AMO Turns Negative(at least temporarily)

[bluewave]

This is very interesting. I too am not as concerned about an index as the actual cold pool 

that developed in the North Atlantic and also the cooling west of Africa.  Also the development

of that warm pool over the northeast Pacific. I have no proof but I recall a massive blocking

ridge that has been also ever present in the north Pacific for months now....and of course

this relates to the negative EPO phase. 

 

In both of these oscillations, the AMO and EPO which came first the oceanic signal or

atmospheric signal?  Using reanalysis data it might be possible to attempt an answer. 

 

The EPO turned negative in January 2013 and then we saw the record breaking low March -AO index to -3.185.

During the spring and summer, the cold pool developed as the NAO and AO rose while the EPO remained negative.

So it looks like the upper  pattern shift lead to the cold pool development that we continue to see this month.

 

 

 

 

[blizzard1024]

The EPO turned negative in January 2013 and then we saw the record breaking low March -AO index to -3.185.

During the spring and summer, the cold pool developed as the NAO and AO rose while the EPO remained negative.

So it looks like the upper  pattern shift lead to the cold pool development that we continue to see this month.

 

MAR.png

 

MAR13.png

 

APRJUL.png

 

JUL13.png

 

This suggests the atmosphere leads to SSTs in this instance. Its probably an interplay between both with various feedbacks that re-enforce each other. This is similar to ENSO...which starts first with the weakening trade winds...less upwelling...weaker higher pressure west of south america and now even weaker trade winds. Kelvins waves I believe are postulated to be in the initial trigger. I am out of the loop on the latest in ENSO research so it is likely much more complicated. The north pacific warm pool we see now...is this related to an atmospheric pattern?  Like the massive upper air block persistent since the fall??? I would suspect....but have not dug too deep into this.

[Msalgado]

Maybe i overreacted but his reply suggests otherwise. Any chance we can get tags for people who do have a background in this field and thus non met? I think it would really help in here.

 

 

 

 

You should try stating such then. If you are a meteorologist then feel free to PM a staff member so you can get the proper credentials aka Met tag. As a scientist you of all people should know better ( How to properly approach and converse with someone in the field )   but yeah i know you were on a fishing expedition. If you weren't you would have stated who/what you are when you involved yourself in the topic.

 

I don't see the need to sit here and post my credentials prior to every post.  The content of my posts is more important; is it not?  Whether I was a layman or a professor, neither would change the the facts.  Why on earth would I have to state my credentials every time I post in a topic?    Thats just outlandish.

[Msalgado]

The Arctic sea ice loss correlates with a warm phase AMO now and likely the loss of summer sea ice in the 30s and 40s before the satellite monitoring era. The North Atlantic current flows up into the Arctic basin so it is plausible that the AMO phase is related to variations in the Arctic sea ice extent. This is really basic stuff. I can't prove it but the evidence based on what limited observations we have leads me to that hypothesis. You see....in meteorology.... we have to make a lot of decisions based on limited data and I am doing the same here. There is limited data especially before the satellite era. We are often wrong too and I may be wrong in this. Computer simulations are not data. Computer simulations are prone to error and bias and often used in the peer reviewed literature as "proof".The CAGW scenarios are based on computer model output. There is observational evidence that they are oversensitive to CO2 increases suggesting the feedbacks are too strong or even of the wrong sign. We don't know for sure. No one does. When I hear things like...this is "basic physics"...it isn't by any means. We are talking about a highly non-linear chaotic system that is poorly measured spatially and temporally relative to the real atmosphere. This is no way "basic physics". I do not dispute that there is positive TOA external radiative forcing from increased CO2. That is basic physics. How the atmosphere reacts to this is NOT basic physics. 

 

The Sun and its variations are also unknown as to how it impacts our climate IMO. If you narrow it to just TSI in the IR spectrum you can't explain the variations. Agreed. But the UV spectrum changes a lot more and that impacts the stratosphere. How does this feedback to the troposphere? Does it? Some suggest it does? How does this impact the climate? I don't have answers but I would hope someone is studying this. Unfortunately, this is  probably not true because the $$$$$ are in CO2 related climate changes. That is the truth. Politics are also into CO2 regulation as well. So I fear research in climate has been hijacked by politics and money hungry universities and research organizations that now can get tremendous funding. Case and point... they are blaming all the cold, snow and individual weather events like Sandy on global warming now!! It is getting crazy. Enough said. By the way, good luck on your PHD. I really mean that...no sarcasm here. 

