Comments 1 to 19:

1. barry1487 at 15:18 PM on 21 April, 2012
   Yeah, those are great vids, and very informative on the jet stream, which has hitherto been a bit of a mystery to me. Well done, greenman.
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2. Eric (skeptic) at 00:33 AM on 22 April, 2012
   The weakening of the polar vortex is probably not a result of lower sea ice as claimed in the second video. The pattern of low sea ice in the Barents sea this year and more ice around Alaska is a result, not a cause, of the jet stream patterns as modulated by strength and other factors. In a nutshell the jet constrains the surface lows (although it is also affected by them) and the surface lows push warm air north, cold air south and likewise push ice. The mainly positive AO this past winter (contrary to the video) was a consistent predicted result of global warming in papers about 10 years ago. For example: ftp://www.edge.alaska.edu/pub/jing/Paper-Cyclone/ArcticCyclone_Reprint_Zhang.pdf showing the increase winter Arctic cyclones and consequential strengthening of the polar vortex (as measured by higher AO). Masters and the others should try to solidify their new theories of lower sea ice causing a weaker and more undulating jet before they present it as settled science in such a video. A potential cause of the weaker undulating jet in 2009 and 2010 was the effect and residual effects of the recent low solar minimum. See http://www.agu.org/pubs/crossref/2008/2008JD009789.shtml for example. In that paper (I have a copy if anyone wants it) they explain that low solar activity does not cause blocking but lengthens its duration. Also the depth and position of upper troughs are basically weather (not solar and not sea ice related) and having a couple in a season (2009/10) was not global "weirding" but coincidence.
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3. grypo at 12:30 PM on 22 April, 2012
   "Masters and the others should try to solidify their new theories of lower sea ice causing a weaker and more undulating jet before they present it as settled science in such a video." This isn't really a problem. The sea ice loss is just an amplifying effect of heat at any given time and the real issue is the difference in temperature between the arctic and lower latitude. This is what causes the slowing of the Rossby waves. The harder problem isn't the known physics, its the statistical issues of attribution, discerning through the noise, etc. This is where the science is on its bleeding edge. For this, we need models and observation. Luckily, scientists are working on this. Full papers Evidence Linking Arctic Amplification to Extreme Weather in Mid-Latitudes A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents Impact of declining Arctic sea ice on winter snowfall Winter Northern Hemisphere weather patterns remember summer Arctic sea-ice extent Warm Arctic—cold continents: climate impacts of the newly open Arctic Sea Impact of sea ice cover changes on the Northern Hemisphere atmospheric winter circulation Abstract only Impact of 2007 and 2008 Arctic ice anomalies on the atmospheric circulation: Implications for long-range predictions Is extreme Arctic sea ice anomaly in 2007 a key contributor to severe January 2008 snowstorm in China? Eric also makes a few points that he seems to have great confidence in, such as that solar a low solar minimum caused the weaker jet that last two years - also - I'm unsure what his point is about the AO. Does he think that this is the dominant signal when looking at sea ice anomalies? More than atmospheric forcing? Since this site wants to get it right, I would invite Eric to back up his assertions with more detail, considering the confidence he has in them. Thanks. The video itself does not show this as 'settled science', as Eric puts it. In fact, Masters says sea ice loss "could" be causing some dramatic effects. The narrator says, it "may" be changing patterns of weather.
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4. TOP at 05:42 AM on 23 April, 2012
   They spend a lot of time mentioning the Summer In March, but don't mention the Winter in April. It is the Winter in April that is doing bad things to the fruit crops in Jeff Master's stomping grounds.
