'Hurricane Sandy: The next climate wake-up call?'

[nzucker]

I'm certainly not an expert on this, but perhaps there is a lag between the warming of the poles and an actual sustained change in the blocking patterns.

The blocking has become much more prevalent in the last ten years or so, especially in the month of October. This composite is pretty staggering.

First of all, the entire Arctic has warmed a lot so heights are going to be higher there compared to earlier years regardless of seeing a strong -NAO/-AO which also has to do with surface pressure patterns (depending how you measure). That map is definitely impressive but that's only October in the last decade or so...not much of a sample size. In order to adequately test the theory that there is more blocking in winter due to the lack of arctic sea ice, you'd have to look at more years and more months.

Interestingly, the two winters following the lowest extent of arctic sea ice, Winter 07-08 and Winter 11-12, both had strong +AO/+NAO regimes.

[Dsnowx53]

First of all, the entire Arctic has warmed a lot so heights are going to be higher there compared to earlier years regardless of seeing a strong -NAO/-AO which also has to do with surface pressure patterns (depending how you measure). That map is definitely impressive but that's only October in the last decade or so...not much of a sample size. In order to adequately test the theory that there is more blocking in winter due to the lack of arctic sea ice, you'd have to look at more years and more months.

Interestingly, the two winters following the lowest extent of arctic sea ice, Winter 07-08 and Winter 11-12, both had strong +AO/+NAO regimes.

While I certainly don't disagree with anything you've said, but I'm just not sure we really have the resources/sample size to begin with to make a 100% definitive conclusion, since the enhanced blocking has seemed to only occur in the last ten years or so. At some point, I feel that some interpolating has to be done based on the data that we do have plus knowledge of what warmth in the high latitudes would lead to, instead of waiting another 10-20 years for more data. I think Dr. Francis makes great points in that interview.

You can also argue that the surface pressure patterns are also correlated to the temperatures, being that the temperature differential affects the jet stream which thus affects surface pressures.

The 07-08 and 11-12 winters are interesting. However, I think the arguments for an increased blocking in the means can be mutually exclusive with an individual winter's lack of blocking after a record low in sea ice. IMO, it's possible to attribute those cases to variability, which will not just go away, but the argument for increased blocking in the means would not be refuted.

I'm just intuitively speculating, though.

[ORH_wxman]

I think the case for October itself is much stronger than winter blocking. We've had precedent for extremely impressive winter blocking before on longer timelines than currently (since '00-'01 for recent times). This run of October blocking definitely does not have a match going back to 1950.

[TerryM]

Thanks. Just read the first one and it is a good read. Haven't read the 2nd yet except the intro.

The only bothersome part about the papers is that they start in 1979. When discussing extreme blocking patterns as they relate to AGW factors such as arctic sea ice, it would be nice to have a longer period that includes the 1950s/1960s which also experienced extreme blocking. Unfortunately our sea ice data doesn't go back that far.

The Environment Canada website charts go back to 1968 on the Canadian side & I believe the Russian data goes back much further. US air surveys go back at least until the early 50's.

Terry

[ORH_wxman]

The Environment Canada website charts go back to 1968 on the Canadian side & I believe the Russian data goes back much further. US air surveys go back at least until the early 50's.

Terry

I'm talking about detailed satellite data...which is what the study uses. You want data accurate enough to do a study on attribution.

[nzucker]

Maybe much further down the road, yes, but I think in the relative shorter term, the increased blocking will do much more to enhance snowfall than the warmer temps would do to negate it. Especially considering all you need for snow is well-timed cold, and not necessarily a below average temperature anomaly for an entire early-season month.

Then why is there a statistically significant decline in early season snowfall?

[Dsnowx53]

Then why is there a statistically significant decline in early season snowfall?

Maybe the frequency of November snowfall events in NYC would decrease, but the amount of major "exceptions" (such as October, 2011 and November, 2012) would increase.

It's just hard to say because in an area like NYC where the average snowfall is so low in November, one big storm can actually make a dent in a 10-year mean, whereas a snowless 10-year period does nothing of that sort.