 

Thank you for your well wishes.  Considering the completion rates for PhDs I'm going to need all the well wishes I can get.

 

I'll respond to the rest later when I have a bit more time.

[bluewave]

This suggests the atmosphere leads to SSTs in this instance. Its probably an interplay between both with various feedbacks that re-enforce each other. This is similar to ENSO...which starts first with the weakening trade winds...less upwelling...weaker higher pressure west of south america and now even weaker trade winds. Kelvins waves I believe are postulated to be in the initial trigger. I am out of the loop on the latest in ENSO research so it is likely much more complicated. The north pacific warm pool we see now...is this related to an atmospheric pattern?  Like the massive upper air block persistent since the fall??? I would suspect....but have not dug too deep into this.

 

I was able to find a SST animation of the rapid warming event over the North Pacific in response to the very

strong ridge that developed there  last June and July. You can also see the cold pool

over the North Atlantic in response to the +NAO /+AO at the same time.

 

http://bobtisdale.files.wordpress.com/2013/08/animation-3.gif

 

[skierinvermont]

You need to just QUIT. I mean REALLY? Look at who you are talking to. Big deal you read something that says one thing where as he has training ( college educated ) on the subject matter. EVERYONE of you people always run and hide behind so called peer reviewed stuff you read that many of you do not even understand! It is laughable at best. When you or someone else gets a education ( degree ) on the matter then feel free to bark all you like.

 

Reasons why i stay out of these debates. If you are not educated on the subject matter then you shouldn't be debating/arguing with someone who IS acting like a know it all and least of all trying to be insulting. This is as bad as snow weenies who go at it with mets because the met is not calling for all the snow they want.

 

FWIW almost every meteorologist knows about the AMO. To see some of you people ( especially those that have been around here long enough posting about the weather ) debating that it exists is beyond words. And please dont give me the lip about some lame peer reviewed paper that says otherwise. One would think people on THIS forum would be smart enough to know how it works. ALL the sudden because a group of people who has a set agenda where a ton of $$$$ ( funding or for others to push their products ) is on the line is gonna now claim something doesn't exist that did KNOWING it is because it does not FIT into their argument and some of you are gonna buy right into it? I mean really?  I can understand someone who doesn't post about or follow the weather believing such garbage but someone who DOES? I don't think so.

 

Get a grip!

 

Are you talking about blizzard? I have as much education on the subject as him and I can assure you I have read more scholarly work on the subject. 

 

But that's beside the point. Neither of us are experts, but the 'educated' IE scholarly consensus is quite clear. I actually agree with your sentiment that it is best to defer to those with formal education and research on the subject. Among those who do, it's quite clear that long-term sea ice decline is due primarily (60-100%) to AGW (a fact which ORH also confirmed for you, which you ignored, and which makes your whole rant pointless). 

 

More broadly, deferring to those with formal training and research on the subject of climate change, it is broadly understood and agreed that close to 1C of warming has taken place since the late 19th century, and that this is primarily (70-90%) due to the net effect of humans (GHG warming and aerosol cooling).

[skierinvermont]

The CAGW scenarios are based on computer model output. 

 

This is a denier lie that I have pointed out to you half a dozen times. There are a half dozen independent lines of evidence to estimate climate sensitivity none of which rely upon computer models.

 

It is universally agreed (even by you) that doubling CO2 leads to 3.7W/m2 of RF and thus 1.1C of warming. There are at least (probably more) half a dozen independent lines of evidence that net feedbacks in the climate system are positive and that climate sensitivity to 3.7W/m2 of forcing is likely somewhere 2-4C. 

[blizzard1024]

This is a denier lie that I have pointed out to you half a dozen times. There are a half dozen independent lines of evidence to estimate climate sensitivity none of which rely upon computer models.

 

It is universally agreed (even by you) that doubling CO2 leads to 3.7W/m2 of RF and thus 1.1C of warming. There are at least (probably more) half a dozen independent lines of evidence that net feedbacks in the climate system are positive and that climate sensitivity to 3.7W/m2 of forcing is likely somewhere 2-4C. 

 

This is untrue. All the paleo studies are based off of computer models using what they think are the boundary conditions of that time. 

