Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Summer storm weakening leads to more persistent heat extremes


Storm activity in large parts of the US, Europe and Russia significantly calmed down during summers over the past decades, but this is no good news. The weakening of strong winds associated with the jetstream and weather systems prolongs and hence intensifies heat extremes like the one in Russia in 2010 which caused devastating crop failures and wildfires. This is shown in a study to be published in the renowned journal Science by a team of researchers from the Potsdam Institute for Climate Impact Research. They link the findings to changes in the Arctic caused by man-made global warming.

“When the great air streams in the sky above us get disturbed by climate change, this can have severe effects on the ground,” says lead-author Dim Coumou. “While you might expect reduced storm activity to be something good, it turns out that this reduction leads to a greater persistence of weather systems in the Northern hemisphere mid-latitudes. In summer, storms transport moist and cool air from the oceans to the continents bringing relief after periods of oppressive heat. Slack periods, in contrast, make warm weather conditions endure, resulting in the buildup of heat and drought.”

**Climate change might further weaken circulation in the warm season**

Previous studies by other researchers mostly focused on winter storms, as these are usually the most damaging. While regionally the frequency or intensity of winter storms might change, on average storm activity in the cold season remains largely unchanged. In summer, however, the analysis of observational data coming from weather stations and satellites reveals a clear decrease in the average storm activity. This means a reduction in either frequency or intensity, or of both. The scientists studied a specific type of turbulences known as synoptic eddies, and calculated the total energy of their wind speeds. This energy, which is a measure for the interplay between intensity and frequency of high and low pressure systems in the atmosphere, dropped by roughly one tenth since 1979.

“Unabated climate change will probably further weaken summer circulation patterns which could thus aggravate the risk of heat waves,” says co-author Jascha Lehmann “Remarkably, climate simulations for the next decades, the CMIP5, show the same link that we found in observations. So the warm temperature extremes we’ve experienced in recent years might be just a beginning.”

**The Arctic factor: warming twice as fast as most other regions**

Rapid warming in the Arctic might be the driver of the observed changes in circulation, according to the study. Greenhouse-gas emissions from burning fossil fuels make temperatures rise globally, but in the high North the warming is faster. Since the Artics’ sea-ice cover is shrinking due to global warming, the polar region takes up more heat. The ice-free dark sea-surface reflects less sunlight back to space than white ice would do. Warmer waters then warm the air, which reduces the temperature difference between the cold polar region and the warmer rest of the Northern hemisphere. Since the temperature difference drives air motion, the reduction of this difference weakens the jet-stream, something the scientists also observed. Furthermore, they link this weakening to the observed reduction in storm activity.

“From whichever angle we look at the heat extremes, the evidence we find points in the same direction,” Coumou says. “The heat extremes do not just increase because we’re warming the planet, but because climate change disturbs airstreams that are important for shaping our weather. The reduced day-to-day variability that we observed makes weather more persistent, resulting in heat extremes on monthly timescales. So the risk of high-impact heat waves is likely to increase.”

Article: Coumou, D., Lehmann, J., Beckmann, J. (2015): The weakening summer circulation in the Northern Hemisphere mid-latitudes. Science (Express)

Weblink to the article once it is published:

Weblink to a previous study on another factor influencing heat extremes, the planetary waves:

Weblink to a previous study on the number of heat extremes:

For further information please contact:
PIK press office
Phone: +49 331 288 25 07
Twitter: @PIK_Climate

Jonas Viering | PIK Potsdam

More articles from Earth Sciences:

nachricht Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union

nachricht UM researchers study vast carbon residue of ocean life
19.10.2016 | University of Miami Rosenstiel School of Marine & Atmospheric Science

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

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...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

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...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

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...

Im Focus: New Products - Highlights of COMPAMED 2016

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...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'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...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>