<a href="https://docs.google.com/viewer?a=v&q=cache:aFTVOZy5_MAJ:journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-11-00003.1+&hl=en&gl=us&pid=bl&srcid=ADGEESjpyKM8oeByWvliNhqN_h1AIXF2PcbKuOkRuOMq0wIYmSV-Z6xn26rvKVvp_lTqqeRBlW4TAlmjSbCAlCyVZdea_S0zH8TfnCzHXRKLQozYtsbbqYGM0qDJfw3j-jja8yUmJI2k&sig=AHIEtbSWD5j3cLkMp_Hly_SK_e2AaW9Wpw" rel="nofollow">Journal of Climate, Feb 2012, Surface Water Vapour & Temperature Trends, (Isaac & van Vijngaarden, York University, Toronto)</a>
Conclusion: <blockquote>A reduction in relative humidity can occur even though water vapor pressure is increasing if temperature is warming sufficiently. Hence, decreases in relative humidity occur at stations experiencing the largest temperature increases in winter and spring as shown in Fig. 7. The strong correlation between increasing temperature and decreasing relative humidity trends agrees with that found by Vincent (Vincent et al; 2007)</blockquote>
Oooooops, so tell me again, how many GCMs have physics which match with the <b>observed reduction in relative humidity</b> with rise temperature and the consequent negative water vapour feedback?
Comment on Trends, change points & hypotheses by Gras Albert
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Comment on Trends, change points & hypotheses by Herman Alexander Pope
The arctic is open, the snows have started and temperature is at or near the peak. Earth is about as warm as it usually gets in a modern warm period.
http://popesclimatetheory.com/page27.html
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Comment on Consensus or not (?) by cwon14
It’s always progress when Dr. Curry makes it to Climate Depot;
Who, what and why there are sausage makers should be clarified but it is progress.
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Comment on Trends, change points & hypotheses by Herman Alexander Pope
You cannot change a person’s mind by just telling them something one time. You must tell them more than once and point them toward data that supports your position. This still don’t work if they don’t read and think.
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Comment on Consensus or not (?) by cwon14
The list of right-wing extremists involved in a “Big Oil” conspiracy at the bottom of the page?
Just kidding.
A tawdry tale indeed.
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Comment on Trends, change points & hypotheses by pokerguy
“By what % would blog comments decrease if everyone was restricted to not repeating conversations?”
Hah! And yet one might as well ask, by what percent would *all* human conversation decrease if no repetition were allowed?
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Comment on Trends, change points & hypotheses by Anteros
Paul S [8th@8.26am] -
Fair point.
I can’t argue with that so I’d better take it on the chin.
Thanks for the clarification.
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Comment on Trends, change points & hypotheses by ceteris non paribus
I think this linear vs. nonlinear change distinction is perhaps a false dilemma.
It’s rather like the theory of ‘punctuated equilibria’ in evolutionary biology. The fossil record shows periods of relative stasis punctuated by periods of relatively rapid change. Some have taken this fact to undermine the theory of natural selection. But it is all a question of scale. When you look closely at the periods of rapid change, they too are commensurate with natural selection. The theory relies upon ordinary speciation, and thus the morphology proposed is a form of evolutionary gradualism, in spite of the name.
Do we need a new non-linear paradigm of the climate?
I don’t know the answer to that question, but I am curious as to what such a paradigm would even look like.
For example – How could the climate paradigm change without a fundamental change in our understanding of the relevant physics? That won’t happen just because we ‘decide’ to adopt a new paradigm – It would require convincing evidence that our current physical theories are false. There is a huge difference between false and uncertain.
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Comment on Trends, change points & hypotheses by billc
dude I don’t think the observed reduction in relative humidity with rising temperature implies a negative water vapor feedback, just a less strongly positive water vapor feedback than has been otherwise postulated.
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Comment on Trends, change points & hypotheses by billc
i still keep thinking the place to start is explaining how it might affect the cloud response. the absolute magnitude of that is so large. maybe i should keep on banging this drum. i’m sure CH think’s he’s answered it but us dummies can’t figure out what he’s really saying.
