New Paper finds Most of the Late-20th Century Warming was Naturally Induced

[skierinvermont]

Wrong...read again. I said nearly all of the GCMs use inverse calculations for their aerosols. There are several ways to use inverse calculations. They all don't have to be from a residual in the temperature record if that is what you are assuming. I gave that as one example. More sophisticated inverse calculations are made from assumptions about aerosol size, distribution, etc. I am fully aware there are forward calculations, but the error bars are quite large. The IPCC has an aerosol average error of + or - 1.9 w/m2 when they combine the total forcing directy and indirecty from aerosols.

I don't think you appreciate how uncertain the estimates are in aerosol forcing and all the caveats that are listed when the calculations are made. I'm willing to consider aerosols as the primary factor to the mid-20th century cooling, but right now, I doubt it. They don't explain the huge drop in temperatures even in the first 8-10 years after the PDO flip. Way too sudden and the timning lines up perfectly with the PDO shift.

If we assume the higher aerosol forcing numbers are correct, then that leads to a whole new problem anyway...that much of the recent warming was aided even more by natural variation than first thought.

I clearly stated the error bars for aerosol forcing in my above post. The forcing estimate is -1.2W/m2 with an error bar from -.6 to -2.4. The published error bars from the IPCC report are not as large as you are stating. This is based solely on the physics of aerosols and not what would be convenient to modeling.

Taking the mid estimate, aerosols caused .26C of cooling 1945-1975. I find it highly unlikely ocean cycles caused an additional .26C of cooling during the same period.

[Snow_Miser]

There is no plausible mechanism by which GCRs could alter the earth's energy budget by 30+ W/m2.. there's no plausible mechanism by which they could have much effect at all.

GCRs are at record levels and yet there has been no perceptible effect on global temperatures or the earth's energy balance. The idea is nonsense at this point. (this is where you propose some magical nonsensical 10+ year delay from the initial change in GCRs to any perceptible effect on earth whatsoever).

Paleoclimate studies conclude sensitivity is around 1W/m2/K. This is also confirmed by the response to volcanic eruptions such as Pinatubo. And again by modeling.

The Cloud Forcing is roughly equatable to around 30 w/m^2 right now actually per the Christl 2004 paper, so if there were periods of much lower GCRs and periods where GCRs were much higher than today, this would create a substantial fluctuation in the Cloud Forcing, and thus have a substantial effect on the Climate, which is what Christl et al. 2004 concluded.

[Snow_Miser]

Because 1910-1940, GHG forcing was stronger. Also solar was ramping up then big time. It's the emergence from an exceptionally cold period to a period with more GHGs, record high solar activity, and no volcanoes. Aerosols do show a footprint 1910-1940. Without them the warming would have been even faster due to GHGs and solar.

The charts speak for themselves.. add up forcing from GHGs, solar, volcanoes, and aerosols and you can explain nearly all the variability. Very little room or need for ocean cycles to explain observations. And there's no fudging involved. Just take the best estimates based on physics (causation) of how aerosols, GHGs, solar, and volcanoes effect forcing. And then add it all together.

CO2 increased about 10 ppm from 1910 to 1940. Are you seriously claiming that such a benign increase in the concentrations of CO2 is enough to overwhelm the impact that increasing aerosols could have had over this timeframe? If so, then the anthropogenic aerosol effect is not a very large one.

[csnavywx]

BAM. The AMO, by definition is literally equivalent to linearly detrended North Atlantic SST. That's it. Subtract the GISS temp trend from the N. Atl. SST anomaly and whalaa, there IS NO TREND IN THE AMO OVER THE PAST 30+ YEARS. This leads to a second and probably more damning piece of evidence that comes from the fact that the phase shift between temps and the AMO doesn't fit Granger causality. In other words, we should see a positive delay (or time lag) between the AMO and temperature increases. But we don't. We instead see a neutral or even negative delay. This is a serious problem for anyone trying to claim that the AMO drives temperature. Pretty crushing actually. Any valid analysis would have to overcome this and show the full physics of the process. In the meantime, I suppose we'll have to settle for works like this that attempt to chase their own tails with circular reasoning.

A better and much simpler explanation exists besides "mysterious ocean cycles". Global warming. That's right, global warming is the cause... not the effect... of most of the changes in N ATL SST.

