'As for the suggestion that the globe is showing a 'robust' upward temperature trend, I find that laughable.'

I like this article which appeared on Skeptical Science on 01/05/12:

http://www.skepticalscience.com/john-nielsen-gammon-commentson-on-continued-global-warming.html 

Within the article is a chart showing trendlines of global temperatures for the 44 years starting in 1967. Individual years are categorised into three groups according to whether the average ENSO condition over 12 months was El Nino, neutral, or La Nina. The upward linear trend is similar for each group.

I would also mention research by Foster & Rahmstorf [2011] which concluded that there has been no recent slowdown or acceleration of global warming when short term noise [ENSO, volcanic eruptions] and solar variations [which are small] are removed from the signal.

I'm puzzled by this post, SC.   John makes it clear that there has been no slowdown (or acceleration) in global wamring when short term noise is excluded, yet you feel it appropriate to restate that temperatures have remained static for the past 15 years.

That ignores, of course, the deeply flawed logic (or attempted deception, depending on your motive) of using 1997/98 as your baseline.  You must have seen my repeated flagging of this point whenever Stephen tries the same trick.

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-11-00640.1?af=R 

There might be room for differences about how the stabilisation was achieved but not as regards the stabilisation itself.

If one says that the stabilisation was achieved by La Ninas then it follows that the earlier warming was caused by El Ninos.

That begs the question as to why the late 20th century El Ninos were so strong.

The best explanation is reduced global cloudiness caused by more zonal jets allowing more sunlight into the oceans.

The problem for AGW theory is that the positive water vapour feedback is supposed to result in more clouds but that didn't happen.

A strongly negative temperature fedback arises from an El-Nino (warm ocean surface anomaly. you really need to read the paper carefully.

Then a strongly negative feedback arises from AGW warming too does it not ?

Both El NIno and CO2 add energy to the air and the system response is the same in both cases (a shift in the global air circulation) but the effect of human emissions of CO2 is infinitesimal compared to the effect of an El Nino.

So what shift in air circulation would you expect from a doubling of CO2 as compared to the solar induced oceanic effect between MWP and LIA or LIA and today ?

John,

Have you noticed that you just accepted that the system response to warming of the air from El Nino events and warming in the air from more CO2 would be the same.

That is, negative.

Yet AGW theory relies upon a positive feedback from more CO2

If we applied the supposed positive feedback of CO2 to El Nino events then the increased water vapour in the air from the El Nino warmth (a GHG after all) would give even more water vapour in the air in an ever increasing feedback loop until a single El Nino event causes catastrophic consequences.

Doesn't happen though does it ?

What is supposed to be so different with regard to the warming of the air by CO2 ?

El-Ninos last a few months to a year the water vapour feedback taskes decades as does CO2 induced warming as we see in the data. The transient response to ENSO is very different to the change in forcing produced by changing atmospheric composition or solar output. That was the big mistake Lindzen made in his Earth Iris paper.

The relative strengths of El Nino and La Nina change over that 1000 year cycle from MWP to LIA to date so we need to compare the scale of that process to the scale of any effect from human emissions.Over 500 years of increasingly strong El Nino events there would be plenty of time for a positive water vapour response to show up but it never did.

Focusing on individual ENSO events is misleading.

The system response to warming of the air by El Nino is negative and not positive at all timescales. There was no visible increase in global humidity during the late 20th century warming, in fact it seems to have reduced.

The response to AGW warming is just the same.

How far do you think the jets and climate zones shift as a result of more human emissions compared to the solar / ocean induced shifts over that 1000 year cycle ?

Not long ago ALL the shifting was being put down to AGW. That proposition is now obviously a dead duck.

All?  Do you have evidence for that assertion?

How so?  What evidence do you have?

Further ENSO events have no long term impact on global temperature they are just internal variability when an El-Nino or La-Nina ends the temperature returns to its pre-existing value in a few months.

On the subject of atmospheric water vapour it has increased (Stephen is confusing water vapour content and relative humidity)

eg

http://www.pnas.org/content/104/39/15248.abstract

Data from the satellite-based Special Sensor Microwave Imager (SSM/I) show that the total atmospheric moisture content over oceans has increased by 0.41 kg/m2 per decade since 1988. Results from current climate models indicate that water vapor increases of this magnitude cannot be explained by climate noise alone. In a formal detection and attribution analysis using the pooled results from 22 different climate models, the simulated “fingerprint” pattern of anthropogenically caused changes in water vapor is identifiable with high statistical confidence in the SSM/I data. Experiments in which forcing factors are varied individually suggest that this fingerprint “match” is primarily due to human-caused increases in greenhouse gases and not to solar forcing or recovery from the eruption of Mount Pinatubo. Our findings provide preliminary evidence of an emerging anthropogenic signal in the moisture content of earth's atmosphere.

Focus on the longer term. Individual ENSO events are simply imposed on the longer term 1000 year cycle from MWP to LIA to date.

Over that period the relative strengths of El Nino and La Nina gradually shift under the effect of solar changes.

That is why one sees upward stepping from one PDO phase to the next when there is a background wasrming trend such as the recovery from the LIA.

Gsandalf asks:

"How so? What evidence do you have?"

CO2 continues to rise but the jets are no longer shifting poleward as evidenced by the current widely acepted change to greater jetstream meridionality.

http://www.stuff.co.nz/science/7400061/Global-warming-science-tackled 

"The theory assumes no other major influence on temperature changed, so the effect of the CO2 must have been amplified threefold, presumably by changes in the atmosphere due to humidity and clouds.

There is no observational evidence for this amplification, but it is nonetheless built into all the models. Sceptics point out that if the extra humidity simply forms extra clouds, then there would be no amplification

"

Clouds have been increasing since around 2000.

There is direct evidence for it from increasing water vapour as I have linked above. You need to post evidence for increasing cloudiness since 2000. The sign of the cloud feedback is very sensitive to the type of cloud that increases. Remember , however, there is direct observed evidence for the increase in water vapour and the positive water vapour feedback. Still I am gald you now conceed , as does the article you link that doubling CO2 causes  a 1C warming alone. As the article says serious sceptics do indeed accept this point.

An increase in high and medium level cloud would cause enhanced warming.