Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Northern climate, ecosystems driven by cycles of changing sunlight

26.09.2003


Emerging geochemical and biological evidence from Alaskan lake sediment suggests that slight variations in the sun’s intensity have affected sub-polar climate and ecosystems in a predictable fashion during the last 12,000 years.



Researchers at six institutions report the findings in the Sept. 26 issue of the journal Science. The data, they say, help to explain past changes on land and in freshwater ecosystems in northern latitudes and may provide information to help project the future.

The scientists identified cycles lasting 200, 435, 590 and 950 years during the Holocene Epoch, said principal investigator Feng Sheng Hu of the University of Illinois at Urbana-Champaign. The pattern of environmental variations they found also matches nicely with cyclic changes in solar irradiance and the extent of sea ice in the North Atlantic.


"We found natural cycles involving climate and ecosystems that seem to be related to weak solar cycles, which, if verified, could be an important factor to help us understand potential future changes of Earth’s climate," Hu said.

"Will changes in solar irradiation in the future mitigate or exacerbate global warming in the future? They may do both," said Hu, a professor in the plant biology and geology departments at Illinois. "A period of high solar irradiance on top of high levels of greenhouse gases could result in unprecedented warming."

The new data come from Arolik Lake sediment in the tundra region near the Ahklun Mountains, along the southwestern coast of Alaska. Hu and co-author Darrell Kaufman of Northern Arizona University in Flagstaff have conducted climate-change research in that region for more than a decade.

"To our knowledge, this is the first data set from the North Pacific high latitudes that has enough details to evaluate the effects of centennial scale solar cycles on climate and ecosystems," Hu said.

Sediment samples were tested for a variety of biological and chemical components related to environmental qualities, including their composition of biogenic silica, pollen and isotopes. The new data combined with recent findings of North Atlantic ice cover and production records of the cosmogenic nuclides beryllium-10 and carbon-14 strongly suggest that variations of Holocene climate on multi-centennial timescales reflect changes in solar intensity, the researchers wrote. Sun-ocean-climate linkages may account for similarities in the North Atlantic and North Pacific, Hu said.

In a Science paper published in 2001, one of Hu’s colleagues, Gerard Bond of Columbia University in New York, and nine other authors documented a close connection between North Atlantic drift ice and changes in the cosmogenic nuclides beryllium-10 and carbon-14. "Now, Hu’s findings in the North Pacific not only strongly corroborate the sun-climate connection we proposed, but they also imply that the response to solar variations may have involved much if not all of the Northern Hemisphere," Bond said.

Hu and colleagues linked the solar cycles to changes in lake productivity and plant densities, as well as variations in temperatures and moisture in the Alaskan tundra. The abundance of pollen from shrubs varied up to 25 percent between cycle peaks.

"When there have been high aquatic production and abundant shrubs, then warmer, more moist weather conditions are found at our site, and these conditions coincide with the presence of less drift ice in the North Atlantic and of higher solar irradiance," Hu said.

Data from biogenic silica (single-celled algae that reflect lake productivity), North Atlantic sea ice, and baryllium-10 and radiocarbon measures were "strikingly consistent" during the cycles, with the exception of conflicting correlations that occurred in a less-defined cycle that occurred between 5,000 and 6,000 years ago, the researchers wrote.

The presence of predictable cycles dating back thousands of years provides data that are not detectable in instrumental records, which are largely restricted to just the last 100 years, Hu said.


Illinois co-authors on the paper were microbiologist Sumiko Yoneji and graduate students David Nelson, Jian Tian and Benjamin Clegg. Other co-authors were Bond of Columbia University, Aldo Shemesh of the Weizmann Institute of Science in Israel, Yongsong Huang of Brown University and Thomas Brown of the Lawrence Livermore National Laboratory in California.

The David and Lucile Packard Foundation, National Science Foundation and Israeli Science Foundation funded the research through individual grants to the participants.

Jim Barlow | EurekAlert!
Further information:
http://www.uiuc.edu/

More articles from Ecology, The Environment and Conservation:

nachricht CO2 tracking in space
25.02.2020 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

nachricht Project provides information on energy recovery from agricultural residues in Germany and China
13.02.2020 | Deutsches Biomasseforschungszentrum

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: High-pressure scientists in Bayreuth discover promising material for information technology

Researchers at the University of Bayreuth have discovered an unusual material: When cooled down to two degrees Celsius, its crystal structure and electronic properties change abruptly and significantly. In this new state, the distances between iron atoms can be tailored with the help of light beams. This opens up intriguing possibilities for application in the field of information technology. The scientists have presented their discovery in the journal "Angewandte Chemie - International Edition". The new findings are the result of close cooperation with partnering facilities in Augsburg, Dresden, Hamburg, and Moscow.

The material is an unusual form of iron oxide with the formula Fe₅O₆. The researchers produced it at a pressure of 15 gigapascals in a high-pressure laboratory...

Im Focus: From China to the South Pole: Joining forces to solve the neutrino mass puzzle

Study by Mainz physicists indicates that the next generation of neutrino experiments may well find the answer to one of the most pressing issues in neutrino physics

Among the most exciting challenges in modern physics is the identification of the neutrino mass ordering. Physicists from the Cluster of Excellence PRISMA+ at...

Im Focus: Therapies without drugs

Fraunhofer researchers are investigating the potential of microimplants to stimulate nerve cells and treat chronic conditions like asthma, diabetes, or Parkinson’s disease. Find out what makes this form of treatment so appealing and which challenges the researchers still have to master.

A study by the Robert Koch Institute has found that one in four women will suffer from weak bladders at some point in their lives. Treatments of this condition...

Im Focus: A step towards controlling spin-dependent petahertz electronics by material defects

The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.

Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...

Im Focus: Freiburg researcher investigate the origins of surface texture

Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.

Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

70th Lindau Nobel Laureate Meeting: Around 70 Laureates set to meet with young scientists from approx. 100 countries

12.02.2020 | Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

 
Latest News

Turbomachine expander offers efficient, safe strategy for heating, cooling

25.02.2020 | Power and Electrical Engineering

The seismicity of Mars

25.02.2020 | Earth Sciences

Cancer cachexia: Extracellular ligand helps to prevent muscle loss

25.02.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>