I wanted to expand on this because, at second blush, it appears I may not have been totally clear on my point. The AMO is equivalent to linearly detrended North Atlantic SST, but the problem is that the global warming signal is significantly non-linear. The problem here is that you're trying to apply a linear detrend to a non-linear data set in the attempt to isolate the AMO. So by default, the forced signal will leak into the AMO definition (which is this linearly detrended data). Remove the GISS N. ATL SST temp anomaly from this and there is no trend in the AMO.

This is why the "AMO causes global warming" argument is a circular one. Any argument in favor of the AMO contributing to global warming would have to overcome this in addition to the negative delay problem I listed above. Then it would have to explain the process with physics since Granger causality doesn't seem to exist in this case. (I'm being overly nice here, because if the temperature goes up even slightly before the AMO does, it basically rules out direct causality.)

[csnavywx]

Wrong...read again. I said nearly all of the GCMs use inverse calculations for their aerosols. There are several ways to use inverse calculations. They all don't have to be from a residual in the temperature record if that is what you are assuming. I gave that as one example. More sophisticated inverse calculations are made from assumptions about aerosol size, distribution, etc. I am fully aware there are forward calculations, but the error bars are quite large. The IPCC has an aerosol average error of + or - 1.9 w/m2 when they combine the total forcing directy and indirecty from aerosols.

I don't think you appreciate how uncertain the estimates are in aerosol forcing and all the caveats that are listed when the calculations are made. I'm willing to consider aerosols as the primary factor to the mid-20th century cooling, but right now, I doubt it. They don't explain the huge drop in temperatures even in the first 8-10 years after the PDO flip. Way too sudden and the timning lines up perfectly with the PDO shift.

If we assume the higher aerosol forcing numbers are correct, then that leads to a whole new problem anyway...that much of the recent warming was aided even more by natural variation than first thought.

The PDO index is used at face value around here quite a bit. It is the basis for a LOT of arguments for quite a number of individuals. This makes a critical assumption: That the PDO index is calculated to remove the effects of the global warming signal accurately.

So, let's look at that. First, how is the PDO that is used in the literature calculated?

"[The PDO index is]...derived as the leading PC of monthly SST anomalies in the North Pacific Ocean, poleward of 20N. The monthly mean global average SST anomalies are removed to separate this pattern of variability from any "global warming" signal that may be present in the data."

(Link)

This is the essence of the Mantua PDO index. Note that the NCDC's index is very closely related as well.

This definition makes a critical assumption itself via this statement:

"The monthly mean global average SST anomalies are removed....", which by default assumes that SST response to climate forcing is spatially uniform. This is very unlikely.

It follows that any differential heating as a result of this forcing is aliased directly into the PDO's definition. Note that this swings both ways: Forcing that causes an inhomogeneous warming response (CO2) and forcing that causes an inhomogeneous cooling response (aerosols) will project or alias some of their effects onto the PDO index.

What does that mean? Using the PDO as a causative factor for global warming or cooling is, at least in part, circular reasoning.

TLDR: The PDO, as defined, aliases the effects of anthropogenic climate forcings into its definition because of its flawed assumption that SST response to climate forcings is spatially uniform.

[ORH_wxman]

The PDO index is used at face value around here quite a bit. It is the basis for a LOT of arguments for quite a number of individuals. This makes a critical assumption: That the PDO index is calculated to remove the effects of the global warming signal accurately.

So, let's look at that. First, how is the PDO that is used in the literature calculated?

"[The PDO index is]...derived as the leading PC of monthly SST anomalies in the North Pacific Ocean, poleward of 20N. The monthly mean global average SST anomalies are removed to separate this pattern of variability from any "global warming" signal that may be present in the data."

(Link)

This is the essence of the Mantua PDO index. Note that the NCDC's index is very closely related as well.

This definition makes a critical assumption itself via this statement:

"The monthly mean global average SST anomalies are removed....", which by default assumes that SST response to climate forcing is spatially uniform. This is very unlikely.

It follows that any differential heating as a result of this forcing is aliased directly into the PDO's definition. Note that this swings both ways: Forcing that causes warming (CO2) and forcing that causes cooling (aerosols) will project or alias some of their effects onto the PDO index.

What does that mean? Using the PDO as a causative factor for global warming or cooling is, at least in part, circular reasoning.

TLDR: The PDO, as defined, aliases the effects of anthropogenic climate forcings into its definition because of its flawed assumption that SST response to climate forcings is spatially uniform.

The PDO is used as a proxy for ENSO...it is a product of ENSO and its residual effects...if you take the raw ENSO numbers (and I don't mean anomalies), they show the same significant drop and then subsequent rise. This is a cop-out explanation that the PDO doesn't matter.

[The_Global_Warmer]

I wanted to expand on this because, at second blush, it appears I may not have been totally clear on my point. The AMO is equivalent to linearly detrended North Atlantic SST, but the problem is that the global warming signal is significantly non-linear. The problem here is that you're trying to apply a linear detrend to a non-linear data set in the attempt to isolate the AMO. So by default, the forced signal will leak into the AMO definition (which is this linearly detrended data). Remove the GISS N. ATL SST temp anomaly from this and there is no trend in the AMO.

This is why the "AMO causes global warming" argument is a circular one. Any argument in favor of the AMO contributing to global warming would have to overcome this in addition to the negative delay problem I listed above. Then it would have to explain the process with physics since Granger causality doesn't seem to exist in this case. (I'm being overly nice here, because if the temperature goes up even slightly before the AMO does, it basically rules out direct causality.)

This is all obvious. I am glad you can explain it better than I can. I hope you get laughed at like I have.

[skierinvermont]

CO2 increased about 10 ppm from 1910 to 1940. Are you seriously claiming that such a benign increase in the concentrations of CO2 is enough to overwhelm the impact that increasing aerosols could have had over this timeframe? If so, then the anthropogenic aerosol effect is not a very large one.

I said in combination with solar TSI which ramped up from record lows to record highs in the period. Also a lack of volcanic activity after experiencing major volcanic activity near the turn of the century.

As I've said a dozen times already, radiative forcing over the 20th century matches very closely to observed temperature without including ocean cycles or GCR fairies. I'm not saying ocean cycles had no effect, but whatever effect is likely quite small. It can probably help explain the slight overshot of observed temperatures in the 1940s compared to radiative forcing.

[Snow_Miser]

I said in combination with solar TSI which ramped up from record lows to record highs in the period. Also a lack of volcanic activity after experiencing major volcanic activity near the turn of the century.

As I've said a dozen times already, radiative forcing over the 20th century matches very closely to observed temperature without including ocean cycles or GCR fairies. I'm not saying ocean cycles had no effect, but whatever effect is likely quite small. It can probably help explain the slight overshot of observed temperatures in the 1940s compared to radiative forcing.

You said that the Greenhouse Gas Forcing was stronger than the aerosol forcing with solar and volcanism contributing as secondary constituents, so that's why we warmed in the early-20th Century. For such small forcings to overwhelm the impact of aerosols means that you are indirectly saying that the anthropogenic aerosol forcing is not all that important in the grand scheme of things.

I'm also not sure off of what basis you are saying that oceanic cycles do not have a large impact on the Climate. A -PDO can lead to more frequent La Ninas, which as we know, has a large and noticeable impact on the Global Surface Temperature.

The total forcing over the solar cycle is seven times more than what you would expect with TSI variations alone. Whether this is due to GCRs, another solar forcing, or both remains to be seen, since there remains considerable uncertainty with GCRs and their impacts on the atmospheric dynamics. However, we can say with relatively good confidence that TSI is not the only Solar Forcing, and is probably the weakest solar forcing. So trying to claim that TSI is the only solar forcing is simply misleading.

[skierinvermont]

You said that the Greenhouse Gas Forcing was stronger than the aerosol forcing with solar and volcanism contributing as secondary constituents, so that's why we warmed in the early-20th Century. For such small forcings to overwhelm the impact of aerosols means that you are indirectly saying that the anthropogenic aerosol forcing is not all that important in the grand scheme of things.

I'm also not sure off of what basis you are saying that oceanic cycles do not have a large impact on the Climate. A -PDO can lead to more frequent La Ninas, which as we know, has a large and noticeable impact on the Global Surface Temperature.