[tacoman25]

Variability still rules.

[tacoman25]

The thing that doesn't make sense is that we didn't have much blocking at all in the 80s and 90s. Don't have time to read the paper this moment but it sounds as if we're cherrypicking the last few years to make this case. The 80s and 90s were largely +AO/+NAO years, and that +AO is actually blamed by some for the start of the decline in the Arctic.

Bingo. +AO/+PDO dominated the 1980s and 1990s. Now we have entered a much more -AO/-PDO period. Doesn't seem to match up well with AGW trends.

[skierinvermont]

Maybe the frequency of November snowfall events in NYC would decrease, but the amount of major "exceptions" (such as October, 2011 and November, 2012) would increase.

It's just hard to say because in an area like NYC where the average snowfall is so low in November, one big storm can actually make a dent in a 10-year mean, whereas a snowless 10-year period does nothing of that sort.

But that's not the case either. Big events have declined as well, as has total snowfall. The 5 largest NYC November snowfalls ALL occurred 60+ years ago. That's an impressive statistic. The climate is simply not cold enough for November snow in NYC anymore. November snowfall has gone from a pretty common occurence to being very rare.

This is such a blatantly obvious trend with a blatantly obvious correlation (warming temperatures) it's hard to believe anybody would argue otherwise.

[The_Global_Warmer]

Maybe the frequency of November snowfall events in NYC would decrease, but the amount of major "exceptions" (such as October, 2011 and November, 2012) would increase.

It's just hard to say because in an area like NYC where the average snowfall is so low in November, one big storm can actually make a dent in a 10-year mean, whereas a snowless 10-year period does nothing of that sort.

This makes extremely logical sense.

More/stronger mid-latitude blocking will open up chances for more early storms of winter variety in a sense. But also the trend is still warming. Until it is to warm for snow to fall in October or November at whatever place it will still snow even in a warming climate, it may be less frequent. The further North you go a zone where more snow falls from possible changes in jet streams, moisture availability from different sources.

Of course we can't say with concrete certainty that this or that has changed.

Further than that since we are in a perpetual state of change with the increasing energy imbalance we will see many different forms of change and climate as time goes on.

And overtime the snow-line will move North, it is what it is. Most of us will be dead for those major changes.

While this temperature graph doesn't discern at which latitude the most important things are happening or where the largest heat exchanges are taking place. It does tell us that we are in by far unprecedented territory with the energy imbalance in the arctic region.

We can see the changes in the Spring Snow Cover, regardless of depth or how cold the previous winter was, everywhere in the Northern Hemisphere the snow line has quickly been receding faster and faster with the onset of solar insolation.

We know the Sun has been declining for a while overall with the normal peak round 1W/M2 or so. The rapid onset of this drop and prolonged min with such a weak solar max has likely been a big factor(maybe 30-70%) in the slowing of OHC and and the "flat line" of global temperatures.

Total solar output is now measured to vary (over the last three 11-year sunspot cycles) by approximately 0.1%,^[3][4][5] or about 1.3 Watts per square meter (W/m²) peak-to-trough from solar maximum to solar minimum during the 11-year sunspot cycle. The amount of solar radiation received at the outer surface of Earth's atmosphere averages 1366 W/m²

This is a great graph to look at. The red line is Hadcrut3. It's out dated Hadcrut4 is updated with better arctic sampling and is warmer. Never the less.

To add to the above graph and get even more into the lowering forcing from the Sun. We can see below how the Sun's out put has

To add to the above graph and get even more into the lowering forcing from the Sun. We can see below how the Sun's out put has fallen down considerably and upbruptly. The most recent solar min was the strongest or weakest in a century, however you would describe it. This has clearly branched over into the solar max, we could be headed into a period of lower solar activity. But there is only so much that can do to mitigate the rapidly growing GHG's and that is without even factoring in a big blow out of clathrates that are going to continue to creep up towards critical levels of eruption all over the planet as regions warm qucikly.

So that is obviously reflected in this graph. We can see quite the drop and a very weak solar max right now. Which will end up with another drop back to the 2007-2010 levels with the next min. Clearly this has had the largest effect on the global temperatures the last half of the last decade and up through now with such a weak solar max. But we still haven't cooled at all.