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5. Eric (skeptic) at 05:43 AM on 23 April, 2012
   grypo, thanks for the reply and references. First let me clarify that we are talking about winter only, as is the second video (I haven't watched the first but assume it is the same topic). The first paper in post 3 notes a trend in lower latitudinal temperature gradient mainly in fall due to lower sea ice and an associated increase in blocking (slower propagation of Rossby waves). However the trend does not extend into winter. Their poorly worded paper e.g. "further exacerbates the increased probability of slow-moving weather patterns" also seems to be poorly researched as one of their references http://weather.missouri.edu/gcc/barriopedro2006etal.pdf shows clearly that blocking is decreasing through 2002 in sectors where sea ice loss is greatest, namely the Atlantic sector. Like the video the second paper improperly places cause and effect in a single direction. Low Barents sea ice is both a cause and an effect of weather patterns, but seems to be more effect than cause. It is a better paper and a better study as they systematically vary the Barents sea ice in their model. Two things are noteworthy in their model, first that the atmospheric response to Barents ice anomaly is highly nonlinear, for example comparing fig 4a to 4b and 4b to 4c. Second, a related phenomenon is the weakening of the westerlies going from 80% to 40% ice coverage switches to a strengthening going from 40% to 1%. Also this model is for winter so it is applicable to the OP. The third paper is speculative and somewhat confused. The correlation that they point out between the Arctic SLP and low sea ice may be part coincidence. The high pressure Arctic & low pressure outside does not "resemble" negative AO, it "is" negative AO. They have worked the problem backwards ignoring other more obvious causes of negative AO. They show a snippet of declining AO from the late 80's ignoring the secular rise before that. Their references are heavy on sea ice but thin on atmospheric response papers. Their hypothesis is supported by the one I read through: http://esrl.noaa.gov/psd/people/michael.alexander/alexander.etal.jclim_04.pdf which simulated higher Arctic heights with diminished ice. I'll read the other papers next.
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6. Eric (skeptic) at 05:48 AM on 23 April, 2012
   TOP, since I live in an area forecasted to get a little snow tonight, allow me to clarify the situation. The current weather disturbance is simply weather, nothing more nothing less. It is not a function of low sea ice, or other global warming effect. However our mild Match was a direct result of two things: a natural pattern (the rest of the globe was more or less average) and a mild winter. The mild winter was a direct result of two things (I am simplifying to keep it simple). First the La Nina pattern, and second, global warming which added to the warmth. Thus, it is safe to say that the current "winter in April", although natural, is worse than it would be without CO2 warming over the past 6 months (and obviously decades before that).
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7. michael sweet at 05:52 AM on 23 April, 2012
   TOP, Your comment about winter in April is simply false. The deniers are claiming that normal April temperatures are unusual. see these graphs that show April temperatures are normal. As Dr. Masters pointed out in March, one of the problems with a warm March is that normal April temperatures freeze the plants that came out in leaf early. Please provide some sort of reference to support your hand waving claim that April was cold in the USA. Use some skepticism when you read these wild denier claims.
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8. Daniel Bailey at 06:20 AM on 23 April, 2012
   The reader will note that TOP has a history of asserting falsehoods in drive-by fashion, such as noted here. The credibility of denial is always zero.
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9. william5331 at 07:13 AM on 23 April, 2012
   Great video They talk about the Jet Stream weakening. Jet streams occur where Hadley cells meet, Each hemisphere has three Hadley cells and It is likely that the polar jet stream will simply disappear. This will occur if the Arctic, when it becomes ice free and hence a giant solar collector, becomes an area of rising air rather than as at present an area of sinking air. This would likely give rise to a two cell system rather than the present three cell system with a jet stream at about 45 degrees north where the two cells meet. Of more interest, this will shift the wheat growing areas of the northern hemisphere with obvious results. We only have, at best, two months of food reserves worldwide. The replacement of Lodge Pole pines by Poplars in the High Chilcoten and in Washington State is an indicator that this process may already be underway.
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10. Eric (skeptic) at 07:13 AM on 23 April, 2012
    The title of the fourth paper "Winter Northern Hemisphere weather patterns remember summer Arctic sea-ice extent" is provocative considering that weather is a short term function of conditions and conditions are not the same thing as anomalies (weather doesn't care if a condition is normal or not). I looked through the paper for explanations of the lag between summer ice extent and winter weather. The authors says "the pattern in the north Atlantic is reminiscent of the North Atlantic Oscillation [Hurrell, 1995]..." As with the third paper, the SLP anomaly is not "reminiscent" of negative NAO, it "is" negative NAO. The connection between low ice and negative NAO, as with the third paper, is coincidence, they both decrease in the interval studied but showed no correlation previously. Hurrell 1995 http://www.cgd.ucar.edu/cas/papers/science1995/sci.html lends no support to the memory or lag between ice extent and NAO. The best explanation is persistence. The NAO and AO reflect patterns that will determine summer ice extent (from clouds, temperature, wind). The NAO and AO are somewhat seasonal but also persist, Thus summer ice extent can correlate with NAO the following winter. The fifth paper "warm Arctic—cold continents" doesn't explain much. Might as well quote the whole meat of it:

    Attribution for the cold mid-latitude winter is difficult given the largely chaotic nature of atmospheric circulation. Since 2002, warmer lower tropospheric temperatures are associated with thin sea ice in marginal Arctic seas (Fig. 5) preceding the autumn period (Schweiger et al. 2008; Serreze et al. 2008). Model studies (Singarayer et al. 2006; Sokolova et al. 2007; Seierstad & Bader 2008; Honda et al. 2009) show a relation between years with minimum sea-ice cover and the negative phase of the AO (weaker zonal wind), although regional details are complicated by storm track and atmospheric long-wave/low frequency dynamic processes. They further suggest that the regions of high and low geopotential heights form a pattern of atmospheric teleconnections with length scales between relative high and low centres of 700–1000 km (Francis et al. 2009). The Arctic 850 mb temperature anomalies and geopotential height fields in December 2009 and 2010 (Fig. 8b, g), may have partially contributed to the resultant meridional hemispheric wind pattern

    Looking at Singarayer http://www.cpom.org/research/jlb-jc19.pdf I see that that there is no correlation between extremes in NAO (highly negative or positive) and the models. More importantly there does not seem to be any support for negative NAO or declining NAO with lower sea ice in that reference. I obviously don't need to go any further with this. The people who wrote these papers need to go back and reread their references. Frankly I am astonished at how poorly this hypothesis is supported.