[blizzard1024]

Are you talking about blizzard? I have as much education on the subject as him and I can assure you I have read more scholarly work on the subject. 

 

But that's beside the point. Neither of us are experts, but the 'educated' IE scholarly consensus is quite clear. I actually agree with your sentiment that it is best to defer to those with formal education and research on the subject. Among those who do, it's quite clear that long-term sea ice decline is due primarily (60-100%) to AGW (a fact which ORH also confirmed for you, which you ignored, and which makes your whole rant pointless). 

 

More broadly, deferring to those with formal training and research on the subject of climate change, it is broadly understood and agreed that close to 1C of warming has taken place since the late 19th century, and that this is primarily (70-90%) due to the net effect of humans (GHG warming and aerosol cooling).

 

Most of the warming seen of 1C is primarily due to humans? We were in a LIA until the late 1800s or even early 1900s. The Earth started warming before CO2 was even a factor. Glaciers started retreating before CO2 forcing was a factor. The climate likely was in an imbalance before CO2 was a factor based on this. The LIA was real. Much of the 20th century warming was related to that. Some was related to CO2, 

[ORH_wxman]

Most of the warming seen of 1C is primarily due to humans? We were in a LIA until the late 1800s or even early 1900s. The Earth started warming before CO2 was even a factor. Glaciers started retreating before CO2 forcing was a factor. The climate likely was in an imbalance before CO2 was a factor based on this. The LIA was real. Much of the 20th century warming was related to that. Some was related to CO2, 

 

 

Yes, most (greater than 50%) is due to humans. It is hard to reconcile otherwise with the current understanding of our climate.

 

 

I think there is some room to disagree with skier's 70-90% though....you could argue it is closer to 50-60% which is supported in some peer reviewed literature...other peer reviewed literature argues higher, but there isn't an air tight consensus on that. Especially considering the more recent papers that argue that roughly 30-40% of the 1975-2005 warming was due to natural factors.

 

If you wanted to narrow it to JUST CO2 though, then it would def be higher since aerosols helped offset some of that....but aerosols are human too, so you have to include them in the overall human contribution. CO2 alone though would be higher.

[StudentOfClimatology]

Physics makes clear that the 3.67W/m^2 figure is physically accurate, especially in a two way interface with zero-perturbations or shared wave spacing in the phases within the boundaries of intra-collisional disequilibrium.

http://www.aip.org/history/climate/co2.htm

In Earth's case, there are complications here so the 3.7W/m^2 figure could be off by a small margin. However, this is likely to be <5% of the stated forcing, hence is not likely to matter much. So, anyone harping on that is just building a straw-man.

Of course there is always the minuscule chance that Loschmidt was correct and Boltzmann/Maxwell were wrong, regarding gravity's effect on thermodynamic equilibrium. http://books.google.com/books?id=VNKCsQt75_UC&pg=PA49&lpg=PA49&dq=loschmidt+vs+maxwell&source=bl&ots=WWr4agXj_R&sig=wVN416t6Hunskz50axiq9ZUzAbs&hl=en&sa=X&ei=S_UGU6mWGc200AGk94HgAw&ved=0CDgQ6AEwBg

I'd consider this unlikely, but much stranger things have happened in science. So I'm not going to be a crank and close my mind.

However, we can say (with fairly high certainty) that significant warming is in store at this point, given the observational data at hand. We don't need models to tell us that, because the physics are right there in front of us. Those why deny the laws of physics only do so for political or religious reasons. So unless something comes along that clearly refutes AGW (unlikely), there is zero use in denying it, unless you just crave attention.

[ORH_wxman]

Physics makes clear that the 3.67W/m^2 figure is physically accurate, especially in a two way interface with zero-perturbations or shared wave spacing in the phases within the boundaries of intra-collisional disequilibrium.

http://www.aip.org/history/climate/co2.htm

In Earth's case, there are complications here so the 3.7W/m^2 figure could be off by a small margin. However, this is likely to be <5% of the stated forcing, hence is not likely to matter much. So, anyone harping on that is just building a straw-man.

