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:
Nathalie Matter | Universität Bern
Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union
UM researchers study vast carbon residue of ocean life
19.10.2016 | University of Miami Rosenstiel School of Marine & Atmospheric Science
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences