Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Missing monsoon lead to «years without a summer»

14.02.2014
Why do cold, rainy summers in Europe follow intense volcanic eruptions in the tropics?

A research team based at the University of Bern may have found the answer: volcanic emissions in the atmosphere block sunlight and can thereby affect the amount of precipitation in other parts of the world.


Intense volcanic eruptions in the tropics lead to a weakening of monsoons and further result in rainy summers in parts of Europe (schematic figure).

Graphic: Stefan Brönnimann

Historical records provide evidence that strong volcanic eruptions in the tropics are often followed by a cold and rainy summer in Central Europe. These «years without a summer» often lead to ca-tastrophic famines; the last time in 1816 after the eruption of the Tambora volcano in Indonesia when even in Switzerland many people starved to death. Although it is known that volcanic eruptions lead to a cooling of the climate, it has until now been unclear where the additional rain comes from.

A newly published study from the international team of the Oeschger Center for Climate Change Research at the University of Bern brings light to this issue: «We believe that oscillations in the African monsoon may be responsible for the rainy European summers», says Stefan Brönnimann, principal investigator of the study from the Oeschger Center.

Less sunlight allows precipitation zones to shift

Brönnimann and his team are researching the effects of 14 intense tropical eruptions of the last 400 years on the climate of Europe and monsoon regions. The eruptions inject large amounts of aerosols into the stratosphere, where these microscopic particles reflect incoming sunlight. The decreased incoming solar radiation following volcanic eruptions leads to a cooling that is more pronounced over the continents than over the ocean. As a result, the summer monsoons in Africa and Asia are weakened.

According to the study, this not only leads to droughts in the Sahel, but also to a southward shift of the Atlantic low-pressure systems as well as enhanced thunderstorm formation. This process can, in turn, explain the increased precipitation over southern Central Europe and the northern Mediterranean, which was characteristic for the case of the year 1816.

Volcanic eruptions threaten food security

«The study shows, once again, how regions separated by great distances can affect each other climatically», says Stefan Brönnimann. The findings of the study therefore hold a very practical relevance for today, as the researcher states: «Cyclic rainfall regimes like the monsoon are important for food security in many parts of the world. Although large volcanic eruptions are quite rare, they help us better understand the monsoon systems.»

As noted by Brönnimann, a better understanding of the connection between volcanic eruptions and precipitation can even prove to be useful in the fight against climate change. The suggestion of slowing down warming using so-called geoengineering techniques – for example by artificially injecting particles into the stratosphere that reflect sunlight – can be seen in a new light, as even this could influence monsoon systems.

Publication details:
Wegmann, M., S. Brönnimann, J. Bhend, J. Franke, D. Folini, M. Wild, J. Luterbacher: Volcanic influence on European summer precipitation through monsoons: Possible cause for «Years Without a Summer». Journal of Climate, doi:10.1175/JCLI-D-13-00524.1.

Nathalie Matter | Universität Bern
Further information:
http://www.unibe.ch

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

Cholesterol-lowering drugs may fight infectious disease

22.08.2017 | Health and Medicine

Meter-sized single-crystal graphene growth becomes possible

22.08.2017 | Materials Sciences

Repairing damaged hearts with self-healing heart cells

22.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>