Weather Extremes Provoked By Trapping Of Giant Waves In The Atmosphere, Likely Boosted By Global Warming

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"Weather Extremes Provoked By Trapping Of Giant Waves In The Atmosphere, Likely Boosted By Global Warming"

In October, a NOAA-led study found that “Warming-Driven Arctic Ice Loss Is Boosting Chance of Extreme U.S. Weather.” A new study offers another mechanism for warming to drive extreme weather — JR

Potsdam Institute for Climate Impact Research news release

The world has suffered from severe regional weather extremes in recent years, such as the heat wave in the United States in 2011 or the one in Russia 2010 coinciding with the unprecedented Pakistan flood. Behind these devastating individual events there is a common physical cause, propose scientists of the Potsdam Institute for Climate Impact Research (PIK). The study will be published this week in the US Proceedings of the National Academy of Sciences and suggests that man-made climate change repeatedly disturbs the patterns of atmospheric flow around the globe’s Northern hemisphere through a subtle resonance mechanism.

“An important part of the global air motion in the mid-latitudes of the Earth normally takes the form of waves wandering around the planet, oscillating between the tropical and the Arctic regions. So when they swing up, these waves suck warm air from the tropics to Europe, Russia, or the US, and when they swing down, they do the same thing with cold air from the Arctic,” explains lead author Vladimir Petoukhov.

“What we found is that during several recent extreme weather events these planetary waves almost freeze in their tracks for weeks. So instead of bringing in cool air after having brought warm air in before, the heat just stays. In fact, we observe a strong amplification of the usually weak, slowly moving component of these waves,” says Petoukhov. Time is critical here: two or three days of 30 degrees Celsius are no problem, but twenty or more days lead to extreme heat stress. Since many ecosystems and cities are not adapted to this, prolonged hot periods can result in a high death toll, forest fires, and dramatic harvest losses.

Anomalous surface temperatures are disturbing the air flows

Climate change caused by greenhouse-gas emissions from fossil-fuel burning does not mean uniform global warming – in the Arctic, the relative increase of temperatures, amplified by the loss of snow and ice, is higher than on average. This in turn reduces the temperature difference between the Arctic and, for example, Europe, yet temperature differences are a main driver of air flow. Additionally, continents generally warm and cool more readily than the oceans. “These two factors are crucial for the mechanism we detected,” says Petoukhov. “They result in an unnatural pattern of the mid-latitude air flow, so that for extended periods the slow synoptic waves get trapped.”

The authors of the study developed equations that describe the wave motions in the extra-tropical atmosphere and show under what conditions those waves can grind to a halt and get amplified. They tested their assumptions using standard daily weather data from the US National Centers for Environmental Prediction (NCEP). During recent periods in which several major weather extremes occurred, the trapping and strong amplification of particular waves – like “wave seven” (which has seven troughs and crests spanning the globe) – was indeed observed. The data show an increase in the occurrence of these specific atmospheric patterns, which is statistically significant at the 90 percent confidence level.

The probability of extremes increases – but other factors come in as well

“Our dynamical analysis helps to explain the increasing number of novel weather extremes. It complements previous research that already linked such phenomena to climate change, but did not yet identify a mechanism behind it,” says Hans Joachim Schellnhuber, director of PIK and co-author of the study. “This is quite a breakthrough, even though things are not at all simple – the suggested physical process increases the probability of weather extremes, but additional factors certainly play a role as well, including natural variability.” Also, the 32-year period studied in the project provides a good indication of the mechanism involved, yet is too short for definite conclusions.

Nevertheless, the study significantly advances the understanding of the relation between weather extremes and man-made climate change. Scientists were surprised by how far outside past experience some of the recent extremes have been. The new data show that the emergence of extraordinary weather is not just a linear response to the mean warming trend, and the proposed mechanism could explain that.

Potsdam Institute for Climate Impact Research news release

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28 Responses to Weather Extremes Provoked By Trapping Of Giant Waves In The Atmosphere, Likely Boosted By Global Warming

  1. James W. Crissman says:

    How is this different from previous research showing the effect of loss of polar ice on the polar vortex and jet stream? That work showed, as I understood it, that with slowing of the vortex you get slowing and amplification of the waves of the jet stream. Same idea, right? Anybody want to clarify?

    • I’m not qualified to clarify, but I think you’re right. I certainly had this impression from reading I’ve done, especially about the work of Jennifer Francis at Rutgers. Maybe it’s just a case of two different research teams coming to more or less the same conclusion — but in this case, it would be hard to imagine that they are not aware or each other’s work.

    • Dano says:

      It is slightly different in that the polar vortex is part of it, but they are quantifying more clearly the larger pattern resulting from heat transfer change.

