We recently presented and discussed modeled and observed global surface temperatures in absolute terms. See the post On the Elusive Absolute Global Mean Surface Temperature – A Model-Data Comparison. The WattsUpWithThat cross post is here. Yesterday, Willis Eschenbach at WUWT furnished EXCEL spreadsheets that included the outputs of climate model simulations of global surface temperatures in absolute terms. See Willis’s post CMIP5 Model Temperature Results in Excel.
Hot on the heels of those two posts comes a discussion at RealClimate of modeled absolute global surface temperatures, authored by Gavin Schmidt, the head of the Goddard Institute of Space Studies (GISS). Gavin’s post is Absolute temperatures and relative anomalies. Please read it in its entirety. I believe you’ll find it interesting. (Thanks, Gavin.)
Here are two quotes from it to get the discussion here rolling. First, Gavin Schmidt wrote (my boldface):
Second, the absolute value of the global mean temperature in a free-running coupled climate model is an emergent property of the simulation. It therefore has a spread of values across the multi-model ensemble. Showing the models’ anomalies then makes the coherence of the transient responses clearer. However, the variations in the averages of the model GMT values are quite wide, and indeed, are larger than the changes seen over the last century, and so whether this matters needs to be assessed.
Second quote (my boldface):
Most scientific discussions implicitly assume that these differences aren’t important i.e. the changes in temperature are robust to errors in the base GMT value, which is true, and perhaps more importantly, are focussed on the change of temperature anyway, since that is what impacts will be tied to. To be clear, no particular absolute global temperature provides a risk to society, it is the change in temperature compared to what we’ve been used to that matters.
See, I told you you’d find Gavin’s post interesting.
Enjoy your holidays.
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[img]http://i.imgur.com/VxyhzVW.jpg[/img]
Sorry
http://i.imgur.com/VxyhzVW.jpg
yep, sorry that even thought it was hind casted to match…it still fell completely apart in 1999
http://www.climatedialogue.org/wp-content/uploads/2013/05/Figure-2-Pielke.jpg
yep, hindcasting to match a massively adjusted temperature series.
Not much skill in that !
yep, they just took a new base line.
From a comment above: “However, if the global anomaly is rising at some very fast rate, e.g., 6 degrees C per century, then we have a big problem.”
6 degrees per century is a problem as far as we understand things – but will it continue for. Century? That is a separate question.
The daily change in temperature, say 15 C in 12 hrs, is “30 degrees rise per day” and “210 degrees per week.”
A rate of change is only meaningful in context. The Younger Dryas ‘rate of change’ was enormous but didn’t last long. Negative feedbacks kick in and cloud cool the planet.
Rate of change of an anomaly has another problem. Was the nighttime temperature anomaly responsible for 100% of the change in the average temperature anomaly? That information is hidden when the average is calculated.
same problem when you average over the globe. most of the temp change has occurred in the arctic, with very little anywhere else. so we are proposing to spend trillions we don’t have to keep the arctic cool? for what benefit? does anyone truly think the arctic is too warm?
“Rate of change of an anomaly has another problem. Was the nighttime temperature anomaly responsible for 100% of the change in the average temperature anomaly? That information is hidden when the average is calculated.”
It is from min temps, but it’s not from any trend in day over day change, but regional excursions.
@ur momisugly Frank K. “Some physical properties and phenomena that are dependent on *** absolute *** temperature: (snip) (3) Thermal radiation heat transfer (depends on Tabsolute^4) and related physical properties.
True, black body radiation goes as T^4 — but Gavin says they have calculated something very different. Absolute Global Mean Temperature does not give a certain specific amount of radiation. Two (or three or four or…) versions of the Earth could all have the same Absolute Global Mean Temperature and each radiate very different amounts of energy from the others. The catch is in that word “mean”. Consider a globe that has the same temperature “T” at all points on the surface. The mean temperature would be the same as the temperature (T) at any given point, and the globe would radiate some certain amount of energy per second. Consider another globe, identical, except that now half the globe is at T+1 and the other half is at T-1. The absolute global mean temperature is the same, but this second globe radiates out more energy per second. That T^4 means that the increase in radiation from the warm side outweighs the drop in radiation from the cool side. The more the surface is differentiated in temperature, the more effective it will be at radiating energy for any given absolute global mean temperature.