We also can't leave out aerosols.

http://tamino.wordpr...global-cooling/

Another study with a graph showing aerosols in the arctic again, it shows global temps at different latitudes. Of course it's not perfect again, but it gives us an idea of different mechanisms that cause warming and cooling. Obviously once the emissions dropped after changes in protocol's. Emissions from countries closest to the 60N barrier dropped the most. Man-Made Aeresols like in China are not reaching the arctic region like before, so it's effects are mitigated quite a bit.

Link below is another paper showing Aerosol's in the arctic dropping up to 2009. Again with rapidly rising GHGs this helps explain quite a bit.

http://www.atmos-che...0-9351-2010.pdf

The new study focused on the most recent decade, when the amount of aerosol in the stratosphere has been in something of a “background” state, lacking sharp upward spikes from very large volcanic eruptions. The authors analyzed measurements from several independent sources – satellites and several types of ground instruments – and found a definitive increase in stratospheric aerosol since 2000.

“Stratospheric aerosol increased surprisingly rapidly in that time, almost doubling during the decade,” Daniel said. “The increase in aerosols since 2000 implies a cooling effect of about 0.1 watts per square meter – enough to offset some of the 0.28 watts per square meter warmingeffect from the carbon dioxide increase during that same period.”

The reasons for the 10-year increase in stratospheric aerosols are not fully understood and are the subject of ongoing research, says coauthor Ryan Neely, with the University of Colorado and the Cooperative Institute for Research in Environmental Sciences (CIRES). Likely suspects are natural sources – smaller volcanic eruptions – and/or human activities, which could have emitted the sulfur-containing gases, such as sulfur dioxide, that react in the atmosphere to form reflective aerosol particles.

So again we see a small increase in Aerosols during the same time the big solar plunge took place. And during a -PDO and more dominate NINA time frame. The aerosols do not make up enough to cause the overall slow down in OHC growth, temperature and so on but when we add in the big solar min and pathetic solar max the picture get's much more clear.

Like on Tamino's blog where I got the graph below, we can clearly see a good match up to aerosol's in the Northern Hemisphere. Where the super majority were produced during the large rise.

Once the Aerosol rise hit the breaks in the 1980s, combined with steady but high solar activitiy and GHG/Co2 exploding in atmispheric emissions and it's radiative forcing rising by about 1.0W/M2 in the last 30 year's it's not surprising that temps sky rocketed. While the Southern Hemisphere dominated by oceans took a more suttle rise with the outside factors playing their role.

With Aerosol's continuing to drop in the arctic region + rising GHG emissions(the highest planetary concentrations reside here = largest radiative forcing) Even with the solar min. Changing surface Albedo makes up for that big time vs a region with small seasonal albedo changes. These feedbacks have helped push the arctic rapidly upwards in warmth and energy in vs energy out with albedo feedbacks leading the charge.

In Conclusion:

I expect there to be many loop holes in my arguement which is very basic. But It's built on logical principle and physical science. I do not expect anyone to agree with my simplistic view of this. I think it's easiest to get this laid down first then try and see how, what, and where it's a happening and what will come of it in terms of our sensible weather patterns.

I want to thank Skier and for opening me up to Aerosol study. The field is far more advanced than this board gives as a whole gives it credit.

We have to not forget that We are currently at record highs in terms of the Earth's energy budget from global temperatures, OHC, SST's, and the big one Ice Melt.

We have to remember this has to be maintained. OHC has risen dramatically since the 1960s and 1970s. If we go back to the late 1800's it was likely much lower than the lowest on this chart. But the point is even with the obvious slow down, it's still going up and it has to be maintained at this level, if Co2 magically dropped to 310PPM tomorrow. OHC would quickly plummet and in response the Earth would start to dramatically cool off. The solar min was a nice blessing in this arguement, it has completely crushed the idea that solar can be responsible for most of the warming and subsequently will bring cooling soon or stop warming for decades to come. So in the face of the strongest solar min in a century or longer.