      When we look at the upper atmosphere, one of the things we do is look at the 500mb pattern and try to determine if there is a wave pattern (the “wave seven” they used in this piece). 3-5- or 7-wave patterns are stable configurations that tend to keep lows off of Iberia and Gulf of Alaska (“Pineapple Express” in US is one manifestation).

      This paper is related to the amplitude of the waves and their placement.

      Best,

      D

  2. Camburn says:

    One might want to read the history of climate events before drawing definitive conclusions about short term observations.

    http://www.breadandbutterscience.com/Weather.pdf

  3. Camburn says:

    There is a very strong relationship between ozone, which is created by UV rays in the stratosphere, and placement of the jet streams.

    This recent finding shows Antarctica. There have been similar findings for the Arctic as well.

    http://news.psu.edu/story/142524/2013/01/31/ozone-depletion-trumps-greenhouse-gas-increase-jet-stream-shift

    • Can’t open the link (would you mind posting it again or writing out the source?). However, the link’s title “…trumps greenhouse gas increase” certainly sounds like denier nonsense.

      Everything I’ve read states that the jet stream is driven by the difference in temperature between the cold poles ant the temperate zones. Why would ozone, or lack thereof, effect the movement of air, unless it effects temperatures. And if temperatures are the issue, why wouldn’t anthropogenic global warming be part of that picture?

    • Alex says:

      Where are the similar findings for the Arctic, given that there isn’t an ozone hole up there? Quote from the article, though: Depletion of Antarctic ozone is a more important factor than increasing greenhouse gases in shifting the Southern Hemisphere jet stream in a southward direction, according to researchers at Penn State.

      And this interesting bit: “The jet stream is expected to shift back toward the north as ozone is replenished, yet the greenhouse-gas effect could negate this.”

      On a side note, the popups on this site are getting a bit annoying.

      • Alex says:

        Or should I say generally not as much depletion in the Arctic (which is associated at least partly with stratospheric cooling from the amplified greenhouse effect)?

  4. Jay Alt says:

    MIT delayer Lindzen is an expert in Rossby waves.
    He is able to formulate one failed hypotheses after another about tropical heat losses. But he’s unable to discern the influence & importance of AGW upon his favored area of study.
    Although famous now for the wrong reasons, history may well find him truly worthless.

  5. Ozonator says:

    Could these waves be trying to form bands like we see on other planets?

    • riverat says:

      We already have bands, for example the trade winds. But the atmosphere is shallow enough and the Earth small enough that they don’t develop to the extent they do on the gas giant planets.

  6. Camburn says:

    I have the paper this article references.

    The article does talk a bit about solar influence on the blocking.

    “The researchers suggest that the anomaly in Northern Europe’s winter temperatures could be to do with a phenomenon called ‘blocking’.

    ‘Blocking’ is related to the jet stream which brings winds from the west, over the Atlantic, and into Northern Europe but, over the past couple of winters, could have lost its way, for weeks at a time, in an ‘anticyclone’ before it reaches Europe.

    The researchers have found strong correlations between weak solar activity and the occurrences of ‘blocking’. As the temperature is affected by a weak Sun so the wind’s patterns also change and, as the warmer westerly winds fail to arrive, the UK is hit by north-easterlies from the Arctic.”

    http://www.sciencedaily.com/releases/2010/04/100415080848.htm

  7. Camburn says:

    http://onlinelibrary.wiley.com/doi/10.1029/2010GL046582/abstract

    “We conclude that the intense 2010 Russian heat wave was mainly due to natural internal atmospheric variability. Slowly varying boundary conditions that could have provided predictability and the potential for early warning did not appear to play an appreciable role in this event.”

    • Camburn says:

      The above Published paper has been cited 33 times. Due to the amount of citation, the validity of the paper is confirmed.

      • This cherry-picking of data is not a refutation of the CO2 hypothesis anymore than the fact that the first two people I knew who died of lung cancer were non-smokers refutes the link between lung cancer and tobacco.

        What is the counter-hypothesis that ties together the shrinking ice cap, the retreating glaciers, the migration of species to higher latitudes and altitudes, the precession of the growing season, the earlier ice-out on lakes, the increased 100-year weather events, and ocean de-alkalinization?

        The CO2 hypothesis accounts for all of the above.

        This is wishful thinking disguised as analysis.

      • Merrelyn Emery says:

        Holy Cow! When did the number of citations get to determine validity? I’m sure that ‘Lord’ Monckton and Mr Watts get a goodly few too, ME

        • John McCormick says:

          ME, I agree. We are all (most of us) amateur ‘scientists’ when it comes to AGW. But, we shouldn’t prove that point. 33 Citations! Arrrgh.