I do not know whether the global climate models base their estimates of radiated global energy on mean temperatures or not… but if they do , they are doing it wrong, and low-balling the amount of energy going into space.
Jason, I have been having a long conversation in my livingroom pondering a reply on exactly this point. An ‘average’ temperature arrived at by area-weighted temperature averaging is useless for calculating the energy radiated. Note that the ‘no atmosphere’ temp is calculated from the input put energy and the emissivity. The average temperature now is a measured and calculated value. Using it and the input energy we can calculate the emissivity. But that is only possible if the average temp is the actual temp, which it is not. The calculation of the energy out based on a known emissivity, or the calculation of the average emissivity (were such a thing meaningful) can only be done by using the initial cell areas and the average temp in each cell, calculated separately and summer because of the huge effect of T^4 on the answers, as you correctly point out.
True: But the LW energy radiated out also requires
(1) (the correct emissivity – which you began. But each “area” requires
(1b) the correct emissivity (farmland, cities and developed areas = not very much actually), desert, jungle, tundra, ice and ice caps and snow, water, forests and taiga, pampas and plains and savannah and steppes, etc.
(1b) AND the correct assumption for total area for that type of surface in each grid AND
(1c) AND the correct assumption for the absolute temperature for that area for that date (or month if you are going to get very crude)
(1d) AND the correct assumption for Tsky (or Tair) that the surface is radiating “up” into from the surface for that day, date, latitude, and hour-of-day
(1e) the correct assumption for the relative humidity, air pressure and/or radiation fudge factor” for that day-of-year, latitude and hour-of-day that makes the “outward radiation” calculation actually work.
Then …
You have to correct the inbound radiation at TOA for its day-of-year variation
AND
the Latitude of the region
AND
total area of the planet being radiated.
Thus, the Arctic sea ice at minimum in Sept 22, for example, is 0.8% of the earth’s surface (3-4 Mkm^2 compared to 510.3 total area.
The latitudes between -45 and +45 latitude is 70.9 percent of the total area.
Even IF 2 degrees causes a social upset, it’s a price worth paying if we don’t have to listen to these fools any more, and if we get to keep our world heritage sites like the Nazca lines
In presenting the CMIP5 dataset, Willis raised a question about which of the 42 models could be the best one. I put the issue this way: Does one of the CMIP5 models reproduce the temperature history convincingly enough that its projections should be taken seriously?
I have now had time to look at this and can comment based upon analysis of the temperature trends produced by each of the 42 models. To reiterate, the models generate estimates of monthly global mean temperatures in degrees Kelvin backwards to 1861 and forwards to 2101, a period of 240 years. This comprises 145 years of history to 2005, and 95 years of projections from 2006 onwards.
I identified the models that produced an historical trend nearly 0.5K/century over the 145 year period, and those whose trend from 1861 to 2014 was in the same range. Then I looked to see which of the subsets could match the UAH trend 1979 to 2014, and which showed the plateau in the last decade.
Out of these comparisons I am impressed most by the model producing Series 31.
It shows warming 0.52K/century from 1861 to 2014, with a plateau from 2006 to 2014, and 0.91K/century from 1979-2014. It projects 1.0K/century from 2006 to 2035 and 1.35K/century from now to 2101.
Thanks for that Ron C.
So is that most impressed, as in very accurate match, or most impressed as least worst?
Without bothering to look for myself, how does series 31 differ from eyeballing a graph of estimated past temperatures?
Is there any way to test series 31’s usefulness as a policy supporting tool?
The match backwards is not bad. A rise of 0.75 since 1850 is fairly widely accepted (that’s about 0.5/century). Series 31 is a little cooler than UAH since 1979. The projections are modest in comparison with most other models, but I don’t know what assumptions are built in.
Just a lurker here.
