Email 536 An excerpt of email from David Thompson of Colorado State to Phil Jones:
…As for the dip in 1945. After iterating with John Kennedy, it appears that the dip in 1945 corresponds to a sudden drop in US measurements in Aug 1945 (the US measurements were known
to be biased warm, so the cooling is consistent with the loss of US data). But it is also now clear that the SST is fraught with many instrument changes between the 30s and 1961. So
a conclusion we’ll likely make is that the trend in SSTs between 1900 and the present is reliable, but the behavior of the time series from the 1930s to the 1960s is not.
That the data are so unreliable between the 30s and 60s means we don’t know for sure what happened in terms of global-mean temperatures during that period. In fact, if you blank out the data from the 30s to the 60s, you can actually imagine the globe warming weakly but continuously during that period…
Hence, the only real evidence we have of a midcentury about-turn in global warming comes from the land data.
Full email
date: Tue, 27 Nov 2007 10:48:58 +1100 from: David Thompson <davet@atmos.xxxxx> subject: a quick comment and a quick question to: Phil Jones <p.jones@uea.xxxx> Phil, The comment…. Thanks for the thoughts on the volcano plots. I’ve spent the last few days playing with different analyses, and I think I’m converging on the main points to make in the paper. It’s my impression that almost all aspects of the volcanic signal have been discussed in the literature, except for the longish timescale suggested by the residual data and the detrending. For sure the timescale is sensitive to the detrending, and I’ll be very careful about that in the writing. But I think using the residual data we can get folks chatting about the possibility that volcanoes impact SSTs much longer than the ~2-4 years suggested by the current literature. Anyway…. that’s how I’m leaning on the results. I should have some text ready soon… The question…. As for the dip in 1945. After iterating with John Kennedy, it appears that the dip in 1945 corresponds to a sudden drop in US measurements in Aug 1945 (the US measurements were known to be biased warm, so the cooling is consistent with the loss of US data). But it is also now clear that the SST is fraught with many instrument changes between the 30s and 1961. So a conclusion we’ll likely make is that the trend in SSTs between 1900 and the present is reliable, but the behavior of the time series from the 1930s to the 1960s is not. That the data are so unreliable between the 30s and 60s means we don’t know for sure what happened in terms of global-mean temperatures during that period. In fact, if you blank out the data from the 30s to the 60s, you can actually imagine the globe warming weakly but continuously during that period… Hence, the only real evidence we have of a midcentury about-turn in global warming comes from the land data. Are there any similar data issues in the land data during the period ~1939-1960? Thanks, Dave ——————————————————————– ——————————————————————– David W. J. Thompson www.atmos.colostate.edu/~davet Dept of Atmospheric Science Colorado State University Fort Collins, CO 80523 USA Phone: 970-xxx Fax: 970-xxx
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Well, you don’t need to go into people’s emails to find this out. It’s what Thompson and Jones and others said in their paper in Nature, 2008.
If instruments changed between the 1930s and 1960s, then how can they say that the 1900-present trend is reliable either? If instrumentation was different in 1900 than now, how can we directly compare measurements between then and now? It seems that changes in the middle of the time series messes up the entire thing on some level, not just one section in the middle.
Continuing recovery from LIA.
I have a problem with sea surface temperatures anyway. Sea surface temps are often a wind speed proxy. Show me a temperature anomaly and I will generally be able to show you a wind anomaly.
Nick Stokes,
You must be getting little sleep having to defend all these scoundrels around the clock.
@crosspatch
UHI may also be a wind speed proxy. See Hinkel, et al. 2003
It took me a few reads before I realised they ment “Global Mean Temperature” rather than “Greenwich Mean Time”.
Then I was reminded that daily “average” temperatures recorded on land are actually the mid point of the highest and lowest temperatures recorded in a “day”. Rather than the the arithmetic mean of all temperature observations recorded in a “day”. Attempting to derive any sort of “mean” from the former just dosn’t make much sense either mathematically or statistically. You might just as well take the midpoint of the highest and lowest temperatures recorded anywhere on the planet between 1st January 00:00:00 and 31st December 23:59:59 and call it something like the “Annual Global Average”. (For which it probably wouldn’t matter if you had sea surface figures at all.)
With the added complication that it could easily matter if “day” is defined according to geo-political time; ditto but without any DST; using a timezone determined by longitude only; using actual local time or some other method.
Something which gets somewhat more complex with the sea considering the International Date line crosses the Equator three times. In some places appears to follow a line of latitude. As well as having changed over the last century.
I wrote a major article on SST’s, delving into their history.
http://judithcurry.com/2011/06/27/unknown-and-uncertain-sea-surface-temperatures/
Since then I’ve had correspondance with the Met office about them. The Records are mostly complete nonsense before around 1961 and I wouldn’t place too much credence on the notion of a ‘global’ record for much of the period since either.
tonyb
@Nick Stokes
The difference is the paper does not use the word ‘unreliable’- their choice of words in private emails.
