Guest essay by Tony Brown
Some readers might recall my recent article ‘The Long Slow Thaw?’
In this I reconstructed Central England temperature to 1538 from its current instrumental date of 1659.
I was surprised by two notable periods of warmth around 1630 and 1530. I am indebted amongst other material, to Phil Jones excellent book ‘Climate since 1500 AD’ plus such books as Le Roy Laduries’ Times of feast times of famine’ which confirm that these were indeed warm periods.
The graph below is from my article but to it has been added the official co2 levels. CET is seen by many scientists as a reasonable but by no means perfect proxy for Northern Hemisphere and Global temperatures.
Please note that the graphing package somewhat inflates the warmth in the decade around 1540, although my recent research- which will extend CET to 1498-demonstrates that the period 1500 to 1540 does indeed appear to be around as warm as the warm period in the recent CET period ending around the year 2000, characterised by the distinct hump.
Also from a graphing viewpoint it is debatable as to where the CO2 line should be placed. I chose to place it around the black trend line as the CO2 and temperature trend line probably needs to start together at the same place. This also provides clarity and context to the graphic although others might feel the CO2 line should be placed elsewhere.
However these are all nuances and the point I want to put over is that temperature is highly variable throughout the CET record -which is at variance to Dr Mann’s (global) work and the assertions of the Met office. This is despite a constant level of co2 until around 1900. The temperature decline since 2000 as the CO2 line rises ever further is especially intriguing.
Does it demonstrate that once you get to around the 300ppm level that the law of diminishing returns sets in as the logarithmic curve of CO2 versus temperatures takes effect? Does it illustrate nothing and the current downward CET slope is merely a blip that will increase sharply again as more CO2 is added?
The apparent effects of adding additional CO2 was clearly shown in an article by David Archibald several years ago,
http://wattsupwiththat.com/2010/03/08/the-logarithmic-effect-of-carbon-dioxide/
I merely present my research and findings for comment. An apparent decline perhaps as the logarithmic effect ceases to have any real world meaning? Or merely a hiatus in the ever upwards rise of temperatures since the start of the record in 1659 which may or may not be affected by CO2 and radiative physics?
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TonyB
Couple of questions:
1. Have you made any allowance for UHI in your reconstruction?
2. You’ve labelled the CO2 curve as Mauna Loa, but I thought that only started in 1958?
To a non-scientist, the information provided by the graph is simply ambiguous. I, having so little other knowledge on the subject matter to bring to bear, would not use it to try to persuade anyone of anything.
…. but, thanks very much for sharing your work, Mr. Brown. No doubt those more informed than I will find it helpful.
WOW — your work reconstructing CET is impressive in itself. Take a bow!
Diverse views are possible about CO2 and temperature being linked or not.
It seems imprudent to accept that pre-measurement levels of CO2 were globally steady at around the accepted 280 pm. Although fossil fuel use might not have varied much in the early part of the graphed period, wood was burned, so one might expect a correlation with human population. Also, at times there were vast animal populations elsewhere like bison on the American Plains, etc. OTOH, the nexus might be too small to be reconstructed.
The methodology of using Mauna Loa CO2, although it might correlate well with Cape Grim, the South Pole, etc, also worries me a little. I’d imagine many pockets of this high density gas at lower altitudes where the concentration might be an order of higher than ML, as in industrialised regions. Others can argue whether these pools of CO2 are candidates for postulated warming mechanisms, or whether the main action is at Top of Atmosphere.
David
The Met office makes a very small allowance since 1976 for UHI. This would not have been a factor in the 16th and 17th century in the central England area which was largely rural and had a very small population.
The co2 figures are from the mauna loa series from 1958. Prior to that it is the general estimate by Keeling and CDIAC that co2 was a constant 280ppm until the industrial revolution (generally considered to commence around 1750) which by 1900 had reached 300ppm and gradually increased to 315ppm by the time Keeling started his measurements
http://en.wikipedia.org/wiki/File:Mauna_Loa_Carbon_Dioxide-en.svg
I suspect the modern ‘hump’ has additional elements of UHI in it as the CET area has becme more urbanised and the stations that are used change.
tonyb
janice
You are right, it is ambigous. CET has dropped sharply in the last decade whilst co2 concentrations continues to rise. It may be that natural variability remains a more potent factor than co2.