It would be fun to see the top five and the bottom five – even if you only eyeball the matches. Then, if we could get someone knowledgeable to look at the main assumptions behind the ‘good’ and ‘bad’ models, their complexity and cost, etc.
The weeding of the garden has to start somewhere!
Good idea, I will look at that. It seems to be more like Goldilock’s soup problem: Some are too hot, some too cold, and some in the middle (can’t say “just right”). All this is about replicating the history; whether the future is like the past or not is where the argument is.
“To be clear, no particular absolute global temperature provides a risk to society, it is the change in temperature compared to what we’ve been used to that matters.” Accepting change or not? Things should not change or there is always change. They seem to be playing the role of the conservatives.
“As an aside, people are often confused by the ‘baseline period’ for the anomalies. In general, the baseline is irrelevant to the long-term trends in the temperatures since it just moves the zero line up and down, without changing the shape of the curve. – See more at: http://www.realclimate.org/index.php/archives/2014/12/absolute-temperatures-and-relative-anomalies/#sthash.05bunHKx.dpuf” ~ Gavin Schmidt
——————————
I, for one, am never confused by this. The “baseline period” is deliberately chosen to push a “predetermined conclusion”.
It is entirely relevant, because policy makers (and their Gruber minions) only look at the zero line — up or down. The shape of the curve is entirely irrelevant.
Beginning and ending points, adjustments and proxies are all also relevant and often chosen to mislead.
It matters nought … plenty of equatorial Africans living in Northern Europe and plenty of Swedes living here in the Antipodes ! What a goose !
More and more friends have been expressing an interest in fleeing winters in New England. I don’t think it will warm up quickly enough to reverse this experiential trend. Sailers often make up shanties to add a rhythm to repetitive work….Like shoveling the deck! “Oh I wanna go where there ain’t no snow and the water flows out the scupper. Oh I wanna go where there ain’t no snow and the only ice comes with supper. Oh I wanna go four days south bear 278 through Town Cut Bermuda! ” Each refrain keeps up the rhythm of two shovel loads…shanties are very personalized and verses made up to keep the mind above the drudgery. It occurs to me that there should be a shanty for the process of digging out and disposing the piles of CAGW horse muffins.
Gavin wrote that global mean temperature anomalies can bei determined with an uncertainty of no more the ± 0.1 K. And cites Jones et al 1999 in order to support this claim. At least 3 papers showed recently that this is wrong. see below. The remaining uncertainty due to their findings ist much higher than any variation of said anomaly.
1:NEW SYSTEMATIC ERRORS IN ANOMALIES OF GLOBAL
MEAN TEMPERATURE TIME-SERIES by Michael Limburg (Germany), ENERGY &
ENVIRONMENT
VOLUME 25 No. 1 2014
2. P. Frank, “Uncertainty in the Global Average Surface Air Temperature Index: A Representative Lower Limit,” Energy & Environment, vol. 21 , no. 8, pp. 969-989, 2010.
3. P. Frank, “Imposed and Neglected Uncertainty in the Global Average Surface Air Temperature Index,” Energy & Environment · , vol. Vol. 22, N, pp. 407-424, 2011.
Global average whatever……temperatures blah bloody blah, Schmidt indubitably: is beating the retreat.
We will remember the Alarmist trouble makers and Schmidt – you were one of the loudest and most raucous. There will be a reckoning, in the US – probably in court.
[ … ] it is the change in temperature compared to what we’ve been used to that matters.
===================
what utter nonsense. If that was the case no one would take a vacation in the tropics. No one would look forward to summer. No one would look forward to the sun coming up in the morning.
One thing is clear “what we’ve been used to” means that humans are able to adapt to a wide range of conditions, because we have people from all over the world, hot and hot that have moved to different countries and climates without any difficulty at all.
According to Gavin’s logic, simply walking outside from inside the house, with the change in temperature would be too much for people. They would all need to stay inside, so that they are not exposed to “the change in temperature compared to what we’ve been used to”.
And this is what passes for Science in the United States.
[ … ] it is the change in temperature compared to what we’ve been used to that matters.