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11. grypo at 07:48 AM on 23 April, 2012
    Eric, I'll get to your individual complaints on the papers in due time. But, I'd politely ask that you please keep the editorial nonsense out of the thread. By that I mean, phrases like "Their poorly worded paper" and "The people who wrote these papers need to go back and reread their references". Just allow your comments to stand on their own, as I'm sure you can defend them without the unjustified commentary. It doesn't help your case.
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12. Killian at 09:31 AM on 23 April, 2012
    Sorry, Erik, but your declarative statements about what is and is not are not useful. Not only are they essentially ad hominem, they are also not supported by the evidence, imo. We know with good confidence that the correlation between alterations in the ice and changes in the jet stream are more than just correlation. To turn that on its head by claiming changes to the jet stream are now causing the strangeness with the ice after being initiated by the strangeness with the ice is simply not logical. While there may be a positive feedbacks involved, you are dismissing that the jet stream is being changed by the warmth and ice changes. We know, for example, that ice loss and the resulting warming signal can extend up to 900 miles inland from the Arctic Ocean. Are you claiming this would not influence the temp differential thus the jet stream? How do you not see the lag? The largest pulse of warmth from the Arctic is in the fall when the sea ice is freezing and heat is lost to the air from the water. This pulse is slowing the fall freeze, shifting a lot of heating far later into the winter. We are not having full freezing till late December. Your comment, and the pejorative finish, merely cause me to question your objectivity. @ TOP: Your comment at #6 is merely dismissive of facts. The extremely warm March - not a mild spring, but a massively anomalous spring - Was, in fact, a direct result of a stalled loop in the jet stream, which is, as discussed above, a direct result of a reduced temp differential between the Arctic and the mid-latitudes - which is a result of melting sea ice from warmer sea water, more runoff, warmer air temps, reduced albedo, etc. As for your comment about the crop losses? You are correct, but your implication is completely backwards. The April is essentially normal. MArch was anomalous. Without the warm March, the fruits would not have budded and blossomed. The did so completely out of sync with typical weather patterns precisely because of the Arctic-jet stream dynamic. The crop losses were completely expected once the month-early blooming occurred because we already know that while spring is coming sooner, spring frosts have not shifted towards early spring. This actually makes sense because low temps are extremes in the variation. Extremes have no reason to shift overall any faster than the overall warming while the shifting of seasons are very sensitive to small changes in overall average temps. See Masters' excellent posts on the spring temps, frosts and crop losses. He, and pretty much anyone who has ever grown food, expected the crop losses as soon as the blooms came out. Your critiques seem to ignore the knowledge at hand.
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    Moderator Response: [DB] Fixed attribution per request.