The total forcing over the solar cycle is seven times more than what you would expect with TSI variations alone. Whether this is due to GCRs, another solar forcing, or both remains to be seen, since there remains considerable uncertainty with GCRs and their impacts on the atmospheric dynamics. However, we can say with relatively good confidence that TSI is not the only Solar Forcing, and is probably the weakest solar forcing. So trying to claim that TSI is the only solar forcing is simply misleading.

I've already debunked your nonsense about solar forcing being 7X TSI forcing in other threads. Complete nonsense. We have had very low solar activity for the last 6+ years with no detectable effects on earth other other than the expected .1-2W/m2 response to the drop in TSI. The earth remains in a massive energy imbalance and the surface has continued to warm slowly consistent with GHG forcing + dampening from a drop in TSI. This is decisive proof against the various nonsensical solar hypotheses out there.

And correction to what I said earlier: GHGs did not overwhel aerosols alone 1910-1945.. the combination of TSI, GHGs, and low volcanic activity did, with perhaps some slight contribution from ocean cycles.

The other thing to remember about the -PDO is that although it causes more frequent Ninas and Ninas cause cooling, -PDOs also have a huge area of +SSTAs in the north Pacific. So although there are more Ninas, there may be a background warming overall due to the expanse of +SSTAs and the two effects may offset each other for a near zero sum effect.

On the one hand, ocean cycle obsessers insist that the expanse of +SSTAs in the Atlantic during a +AMO must cause global warming, but deny the fact that during -PDOs the expanse of +SSTAs is much larger than the expanse of -SSTAs in the north Pacific, and that this would also cause a background waming which is perhaps neutralized by the increased frequencies of Ninas in the tropical Pacific. The causative mechanism is on very shaky grounds and can give us no idea of magnitude. Whereas the causative mechanisms for GHGs, aerosols, TSI etc. are well established and can give us reasonable estimates of the magnitude of the effect.

[csnavywx]

I'm sure emissions leveling off had nothing to do with normal economic activity screeching to a halt as half of Europe was being conquered and destroyed. Or the '37 recession....

[CoastalWx]

I've already debunked your nonsense about solar forcing being 7X TSI forcing in other threads. Complete nonsense. We have had very low solar activity for the last 6+ years with no detectable effects on earth other other than the expected .1-2W/m2 response to the drop in TSI. The earth remains in a massive energy imbalance and the surface has continued to warm slowly consistent with GHG forcing + dampening from a drop in TSI. This is decisive proof against the various nonsensical solar hypotheses out there.

And correction to what I said earlier: GHGs did not overwhel aerosols alone 1910-1945.. the combination of TSI, GHGs, and low volcanic activity did, with perhaps some slight contribution from ocean cycles.

The other thing to remember about the -PDO is that although it causes more frequent Ninas and Ninas cause cooling, -PDOs also have a huge area of +SSTAs in the north Pacific. So although there are more Ninas, there may be a background warming overall due to the expanse of +SSTAs and the two effects may offset each other for a near zero sum effect.

On the one hand, ocean cycle obsessers insist that the expanse of +SSTAs in the Atlantic during a +AMO must cause global warming, but deny the fact that during -PDOs the expanse of +SSTAs is much larger than the expanse of -SSTAs in the north Pacific, and that this would also cause a background waming which is perhaps neutralized by the increased frequencies of Ninas in the tropical Pacific.

I think it's important to be careful when comparing +0.5C anomaly with waters that are very warm and allow for more latent heat release than cold north pacific waters with 0.5C anomaly.

[skierinvermont]

I think it's important to be careful when comparing. +0.5C anomaly with waters that are very warm and allow for more latent heat release than cold north pacific waters with 0.5C anomaly.

I'm pretty sure there is almost no difference in the increase in outgoing longwave radiation.

The emissivity of an object is proportional to the 4th power of its thermodynamic temperature. If you increase the temperature from 300 to 300.5K or 310K to 310.5K the effects would be nearly the same.

[CoastalWx]

I'm pretty sure there is almost no difference in the increase in outgoing longwave radiation.

The emissivity of an object is proportional to the 4th power of its thermodynamic temperature. If you increase the temperature from 300 to 300.5K or 310K to 310.5K the effects would be nearly the same.

I'm talking more of the heat budget and the release of latent heat. The whole reason why we tend to be warmer in Ninos.

[skierinvermont]

I'm talking more of the heat budget and the release of latent heat. The whole reason why we tend to be warmer in Ninos.

Yes that's what I'm saying.. the release of heat would increase by very nearly the same amount. The main reason warm SSTs warm the atmosphere is radiation which is proportional to the 4th power of the thermodynamic temperature. Evaporation is a much smaller factor. I'm guessing evaporation does increase exponentially with temperature and a .5C increase in warm water would have a much bigger effect than a .5C increase in cold water. But overall, evaporation is not that big a player. Think of Trenberth's energy budget.

Surface radiation on earth is 396W/m2... evapotranspiration is a mere 80W/m2.

Surface radiation would increase proportional to temperature^4th. Thus raising temperature in cold or warm water by .5C has nearly the same effect.

[csnavywx]

The PDO is used as a proxy for ENSO...it is a product of ENSO and its residual effects...if you take the raw ENSO numbers (and I don't mean anomalies), they show the same significant drop and then subsequent rise. This is a cop-out explanation that the PDO doesn't matter.

It's a response to several different factors, including ENSO via the atmospheric bridge, so called "red noise" and Rossby wave propagation.

Taking raw ENSO numbers doesn't escape the problem listed in the previous post, so I hardly see why that's a "cop out". That data assumes no differential heating and spatially uniform forcing across the entire ENSO region, which is quite large. This is unlikely to be the case. In addition, well... this argument has been made and some work on it has already been done, so let me link to it:

Atmoz blog argument from 2008 (uses PC analysis on the PDO region and the global ocean)

Investigating the possibility of a human component in various pacific decadal oscillation indices

(Peer-reviewed paper)

Blaming the Pacific Decadal Oscillation (Skeptical Science post)

[tacoman25]

I said in combination with solar TSI which ramped up from record lows to record highs in the period. Also a lack of volcanic activity after experiencing major volcanic activity near the turn of the century.

As I've said a dozen times already, radiative forcing over the 20th century matches very closely to observed temperature without including ocean cycles or GCR fairies. I'm not saying ocean cycles had no effect, but whatever effect is likely quite small. It can probably help explain the slight overshot of observed temperatures in the 1940s compared to radiative forcing.

You can keep repeating this mantra over and over, but you have failed to address several key points made by myself and others in this thread.

1) ENSO exhibits the clearest and most consistent influence on global temps. This is well documented.

2) ENSO trends are closely tied to PDO phases. -PDO phases tend to bring about twice as many -ENSO events as +PDO phases.

3) The timing of PDO phase changes matches almost perfectly with abrupt changes in global temp trends. This match is much better than the correlation with aerosols.

4) The coldest decade globally during the past 60+ years just happened to occur during the overlap of -PDO and -AMO phases, as global SSTA dropped to their coldest levels. But this must just be coincidence!

[tacoman25]

Your total forcing is using an assumption for the forcing of human aerosols. It fits decently when you do that, but we don't know for a fact what the actual forcing is. Various models have various levels of forcing to try and simulate 20th century temperatures.

The PDO isn't that hard to calculate for the temporary temperature change. The average change in ENSO is about 0.5C to 0.6C on a multi-decadal scale. That is going to cause significant warming or cooling. I don't have the exact numbers off hand, but that type of change in average ENSO is not going to be insignificant to temperatures. The PDO is just a product of ENSO. In addition to the PDO, there was an internal rapid cooling of the Atlantic in the late 1960s and the Pacific temps also accelerated their fall a bit during this time...just not to the extent of the Atlantic.

The sudden drops SSTs in the late 1940s and the sudden rise in the late 1970s is much better explained by internal cycles like the PDO rather than a piece meal of other factors that change on a slower scale than the change in SSTs occured. I'm sure those other factors played a role. I don't buy it was the dominant role though when we are talking about multi-decadal variability.

Exactly! There is a much greater uncertainty about the forcing effect of aerosols than there is about ENSO and global SSTA effecting temps, a point that skiier is unwilling to honestly address.