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Comment on Trends, change points & hypotheses by manacker
Chris
Breaking the record into the apparent 30-year cycles (as Girma has done) there is the 30-year warming cycle from ~1911 to ~1940 (which was “statistically indistinguishable” from the latest 30-year warming cycle from ~1971 to ~2000, according to Phil Jones), followed by the 30-year cycle of slight cooling from ~1941 to ~1970 (which occurred despite the fact that CO2 emissions were beginning to accelerate as a result of the post-WWII boom years).
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1941/to:1970/plot/hadcrut3vgl/from:1941/to:1970/trend/plot/hadcrut3vgl/from:1911/to:1940/plot/hadcrut3vgl/from:1911/to:1940/trend/plot/hadcrut3vgl/from:1971/to:2000/plot/hadcrut3vgl/from:1971/to:2000/trend/plot/hadcrut3vgl/from:2001/to:2011/plot/hadcrut3vgl/from:2001/to:2011/trend
The warming/cooling cycles are underlaid by a slight warming trend of around 0.5 to 0.6°C per century, like a sine curve on a tilted axis.
It is quite apparent that these cycles, as well as the latest 11 years (starting in 2001 (which again shows slight cooling), bear little correlation with the steadily increasing CO2 levels.
This is Girma’s point, and it is pretty hard to invalidate based on empirical evidence, as you will have to admit.
One can deny that the cycles exist, but that would simply be sticking ones head in the sand in denial.
The unanswered question remains: will the current trend of slight cooling continue for another 19 years or so to become another 30-year cooling cycle, or will it reverse to a new warming cycle?
No one knows the answer to that question.
Certainly not the scientists and climate models cited in IPCC AR4, who had projected that it would warm by 0.2°C per decade instead of cooling slightly, as it actually did.
The second question (also unanswered) is: what has caused these observed ~30-year warming and cooling cycles?
And finally, the third question could be: what has caused the underlying long-term warming trend of around 0.6°C per century?
Max
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Comment on Trends, change points & hypotheses by manacker
R. Gates
Wisely stated Just think how much more we will all know in 10 years…and then again in 20 about the relative strength of solar and anthropogenic forcing
This is precisely the point I was trying to make to Chris.
We simply DO NOT KNOW whether it will continue to cool slightly as it has over the past 11 years, or start warming again.
We don’t even know WHY it has warmed and cooled slightly in roughly 30-year half-cycles over the long-term record.
We think we know (but aren’t sure) why there was an underlying warming trend of around 0.6 degC per century – but IF it continues to cool slightly over the next several years despite ever-increasing CO2 levels, we will have to revise our theory on that, as well.
Yes. It is an exciting time for climate science – actually much more so than the much-ballyhooed IPCC late 20th century “poster period”, because we will get a real-life test of the CAGW hypothesis and assumptions, which are principally based upon that period.
Max
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Comment on Trends, change points & hypotheses by Chris Ho-Stuart
Manaker, my reply was basically that we are not limited to observations of temperature. It’s physics which leads us to think that this isn’t just cycles.
Looking at nothing at all but the temperature trends, without any consideration of what is actually causing them, would remove entirely my whole basis for expecting the 30 year trend to remain comparatively strong warming.
I know Girma’s point was that the temperature data doesn’t (by itself) give strong evidence for a persistent ongoing trend. I agree that we need more. I think we HAVE more, and said so. I know we have have more, because it’s really the physics which is more my particular interest than statistics on trends.
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Comment on Trends, change points & hypotheses by Tonyb
R gates
Your visits here are all too infrequent, guess you’re still trying to convert them all over at wuwt 
You say no continued increase in temperatures over the last decade. This is a refreshing admission from someone primarily on the agw side.
We have had people coming up with all sorts of graphs to prove temperature is increasing, decreasing, or static.
No snark here, but which graph would you cite that has a degree of authority, i.e one not manufactured on wood for trees using dubious end points and data.
Tonyb
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Comment on Trends, change points & hypotheses by steven mosher
at .15C you become a lukewarmer.
