif Kullman.

New methods yield more reliable results

The success of the project is based, apart from hard and patient field work, on the consistent application of a new methodology. The history of trees, forests, and the climate has been recreated by so-called megafossil-analysis. This means that large plant remains, like trunks, roots, and cones that have been preserved in peat and sea sediment, are sought out and dated using the C14 method. This yields a decidedly more reliable picture than previous research did, being based almost exclusively on pollen analysis. A more general aspect of the findings of the project is that earlier research into the history of vegetation based on pollen analysis can and should be reinterpreted.

Ulrika Bergfors Kriström | alphagalileo
Further information:
http://www.umu.se

More articles from Earth Sciences:

nachricht Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center

nachricht NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>