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

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

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

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>