Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Temperature response in the Altai lags solar forcing

30.12.2008
New results from climate research using ice cores from the Siberian Altai

An ice core drilled at the Belukha glacier in the Siberian Altai by a Swiss-Russian research team under the leadership of the Paul Scherrer Institute (PSI) in 2001 has now provided new findings in climate research. Oxygen isotopes in the ice were used to reconstruct the temperatures in the Altai over the past 750 years.

The scientists discovered a strong link between regional temperatures and the solar activity in the period 1250-1850, concluding that the sun was an important driver of preindustrial temperature changes in the Altai. The observation that the reconstructed temperatures followed the solar forcing with a delay of 10 to 30 years is particularly interesting. The strong rise in temperature in the Altai between 1850 and 2000 can not be explained by solar activity changes, but rather by the increased concentration of the greenhouse gas CO2 in the atmosphere. The researchers report on these findings in the online edition of the scientific journal Geophysical Research Letters.

The Altai mountains lie on the border between Russia, Kazakhstan, Mongolia, and China, in a region with a particularly pronounced continental climate. In 2001, an international research team under the leadership of Margit Schwikowski (Paul Scherrer Institute) drilled a 139 m-long ice core at the Belukha glacier, near the highest mountain of the Altai. Following extensive work in the laboratory, this core has now revealed its secrets.

Ice core acting as a thermometer
The ice core was cut into 3600 samples at -20°C in the PSI’s cold room, and the 16O and 18O oxygen isotope content determined with an isotope mass spectrometer. It was demonstrated that the behaviour of the stable oxygen isotope ratio has closely followed the record of the temperature measured at a nearby weather station over the past 130 years. This parameter can therefore be used as a measure for temperature in the past. The deepest sample was dated to the year 1250, which means that the ice core contains climate information covering the past 750 years.
Solar activity influences temperature
The total solar irradiance is not a constant factor. It fluctuates periodically around a value of 1365 watts per square metre. The best-known cycle has an average duration of 11 years. It has only been possible to measure solar activity directly since 1978, but the number of sun spots – a measure of solar activity – has been observed through telescopes from as far back as the year 1610. Information about the solar activity before that time can be provided by other indirect methods: analysis of the cosmogenic radio-nuclides 10Be from polar ice cores, and 14C from tree rings, which are also dependent on solar activity.

In the period between 1250 and 1850, the regional temperatures in the Altai showed a high correlation with the reconstructed solar activity. This indicates that the changes in solar activity during this time were a main driver of temperature changes.

The temperature follows the sun
Interestingly, the regional temperatures followed the solar forcing with a time lag of 10 to 30 years. The PSI researchers’ study is the first in which such a delay has been observed over a period of more than 500 years. Since the influence of solar activity on climate has not yet been fully resolved, such observations provide an important contribution to its understanding. One possible mechanism discussed by various authors, which might explain this average lag of 20 years, is the indirect effect of the sun on temperature changes involving ocean-induced changes in atmospheric circulation. Ocean water warms up to a higher level in places where the solar radiation is most powerful, i.e. in the sub-tropics and the tropics. The heat energy is carried from the lower to the higher latitudes by the ocean, then released back into the atmosphere. Because of the high thermal capacity of the oceans and the variable velocities of their currents, these processes are subject to considerable delay. Changes in the North Atlantic atmospheric circulation system, which is responsible for temperature changes in the Altai, may be initiated 20 years earlier by changes of solar radiation in the tropical oceans.
Strong temperature increase in the 20th century can not be explained by the sun
“Our study distinguishes between the pre-industrial era (1250-1850) and the period covered by the past 150 years”, emphasises Anja Eichler, scientist at the Paul Scherrer Institute. “While changes in the solar activity were a main driver of temperature variations in the pre-industrial period, the temperatures in the Altai have shown a much higher rate of increase than that of solar activity during the past 150 years. The strong increase in the industrial period, however, correlates with the increase in the concentration of the greenhouse gas CO2 over this time. The results of our regional study indicate that changes in solar activity explain less than half of the increase in temperature in the Altai since 1850. This agrees with global studies, based on reconstructed northern hemispheric temperatures”, says the researcher.

This work was undertaken in a collaborative project between the Paul Scherrer Institute and the Eawag - Swiss Federal Institute of Aquatic Science and Technology, the Oeschger Centre for Climate Change Research, and the Department of Chemistry and Biochemistry at the University of Bern, together with the Institute for Water and Environmental Problems at Barnaul (Russia).

The Paul Scherrer Institute develops, builds and operates large and complex research facilities, and makes them available to the national and international scientific community. Its own work concentrates on solid-state research and material sciences, elementary particle physics, biology and medicine, energy research and environmental research. With a staff of 1300 and an annual budget of approximately CHF260 million, this is Switzerland’s largest research institution.

Dagmar Baroke | alfa
Further information:
http://www.psi.ch

More articles from Earth Sciences:

nachricht Monitoring lava lake levels in Congo volcano
16.05.2018 | Seismological Society of America

nachricht Ice stream draining Greenland Ice Sheet sensitive to changes over past 45,000 years
14.05.2018 | Oregon State University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>