From all of the conversations I have had on here, I can't stress it enough that we are at a new all time high baseline of energy on this planet in our modern Global Warming and this is for instance much harder to maintain than 1960 levels or 1900 levels. This actually shows how impressive the GHG force + feedbacks has becomes and how these "natural" bumps can be misconstrued as something that proves it's not that bad.

It's bad.

http://www.nodc.noaa...ontent55-07.png

[The_Global_Warmer]

But that's not the case either. Big events have declined as well, as has total snowfall. The 5 largest NYC November snowfalls ALL occurred 60+ years ago. That's an impressive statistic. The climate is simply not cold enough for November snow in NYC anymore. November snowfall has gone from a pretty common occurence to being very rare.

This is such a blatantly obvious trend with a blatantly obvious correlation (warming temperatures) it's hard to believe anybody would argue otherwise.

Yeah, pretty big changes in NY during November.

November 1895 - 2011 Average = 45.91 degF

November 1895 - 2011 Trend = 0.41 degF / Decade

n my

In my neck of the woods, STL, it's pretty similar. It's no contest. November changes have been dramatic. It's seriously pretty much a joke at this point. I know we do not get much snow in November. Since 1997 we have had snow twice of measure 2004 we had 1.4" on November 24th and 2008 2.4" on November 30th. So even then both were towards the end of the month. You can see below how much warmer it as become.

I don't think it's something impossible at this point but I would say people around here no longer expect any sort of wintry weather besides a few freezes like lows in the upper 20s until after the 20th at least. Outside of the major record cold out break of 1991. it's laughable how far back you gotta go for record lows.

Five 1970s dates had record lows. None in November since 1977. Which makes sense because that was right before the big warm up. Before that records are more spread out.

I am just tired of being told mostly by "local blogger" snow bunnies that nothing has changed and global warming is a hoax and this is just some cycle. Yeah sure.

November 1941 - 2011 Average = 45.64 degF

November 1941 - 2011 Trend = 0.54 degF / Decade

No change eh? I am not surprised the Winter months of Dec-Feb are far less effected temperature wise by AGW. But the two fringe months for a mid-latitude city like St. Louis during the transition phase from solar dominated times to polar dominated times back to solar dominated times there is a distinct, rapid, and clear warming trend taking place and both months have seen a drop in snow and large snow events. This has really shortened our snow season. It may not be to the point where it is impossible for it to happen, but the likely hood/probibility of it happening has continued to drop considerably.

March 1941 - 2011 Average = 44.70 degF

March 1941 - 2012 Trend = 0.82 degF / Decade

It's not like we didn't break two record monthly high temps this year so far and are on pace to break the all time yearly record as well. We obliterated March's record by 3F. And are currently still running in first, We will see how that goes.

St. Louis, Missouri

Period of record: 1874- Present

Top Ten Avg. Temperatures

1) 64.2 2012

2) 63.1 1921

3) 62.1 1938

4) 61.8 1991/1990

6) 61.6 2010/2007

8) 61.5 2005/1954

10) 61.3 1998/1901

[bluewave]

First of all, the entire Arctic has warmed a lot so heights are going to be higher there compared to earlier years regardless of seeing a strong -NAO/-AO which also has to do with surface pressure patterns (depending how you measure). That map is definitely impressive but that's only October in the last decade or so...not much of a sample size. In order to adequately test the theory that there is more blocking in winter due to the lack of arctic sea ice, you'd have to look at more years and more months.

Interestingly, the two winters following the lowest extent of arctic sea ice, Winter 07-08 and Winter 11-12, both had strong +AO/+NAO regimes.

Last winter the blocking was focused on the Russian Arctic side which was a new winter record for that region

of the Northern Hemisphere.

2007-2008 was an interesting season in that the record blocking was brief and intense north of Alaska precisely where

the summer DA was really cranking with the record sea ice loss.

http://www.weather.c...permalink_month

Several papers address that you will see a variability of location and sometimes like 2007-2008 duration

of extreme blocking events.