Of course there is always the minuscule chance that Loschmidt was correct and Boltzmann/Maxwell were wrong, regarding gravity's effect on thermodynamic equilibrium. http://books.google.com/books?id=VNKCsQt75_UC&pg=PA49&lpg=PA49&dq=loschmidt+vs+maxwell&source=bl&ots=WWr4agXj_R&sig=wVN416t6Hunskz50axiq9ZUzAbs&hl=en&sa=X&ei=S_UGU6mWGc200AGk94HgAw&ved=0CDgQ6AEwBg I'd consider this unlikely, but much stranger things have happened in science. So I'm not going to be a crank and close my mind.

However, we can say (with fairly high certainty) that significant warming is in store at this point, given the observational data at hand. We don't need models to tell us that, when the physics are right there in front of us. Those why deny the laws of physics only do so for political or religious reasons. So unless something comes along that clearly refutes AGW (unlikely), there is zero use in denying it.

 

 

 

This isn't really relevant to the crux of the debate though. This part of the debate argues for about 1.1C of warming per doubling of CO2. That is not nearly enough to explain the "rest" of the AGW theory as IPCC presents it.

 

If this was all there was to see, then AGW wouldn't be an issue...since 1.1C of warming would be benificial without further risk of warming.

[FloridaJohn]

We were in a LIA until the late 1800s or even early 1900s.

Was the LIA a regional or global phenomenon?

[ORH_wxman]

Was the LIA a regional or global phenomenon?

 

 

It was global, but definitely most pronounced in the northern hemisphere. Studies showed that antarctica cooled about one half the amount that Greenland/Arctic did.

[sokolow]

Was the LIA a regional or global phenomenon?

per ORH there's argued to be a hefty slice of hemispheric & regional variability in relative cooling, but also in chronology of exit from the period. Edit and as U Washington's paleoclimate & atmospheres guy Roe says, the more the LIA gets stretched, the more attentive one should be to presenting the data regionally & in parallel when attempting to work out the scope of the LIA.

[ORH_wxman]

Here's some recent papers on the Antarctica response to the LIA...the northern hemisphere is pretty well documented already:

 

http://www.sciencedirect.com/science/article/pii/S0012821X11002925

 

http://web.b.ebscohost.com/abstract?direct=true&profile=ehost&scope=site&authtype=crawler&jrnl=18149340&AN=74247843&h=%2fUYZTbSM98cPxVA9dBUWfQF%2fCST8m1eqW1I4zd7o0%2f0d9GNvdxvNzmLBPv60drGvo2awCLxw54xSfbC4fWDHdw%3d%3d&crl=c

 

 

 

This paper here is where it was showed that the response was about half the magnitude of Greenland:

 

http://onlinelibrary.wiley.com/doi/10.1029/2012GL051260/abstract;jsessionid=40F6360BBAFD64463F3BFE36E044DD0B.f01t02?deniedAccessCustomisedMessage=&userIsAuthenticated=false

 

 

 

This one isn't Anarctica, but pretty close...discussing the maximum of glacial advance in Patagonia, South America during the Little Ice Age and the subsequent retreat since then:

 

http://www.ingentaconnect.com/content/igsoc/jog/2012/00000058/00000212/art00004

[blizzard1024]

Yes, most (greater than 50%) is due to humans. It is hard to reconcile otherwise with the current understanding of our climate.

 

 

I think there is some room to disagree with skier's 70-90% though....you could argue it is closer to 50-60% which is supported in some peer reviewed literature...other peer reviewed literature argues higher, but there isn't an air tight consensus on that. Especially considering the more recent papers that argue that roughly 30-40% of the 1975-2005 warming was due to natural factors.

 

If you wanted to narrow it to JUST CO2 though, then it would def be higher since aerosols helped offset some of that....but aerosols are human too, so you have to include them in the overall human contribution. CO2 alone though would be higher.

 

If 30 to 40% of the warming between 1975 and 2005 was natural....that makes the longer term likely around the 50% category related to CO2 all things being equal. The warm up in the early 20th century is thought to be mainly natural since CO2 levels before 1945 were not that significant and we were recovering from the end of the LIA.   Below is the global average temperature from NASA and NOAA.

 

 

Looking at this graph one could argue that the ave temp was around -.2C until 1930 when it shot up to around 0 departure through mid century. It held at around 0 until 1975 or so. Then from 1975 to 2005 it warmed to about .5C.  So if 35% of the warming between 1975 and 2005 was natural that = about .35C for CO2. So CO2 was responsible for about .35C out of .7C on this graph. That's 50%. However the more reliable UAH satellite record shows only about .35C warming since the late 70s. this would put CO2 at  around.25C of warming relative to .maybe +.6C (assuming a little less warming as the satellite record shows).  Again that equals between 40 and 50%.