[tacoman25]

The other thing to remember about the -PDO is that although it causes more frequent Ninas and Ninas cause cooling, -PDOs also have a huge area of +SSTAs in the north Pacific. So although there are more Ninas, there may be a background warming overall due to the expanse of +SSTAs and the two effects may offset each other for a near zero sum effect.

On the one hand, ocean cycle obsessers insist that the expanse of +SSTAs in the Atlantic during a +AMO must cause global warming, but deny the fact that during -PDOs the expanse of +SSTAs is much larger than the expanse of -SSTAs in the north Pacific, and that this would also cause a background waming which is perhaps neutralized by the increased frequencies of Ninas in the tropical Pacific. The causative mechanism is on very shaky grounds and can give us no idea of magnitude. Whereas the causative mechanisms for GHGs, aerosols, TSI etc. are well established and can give us reasonable estimates of the magnitude of the effect.

Except that -ENSO events are almost always with -PDO, and global temperatures always respond in a downward direction. So clearly the warm waters in the North Pacific associated with the -PDO do not offset the effect of the colder waters in equatorial regions.

You like labeling people "ocean cycle obsessers"? How about "natural variability deniers"? That's a fun one too!

[skierinvermont]

Exactly! There is a much greater uncertainty about the forcing effect of aerosols than there is about ENSO and global SSTA effecting temps, a point that skiier is unwilling to honestly address.

False. I have used the published 95% confidence interval for aerosol forcing (-.6 to -2.4W/m2, best guess -1.2W/m2). There are no published confidence interval estimates for the effect of ocean cycles on surface temperature because there is too much uncertainty to even know where to begin.

[skierinvermont]

Except that -ENSO events are almost always with -PDO, and global temperatures always respond in a downward direction. So clearly the warm waters in the North Pacific associated with the -PDO do not offset the effect of the colder waters in equatorial regions.

You like labeling people "ocean cycle obsessers"? How about "natural variability deniers"? That's a fun one too!

So the huge area of +SSTAs during AMOs causes warming, but the huge area of +SSTAs in -PDOs doesn't. Gotcha. It's like magic! Except stupider and more hypocrtical.

Obviously the earth is colder during La Ninas. But perhaps the huge area of +SSTAs in the north pacific raises the general background temperature during a -PDO. This warmer background temperature is then more frequently punctuated by cooling from the tropical pacific. The net effect would be close to a wash. Since almost all of the multi-decadal variability is explained by the combination of TSI, aerosols, GHGs, and volcanoes, don't point to the loose correlation between the PDO and global T to prove causation.

[tacoman25]

False. I have used the published 95% confidence interval for aerosol forcing (-.6 to -2.4W/m2, best guess -1.2W/m2). There are no published confidence interval estimates for the effect of ocean cycles on surface temperature because there is too much uncertainty to even know where to begin.

Yes, you have demonstrated the great uncertainty that exists for aerosol forcing, but you have failed to address the fact that this is a much greater uncertainty than ENSO forcing. ENSO forcing is directly related to the PDO cycles as has been reiterated to you over and over, and the correlation between ENSO and global temps is very clear.

If there is so much uncertainty, then how is it possible to remove ENSO from temp trends to show the underlying AGW trend? The fact is, there is much more uncertainty with aerosols, and the records we have for ocean cycle variation are much more complete.

[skierinvermont]

Yes, you have demonstrated the great uncertainty that exists for aerosol forcing, but you have failed to address the fact that this is a much greater uncertainty than ENSO forcing. ENSO forcing is directly related to the PDO cycles as has been reiterated to you over and over, and the correlation between ENSO and global temps is very clear.

If there is so much uncertainty, then how is it possible to remove ENSO from temp trends to show the underlying AGW trend? The fact is, there is much more uncertainty with aerosols, and the records we have for ocean cycle variation are much more complete.

The effect of ENSO on short-term global temperature is very clear. However, the effect of the PDO, for example, the large expanse of +SSTAs in the north Pacific, is not as clear.

You are intentionally ignoring the contradiction between your claims that large areas of +SSTAs in a +AMO cause warming and your the denial that the even larger expanse of +SSTAs during a -PDO must also cause even more warming.

Also, even your suggested methodology, taking the correlation between the PDO and ENSO and then ENSO and global temperature to figure out the effect of the PDO on global temperature, the calculated effect is only .04C. ENSO is .4C higher in +PDO than -PDO. Every .4C of ENSO has an effect of .04C on global temperature, according to the correlations.