However all through the record there is considerable variability despite constant levels of co2. I am hoping someone here has an explanation for this as my first thoughts are that the effects of increasing co2 -once you reach around 300ppm-appear to be limited. This flies in the face of radiative physics theory which is why I wa querying if the logarithmic effect of co2 is showing itself. The answer judging from the last thread also appears to be ambigous.
tonyb
To my mind,almost all of the graphs I have seen can be easily explained by the simple hypothesis that CO2 has no discernible effect on temperature whatsoever. I think this one is no different.
I’d like to see that hypothesis disproved, rather than so much effort trying to disprove the opposite (if that makes sense.
From davidmhoffer on May 8, 2013 at 3:55 pm:
Note how it’s chronically assumed the atmospheric CO₂ concentration is normally controlled by Nature, which prefers it completely unchanging and will self-regulate it to a fixed value for countless millenia. Thus the dead flat line until the purported Industrial Revolution start, around 1850, then there’s a flat continuous linear rise no matter what humans and the world were really doing, culminating with the Mauna Loa records with perfect blending while indicating how humans have suddenly completely screwed the planet with about 3x the CO₂ rise as before.
See how perfectly the three distinct records blend together? What more proof do you need that it’s all true?
Tony Brown,
Thank you for taking the time to respond to my low-information post. Just to remove any doubt as to where I stand on AGW:
1) the Pro-AGW Gang has the burden of proof to show human-emitted CO2 affects climate to any statistically significant degree;
2) they have not come up with even one piece of persuasive evidence; and
3) what evidence exists appears to me to indicate AGW conjecture is wrong.
I’m mostly just learning, here, so don’t waste your time with me. Thank you for honoring me with the reply above.
Janice
What it shows me is that there is essentially zero correlation between CO2 concentrations and temperatures. Temperature is all over the place when the CO2 concentration was essentially uniform for about 3 centuries and now that CO2 is rising rapidly temperatures spiked in the early phase of the increasing concentration then simply stopped rising as the concentration curve turns up. A stock analyst would look at those two plots and toss out the CO2 concentration as being meaningless for predicting the temperature.
” temperature is highly variable throughout the CET record -which is at variance to Dr Mann’s (global) work”
No, it isn’t at variance to Dr Mann’s work. His is a global average, yours is a single location. Global averages are always less variable.
Nick
Thats why I made sure to insert the word ‘global.’ As you well know a variety of scientists believe CET has a global reasonance, or at least some correlation with the Northern Hemisphere which is more akin to Dr Manns reconstruction. As you also know CET is a good match to BEST ‘global’
Have you any comments as to the considerable variability of temperature over the last few hundred years at a constant level of co2, the recent decade long drop in temperatures we can observe , or indeed the centuries long uptick we can note, which makes GISS from 1880 a staging post and not the starting post for rising temperatures?
tonyb
Geoff Sherrington, in the troposphere there is no significant stratification because the turbulent mixing time from convection is many orders of magnitude shorter than the settling time for a density difference. Consider minutes to hours timescales for convection, vs centuries for gravitational settling. Centrifuge separators for uranium processing get tiny variations after hours at thousands of gees, and require cascades to achieve useful separations. So no, CO2 will not settle in low spots, unless high concentrations from other sources (such as volcanic vents or organic decay) deliver to gas the low spots. Even so, convection dissipates such local hot spots within hours to days.
Following on from Geoff Sherrington’s points.
Humans have been influencing CO2 levels for millenia. Cutting down forests, killing the herd grazers,
I find the CO2 levels rising from the start of the Industrial Revolution especially questionable. Coal replaced charcoal as the industrial fuel, and producing charcoal with pre-industrial technology requires a fire that burns for about 3 days (I’ve seen it done). Producing large amounts of CO2, black carbon and organic carbon. Whereas, mining coal produces little CO2.
It’s likely CO2, and atmospheric black carbon and organic carbon all declined around the time of the industrial revolution, as charcoal production declined and forests grew back.
