Two fundamental atmospheric flow patterns may be resonating more often due to global warming
A number of papers have been published showing that these two patterns can interact and resonate in a way that amplifies the standing wave pattern, causing the planetary waves to freeze in their tracks for weeks, resulting in an extended period of extreme heat or flooding, depending upon where the high-amplitude part of the wave lies. But what the Potsdam Institute scientists found is that because human-caused global warming is causing the Arctic to heat up more than twice as rapidly as the rest of the planet, the two patterns are interacting more frequently during the summer.
During the most recent eleven years, 2002 - 2012, there were eight Julys and Augusts that showed this unusually extreme resonance pattern (this includes the U.S. heat wave of July - August 2012.) The two previous eleven year periods, 1991 - 2001 and 1980 - 1990, had just four extreme months apiece. Global warming could certainly cause this observed increase in the resonance phenomenon, but the researchers cautioned, "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 definitive conclusions. So there's no smoking gun on the table yet--but quite telling fingerprints all over the place."
Figure 4. The northward wind speed (negative values, blue on the map, indicate southward flow) at an altitude of 300 mb in the mid-latitudes of the Northern Hemisphere during July 2011 and July 1980. July of 2011 featured an unusually intense and long-lasting heat wave in the U.S., and the normally weak and irregular waves (like observed during the relatively normal July of 1980) were replaced by a strong and regular wave pattern. Image credit: Vladimir Petoukhov.
Commentary
The new Potsdam Institute paper gives us a mathematical description of exactly how global warming may be triggering observed fundamental changes in large-scale atmospheric flow patterns, resulting in the observed increase in unusually intense and long-lasting periods of extreme weather over the past eleven years. The paper also adds important theoretical support to the research published in 2012 by Dr. Jennifer Francis of Rutgers University, which found that the amplitude of Earth's planetary waves had increased by over 100 miles (161 km) in summer over the past decade in the Northern Hemisphere. Dr. Francis theorized that this change was connected to increased heating of the Arctic relative to the rest of the Earth, due to the observed decline in late spring Northern Hemisphere snow cover.
Humans tend to think linearly--one plus one equals two. However, the atmosphere is fundamentally non-linear. What may seem to be modest changes in Earth's climate can trigger unexpected resonances that will amplify into extreme changes--cases where one plus one equals four, or eight, or sixteen. In some cases, when you rock the boat too far, it won't simply roll a bit more, it will reach a tipping point where it suddenly capsizes. Similarly, human-caused global warming is capable of pushing the climate past a tipping point where we enter a new climate regime, one far more disruptive than what we are used to.
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Jeff Masters has talked about these anomalies in the jet. Ah yes, the link.
Tried to read James Gleick's book Chaos once and couldn't get beyond the first chapter. The essence seems to be that the entropy (disorder) of some systems can suddenly jump, on new input, to a "state of chaos" where it's mostly impossible to predict what the output will be.
I have a hard time intuitively seeing how that differs from simply not knowing enough about the details and/or not having enough processing power to compute the chain of interactions of elements in the system. Chaos, in my understanding, is ignorance. I don't see why we need a new field of study about it.
The study of harmonic oscillation and resonances is a fascinating one that has application in a wide range of disciplines, from engineering to economics to weather. I spent way too much time in music school reading about Helmholtz and what makes a flute toot when I should have been studying species counterpoint. A friend was employed by JPL for years finding unique ways to deaden vibration during launches for projects like the Mars Rover. It's how the proverbial opera singer breaks the proverbial wine glass, which has contributed immensely to our knowledge of how to break wine glasses. 
Mitsubishi engineers on the San Onofre project were apparently counting on chaos, or near random vibrations, to harmlessly dissipate any energy that was transferred to the tubes by the many elements of the steam generator as they hummed along in chorus. Since the turbine was a one-off, unlike any other in its specifics, it's impossible to predict exactly how it will behave in operation. Apparently at full steam the turbine began to "sing" at a frequency that was resonant for some of the tubes. That caused them to vibrate in a way where they rubbed other tubes, and eventually one broke, releasing a few gallons of radioactive water over the course of a day. When excess radiation was detected, the reactor was shut down as designed. There was never any danger to the public and it would have been fixed in a week and back up and running if it were a hydro dam.
For public hysteria to be able to keep San Onofre closed over a year for this trivial, trivial issue is criminal.