This still ignores the large expanse of +SSTAs, which according to your past statements, must cause warming.

The .26C of cooling from aerosols 1945-1975 is easily larger than the .04C cooling from the more frequent ENSOs, which still ignores the large expanse of +SSTAs in the north pacific.

[tacoman25]

Obviously the earth is colder during La Ninas. But perhaps the huge area of +SSTAs in the north pacific raises the general background temperature during a -PDO. This warmer background temperature is then more frequently punctuated by cooling from the tropical pacific. The net effect would be close to a wash. Since almost all of the multi-decadal variability is explained by the combination of TSI, aerosols, GHGs, and volcanoes, don't point to the loose correlation between the PDO and global T to prove causation.

This is all speculation by you that is not backed up at all by actual facts. If the net effect was a wash, then -PDO Ninas would not see the global temperature drop. But it does, regardless of how strong the -PDO area in the North Pacific is. So are you suggesting that somehow the SSTAs in the North Pacific have a mysterious delayed effect on global temperatures, and only the -ENSO equatorial SSTAs have an immediate and measurable effect?

[tacoman25]

The effect of ENSO on short-term global temperature is very clear. However, the effect of the PDO, for example, the large expanse of +SSTAs in the north Pacific, is not as clear.

You are intentionally ignoring the contradiction between your claims that large areas of +SSTAs in a +AMO cause warming and your the denial that the even larger expanse of +SSTAs during a -PDO must also cause even more warming.

1. The AMO and PDO are separate entities. The tie between the PDO phases (ENSO) and global temps is much clearer than the AMO (which from the evidence I've seen mainly has a warmer effect on higher latitudes in the NH, and that is probably mainly due to shifts in ocean currents). We do not see an ENSO-like modulation in the Atlantic, or at least nothing of that magnitude.

2. The PDO phase is directly tied to ENSO. During -PDO phases, not only is the -PDO signal stronger overall, but -ENSO events tend to be stronger and more frequent. There is no great mystery to how this would affect global temp trends, since we can clearly see the combined affects of PDO/ENSO together on global temps through every ENSO event that occurs.

[skierinvermont]

This is all speculation by you that is not backed up at all by actual facts. If the net effect was a wash, then -PDO Ninas would not see the global temperature drop. But it does, regardless of how strong the -PDO area in the North Pacific is. So are you suggesting that somehow the SSTAs in the North Pacific have a mysterious delayed effect on global temperatures, and only the -ENSO equatorial SSTAs have an immediate and measurable effect?

-PDOs saw global temperature drop largely because it coincides with a rapid increase in aerosols.

And I am not inventing some mysterious mechanism by which large expanses of +SSTAs cause warming. I am merely relying on your previous statements about the AMO. This warming would necessarily cancel some, all or overwhelm the cooling from more frequent Ninas (which even on their own only have a -.04C cooling effect). The signal would be impossible to detect because there are too many other variables at play (TSI, aerosols, GHGs, volcanoes).

This whole discussion began because I pointed out that the loose correlation between the PDO and global T is not necessarily causative. You then proposed a causative mechanism (-ENSO). I pointed out that you are ignoring the huge expanse of +SSTAs. To prove that the +SSTAs have no effect (contradicting your previous statements) you return to the original correlation that started the whole discussion.

Circular reasoning. You can't prove causation using a correlation which you don't know is causative.

[tacoman25]

And I am not inventing some mysterious mechanism by which large expanses of +SSTAs cause warming. I am merely relying on your previous statements about the AMO. This warming would necessarily cancel some, all or overwhelm the cooling from more frequent Ninas (which even on their own only have a -.04C cooling effect). The signal would be impossible to detect because there are too many other variables at play (TSI, aerosols, GHGs, volcanoes).

This whole discussion began because I pointed out that the loose correlation between the PDO and global T is not necessarily causative. You then proposed a causative mechanism (-ENSO). I pointed out that you are ignoring the huge expanse of +SSTAs. To prove that the +SSTAs have no effect (contradicting your previous statements) you return to the original correlation that started the whole discussion.

Circular reasoning. You can't prove causation using a correlation which you don't know is causative.