[tacoman25]

But that's not the case either. Big events have declined as well, as has total snowfall. The 5 largest NYC November snowfalls ALL occurred 60+ years ago. That's an impressive statistic. The climate is simply not cold enough for November snow in NYC anymore. November snowfall has gone from a pretty common occurence to being very rare.

This is such a blatantly obvious trend with a blatantly obvious correlation (warming temperatures) it's hard to believe anybody would argue otherwise.

But again we have to be careful not to draw to large of conclusions from one location. Sure, snowfall overall in NYC has gone down in November, but if it can still snow in late October/early November in NYC, than surely the climate is still cold enough for November snows to be more common than they have the past few decades, given the right patterns.

In addition, one could look at another city like Seattle, where they had major and unusual Arctic events with snowfall in November in a couple recent years, and conclude that the climate is becoming more conducive to earlier snowfalls there. But it's just too small of a sample size.

[tacoman25]

Last winter the blocking was focused on the Russian Arctic side which was a new winter record for that region

of the Northern Hemisphere.

2007-2008 was an interesting season in that the record blocking was brief and intense north of Alaska precisely where

the summer DA was really cranking with the record sea ice loss.

http://www.weather.c...permalink_month

Several papers address that you will see a variability of location and sometimes like 2007-2008 duration

of extreme blocking events.

Yes, but that blocking on the Russian side was nearly equaled by anomalous troughing over Alaska. Fairbanks recorded their 4th coldest November on record and their 2nd coldest January. And as you said, the big-time -AO in 2007 was very brief.

Overall, there's no getting around that there has not seemed to be a direct connection between the lowest Arctic ice in fall and the following winter's blocking. Both 2007-08 and 2011-12 were +AO winters overall, which is simply more common with Ninas. 2012 has seen a -AO fall, but that was signaled in the summer AO well before we saw the record low minimum.

[bluewave]

Yes, but that blocking on the Russian side was nearly equaled by anomalous troughing over Alaska. Fairbanks recorded their 4th coldest November on record and their 2nd coldest January. And as you said, the big-time -AO in 2007 was very brief.

Overall, there's no getting around that there has not seemed to be a direct connection between the lowest Arctic ice in fall and the following winter's blocking. Both 2007-08 and 2011-12 were +AO winters overall, which is simply more common with Ninas. 2012 has seen a -AO fall, but that was signaled in the summer AO well before we saw the record low minimum.

From Overland and Wang:

Given a continuing trend for increased tempera- tures and thinner sea ice in the Arctic, modelling results and the data from recent late autumns, December 2008, 2009 and 2010, suggest that the frequency of an autumn warm Arctic*cold continents climate pattern will in- crease, but because of competing processes, such as changes in Arctic stratospheric flow and the chaotic nature of atmospheric circulation in the sub-Arctic including blocking events, it will not be clearly manifest in the same way in every year.

And Seminov:

Furthermore, our results suggest that high-latitude atmospheric circulation response to the B-K sea ice decrease is highly nonlinear and characterized by transition from anomalous cyclonic circulation to anticyclonic one and then again back to cyclonic type of circulation as the B-K sea ice concentration gradually reduces from 100% to ice free conditions. We present a conceptual model which may explain the nonlinear local atmospheric response in the B-K Seas region by counter play between convection over the surface heat source and baroclinic effect due to modified temperature gradients in the vicinity of the heating area.

[TerryM]

Yes, but that blocking on the Russian side was nearly equaled by anomalous troughing over Alaska. Fairbanks recorded their 4th coldest November on record and their 2nd coldest January. And as you said, the big-time -AO in 2007 was very brief.

Overall, there's no getting around that there has not seemed to be a direct connection between the lowest Arctic ice in fall and the following winter's blocking. Both 2007-08 and 2011-12 were +AO winters overall, which is simply more common with Ninas. 2012 has seen a -AO fall, but that was signaled in the summer AO well before we saw the record low minimum.

The thread spends 2 days arguing the relative merits of Dr. Francis's work, then you post as though you never noticed the discussion.

Have you read her paper and the followup articles?

Are you simply claiming that she is wrong & you are right?