Doug Jones , your post reminded me of this . http://www.history.com/this-day-in-history/gas-cloud-kills-cameroon-villagers
Tony – Your work on CET is inspiring, and unless Britain has been a climate law unto itself for centuries, you can ignore Stokes. Will buy you a pint someday.
To me the rise of about 2 degrees C from 1695-1730 is of immense interest….
It might be worth doing a re-run of historic instrumental atmospheric CO2 readings which I believe were posted on this site many years ago. I seem to recall the early measurements which off the top of my head (TOMH) go back to a remarkable 1756 show wide variations prior to this century with the C19/C20 textbook level being 400ppm and levels 2 centuries ago being very significantly higher than 100 years ago.
As regards the radiation/radiation issue CO2 produces much less “back radiation” than does thermal/radiation i.e. the net conduction/convection/latent heat of evaporation from the Earth’s surface also produces back radiation which is approximately equal to that radiated out into space from these initially thermal transport mechanisms. Half the net thermal energy picked up by these mechanisms is re-radiated downwards and half is lost to space, this is a much higher fraction than that via radiation from the surface being returned by CO2 which is about 1% (?) (TOMH) which is very inefficient at producing “back radiation” and in consequence most outgoing surface radiation makes it out into space. Interestingly when the surface average temperature goes up the fraction of back radiation to forward radiation from adding together both sources actually goes down (obviously) as more energy leaves the surface as radiation (T^4) than as thermal energy. As in excess of 80% of initial incoming solar radiation is lost from the surface via the thermal route this source of “back radiation” is hundreds of times higher than the other CO2 route.
Note that a domestic CH radiator is a convector heater but if you could turn its temperature up to 2000 centigrade the ratios of heat lost via both mechanisms would switch from about 90/10 to 10/90 (guesstimate). Same thing with the planet as it warms the surface radiation increases faster than thermal loss and therefore back radiation becomes proportionately less.
Why does no one cover this? If back radiation warms the planet as we are told how does reducing the fraction of back radiation (through warming) warm the planet? Looks to me like these two mechanism work as a strong lock (negative feedback).
Climate alarmists are learning a very painful lesson these days. They thought that co2 was a magical gas. It is when younger, then loses it’s muscle power as it gets nearer to retirement. Natural climate variations have exposed it’s charlatan ways. Over 15 years of a global temperature standstill………………………………………and counting. At 18 years or thereabouts the debate should be over as per Santer et. al. and model projection failures at 100% confidence. 🙂 Yet we have a consensus. &^%$#%%^
I meant:
“then loses its muscle power “
Why is ‘its’ and ‘it’s’ such a damned pain in my arse?
eco-geek says:
May 8, 2013 at 5:16 pm
You are right. Ernst Beck collated many atmospheric CO2 measurement series made by various chemists over different periods some of them Nobel Laureates (when it meant something). The values that these chemists produced were well above the 280ppm claimed by the proponents of totally stable CO2. I believe the AGW proponents may have been deceived by the ice cores and lack of understanding of CO2 diffusion in ice which effectively produces an average value in bubbles (that may have formed during drilling) that equates to ~280ppm. as this is useful to their argument (the handle of the hockey stick) they will not research it further and excoriated Ernst Beck despite his work being the collation of other scientists’ reports.
Nick Stokes says:
“” temperature is highly variable throughout the CET record -which is at variance to Dr Mann’s (global) work”
No, it isn’t at variance to Dr Mann’s work. His is a global average, yours is a single location. Global averages are always less variable.”
Nick, which is/are bettter proxies for North American temperatures, the CET record or Mann’s proxies?:
http://www.multi-science.co.uk/mcintyre-mckitrick.pdf
If your answer is Mann’s proxies, please explain why.
Check out the work of Austrailian Prof. Murry Salby, he demonstrates a clear link between temperature and CO2, with temperature leading all the time and CO2 levels following (definately not constant prior to the Industrial Revolution).
“its’ and ‘it’s’” LOL, Jimbo, its a problem for all of us. Don’t tell anybody, but I didn’t even notice your mistake until you pointed it out! For me, its that bad!
Nice metaphor, BTW (@ur momisugly 1720).