Summer storm weakening leads to more persistent heat extremes

pauldouglas_1407855705_heatfloodPress Release by the Potsdam Institute for Climate Impact Research

03/13/2015 – Embargo lifted

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) [DOI:10.1126/science.1261768]

Weblink to the article: http://www.sciencemag.org/lookup/doi/10.1126/science.1261768
Weblink to a previous study on another factor influencing heat extremes, the planetary waves: https://www.pik-potsdam.de/news/press-releases/trapped-atmospheric-waves-triggered-more-weather-extremes
Weblink to a previous study on the number of heat extremes: https://www.pik-potsdam.de/news/press-releases/multifold-increase-in-heat-extremes-by-2040

For further information please contact:
PIK press office
Phone: +49 331 288 25 07
E-Mail: press@pik-potsdam.de
Twitter: @PIK_Climate

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Comment on “Summer storm weakening leads to more persistent heat extremes”

  1. Quick, run and tell the king! The latest Potsdam Panic Alert is in.

    North America spent the winter in either one of two ways, warmer than usual or just plain frigid. The west got the warmer. The east, not so much. Pity the folks in Boston never get weather reports from across the border. It would make them feel better. It is still snowing in the Canadian Maritime Provinces! Not so unusual from a place where residents of P.E.I. regularly exit from the second floor in winter. It’s the snow you know.

    As stated many times in the past, I have little confidence in Potsdam and their strident one note symphony but at least they are not wasting my money. Not that I know of in any case. The U.N., however, with its morass of overly extravagant agencies and departments, squanders a good deal of my Country’s tax dollars. I have as much confidence in IPCC Reports as the UN steno pool has in their safety when Rajendra Pachauri is in the house. I should say was in the house, proving that things do change, courtesy the girls in India. Canada should withdraw from the whole mess at our earliest opportunity. We’re one of the few that actually pays dues anyway.

    Climate is supposed to be a scientific matter made up of rigorous research, observation, discourse and of course, publication. Unfortunately, it has become political, ideological and most significantly, an exercise in P.R. Those who bang drums the loudest while professing to follow the “science” don’t act much like real scientists.

    “Unfortunately, some scientists behave like preachers, delivering sermons to people,” says Hans von Storch, Professor at the Meteorological Institute of the University of Hamburg, and Director of the Institute for Coastal Research at the Helmholtz Research Centre in Geesthacht, Germany.

    Real scientists do not participate in ideological warfare and the shunning of colleagues. The Climate Science world has become a name calling shame game. Agree or be denounced. That’s the choice many face. Agree or have your funds cut off. That’s the other choice.

    Amidst the cacophony it is worthy of mention that the ‘Flat Earth’ theory was once considered to be “settled science”, not denial. Please do not make me recite the laundry list of medical and scientific discoveries that have upset “settled science.” We should have learned long ago that claiming “settled science” is a statement, not an argument. Truth is not discovered by voting or inefficient computer models. Dr. Lorenz and Dr. Essex among others have been proving this for years. Long-term climate forecasting is impossible. The math just doesn’t exist to gather and “model” all the facts, known, nuanced and unknown. There it is. The late Edward Norton Lorenz, of MIT fame and the Father of Chaos Theory, clearly pointed out that all the current “initial’ conditions throughout the atmosphere must be known precisely to predict what the atmosphere will be doing in the distant future. In addition, all the current conditions throughout the oceans must be known as well, since the oceans control the atmosphere. “In view of the inevitable inaccuracy and incompleteness of weather observations, precise very-long-range forecasting would seem to be nonexistent,” Lorenz concluded. “So even if the molecules in the air all interacted non-randomly, in a totally cause-and-effect (deterministic) manner, you still couldn’t predict with certainty what they would do or what the weather would be.”

    Dr Christopher Essex, Chairman, Permanent Monitoring Panel on Climate, World Federation of Scientists, and Professor and Associate Chair, Department of Applied Mathematics, University of Western Ontario (Canada) has further underlined what the IPCC has already admitted. The models are 97% wrong. That is to say they are lucky when they are correct. The scientific problem of climate has not been solved in terms of basic physics and mathematics. “For decades, the most rigorous treatments of climate have been done through climate models. The clever model pioneers understood many of their inherent limitations, but tried to persevere nonetheless. Today, few academics are even aware of what the pioneers understood, let alone what has been learned since about the full depth of modelling difficulties.”

    Some climatologists, not from Potsdam, admit that although the models cannot predict short-term climate variations (such as the current 20 year “pause”) they are still valid for long-term projections. Huh? Chaos theory proves that uncertainty of projections increases exponentially with time. Long-term climate model projections are, in fact, impossible to rely upon. Common sense proves it too.

    Today’s “settled science” is tomorrow’s mistaken belief. The “settled science” of today somehow seems to fit just a little too neatly with the agenda of those arguing for ever greater state control of our economic life. Think the U.N. here. Just another among many of their attempts to redistribute the wealth of nations, under U.N. auspices of course. This is the very negotiating posture adopted by the Greeks with their EU partners. They won’t pay taxes but they think their partners should, for them that is.