Or are you saying we should ignore Dr. Francis's findings, pretend there are no connections and argue about unrelated issues.

Terry

[bluewave]

The blocking focused around this summers record melt season was very persistent from the spring

right into the fall.

[bluewave]

The thread spends 2 days arguing the relative merits of Dr. Francis's work, then you post as though you never noticed the discussion.

Have you read her paper and the followup articles?

Are you simply claiming that she is wrong & you are right?

Or are you saying we should ignore Dr. Francis's findings, pretend there are no connections and argue about unrelated issues.

Terry

Terry

It's interesting that her recent paper just came out and compliments from what I was able to read

the European study in my previous post.

http://www.agu.org/p...2GL053268.shtml

[tacoman25]

http://www.americanw...n-sea-ice-loss/

From Overland and Wang:

Given a continuing trend for increased tempera- tures and thinner sea ice in the Arctic, modelling results and the data from recent late autumns, December 2008, 2009 and 2010, suggest that the frequency of an autumn warm Arctic*cold continents climate pattern will in- crease, but because of competing processes, such as changes in Arctic stratospheric flow and the chaotic nature of atmospheric circulation in the sub-Arctic including blocking events, it will not be clearly manifest in the same way in every year.

And Seminov:

Furthermore, our results suggest that high-latitude atmospheric circulation response to the B-K sea ice decrease is highly nonlinear and characterized by transition from anomalous cyclonic circulation to anticyclonic one and then again back to cyclonic type of circulation as the B-K sea ice concentration gradually reduces from 100% to ice free conditions. We present a conceptual model which may explain the nonlinear local atmospheric response in the B-K Seas region by counter play between convection over the surface heat source and baroclinic effect due to modified temperature gradients in the vicinity of the heating area.

This is the problem I have with the overall theory. We have a series of very blocky Decembers, and all of the sudden scientists are scrambling to link it to AGW. With little to no study going into possible links to solar activity, which have a greater correlation over a much longer period of time.

AGW does not have to be behind every climate event/phenomena. This seems like an obvious statement, but as this forum shows, some people are intent on pinning anything notable on this catch-all.

[tacoman25]

The thread spends 2 days arguing the relative merits of Dr. Francis's work, then you post as though you never noticed the discussion.

Have you read her paper and the followup articles?

Are you simply claiming that she is wrong & you are right?

Or are you saying we should ignore Dr. Francis's findings, pretend there are no connections and argue about unrelated issues.

Terry

That comment was not a direct response to her work, but rather the general idea that AGW/Arctic ice melt is leading to greater blocking in the NH.

I'm not going to bother with the rest of your post, because quite frankly, you haven't had a response to many questions posed to you.

[TerryM]

Terry

It's interesting that her recent paper just came out and compliments from what I was able to read

the European study in my previous post.

http://www.agu.org/p...2GL053268.shtml

It all seems to tie together with what we're experiencing.

I wonder if you've noticed the blog entry below. I'm not sure he has all the i's dotted yet, but feel that he may be on to something. He thinks the positioning of Arctic lows has changed & I've certainly noticed that they now show a preference for the edge between ice and open water. He then draws connections between this and southward extensions of the Greenland block, the Hudson Bay low and other mid-latitude events.

http://eh2r.blogspot.ca/

What I'm most impressed with is his breaking the AO into component parts & examining the changes in these as ice conditions change. Any thoughts?

Terry

[LocoAko]

AGW does not have to be behind every climate event/phenomena. This seems like an obvious statement, but as this forum shows, some people are intent on pinning anything notable on this catch-all.

It doesn't have to be the cause of everything, no. But if the entire Earth is warming, how could it not affect everything?

[tacoman25]

It doesn't have to be the cause of everything, no. But if the entire Earth is warming, how could it not affect everything?

We've been over this. It's like assigning god-like attributes to AGW...this mysterious force that influences everything, though exactly how and to what degree we aren't sure. The same could be said of chaos theory - one small event in a random place could have far-reaching affects, but it would be almost impossible to trace back to the source or know what would have happened otherwise.

