Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Climate change does not cause extreme winters

30.03.2015

Cold snaps like the ones that hit the eastern United States in the past winters are not a consequence of climate change. Scientists at ETH Zurich and the California Institute of Technology have shown that global warming actually tends to reduce temperature variability.

Repeated cold snaps led to temperatures far below freezing across the eastern United States in the past two winters. Parts of the Niagara Falls froze, and ice floes formed on Lake Michigan. Such low temperatures had become rare in recent years. Pictures of icy, snow-covered cities made their way around the world, raising the question of whether climate change could be responsible for these extreme events.


Boston was hit by extraordinary cold snaps in the past two winters (Photo: iStock.com – mjbs).

It has been argued that the amplified warming of the Arctic relative to lower latitudes in recent decades has weakened the polar jet stream, a strong wind current several kilometres high in the atmosphere driven by temperature differences between the warm tropics and cold polar regions.

One hypothesis is that a weaker jet stream may become more wavy, leading to greater fluctuations in temperature in mid-latitudes. Through a wavier jet stream, it has been suggested, amplified Arctic warming may have contributed to the cold snaps that hit the eastern United States.

Temperature range will decrease

Scientists at ETH Zurich and at the California Institute of Technology, led by Tapio Schneider, professor of climate dynamics at ETH Zurich, have come to a different conclusion. They used climate simulations and theoretical arguments to show that in most places, the range of temperature fluctuations will decrease as the climate warms.

So not only will cold snaps become rarer simply because the climate is warming. Additionally, their frequency will be reduced because fluctuations about the warming mean temperature also become smaller, the scientists wrote in the latest issue of the Journal of Climate.

The study's point of departure was that higher latitudes are indeed warming faster than lower ones, which means that the temperature difference between the equator and the poles is decreasing. Imagine for a moment that this temperature difference no longer exists.

This would mean that air masses would have the same temperature, regardless of whether they flow from the south or north. In theory there would no longer be any temperature variability. Such an extreme scenario will not occur, but it illustrates the scientists' theoretical approach.

Extremes will become rarer

Using a highly simplified climate model, they examined various climate scenarios to verify their theory. It showed that the temperature variability in mid-latitudes indeed decreases as the temperature difference between the poles and the equator diminishes. Climate model simulations by the Intergovernmental Panel on Climate Change (IPCC) showed similar results: as the climate warms, temperature differences in mid-latitudes decrease, and so does temperature variability, especially in winter.

Temperature extremes will therefore become rarer as this variability is reduced. But this does not mean there will be no temperature extremes in the future. "Despite lower temperature variance, there will be more extreme warm periods in the future because the Earth is warming," says Schneider. The researchers limited their work to temperature trends. Other extreme events, such as storms with heavy rain or snowfall, can still become more common as the climate warms, as other studies have shown.

North-south shift makes the difference

And the jet stream? Schneider shrugs off the idea: "The waviness of the jet stream that makes our day-to-day weather does not change much." Changes in the north-south difference in temperatures play a greater role in modifying temperature variability.

Schneider wants to explore the implications these results have in further studies. In particular, he wants to pursue the question of whether heatwaves in Europe may become more common because the frequency of blocking highs may increase. And he wants to find why these high pressure systems become stationary and how they change with the climate.

Media Contact

Tapio Schneider
tapio@ethz.ch
41-446-332-621

 @ETH_en

http://www.ethz.ch/index_EN 

Tapio Schneider | ETH Zurich

More articles from Earth Sciences:

nachricht Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>