    As Essex says, “…popular expressions of the scientific technicalities are largely superficial, defective, comically nonsensical, and virtually uncorrectable. All of the best physics and all of the best computer models cannot put this Humpty Dumpty together, because we face some of the most fundamental problems of modern science in climate, but hardly know it.”

    The marketing shift from “global warming” to “extreme weather” has opened up the Pandora’s Box of possibilities all pointing in whichever direction the research beggars’ wish. The money is in disaster so disaster it is. Sprinkled among all the standard disaster buzz words, you know the ones…..”extremes”….”failures”….”risks”…and the like are the old chestnuts….”probably”…”likely”…”might” and “simulations,” derived from their widely discredited “models.” Real scientific language that. Meanwhile, the eco-warrior/scientists grovel after dollars from only the like-minded with deep pockets. The more things change………………….

    My favorite was, “This means a reduction in either frequency or intensity, or of both. Can you fit in any other possibility? If not this then that or both. Wow, that’s scientific. And as usual Potsdam dismisses “Previous studies by other researchers” without naming them or their research. Now that is what I call real science! I also liked, “The scientists studied a specific type of turbulences known as synoptic eddies…” I wonder if they were trying to impress or confuse as the layman was unlikely to know the difference between frontal or open-ocean eddies. Or, as Potsdam would say, “Both?”

    The principal global priority this side of peace ought to be the development of the poorer nations. More government or U.N. control won’t help them. They have suffered from too much of it already. Mind you, the do-gooders and eco-warriors always say they want to help. Take Rajendra Pachauri, former head of the IPCC from 2002 to 2015, as an example. His letter of resignation, amid a swirl of sexual harassment charges, included this insightful confession: “For me the protection of Planet Earth, the survival of all species and the sustainability of our ecosystems is more than a mission. It is my religion and my dharma.”

    Whoa, get a grip. Even a casual observer would see that the Mr. Pachauri worships himself more than is considered healthy but his work? Is that a religion too? The creation of a new religion would fit better with the jihadists of ISIS than the eco-warriors of the IPCC and Potsdam. Perhaps his choice of words was motivated more by vanity and ego what with the salvation motif and all. That he would do anything to get his way though, scientific, true or not has been proven again and again.

    I’ll leave the religious argument to the religious (place sigh of relief here). But Mr. Pachauri and Potsdam travel identical ideological paths. It is not religion but it is not science either. Ideology in Climate Science is science corrupted. Science is observed. It is not preached from a U.N. pulpit nor spit out of a Potsdam model. This modern science is also known as “alternative science.” Jerome Ravetz, an America-British social philosopher, tracked the decline of rational science in an essay in Companion. “A new generation of epistemologically-radical social scientists soon found their target in the old faith that science proceeds by discovery of something objective out there.” Instead of being sourced by discovery, “Scientific knowledge was shown to be the product of social construction, of negotiation among interests, or merely ‘relative’ to a professional consensus and capable of being illuminated by the approach of cultural anthropology.”

    The politics of science as propagated by the likes of the IPCC and Potsdam, to name just 2, ended, in the words of Ravetz, “three triumphalist centuries” of rationalist science. Now we have flawed models. For years now climate experts and their models have predicted that temperatures would rise in parallel with greenhouse gas emissions. But, for 15 years, they haven’t. This has produced a “puzzle” that “might” force scientists to alter what “could be” “fundamentally wrong” models. Any word from Potsdam on that?

    Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research was Chancellor Angela Merkel’s climate adviser. “Conscience”, Schellnhuber said with regards to the unanswered questions concerning climate science, does not need absolute certainty: “In a world where Hiroshima and Auschwitz happened, I can’t trust that everything will always turn out well.” Democracy, to him, is an “obstacle.” Small wonder Merkel stopped listening to this megalomaniac.

    “I’ve never been chancellor myself.” Hans von Storch said. “But I do think it would be unwise of Merkel to listen to just a single scientist. Climate research is made up of far too many different voices for that. Personally, though, I don’t believe the chancellor has delved deeply into the subject. If she had, she would know that there are other perspectives besides those held by her environmental policy administrators.” Here. Here! “Certainly the greatest mistake of climate researchers has been giving the impression that they are declaring the definitive truth. The end result is foolishness along the lines of the climate protection brochures nurtured by Potsdam and published by their sponsor, Germany’s Federal Environmental Agency under the title “Sie erwärmt sich doch.” That is ‘The Earth is getting warmer’ to non-German speakers.

    Hans Joachim Schellnhuber and Rajendra Pachauri represent a one-dimensional, close-minded ideology rather than a rational science. Even a theologian would be more open-minded.

    P.S. It is supposed to get warmer. We’re only 165 years removed from the Little Ice Age, remember? That’s when the Seine, the Thames and the Hudson completely froze over.

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