AGW may in some way have some sort of affect on all sorts of weather to a certain degree, but in a general sense, it doesn't significantly change the fundamental factors that create the weather and events we see every day. And if we don't see some sort of longterm trend that shows a possible correlation to AGW, then it is highly unlikely AGW played much of a role in that weather event occurring.

[ORH_wxman]

This is the problem I have with the overall theory. We have a series of very blocky Decembers, and all of the sudden scientists are scrambling to link it to AGW. With little to no study going into possible links to solar activity, which have a greater correlation over a much longer period of time.

AGW does not have to be behind every climate event/phenomena. This seems like an obvious statement, but as this forum shows, some people are intent on pinning anything notable on this catch-all.

Attribution studies are inhenrently the most uncertain, especially when dealing with short datasets or incomplete datasets. Attribution studies are always ongoing and they even change almost completely. Around the turn of the century, you can find several peer reviewed papers that suggest AGW is the cause of the positive trend in the Arctic Oscillation since the mid 20th century. Obviously what we see now is a 180 degree view of that. Its not unnatural to want to find a reason for observed changes in our climate...but it definitely does not have to be due to AGW, or at least the primary reasons do not always have to be due to AGW.

That is one reason I am always hesitent on studies that cover an incomplete cycle of a known decadal oscillation such as the AO or PDO or AMO. Depending on the starting point, the natural variation of the cycle can be the reason for a large part of the trend.

[Snow_Miser]

That is one reason I am always hesitent on studies that cover an incomplete cycle of a known decadal oscillation such as the AO or PDO or AMO. Depending on the starting point, the natural variation of the cycle can be the reason for a large part of the trend.

100% Agree with this statement. The Zhou and Tung 2012 study of the late-20th Century Warming being mostly caused by internal variability from the AMO comes to mind.

The sun being responsible for all of the incoming shortwave energy that interacts with Earth's Atmosphere, probably means that changes in solar activity will have a noticeable impact on the climate.

Simply put, the sun influences the Earth's Climate in many different ways, not just through TSI.

http://www.agu.org/p...1JD017390.shtml

[tacoman25]

Attribution studies are inhenrently the most uncertain, especially when dealing with short datasets or incomplete datasets. Attribution studies are always ongoing and they even change almost completely. Around the turn of the century, you can find several peer reviewed papers that suggest AGW is the cause of the positive trend in the Arctic Oscillation since the mid 20th century. Obviously what we see now is a 180 degree view of that. Its not unnatural to want to find a reason for observed changes in our climate...but it definitely does not have to be due to AGW, or at least the primary reasons do not always have to be due to AGW.

That is one reason I am always hesitent on studies that cover an incomplete cycle of a known decadal oscillation such as the AO or PDO or AMO. Depending on the starting point, the natural variation of the cycle can be the reason for a large part of the trend.

Right. Just like there were theories around that time that AGW was leading to increasing +ENSO. I think it comes down to if you are looking for something, you can usually find it. If you are looking for ways that AGW could be linked to any number of things, any number of plausible-sounding theories can be produced. If your viewpoint is based on the idea that AGW is the driving force in climate, then your natural assumption will be to look for a link to AGW in just about any climate trend.

But the problem is that sometimes people forget there are other powerful forces at work, and they don't just go away or get overwhelmed in a slowly warming world.

[TerryM]

AMO seems to have taken over from Patriotism for at least a sub set of scoundrels.

Was it Rusty or Blue that pointed out that since AMO is defined by AGW, it can hardly be used when attempting to quantify AGW.

I'd assumed that this had been as thoroughly debunked as Solar Radiation, Magnetic Oscillations Cloud Increases (or decreases) or any of the other hare brained schemes designed to postpone any meaningful reductions in CO2 by the energy giants. For some reason AMO keeps popping back up like an demented mole at a cheap carnival arcade.

I suppose it's just because all of the other excuses for ignoring the obvious have such evident flaws & the AMO is so nebulously defined. It's impossible to reference AMO without admitting the presence of AGW - although many seem unaware of this little glitch in their ideologically driven narrative.