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Comment on Trends, change points & hypotheses by Steve Milesworthy
Attention has been drawn by Judith to three “features” of the temperature record without any formal assessment of whether the features are real or are just a figment of the mind being drawn to two cherries – one at around 1910 and another at around 1940.
These features are being attributed to some sort of non-specific “regime change” that forces climate into a different state.
But two of the features are accentuated only by two short-term periods of what could be “high frequency ‘noise’” which is apparently explainable by “Hypothesis I” – i.e. a short term period when some of the “natural” cooling or warming influences converge.
If you look at datasets with different coverage (eg. Land only, northern or southern hemisphere only, US only) then these “features” look very different suggesting that they would be sensitive to changes in coverage of the datasets.
None of this, though, takes anything away from ongoing warming driven by ongoing increases in forcing as Hypothesis 3 is only concerned with shifts away from the longer term forced trend. It doesn’t displace “AGW theory”.
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Comment on Trends, change points & hypotheses by manacker
Just a remark to the article by Jonathan Leake.
If one picks 1998 as the "start date" for the current cycle of "lack of warming", one arrives at an essentially flat trend (Met Office tells us: <em>“Our records for the past 15 years suggest the world has warmed by about 0.051C over that period” </em>).
If one takes only the past 10 years (2002-2011) one arrives at a more significant <em>cooling</em> rate of 0.1C per decade.
There are good arguments for NOT starting in 1998 (a record high, strong El Nino year).
Starting in 2002 (or 2001) gives a more pronounced trend, but only over a shorter time period.
Cherry-picking?
Max
PS The fact of the matter is it is <em>cooling</em> slightly, as it did from around 1941 to around 1970 (not <em>warming</em> imperceptibly, as Met Office would have us believe).
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Comment on Letter to the dragon slayers by Doug Cotton
EM radiation has a frequency of course. Wien’s Displacement Law links an emitting temperature to peak frequency. In that sense frequency indicates temperature of the emitting source, assuming it is spontaneous emission, not electrically generated emission such as radio broadcast waves etc. If you had read Johnson’s note then you would have understood what I was talking about.
Whether you choose to believe him or not, Claes is correct in saying that spontaneously emitted (blackbody) radiation will not be converted to thermal energy when it meets a surface which is (significantly) warmer than the source of the radiation.
You cannot refer me to any experiment which proves the contrary for spontaneous emission, now can you? I am not interested in the “politics” – only in empirical evidence – which cannot be forthcoming because it cannot happen. Backradiation does not add thermal energy to the surface.
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Comment on Trends, change points & hypotheses by Edim
1930 – 1980 (50 years) was ~flat.
http://www.woodfortrees.org/plot/hadcrut3vgl/plot/hadcrut3vgl/from:1930/to:1980/trend
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Comment on Trends, change points & hypotheses by Latimer Alder
@steve milesworthy
Talk me through the argument once again, please:
Problem:
We have two periods off apparent warming 1910-1940 and 1970-2000 They have about the same slope and are of about the same length. They are both pronounced enough to be considered a trend.
You then say that the first ‘could be attributed to short term periods of high frequency noise’, but are adamant that the second is due to some other cause (I guess CO2 emissions).
Maybe Occam’s Razor is no longer fashionable, but when you have two very similar phenomena occurring within the same system. isn’t it a wise idea to have as your starting point the idea that they are the same thing happening twice? (I fully accept that your investigation may in fact show them to be different, but such examples will be the exception rather than the rule).
Because it seems to me that to really demonstrate a proper understanding of climate you have to be able to explain both periods with exactly the same rigour and within a comprehensive theory.
You can’t really say …’We’ve done oodles of work on the recent stuff and have totally convinced ourselves that the only possible cause is CO2′ and then just dismiss the earlier period as ‘could be high frequency noise’. It will not take an Hercule Poirot to smell a rat and to conclude that your homework really hasn’t been done, nor your comprehensive (Its all down to CO2, stupid) theory submitted to any sort of real test.
So please explain once more how you come to two very different conclusions about the two periods in question. You may also recall that – as a one-time chemist – I just love to see experimental evidence rather than vague generalised hand-waving.
Thanks.
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