 

So let's say CO2 has caused .35C warming out of .7C. The current radiative forcing is at ~ 2w/m2 so add 1.7 w/m2 for a hypothetical doubling and that equals around .3C warming the rest of this century which is close to  .7C  or so which is under the theoretical neutral feedback radiative forcing of 1.2C. So the question is: where's your positive feedbacks skierinvermont??? They better start kicking in soon. 

 

Of course, this all assumes we understand how cloud cover and tropical convection responds which we don't.  It is interesting to note that the global cloud cover variations have a very high correlation to the global average temperature. This is the supposedly "unreliable" ISCCP dataset. It has tremendous correlation to the satellite temperatures. When there was more clouds it was colder, and less clouds it was warmer(1983-2009). The graphs are remarkably inverse related suggesting cloud cover is affecting global temperature. Of course, climate scientists have discounted this dataset. It would invalidate the importance of CO2 concentrations. 

[sokolow]

blizzard the accounting for forcings in 20th century climate by component, looking to isolate the human influence vs. solar, volcanic eruptions, ENSO, &c. is pretty thoroughly explored in the IPCC reports chh. 2 and 9 and in Foster and Rahmstorf (2011).

The latter conclude the human caused contribution to global warming since 1979 is ~.17C/decade for surface temps and ~.14-.15C/decade in the lower troposphere, in line with similar research (Huber and Knutti 2011). I don't know which studies ORH has in mind, but tying to isolate a lesser GHG signal via back of the envelope math is a nonoptimal way to try and tip over the established science.

[blizzard1024]

blizzard the accounting for forcings in 20th century climate by component, looking to isolate the human influence vs. solar, volcanic eruptions, ENSO, &c. is pretty thoroughly explored in the IPCC reports chh. 2 and 9 and in Foster and Rahmstorf (2011).

The latter conclude the human caused contribution to global warming since 1979 is ~.17C/decade for surface temps and ~1.4-1.5C/decade in the lower troposphere, in line with similar research (Huber and Knutti 2011). I don't know which studies ORH has in mind, but tying to isolate a lesser GHG signal via back of the envelope math is a nonoptimal way to try and tip over the established science.

1.4 to 1.5C per decade? are you sure it isn't .14 to .15C per decade? That would be more in line with what is observed...

 

This is how the real atmosphere's temperatures has been changing vs the models.... 

 

 

I would say the feedbacks in the models are probably overstated and/or natural variability is stronger than what the consensus thinking is. 

[FloridaJohn]

I would say the feedbacks in the models are probably overstated and/or natural variability is stronger than what the consensus thinking is.

Or you don't have a clear understanding of what the models are showing you.

Here's a good overview of what the models are showing.

[AvantHiatus]

HadCRUT version 2 is supposedly more accurate and is more in-line with climate models. Temperatures were rising faster than model projections in the 1990s. No reason to think it cannot happen again. 2010 was also the warmest year on record even if only by a few tenths of a degree, we know this by looking at several proxies such as ice melt and precipitation changes.

 

Another cherry-picked skepticism and a case of seeing the trees before the forest.

[sokolow]

1.4 to 1.5C per decade? are you sure it isn't .14 to .15C per decade? That would be more in line with what is observed...

Thanks, I moved the decimal point.

This is how the real atmosphere's temperatures has been changing vs the models....

http://www.americanwx.com/bb/index.php?app=core&module=attach§ion=attach&attach_rel_module=post&attach_id=122828"]CMIP5-90-models-global-Tsfc-vs-obs-t

I would say the feedbacks in the models are probably overstated and/or natural variability is stronger than what the consensus thinking is.

That's interesting. You should submit a note correcting the authors, or drop Foster a line in the comments section at Tamino's Open Mind. I'm sure they'll be glad to revise their work and reassess the parameters for variability in light of your research. Until then / absent detailed justification we should probably use the best published figures as the basis for our thinking.

[blizzard1024]

HadCRUT version 2 is supposedly more accurate and is more in-line with climate models. Temperatures were rising faster than model projections in the 1990s. No reason to think it cannot happen again. 2010 was also the warmest year on record even if only by a few tenths of a degree, we know this by looking at several proxies such as ice melt and precipitation changes.

