Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

International team of researchers finds a link between cold European winters and solar activity

27.08.2012
Studies of Germany’s largest river reveal a correlation between periods of low activity of the sun and regional cooling

Scientists have long suspected that the Sun's 11-year cycle influences climate of certain regions on Earth. Yet records of average, seasonal temperatures do not date back far enough to confirm any patterns.


Scan of a historic postcard: Frozen Rhine river close to Mainz, winter 1962/1963, with one of the Mainz signature bridges in the background.
©: Frank Sirocko

Now, armed with a unique proxy, an international team of researchers show that unusually cold winters in Central Europe are related to low solar activity - when sunspot numbers are minimal. The freezing of Germany's largest river, the Rhine, is the key.

Although the Earth's surface overall continues to warm, the new analysis has revealed a correlation between periods of low activity of the Sun and of some cooling - on a limited, regional scale in Central Europe, along the Rhine. "The advantage with studying the Rhine is because it's a very simple measurement," said Professor Dr. Frank Sirocko, lead author of a paper on the study and Professor of Sedimentology and Palaeoclimatology at the Institute of Geosciences of Johannes Gutenberg University Mainz. "Freezing is special in that it's like an on-off mode. Either there is ice or there is no ice."

But how to find this information? Easily done: From the early 19th through the mid-20th centuries, riverboat men used the Rhine river for cargo transport. And so docks along the river have annual records of when ice clogged the waterway and stymied shipping. The scientists used these easily accessible documents, as well as other additional historical accounts, to determine the number of freezing episodes since 1780. Sirocko and his colleagues found that between 1780 and 1963, the Rhine froze in multiple places fourteen different times. "The sheer size of the Rhine river means it takes extremely cold temperatures to freeze over making freezing episodes a good proxy for very cold winters in the region," Sirocko said.

Mapping the freezing episodes against the solar activity's 11-year cycle, a cycle of the Sun's varying magnetic strength and thus total radiation output, Sirocko and his colleagues determined that ten of the fourteen freezes occurred during years when the Sun had minimal sunspots. Using statistical methods, the scientists calculated that there is a 99% chance that extremely cold Central European winters and low solar activity are inherently linked. "We provide, for the first time, statistically robust evidence that the succession of cold winters during the last 230 years in Central Europe has a common cause," Sirocko said.

"With the new paper, Sirocko and his colleagues have added to the research linking solar variability with climate," said Thomas Crowley, Director of the Scottish Alliance for Geoscience, Environment, and Society, who was not involved with the study. "There is some suspension of belief in this link," Crowley said, "and this study tilts the argument more towards thinking there really is something to this link. If you have more statistical evidence to support this explanation, one is more likely to say it's true."

When sunspot numbers are down, the Sun emits less ultraviolet radiation. Less radiation means less heating of Earth's atmosphere, which sparks a change in the circulation patterns of the two lowest atmospheric levels, the troposphere and stratosphere. Such changes lead to climatic phenomena such as the North Atlantic Oscillation, a pattern of atmospheric pressure variations that influences wind patterns in the North Atlantic and weather behavior in regions in and around Europe. "Due to this indirect effect, the solar cycle does not impact hemispherically averaged temperatures, but only leads to regional temperature anomalies," said Stephan Pfahl, a co-author of the study who is now at the Institute for Atmospheric and Climate Science in Zurich. The authors show that this change in atmospheric circulation leads to cooling in parts of Central Europe but warming in other European countries, such as Iceland. "Sunspots do not necessarily cool the entire globe; their cooling effect is more localized," Sirocko said.

In fact, studies have suggested that the extremely cold European winters of 2010 and 2011 were the result of the North Atlantic Oscillation, which Sirocko and his team now link to the low solar activity during that time. The 2010 and 2011 European winters were so cold that they resulted in record lows for the month of November in certain countries. Some who dispute the occurrence of anthropogenic climate change argue that this two-year period shows that Earth's climate is not getting any warmer. But climate is a complex system, Sirocko said. And a short-term, localized dip in temperatures only temporarily masks the effects of a warming world. "Climate is not ruled by one variable," said Sirocko. "In fact, it has at least five or six variables. Carbon dioxide is certainly one, but solar activity is also one."

Moreover, the researchers also point out that, despite Central Europe's prospect to suffer colder winters every 11 years or so, the average temperature of those winters is increasing and has been for the past three decades. As one piece of evidence of that warming, the Rhine river has not frozen over since 1963. Sirocko said such warming results, in part, from climate change. To establish a more complete record of past temperature dips, the researchers are looking to other proxies, such as the spread of disease and migratory habits. "Disease can be transported by insects and rats, but during a strong freezing year that is not likely," said Sirocko. "Also, Romans used the Rhine to defend against the Germanics, but as soon as the river froze people could move across it. The freezing of the Rhine is very important on historical timescales."

However, it wasn’t the Rhine that first got Sirocko to thinking about the connection between freezing rivers and sunspot activity. In fact, it was a 125-mile ice-skating race he attended over 20 years ago in the Netherlands that sparked the scientist’s idea. "Skaters can only do this race every 10 or 11 years because that’s when the rivers freeze up," Sirocko said. "I thought to myself, ‘There must be a reason for this,’ and it turns out there is."

The study, conducted by researchers at Johannes Gutenberg and the Institute for Atmospheric and Climate Science in Zurich, Switzerland, is published in the Geophysical Research Letters, a journal of the American Geophysical Union (GPU).

Publication:
Sirocko, F., H. Brunck, and S. Pfahl (2012), Solar influence on winter severity in central Europe, Geophysical Research Letters, 39, L16704
DOI:10.1029/2012GL052412
http://www.agu.org/pubs/crossref/2012/2012GL052412.shtml

Petra Giegerich | idw
Further information:
http://www.uni-mainz.de/presse/15622_ENG_HTML.php
http://www.geocycles.de/eng/index.php
http://www.agu.org/

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 >>>