New Research Links Climate Change to Extremes

February 27, 2013

Above, 5 minute clip from Dr. Jennifer Francis’ most recent lecture online, discussing jet stream dynamics.

As followers of these videos know, Dr. Francis has been on the cutting edge of new research showing how newly open arctic ocean water has affected jet stream movement, and may be causing a dramatic shift to to a new state in temperate zone weather conditions.


Global warming may have caused extreme events such as a 2011 drought in the United States and a 2003 heatwave in Europe by slowing vast, wave-like weather flows in the northern hemisphere, scientists said on Tuesday.

The study of meandering air systems that encircle the planet adds to understanding of extremes that have killed thousands of people and driven up food prices in the past decade.

Such planetary air flows, which suck warm air from the tropics when they swing north and draw cold air from the Arctic when they swing south, seem to be have slowed more often in recent summers and left some regions sweltering, they said.

“During several recent extreme weather events these planetary waves almost freeze in their tracks for weeks,” wrote Vladimir Petoukhov, lead author of the study at the Potsdam Institute for Climate Impact Research in Germany.

“So instead of bringing in cool air after having brought warm air in before, the heat just stays,” he said in a statement of the findings in the U.S. journal Proceedings of the National Academy of Sciences.

A difference in temperatures between the Arctic and areas to the south is usually the main driver of the wave flows, which typically stretch 2,500 and 4,000 km (1,550-2,500 miles) from crest to crest.

But a build-up of greenhouse gases in the atmosphere, blamed on human activities led by use of fossil fuels, is heating the Arctic faster than other regions and slowing the mechanism that drives the waves, the study suggested.

Potsdam Institute for Climate Impact Research:

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.



15 Responses to “New Research Links Climate Change to Extremes”

  1. My son was explaining to me today how the jet stream, and ocean currents were changing, and what changes might happen on the planet.
    Thank you for posting this video. I think the disbelievers of climate change are planning on leaving our planet before this event.

    • uknowispeaksense Says:

      I could make a quip with a sweeping generalisation about the demographics of deniers but I won’t……actually I will. An aweful lot of them were born in the 40’s and 50’s….so it won’t be long now.

      Our greatest hope is that the younger, highly educated members of our globe can start to really put a dent in this idiocy….if only through sheer weight of numbers.

      • ahaveland Says:

        Not if the anti-science nuts have anything to do with it – wanting to corrupt the education of children to keep them scientifically illiterate.
        Intelligence and knowledge is a threat to them.

        • uknowispeaksense Says:

          I think that’s mainly a US problem. We don’t see that happening here in Australia and I’m reliably informed its not a big problem in European countries. I wonder how much of a role the same religious fundamentalists who keep pushing for the anti-evolution garbage to be included in curriculums play in pushing anti-climate garbage?

  2. Jean Mcmahon Says:

    I have been telling people I know that we have messed up the jet stream and that explains a lot of extreme weather…..they are interested and no longer arguing w me Thanks for that longer lecture good to listen to while doing chores!

  3. […] Above, 5 minute clip from Dr. Jennifer Francis' most recent lecture online, discussing jet stream dynamics. As followers of these videos know, Dr. Francis has been on the cutting edge of new resear…  […]

  4. On the ground the impact of Arctic ice loss, if this study is correct, is having a crippling effect. As a food producer my 2012 fruit crop was a failure in western UK, my neighbours who include big farms saw potatoes crops rot in the fields, oilseed rape down 25% cereals down about the same and sheep and beef farming heavily in debt having to keep animals indoors and fed on inflated feed.

    We had a winter drought and super hot March only to be followed by record rain and a cool summer. The jet stream stalled to the south of the country and curiously the last time such a poor summer occurred was 2007.

    Unlike the US or Europe much of our climate is driven by the Atlantic as well so whilst heat wave and drought are a real problem for others we seem to be heading the other way.