 

Another cherry-picked skepticism and a case of seeing the trees before the forest.

 

Yep. Hadcrut2 version is now more in line with climate models. Bingo. Now 2010 was the warmest...not 1998. Ok i see what is going on here. enough said. The observations HAVE to be wrong when they don't agree with the climate models. 

[blizzard1024]

Or you don't have a clear understanding of what the models are showing you.

Here's a good overview of what the models are showing.

 

Thanks I will read this. But the title... "Why trust climate models? It’s a matter of simple science"  Bold is my emphasis.  Simple science?? LOL   Atmospheric modeling is simple science??? The person who wrote this article has no clue. I often run into people who equate things as simple as gravity or a round earth to global climate change. Ignorance. Anyway I will check this out. I appreciate it. Thanks. 

[FloridaJohn]

The reason for the title of that article will become clear once you read it. Climate models are not the same as atmospheric models.

I'm not sure you can claim that "the person who wrote this article has no clue" when you admit that you haven't even read the article yet. Here is the first paragraph of the article:

"Talk to someone who rejects the conclusions of climate science and you’ll likely hear some variation of the following: “That’s all based on models, and you can make a model say anything you want.” Often, they'll suggest the models don't even have a solid foundation of data to work with—garbage in, garbage out, as the old programming adage goes. But how many of us (anywhere on the opinion spectrum) really know enough about what goes into a climate model to judge what comes out?"

Your confirmation bias is showing.

[blizzard1024]

The reason for the title of that article will become clear once you read it. Climate models are not the same as atmospheric models.

I'm not sure you can claim that "the person who wrote this article has no clue" when you admit that you haven't even read the article yet. Here is the first paragraph of the article:

"Talk to someone who rejects the conclusions of climate science and you’ll likely hear some variation of the following: “That’s all based on models, and you can make a model say anything you want.” Often, they'll suggest the models don't even have a solid foundation of data to work with—garbage in, garbage out, as the old programming adage goes. But how many of us (anywhere on the opinion spectrum) really know enough about what goes into a climate model to judge what comes out?"

Your confirmation bias is showing.

 

So a climate model is not an atmospheric model? No that is not true. That is not what this article said. I know some about climate models and they are crude representations of atmospheric processes similar to weather models. The difference is that weather models are initial value problems and climate models are boundary value problems in the arena of partial differential equations. The fact that when a climate model has excess energy or "leaks" energy in the initialization process, they used to adjust heat fluxes to balance the model before the simulation to stabilize the simulated climate. Now they have better fluxes and don't have to adjust them. But the models still either accumulate excess energy or leak energy and still need to be stabilized before doing experiments. So they adjust cloud cover to achieve balance. UGH. 

 

Here is a module that discusses this from UCAR COMET. This is source is actually

pro CAGW just so you know... 

 

 

http://www.meted.ucar.edu/nwp/climate_models/index.htm

 

 

You have to get a meted account through UCAR. Its free. I recommend you go through this. It is

much more rigorous.  

[ORH_wxman]

There is literature on the troubles of the IPCC models on recent warming or lack thereof. Its not some tampered graph that John Christy or Roy Spencer came up with...

 

http://www.nature.com/nclimate/journal/v3/n9/full/nclimate1972.html

 

 

 

The Tung et al paper (2013) was critical of the Foster/Rahmstorf (2011) paper on seperating the anthropogenic vs unforced warming trends

 

http://depts.washington.edu/amath/research/articles/Tung/journals/Zhou_and_Tung_2013_MLR.pdf

 

 

The recent Trenberth et al paper focused on the recent slowing of surface warming...but it did conclude within the paper that the late 20th century warming was aided by unforced ocean oscillations although they did not quantify this part. In short, there's certainly some disagreement in the literature on exactly how much anthopogenic trend there is.

[FloridaJohn]

So a climate model is not an atmospheric model?

If you go back and read my post, you will find that is not what I said.

[blizzard1024]

The reason for the title of that article will become clear once you read it. Climate models are not the same as atmospheric models.

 

 

Climate models are atmospheric models. This statement is just plain wrong. I already stated what the difference is between

climate models and weather models, assuming that is what they meant by "atmospheric" models. Garbage in does equal garbage out

with all models not just climate, weather or "atmospheric" models... 