===================
so in other words, people are too stupid to dress for the weather. they are too stupid to put on warm clothing when it is cold outside. they are too stupid to put on cool clothing when it is hot outside. they are too stupid put on waterproof clothing when it is wet outside.
and farmers are also too stupid to plant the correct varieties crops for the local climate and they are too stupid to raise the the correct varieties of animals for the local climate. And heaven forbid the climate was to change in, farmers would be too stupid to recognize the change and make adjustments.
we need scientists like Gavin to prevent any change, because we are all too stupid to deal with change. we are all so inflexible, unable to learn, unable to adapt, unable to respond to temperature change compared to what we’ve been used to.
it is the change in temperature compared to what we’ve been used to that matters……that explains the annual migration of the Winnebagos
Typical day at GISS for “Dr.” Gavin Schmidt (Lord Warphin/Dr. Lazardo):
Ha ha
And the biased, politically motivated “adjustments”, “infilling”, “homogenization”, and all the rest produce a band that is even wider. It would help if we could trust the honesty of these government minions pretending to be scientists. If I could, I would fire every one of them right down to the guy who has to clean the restrooms. I would start fresh with new people and a mandate to get honest data —- and to be honest about all the problems associated with whatever data we come up with.
How about the non-scientist public servants who keep filling the money trough from our pockets for these pigs to snuffle in?
If I had mine, I’d sack every government employee and start again.
PS Happy Christmas, Anthony. I hope your hearing is still holding up, mate.
These guys remind me of my old fishing days when eels were in plentiful supply. The only way you could get them off the barbed hook was to cut their heads off. Slimy isn’t the word.
So only the change in temperature matters … well it seems the average temperature went from 56.8 degrees F. in 1880 to 58.1 degrees F. in 2013 (GISS).
.
Thanks “Latitude” for the “132 Thermometers” (132 red lines) chart you pasted in the comment section — that says it all.
.
I have no idea how many “adjustments” were made to the raw surface data, whether the measurements are anywhere near accurate or global, or whether the average temperature of Earth has any importance … although I know it is a statistic that can be compiled in many ways (hundreds?) rather than a single measurement of something.
The 1880 temperature is probably too low since thermometers of that era tend to read low,
and who even knows what the raw data are, and how many measurements were “adjusted”.
.
No one knows what temperature is “normal”, or whether a little warming is good or bad news.
.
No one knows what caused the warming already measured (assuming the data are accurate).
.
Without a jagged anomaly chart showing 0.1 degree temperature changes, scary predictions of the future climate, and some politician claiming life on Earth is going to end as we know it … the average temperature becomes a boring subject to the layman … similar to most science subjects … where scientists calmly collect data, make observations, and do experiments … rather than taking taxpayer dollars to play computer games and make scary wild guess predictions about the future climate … that (heh, heh) requires a lot more study … and more grants!.
.
When absolute temperatures are shown on a chart — a type of chart rarely presented by “skeptics”, and never used by “warmists” — the subject of climate change becomes about as interesting as staring at an outdoor thermometer for an hour.
.
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“The 1880 temperature is probably too low since thermometers of that era tend to read low”
…
Citation?
Your search engine doesn’t work?
Ps Your query is a well- known troll trick…
Alan Robertson December 26, 2014 at 4:04 pm
Say what? Asking for a citation for an unsupported assertion is not a “troll trick” of any kind, it is a perfectly legitimate request.
w.
Further to my comment about Series 31 above, I have looked more into the details, and I am less impressed, though it is probably one of the best in the CMIP set. The historical part of the series does not present any plateau, either last century or this one. Moreover, as is typical of all these models, the future is projected to warm at a rate 3 times that in the history up to 2005.
“To be clear, no particular absolute global temperature provides a risk to society, it is the change in temperature compared to what we’ve been used to that matters.”
What a poor sloppy scientist…
.. don’t worry about Gavin
.. he’s still raking in million$ selling DVDs of Al Gore’s Inconvenient Truth
.. through his RealClimate network of cloned warming alarmist blogs