    Food producers are trying to be smart and we can at least borrow money to adapt [I spent a small fortune installing ponds and water tanks for a drought in 2011!], but debt has already become a problem for many. And the biggest issue is the natural world- I need insects, and local beekeepers were forced to feed their ‘livestock’ who stayed in their hives for most of the summer.
    If the frequency of ice melt is once every 5 years then I can cope, and the likelihood of 2013 being another record low is slim. No doubt the deniers will claim the ice has recovered! But in the coming 5 years I don’t see the ice stabilising.
    Perhaps it is easy for people to ignore the problem when it i is far away but my feeling is the problem will be coming to a supermarket near you.. Climate Change is turning into our weather.

  5. Recent (and work with Vavrus 2012) scientific achievements Dr. J. Francis are really impressive.

    The conclusions are very cautious. There is, after all, and in fact the sentence: “Also, the 32-year period studied in the project provides a good indication of the mechanism involved, yet is too short for definite conclusions.”

    I recall here the considerations – also outstanding scientist – T. Knutson ($file/EE-0566-103.pdf):
    “These damage potential projections do not include important influences such as sea level rise, coastal development, and societal adaptation.”

    “One reason this approach is often favored in the case of climate change is that one assumes that the fundamental laws are more likely to be applicable in a changed climate than empirical relations derived by training a statistical model on past climate data alone.”

    “However, it is possible that more dramatic future changes could occur over the 21st century. While, in my opinion, these more dramatic changes remain speculative, they are at least plausible enough to merit discussion here.
    First, it is possible that 21st century changes in tropical cyclones will be less potentially damaging than the scenarios outlined in the projections section. For example, some studies suggest that TC activity in some basins, such as the NW Pacific and North Atlantic, could shift eastward away from current landfalling regions and thus perhaps reduce the percentage of storms that make landfall in major population regions. Global climate transient sensitivity or sea level rise could be at the low end, or even lower than, the range shown in IPCC AR4. Future greenhouse gas concentrations could be toward the lower end or lower than IPCC AR4 scenarios. Alternatively, it is also possible that the reverse could be true in these cases, i.e., that transient climate sensitivity, future greenhouse gas concentrations, sea level rise, and so forth could be higher than expected, or even that storm tracks could shift systematically more toward major landfalling regions, in contrast to a number of current projections.”

    There is also the so called: paradox equable climate(curveball) occurring for example in a maximum Eemian and mid-Holocene (6,000 years ago and the last interglacial period 125,000 years ago –
    “So in both seasons [mid-Holocene 6,000 years ago and the last interglacial period 125,000 years ago], the detectable segment of the pole-to-equator temperature difference was smaller than at present, and at high latitudes the seasons were less dramatic than at present.
    Climate models don’t do this. In the mid-Holocene, for example, they get that the high-latitude temperatures were warmer compared to present than low-latitude temperatures, but they are generally too warm on summer and way too warm in mid-latitudes in winter. The models produce a weaker seasonal difference over the Arctic Ocean, but the proxies extend the reduced seasonality all the way down to 50N. It’s not even clear anymore that the mid-Holocene was warmer than the present.
    What could cause such a thing? The answer probably lies either in the position and latitudes of the jet stream … “

    Probably as a result of global warming more than 2-3 ° C, the jet stream weakened so that it can disappear (in the temperate zone – also UK), disappear … – just as climatic extremes …

  6. tonyloman Says:

    Here is something else to think about. I don’t remember any discussion or analysis of the effects of polar warming and ice loss on the jet stream and thence on weather extremes until about a year- possibly 18 months-ago. Maybe climatologists knew about it but nothing had made it into the popular science lit. Now we have Jennifer Frances and the Potsdam group and others explaining it and doing empirical work demonstrating it. Is this yet another example of unforeseen effects of monkeying with the complex system that is our climate? The really frightening question is what else is around the corner? What’s going to slap us upside the head next?

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  8. Thanks for sharing this video, it was interesting and informative. I’d be really interested in seeing a more detailed physical discussion of this phenomenon. Maybe some of you who post on this blog know the science behind why the wave amplitude increases, I know she said it stalls because… er… have I already forgotten? I better go back and listen a couple more times.

    • My take on the waveyness of the jet stream is similar to that of a flag – well waving in the wind- the waveyness is caused by pressure difference as you find on an plane wing- if that difference becomes less then the flag just flops about in a rather weak way.

      that is my simple take on things but I am open to correction.

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