 

If you want to learn more about climate models take that UCAR COMET module on climate models. It is a pretty basic overview. 

[bluewave]

While this isn't in the form of a published paper, the author has published recently.

This post could explain why the temperatures are lower than the models had projected.

But he acknowledges the uncertainty of his analysis.

 

http://link.springer.com/article/10.1007/s00382-013-1770-4

 

 

http://troyca.wordpress.com/2014/02/21/breaking-down-the-discrepancy-between-modeled-and-observed-temperatures-during-the-hiatus/

To me, it seems that if you are going to leave room for the PDO to explain a portion of the recent hiatus, it means that models probably overestimated the anthropogenic component of the warming during that previous positive phase of the PDO. Thus, for my second approach, I again use the ENSO-adjusted CW13 as my dependent variable in the regression, but in addition to using the integrated PDOI as one explanatory variable, I include the adjusted MMM temperatures as a second variable. This will thus find the best “scaling” of the MMM temperature along with the coefficient for the PDO.

After using this method, we indeed find the “correct” direction for the influence of the PDO:

 

According to this regression, the warm phase of the PDO contributed about 0.1 K to the warming from 1979-2000, or about 1/3 of the warming over that period. Since shifting to the cool phase at the turn of the 21^st century, it has contributed about 0.04 K cooling to the “hiatus”. This suggests a somewhat smaller influence than England et al. (2014) finds.

For the MMM coefficient, we get a value of 0.73. This would imply that the transient climate sensitivity is biased 37% too high in the multi-model mean. Since the average transient climate sensitivity for CMIP5 is 1.8 K, this coefficient suggests that the TCR should be “adjusted” to 1.3 K. This value corresponds to those found in other observationally-based estimates, most notably Otto et al. (2013).

When we put everything together, and perform the “TCR Adjustment” to the CMIP5 multi-model-mean as well, we get the following result:

 

Using the above methodology, the table below shows the estimated contribution by each factor to the modeled vs. observational temperature discrepancy during the hiatus (note that these rows don’t necessarily add up to 100% since the end result is not a perfect match):

 

 

According to this method, the coverage bias is responsible for the greatest discrepancy over this period. This is likely contingent upon using Cowtan and Way (2013) rather than simply masking the CMIP5 MMM output (and using HadCRUT4 rather than GISS). Moreover, 65% – 79% of the temperature discrepancy between models and observations during the hiatus may be attributed to something other than a bias in model sensitivity. Nonetheless, this residual warm bias in the multi-model mean does seem to exist, such that the new best estimate for TCR should be closer to 1.3K.

Obviously, there are a number of uncertainties regarding this analysis, and many of these uncertainties may be compounded at each step. Regardless, it seems pretty clear that while the hiatus does not mean that surface warming from greenhouse gases has ceased – given the other factors that may be counteracting such warming in the observed surface temperatures – there is still likely some warm bias in the CMIP5 modeled TCR contributing to the discrepancy.

 

http://www.iac.ethz.ch/people/knuttir/papers/otto13nat.pdf

 

From Otto et al:

 

 

The best estimate of TCR based on observations of the most recent decade is 1.3 °C (0.9–2.0 °C; dark red, Fig. 1b). This is lower than estimates derived from data of the 1990s (1.6 °C (0.9–3.1 °C); yellow, Fig. 1b) or for the 1970–2009 period as a whole (1.4 °C (0.7–2.5 °C); grey, Fig. 1b). However, because the most recent estimate has the strongest forcing and is less affected by the eruption of Mount Pinatubo in 1991, it is arguably the most reliable. Our results match those of other observation-based studies15 and suggest that the TCRs of some of the models in the CMIP5 ensemble10 with the strongest climate response to increases in atmospheric CO2 levels may be inconsistent with recent observations — even though their ECS values are consistent and they agree well with the observed climatology. Most of the climate models of the CMIP5 ensemble are, however, consistent with the observations used here in terms of both ECS and TCR. We note, too, that caution is required in interpreting

 

 

ny short period, especially a recent one for which details of forcing and energy storage inventories are still relatively unsettled: both could make significant changes to the energy budget. The estimates of the effective radiative forcing by aerosols in particular vary strongly between model-based studies and satellite data. The satellite data are still subject to biases and provide only relatively weak constraints (see Supplementary Section S2 for a sensitivity study). ❐