The Records are mostly complete nonsense before around 1961 and I wouldn’t place too much credence on the notion of a ‘global’ record for much of the period since either.
I’ll second that.
In addition increasing SSTs contain both a global warming signal and an ocean heat lose signal. the former showing climate warming and the latter climate cooling. Separating the two requires good ocean heat content data, which we have only since 2002. And to my knowledge no one has done this and published.
A global average temperature derived from accurate SSTs (which we don’t have) would be a poor measure of GHG warming at least on a decadal timescale.
Why do they persist with it, you ask?
There isn’t an alternative for the oceans and the many problems and instrument changes are an adjusters delight.
@Mark:
The method is not quite as insane as you make out.
It is true that a ‘proper’ mean involves a continuous integration of temperature with respect to time. However, it is quite difficult to actually do that – you have to use analog computers, with their inherent inaccuracies, or you have to use discrete, sampled data and approximate the integral using some method. The question then becomes, what is your sampling rate? Obviously, in the modern age, we would choose something quite fast compared to the rate at which temperature varies, perhaps on the order of once per minute, to give us a good approximation to the true integral.
But in the age when the only way of taking a measurement was for someone to go and look at a thermometer and write down the number, before anyone was worried about climate change, before anyone knew much about forecasting weather, we are very lucky that a significant number of people thought it was worthwhile to take two measurements per day, and that they are not just the temperature at 6AM and noon, but the actual minimum and maximum.
Given that temperature varies over 24 hours in a roughly sinusoidal shape, taking the mean of the minimum and maximum as an approximation to the true mean is not so bad. And when those happen to be the two data points that we have for a considerable portion of the temperature record, it is absolutely the right thing to do.
The only question I have left is why it is still necessary to explain this to people. Yes, it might be better to have minute-resolution temperature data to construct accurate approximations to real means, but the bone-headed, bleedin’ obvious fact is that we don’t have it.
North Atlantic has probably the best coverage and since 1910 it just goes 30 years up, 30 years down, 30 years up and now reverting down again. Interesting that the periods are pretty much linear with sudden breaks into different slope. Its variability is so pronounced that it overrides not too distinctive SH record and puts its shape into the “global” record.
All these SST plays by the Team were to remove the inconvenient 1945-1975 cooling and decreasing the “1940 blip”.
I agree with Nick Stokes. (How’d you like that, Nick? We agreed on something again.) This is one of the bases of Thompson et al (2008), and is one of the things the Hadley Centre attempted to correct with HADSST3.
The reliability of the data and the certainty of the findings appear to have been grossly overestimated here. By their own lights, these findings should be hung about with so many caveats that the caveats outweigh the report. Instead we get “settled” science.
Something is seriously wrong, and I no longer find it easy to believe that it was innocent self-delusion. Some of these guys at least were deliberately out to cook the books.
Verity Jones says: November 28, 2011 at 12:35 am
“The difference is the paper does not use the word ‘unreliable’- their choice of words in private emails.”
You have to give a bit more backing in a Nature paper. So they say, in their bolded introduction:
“We argue that the abrupt temperature drop of 0.3 °C in 1945 is the apparent result of uncorrected instrumental biases in the sea surface temperature record.”
Sounds unreliable to me.
Strikes me as more a case of trying to hide/underplay the decline in SSTs mid-century. There’s patchy (Patchi?) data elsewhere that warmists are happy to use to further The Cause, such as in the high Arctic, but in this case it’s an opportunity to dump a cooling period that isn’t passed up.
Bob Tisdale says:
November 28, 2011 at 2:12 am
I agree with Nick Stokes. (How’d you like that, Nick? We agreed on something again.) This is one of the bases of Thompson et al (2008), and is one of the things the Hadley Centre attempted to correct with HADSST3.
Hi Bob,
this ongoing post on my blog may interest you. Your input is very welcome.
http://tallbloke.wordpress.com/2011/11/07/station-change-over-time-and-ghcn-v2
The ICOADS vs HADsst3 comparisons further down the thread are relevant I think.
I’ve just plotted up the difference between hadSST3 and the original ICOADS data. It’s hard to imagine this being some careful correction for buckets and other sampling issues.
http://oi44.tinypic.com/1zee6ut.jpg
key features of this “correction”.
huge warming of the whole pre 1950 record. (remove pre CO2 warming)
reduction of 1910-1920 minimum (reduce extent of natural variations)
warming adjustment falls away during 1920-1960 by almost 0.5C (remove inconvenient early warming that was greater than late century trend)
deepen Krakatoa and Mt. Agung volcano impacts (justify increasing volcanic adj means more CO2 warming needed counter balance late 20th volcanoes )
Gentle late 20th boost to help AGW (can’t get away with much here, too many other datasets)
Ironically, the only bit that does not get modified (zero difference) is the war time period that showed the most blatantly obvious anomaly.
The profile of this “correction” is a blueprint of all you’d want to do to the SST data if your were trying to get rid of some inconvenient truths that were messing up your AGW hypothesis.