13. Eric (skeptic) at 11:24 AM on 23 April, 2012
    Killian, for the record we agree completely that the crop losses can be blamed on anomalous warmth in March, not the normal April weather. Some trees in some places were as much as 3-4 weeks early. For that I blame AGW on top of a modified La Nina pattern which kept the eastern US much warmer and drier this past winter. More importantly (and on topic) we had a positive AO winter, except for February. This is consistent with the traditional theory of AGW, e.g. http://courses.washington.edu/pcc587/readings/Held1993.pdf that the relatively weak NH winter jet (compared to the SH) with more Rossby waves due to irregular land masses would become more like the SH jet: stronger polar jet, weaker meridional penetration and very cold polar temperatures. This Held reference is old, 1993, but I have yet to find a paper that disputes it or any of the many papers that followed the same theory up until about 2002. To me it looks like a common source of the change from the theory of stronger jets with AGW to weaker came from the Alexander paper (my last link in #5). I've been looking through the references in that paper, but many are paywalled. One that is not is http://acacia.ucar.edu/cas/cdeser/Docs/deser.arcticseaice.jclim00.pdf where they show that as sea ice decreases, NAO increases (see fig 5). Again as I stated above this means less blocking, stronger jet, less undulation, etc as sea ice decreases. I could certainly be wrong, but in order for me to be wrong there should be an explanation somewhere that the stronger jet (Held, etc) theory and weaker jet theory have been simultaneously investigated over the years and the weaker jet theory has been found to be more supported (or stronger jet less supported). I have yet to find such a statement in any paper and not for lack of trying. My conclusion until other evidence shows up is that the Alexander results are unsupported.
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14. TOP at 03:42 AM on 24 April, 2012
    @8 Michael Sweet Which post on a denier blog are you attributing to me? This is the only climate blog I hang out on. @8 Daniel Bailey As usual the ad hominem attack. He can't even prove I am a climate denier. I wonder if apophenia can be treated? Maybe I should post a copy of my heating bill when it arrives. Of course Summer in March was a phenomenon affecting an area in the Midwest United States in which I live. (Courtesy of WunderGround for Niles, MI) Effect of blocking system on SW Michigan temperatures followed by below normal temperatures. Other nearby locations saw far lower (hard freeze) temperatures. #12 Killian It is typically touch and go with fruit trees the last few years. This year was really bad, but I think my orchard may have squeaked by except maybe the fact that the bees may not have been as busy as they should have been in March. Ants and wasps are very confused right now.
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15. TOP at 03:51 AM on 24 April, 2012
    In addition to Dr. Masters appearing in this video he has made an addition to his wunderground website allowing viewers to plot a line on temperatures showing temperature rise or fall anywhere in the world where records have been kept. Climate Change
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16. Daniel Bailey at 05:21 AM on 24 April, 2012
    Alas, poor TOP! Once again you get things wrongeth! Not only doth thee misapplyeth the term ad hominem (Note: My noting your wont of making assertions proven time and again to be wrong without owning up to the error, thus constituting a lack of credibility on your part, is hardly ad hominem; it is on a par with saying that since the sky is blue, it is not green), thou dost err in in saying that I cannot proveth thee a denier (straw man argument: I said, quote "The credibility of denial is always zero")! Hadst thee but said that I had intimated thee to be trøll then perhaps there maight be substance to thy yon gossamer rhetorical bones thee jangleth. While unintended, the maladroit malaprops are appreciated.
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17. TOP at 14:29 PM on 24 April, 2012
    2009 had a somewhat similar temperature pattern in March and April, but March was just to the high side of normal and April was near the low side of normal. In 2007 the pattern was a bit later, but April got real cold. Wrecked my pears. Blocked systems and a warm and then cold spell this time of year is common. Just not to the extreme as this year. As I recall there was the opposite pattern occurring in eastern Europe all the way down to Tripoli, Libya with unusual cold and snow a short time before Summer in March.
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18. michael sweet at 09:20 AM on 27 April, 2012
    Jeff Masters referred to the "winter in April" theme TOP started today on his blog "At least 36 of the roughly 400 major U.S. cities that maintain automated weather sensors at their local airports (8%) have set or tied all-time April high temperature records so far this month; no all-time April cold records have been set. The U.S. has been on an extraordinary pace of setting high temperature records so far in 2012. During March 2012, an astonishing 32% of all the major airports in the U.S. set all-time March high temperature records. For the year-to-date, there have been 184 new all-time monthly high temperature records set at the major airports, and 6 all-time monthly low temperature records. Not surprisingly, the period January - March this year has been the warmest such period in the U.S. since record keeping began in 1895." This did not include the past 24 hours of records which had at least 6 monthly all time highs (but no low records). I cannot imagine why the press is not trumpeting all the cold! There is still 4 days left in April, perhaps we will have one cold record for the month.
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19. Eric (skeptic) at 20:31 PM on 28 August, 2012
    I'm adding a little to this thread and a pointer from another thread, not to suggest that I have all the answers of what causes "weird" weather, more specifically high amplitude patterns in winter, but to show that there are more substantial theories than "low sea ice". Here's a description on the phenomenon: Breaking Planetary Waves in the Stratosphere One possible explanation: Effects of Solar UV Variability on the Stratosphere which I must again stress is not the explanation. At best it is part of an explanation.
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