To put bounds on AMO it's necessary to make 3 assumptions about AGW. First that AGW exists, secondly that it's increasing and third that the increase is linear. The first 2 should be no problem for anyone with a triple digit IQ, but the third requirement get's sticky when we're getting into an area where AA is so much in evidence.

For those that swear that AGW has halted or reversed the problem becomes evident - AGW to these benighted few is obviously not linear. For the rest of us evidence of AA in the North Atlantic seems overwhelming. The effects appear to be increasing, probably not exponentially but certainty not linearly.

Whenever anyone argues that the AMO effect is strong, they're arguing that the value given to the AGW trend was too low, conversely to argue that AMO effects are weak, is to argue that the trend line is too steep. The underlying oscillation that AMO is trying to track is real enough, but defining it requires assigning a value to AGW, so AMO can never reveal anything about AGW.

Pedagogically, but never pedantically

Terry

[ORH_wxman]

AMO seems to have taken over from Patriotism for at least a sub set of scoundrels.

Was it Rusty or Blue that pointed out that since AMO is defined by AGW, it can hardly be used when attempting to quantify AGW.

I'd assumed that this had been as thoroughly debunked as Solar Radiation, Magnetic Oscillations Cloud Increases (or decreases) or any of the other hare brained schemes designed to postpone any meaningful reductions in CO2 by the energy giants. For some reason AMO keeps popping back up like an demented mole at a cheap carnival arcade.

I suppose it's just because all of the other excuses for ignoring the obvious have such evident flaws & the AMO is so nebulously defined. It's impossible to reference AMO without admitting the presence of AGW - although many seem unaware of this little glitch in their ideologically driven narrative.

To put bounds on AMO it's necessary to make 3 assumptions about AGW. First that AGW exists, secondly that it's increasing and third that the increase is linear. The first 2 should be no problem for anyone with a triple digit IQ, but the third requirement get's sticky when we're getting into an area where AA is so much in evidence.

For those that swear that AGW has halted or reversed the problem becomes evident - AGW to these benighted few is obviously not linear. For the rest of us evidence of AA in the North Atlantic seems overwhelming. The effects appear to be increasing, probably not exponentially but certainty not linearly.

Whenever anyone argues that the AMO effect is strong, they're arguing that the value given to the AGW trend was too low, conversely to argue that AMO effects are weak, is to argue that the trend line is too steep. The underlying oscillation that AMO is trying to track is real enough, but defining it requires assigning a value to AGW, so AMO can never reveal anything about AGW.

Pedagogically, but never pedantically

Terry

The AMO is detrended data...in other words, the backround global warming signal is removed to see how the North Atlantic SSTs oscillate internally. There are versions of the AMO that are not detrended, but those are not the correct way to measure the natural component to the oscillation...and are generally used for other purposes. The AMO is not made up. There are a lot of papers on the AMO that have been linked in this forum numerous times. Its oscillations have historically been tied to Atlantic hurricane activity, U.S. droughts and summer heat, and Arctic temperatures (the strongest correlation being in Greenland).

Regardless, that isn't really the topic in this thread. Attribution of AGW to weather events like big storms or blocking patterns that cause them is.

[TerryM]

The AMO is detrended data...in other words, the backround global warming signal is removed to see how the North Atlantic SSTs oscillate internally. There are versions of the AMO that are not detrended, but those are not the correct way to measure the natural component to the oscillation...and are generally used for other purposes. The AMO is not made up. There are a lot of papers on the AMO that have been linked in this forum numerous times. Its oscillations have historically been tied to Atlantic hurricane activity, U.S. droughts and summer heat, and Arctic temperatures (the strongest correlation being in Greenland).

Regardless, that isn't really the topic in this thread. Attribution of AGW to weather events like big storms or blocking patterns that cause them is.

The first paragraph does qualify as pedantic - and paraphrases what I'd said above.

I'm in total agreement with you're point in your final paragraph, but feel the remonstrances should be directed to whoever brought AMO into the discussion.

"That is one reason I am always hesitent on studies that cover an incomplete cycle of a known decadal oscillation such as the AO or PDO or AMO."

Terry