You did not address the problem with your speculation. You proposed that the +SSTA in the North Pacific could offset -SSTA in equatorial regions during a -ENSO/-PDO regime. However, there is no evidence that this is the case, based on the fact that every time we see -ENSO/-PDO events, the global temperature responds negatively.

Therefore, the physical basis for PDO/ENSO phases modulating global temperatures remains intact and the overall evidence for PDO/ENSO/global SST affecting global temp trends is easily stronger than for aerosols, which have a lot more uncertainty in their forcing effect and a weaker correlation to global temp trends.

[skierinvermont]

You did not address the problem with your speculation. You proposed that the +SSTA in the North Pacific could offset -SSTA in equatorial regions during a -ENSO/-PDO regime. However, there is no evidence that this is the case, based on the fact that every time we see -ENSO/-PDO events, the global temperature responds negatively.

Therefore, the physical basis for PDO/ENSO phases modulating global temperatures remains intact and the overall evidence for PDO/ENSO/global SST affecting global temp trends is easily stronger than for aerosols, which have a lot more uncertainty in their forcing effect and a weaker correlation to global temp trends.

Yes I did respond. To the bold: You have no evidence that the cooling during -PDO events (really just one sample 1945-1975) is causative. It could be mere coincidence, especially considering that most/all of that cooling is already explained on solid causative grounds by the combination of TSI, aerosols, GHGs, and volcanoes.

You are using circular reasoning. I asked how you know the loose correlation is causative. You hypothesize a causative mechanism. I question this causative mechanism. As proof of the causative mechanism you cite the loose correlation that I originally questioned. It's completely circular.

Finally, you have again ignored that even if we COMPLETELY IGNORE the huge expanse of +SSTAs in the north pacific, the increased -ENSO frequency would only have a cooling effect of -.04C.

Compare this effect of -.04C (ignoring the huge expanse of +SSTAs in the N. Pac) to the maximum confidence intervals of aerosol cooling during the period of -.13C to -.52C (best estimate -.26C).

[tacoman25]

Yes I did respond. To the bold: You have no evidence that the cooling during -PDO events (really just one sample 1945-1975) is causative. It could be mere coincidence, especially considering that most/all of that cooling is already explained on solid causative grounds by the combination of TSI, aerosols, GHGs, and volcanoes.

You are using circular reasoning. I asked how you know the loose correlation is causative. You hypothesize a causative mechanism. I question this causative mechanism. As proof of the causative mechanism you cite the loose correlation that I originally questioned. It's completely circular.

Finally, you have again ignored that even if we COMPLETELY IGNORE the huge expanse of +SSTAs in the north pacific, the increased -ENSO frequency would only have a cooling effect of -.04C.

Compare this effect of -.04C (ignoring the huge expanse of +SSTAs in the N. Pac) to the maximum confidence intervals of aerosol cooling during the period of -.13C to -.52C (best estimate -.26C).

No, you did not address the fact that your hypothesis about North Pacific -PDO SSTAs offsetting ENSO SSTAs is junk: the evidence clearly shows that this is not the case. When there is -PDO/-ENSO, it negatively effects global temperatures - and vice versa. If you can't even acknowledge that simple and obvious fact, there is no point in discussing this with you, because that is the entire basis of this discussion. The -PDO warm anomalies in the North Pacific DO NOT offset the -ENSO cool anomalies in the equatorial regions. If they did, we would not consistently see tempertures drop with -PDO/-ENSO events - but we do.

[skierinvermont]

No, you did not address the fact that your hypothesis about North Pacific -PDO SSTAs offsetting ENSO SSTAs is junk: the evidence clearly shows that this is not the case. When there is -PDO/-ENSO, it negatively effects global temperatures - and vice versa. If you can't even acknowledge that simple and obvious fact, there is no point in discussing this with you, because that is the entire basis of this discussion.

Yes it has happened to cool during the one -PDO we have good temperatures for. That could easily mostly or entirely be mere coincidence. It is not evidence of anything, especially the idea that a -PDO causes significant cooling globally. Especially considering there are fairly solid explanations for 20th century temperature already without including the PDO.

You are using circular reasoning.

Your idea that the number of babies born/year does not effect global temperature is junk. There is a clear correlation.