>>
In fact, if you blank out the data from the 30s to the 60s, you can actually imagine the globe warming weakly but continuously during that period…
Hence, the only real evidence we have of a midcentury about-turn in global warming comes from the land data.
>>
In fact , if you blank out the same period in the land data , we don’t have *any* evidence of a midcentury about-turn in global warming. Sorted.
Next all we have to do is blank out later warming period as well and we can shut down the IPCC, sack Jones and the others and get on with our lives.
It may need some work on the wording but I think Thompson’s approach has a lot merit.
As a former collector of sea-surface temperatures, I am a little bit curious as to how this information is collected now; met. ships are probably now in very short supply, so is this data from satellite observation? If so, has there been adequate correlation with locally-collected data to verify the accuracy of these satellites?
So our Phil would like to revisit volcano adjustments. Probably a good idea, they maybe need reassessing too since they are build on simplistic approximations of how much ash gets ejected high enough into the atmosphere and what affect is has when it gets there. Has this ever been measured rather than modelled?
http://oi44.tinypic.com/16k1iiu.jpg
What can we note?
One thing I have not seen covered in the literature is that the winter following a major eruption seems to be *warmer* than the detrended average. This is logical if compared to night-time cloud. Perhaps more money is needed to study this issue. 😉
In fact despite the magnitude of Mt Agung it seems to have cause a good year of warming before the later cooling. That probably explains why this period got some extra special care in the hadSST3 corrections. The temperature record must be wrong, it does fit our model.
El Chichon is a bit tricky as well . It also seems to have caused a fair amount of warming, apart from the initial glitch that was no bigger than the short term noise in the period preceding the eruption.
Mt Pinatubo caused two warm winters that were about same as average before and after. When I say “winter” it looks like more than 6 months of each of those years was not cooled by the eruption at all. Is that part of the model.
Yes , I think this area probably needs some further adjustment. But when you look closely it may not be in the direction you were hoping for Phil. But then you’re an honest scientist aren’t you? You are surely going to publish whatever you find. This could be a significant contribution to climate science.
Land surface vs Sea Surface
Even with proper instrumentation and measurement ->
Land temperature and Sea temperature data are different animals.
The Sea measurements are dipped from the liquid, hence they represent the true ‘surface’ – not the air above the surface.
The Land measurements are made in AIR at one to two meters above the actual surface.
Why would that matter? For an energy balance or heat transfer calculation, the temperature of the actual surface (liquid or solid) is the start of the energy path out to space. The air above the surface could be either warmed or cooled by the surface below, but on a sunny day, the surface is likely warmer than the air and hence heating the air above. The air temp is not the same as the land surface temp.
At the point Land temperature readings are taken, the energy is already on the path out toward space. Air measurements one to two meters above the surface already reflect the combined convection and radiant energy transfer from surface to air. Sea measurements are the ‘surface’ itself (albeit affected by evaporation, circulation, currents etc). One should expect an ‘offset’ between land and sea measurements even with perfect data. I believe there are papers on this (Christy? Spencer?) although I don’t have a reference close to hand as I write this.
cheers, D in De
In the past, before the installation of satellite dependent weather reporting buoys, most open-ocean marine temperature data came from measurements made by ships in transit. It is my understanding that these catch-as-catch-can measurements were disrupted during World War II by changed shipping patterns. Data collected by ships in convoy would not be as extensive as measurements made by the same vessels travelling alone in peacetime. Atlantic traffic was probably diverted to the more northerly routes during the war where shore-based air cover was more likely.
Yes, it might be better to have minute-resolution temperature data to construct accurate approximations to real means, but the bone-headed, bleedin’ obvious fact is that we don’t have it.
We have fixed time temperature measurements from as far back as 1900. We have large numbers of fixed time measurements from the 1960s onwards,many stations with hourly data.
The reason they aren’t used is they show substantially less warming in the average than the min max average. Minute by minute data is a red herring.
Just a quick thought on the subject of volcano after effects. Look again at the periods following major eruptions.
http://oi44.tinypic.com/16k1iiu.jpg
About 5-6 years after each of these events there was a net warming. Could it be that climate, being intrinsically stable actually manages to compensate for the cooling effect (by adjusting cloud cover or whatever mechanism) ?
6y after El Cnichon there was a warming peak, 6y after Mt Pintubo there was the strongest El Nino in recent history (was this extra strength volcanic rebound?) , 6y after Mt Agung there was a warming peak.
Far from positive feedback and tipping points this suggests a substantial negative feedback.
This is just speculation , an hypothesis, more money is needed for further research. 😉
At least there is some empirical evidence that merits further study.
Hansen’s volcanic forcings are generally reckoned to be over stated. But since this is all pure modelling and supposition maybe this effect needs to be investigated. After all “volcanic correction” is a major player in upping the actual scientifically calculated CO2 forcing and a significant part of what underlies the positive climate feedback conjecture.