The increase of devastating weather extremes in summer is likely linked to human-made climate change, mounting evidence shows. Giant airstreams are circling the Earth, waving up and down between the Arctic and the tropics. These planetary waves transport heat and moisture. When these planetary waves stall, droughts or floods can occur. Warming caused by greenhouse-gases from fossil fuels creates favorable conditions for such events, an international team of scientists now finds.
“The unprecedented 2016 California drought, the 2011 U.S. heatwave and 2010 Pakistan flood as well as the 2003 European hot spell all belong to a most worrying series of extremes,” says Michael Mann from the Pennsylvania State University in the U.S., lead-author of the study now to be published in Scientific Reports.
“The increased incidence of these events exceeds what we would expect from the direct effects of global warming alone, so there must be an additional climate change effect. In data from computer simulations as well as observations, we identify changes that favor unusually persistent, extreme meanders of the jet stream that support such extreme weather events. Human activity has been suspected of contributing to this pattern before, but now we uncover a clear fingerprint of human activity.”
+++ How sunny days can turn into a serious heat wave +++
“If the same weather persists for weeks on end in one region, then sunny days can turn into a serious heat wave and drought, or lasting rains can lead to flooding”, explains co-author Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research (PIK) in Germany. “This occurs under specific conditions that favor what we call a quasi-resonant amplification that makes the north-south undulations of the jet stream grow very large. It also makes theses waves grind to a halt rather than moving from west to east. Identifying the human fingerprint on this process is advanced forensics.”
Air movements are largely driven by temperature differences between the Equator and the Poles. Since the Arctic is more rapidly warming than other regions, this temperature difference is decreasing. Also, land masses are warming more rapidly than the oceans, especially in summer. Both changes have an impact on those global air movements. This includes the giant airstreams that are called planetary waves because they circle Earth’s Northern hemisphere in huge turns between the tropics and the Arctic. The scientists detected a specific surface temperature distribution apparent during the episodes when the planetary waves eastward movement has been stalling, as seen in satellite data.
+++ Using temperature measurements since 1870 to confirm findings in satellite data +++
”Good satellite data exists only for a relatively short time – too short to robustly conclude how the stalling events have been changing over time. In contrast, high-quality temperature measurements are available since the 1870s, so we use this to reconstruct the changes over time,” says co-author Kai Kornhuber, also from PIK. “We looked into dozens of different climate models – computer simulations called CMIP5 of this past period – as well as into observation data, and it turns out that the temperature distribution favoring planetary wave airstream stalling increased in almost 70 percent of the simulations.”
Interestingly, most of the effect occured in the past four decades. “The more frequent persistent and meandering Jetstream states seems to be a relatively recent phenomenon, which makes it even more relevant,” says co-author Dim Coumou from the Department of Water and Climate Risk at VU University in Amsterdam (Netherlands). “We certainly need to further investigate this – there is some good evidence, but also many open questions. In any case, such non-linear responses of the Earth system to human-made warming should be avoided. We can limit the risks associated with increases in weather extremes if we limit greenhouse-gas emissions.”
Article: Michael E. Mann, Stefan Rahmstorf, Kai Kornhuber, Byron A. Steinman, Sonya K. Miller, Dim Coumou (2017): Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events. Scientific Reports [DOI: 10.1038/srep45242]
Weblink to the article once it is published (which should be the case within 24 hours from now): www.nature.com/articles/srep45242
Weblink to video that explains the planetary waves phenomenon: https://www.youtube.com/watch?v=MzW5Isbv2A0
For further information please contact:
PIK press office
Phone: +49 331 288 25 07
Jonas Viering, Sarah Messina | Potsdam-Institut für Klimafolgenforschung
Stagnation in the South Pacific Explains Natural CO2 Fluctuations
23.02.2018 | Carl von Ossietzky-Universität Oldenburg
First evidence of surprising ocean warming around Galápagos corals
22.02.2018 | University of Arizona
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy