Bishop Hill Nature and the Sunday Sport
Jan 2, 2014 Climate: Models Journals The paper by Steven Sherwood has been agitating those of a green disposition in recent days, with all sorts of wailing on Twitter about how we're going to hit four degrees of warming by the end of the century. This is certainly the story that Nature gave out in its press release:
Global average temperatures will rise at least 4°C by 2100 and potentially more than 8°C by 2200 if carbon dioxide emissions are not reduced according to new research published in Nature. Scientists found global climate is more sensitive to carbon dioxide than most previous estimates.
The research also appears to solve one of the great unknowns of climate sensitivity, the role of cloud formation and whether this will have a positive or negative effect on global warming.
As readers here know, climate models all run far too hot. As far as the latest CMIP5 generation go, this is at least partly because they use estimates of aerosol forcing that are much higher than observations suggest is the case. And if the latest hypothesising about the hiatus in surface temperature rises is correct, the models are all missing a key climate subsystem too, namely transport of heat to the deep oceans.
I haven't got hold of a copy of the Sherwood paper as yet, but from what I have been able to glean from the abstract, the press release, and from conversations around the web, he and his colleagues looked at climate models to see how well these reproduced observations of clouds, finding that the best match came from the models that ran hottest.
In other words, the models that had the most realistic simulations of clouds had the least realistic representations of temperature changes.
If I've understood what was done correctly, this is an interesting conundrum for climate scientists to explore. What it is not is any reason to think that the output of such models is policy-relevant or reason to think that we will warm by 4°C by the end of the century.
Nature really has sunk to the level of the Sunday Sport.
Reader Comments (129)
EM
1) DWIR=OLR 2)DWIR + OLR = surface radiation
Not according to Trenberth's 'Global Energy Flows' which have DWIR at 139% of OLR. If you are going to be wrong then be consistently wrong.
Jan 3, 2014 at 8:24 PM | Unregistered Commenterssat>>>>>>>>>>>>
As I said before - silly simplistic mind games using guessed at conditions which are not universal.
One post the idiot says clouds are of most importance then gives us silly mind games based on 'clear skies'
Why do we continue to take any notice of the repeat nonsense from this idiot which is completely at variance with empirically derived [real world] data.
In the long term the models are running cool because they generate the wrong balance between low and high cloud.
Jan 3, 2014 at 8:29 PM | Unregistered CommenterEntropic man>>>>>>>>
Rubbish!
The models are running HOT because they fail to produce results that describe real world temperature data.
2013 is looking like yet another cool year and, closer to home, central England temperatures are now at the lowest annual levels since the 1980's, North America is having it's traditional annual winter and the UK is having winter storms no different than those of the 1960's and 70's
I'll listen to the many serious climate scientists, such as Richard Lintzen, who do not agree with the alarmist propaganda posing as science these days - especially when it comes to climate sensitivity and the net effects of CO2.
If I use a mirror to reflect 100% of radiated IR back to an electrically heated black radiating plate will it get hotter?
Of course not, so how is supposed back radiation going to increase the temperature of the Earth's surface emitting the ir in the first place?
Jan 3, 2014 at 6:24 PM | RKS
Lets start with your mirror and hot plate.
Case 1. The plate is switched on without the mirror. It will warm to a temperature at which the rate of heat loss matches the rate of heat input from the electricity supply. Energy out=energy in.
Case 2 The plate is switched off, but a neighbouring plate radiates the same amount of energy towards it as the mirror would have done. Once again it warms until energy out=energy in.
Case 3 The plate is switched on and warms until it reaches its usual temperature.. The mirror is then added. The extra reflected energy then warms the plate to an even higher temperature, which will stabilise when the increased energy in =increased energy out.
Now consider the Earth's surface. Solar insolation is the equivalent of the electric heating. Downwelling radiation is the equivalent of the reflected heat from the mirror, though a much smaller proportion. Insolation and DWIR together keep the surface slightly warmer than it would be with insolation alone. Increased convection and surface radiation due to the increased temperature bring it to equilibrium.
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Your second point claimed that IR could not warm the ocean since all the energy would be promptly transferred to the air.
Consider the process in a little more detail. An IR photon is absorbed by a water molecule which gains kinetic energy. Where does the energy go?
1) The molecule can move or transmit KE upwards to the surface. There a water molecule may collide with an air molecule and transfer its KE into the air.
2) At the surface a molecule may be moving with enough KE to evaporate into the air.
1) and 2) are the sort of process you discuss.
3) The molecule hit by the IR can move or transfer its KE downwards, conducting energy into the bulk of the ocean.
4) Wave action and wind ripples mix the water film, transferring the warmer water, with its extra heat, down into the bulk.
3)and 4) are processes which allow IR to produce an increase in bulk water temperature.
Some of the DWIR will end up warming the air, but by no means all.
Entropic
You clearly believe that energy flows against a temperature gradient rather than with. What a cruel irony it is that your parents named you so.
Jan 3, 2014 at 9:34 PM | Unregistered CommenterEntropic man>>>>>>>>>>>>
More childish mind games giving yet more unsubstantiated imaginary results.
What are the comparative effects of convective cooling compared to the unproven imaginary effects of 'back radiation'
Kinetic energy imparted by ir to the surface of the oceans and then [somehow] to the depths? You might just as well deduce that kinetic energy from wave motion can heat the depths of the ocean - Is there any proof of this nonsense from you or is this yet more imaginary twaddle? - Perhaps you've published a paper on this amazing discovery which might, at the same time, explain why the imaginary 'missing heat' has not been measured in the deep oceans where it's claimed to be by some alarmists - now including yourself.
That's it for today. The idiot's been given more than enough rope to show the readers how his funny little alarmist mind works.
ssat
Which temperature gradient?
Water will evaporate into warmer air or warm cooler air by conduction.
The oceans get cooler with increasing depth, so conduction is not a problem.
Within broad limits an IR photon doesn't mind what temperature its source and sink are.
Entropic man (8:07 PM): "Otto's estimate of climate sensitivity is only valid if 21st century temperature records represent the norm. If they are a transient period of reduced warming rate Otto's estimate of sensitivity will be too low."
I think you're mis-reading the paper then. The main result (cited as for the "2000s", that is, the decade 2000-2009) compares the average temperature and forcing in the 2000s to those of the base period 1860-1879. It's not based on the temperature change over a 10-year period, but on over more than a century. The results for other periods, shown in figure 1, are fairly similar in their best estimates, but the 2000s data has the narrowest uncertainty.
"Oh for a time machine! :-)" I second your wish for a time machine. I would have higher priorities for its first use, than to evaluate climate sensitivity, however. The Eloi are far more important.
Entropic
Ignoring conduction, a different subject, you are implying with your last statement that an IR photon leaving a colder body will raise the energy state of a warmer one if intercepted by it. This ignores the fact that the warmer one will also be emitting and the net exchange of energy will be from the warmer to the cooler. There is your gradient. All explained by normal physics. Cli-Phy requires the acceptance of the hypothesis that some work has been done on the warmer body by the cooler where normal physics rejects that: temperature is a function of the potential energy of a body; flux is a function of the difference of potentials; flux direction is from the higher potential to the lower
HaroldW
2000-2009 forcings are my concern. CO2 forcing continued to increase. Decreased solar insolation weaked that forcing. Above average volcanic aerosols and a jump in industrial aerosols created an increased negative forcing. The 21st century has also tended to a low ENSO index.
This is why energy content, forcing and temperatures are lower than CO2 increase alone would generate.
Otto therefore saw a lower temperature change for the century than would otherwise have been measured, and therefore gets a lower sensitivity. This is common to all the "empirical" estimates of sensitivity. It probably explains why climate sensitivity based on paleo data tend to be larger than those based on modern records.
Damn, I'm talking about short term/long term again! Sorry, SandyS. :-)
Ssat
An absorbed photon will raise the energy state of the molecule which absorbs it, independently of the temperature of the emitting molecule. Other energy flows then balance the energy budget.
There is no thermodynamic impossibility about DWIR. It is just an extra ripple on the normal energy flow through the climate from insolation to OLR. You can't isolate it from the rest of the energy budget and claim that its impossible.
Entropic
I wish to measure the flow of energy, as you describe, from a cooler to a hotter body. Could you outline the apparatus I would need and the method I should adopt please?
In Sherwood et.al (2014) a positive tropical cloud feedback is postulated which leads to CS 4...5. Anyway, in the paper is no empirically evidence from observations included. So I tried this one: Have a look at fig. 3 and 4 where the you can see, that the lower altitude drying effect is located at an area -30...30N over the oceans. So I looked at the SST ( HadISST1) there and found, that the saisonal variation is about 1,1 K between April ( max.) and August ( min). If the effect is at work one should assume, that the slope of the SST of Aprils is higher than the slope of the SST of Augusts over the years 1900...2013. This is not the case: http://www.dh7fb.de/reko/tropminmax.gif . So my question: is such an observation able to confirm or falsify the described effect in http://www.nature.com/nature/journal/v505/n7481/full/nature12829.html ?
Entropic man (12:33 PM) -
Otto et al. wrote "We include the historic record from 1850–2005 and the RCP4.5 scenario values from 2006–2010" so they should have been fairly close to actuals for the 2000s. [Well, it's not as though actual forcings are directly measurable, but...] Regardless, as mentioned above, their "best estimate" ECS values for periods which exclude the 2000s are also a shade under 2.0 K. So it seems unreasonable to complain that it might be that the 2000s forcings were lower than Otto allowed, and that's the reason why their ECS is incorrectly too low.
As for the paleo data, if you think that the 2000s aerosol forcings used by Otto are off, based as they are on the many recent measurements available, I can't understand how you think that the paleo data is accurate. What was the average optical depth at the last glacial maximum? What was the extent of sea ice seasonally? Don't get me wrong, I think it's cool that by a completely different method one can obtain an ECS in the same ballpark, but it surely has an uncertainty of a factor of 2 (at least).
Frank -
I've been unable to find a non-paywalled version of Sherwood et al., and I haven't yet visited my local university library to look at it. Are you aware of a free version on the web?
ssat
Measure ALL the variables. The overall energy flow always follows increasing entropy. Within that overall pattern there are a lot of temporary and localised reversals.
Looked at in isolation you own body is an impossible accumulation of energy and negative entropy.Only in the larger context is it properly seen as a localised and temporary reversal in the larger entropic trend.
Even a refrigerator manages to make heat flow from colder to hotter, but only locally, at the expense of enough extra energy to increase entropy overall.
HaroldW
I haven't found a complete copy. I have found summaries on the National Geographic website and on Skeptical Science.
Entropic man -
Thanks. I've read the summary at RC as well. But none of them help me with details such as those which Frank mentioned.
HaroldW
The modern figureds Otto used aren't wrong, just not representative of the long term trend.
It's a more subtle version of the warming trend problem. If you calculate a trend line starting with a low year or ending with a high year, you overestimate the rate of change. If you start with a high year and end with a low year you underestimate the change. The short term variations generate uncertainty in the trend. Otto's calculation is based on what, in my opinion, are low end figures.
This is probably where we differ. I think that the 21st century numbers are near the bottom of the noise range and that the ensemble model range is more typical of the long term trend. I suspect that you think recent temperatures reflect normality and the models are too warm. We won't settle that till you get back from saving the eloi. :-)
Entropic
More blather and no substance. It was the simplest of questions, Entropic, and you can't answer it. Cli-Phy is based on these shonky foundations and while you swan around in the sky lounge, from outside the edifice, we observe the increasing angle of lean.
And yes, I know how an effin refrigerator works.
Entropic Man -
I really don't understand the claim that this is a short-term trend problem, in which the choice of a given start or end year can make a significant difference. The differences were calculated from a modern decade (say, the 2000s) to a 19th century base period (1860-1879). If you object to the 2000s, there are also calculations from the same base period to the 1990s or 1980s. They can't *all* be "bad" years.
Ssat
Heat moving from colder to hotter?
An experiment you can do at home.
Switch off your fridge and let it defrost to room temperature.
Put in a thermometer inside the fridge and another on the coil behind it. Watch the temperatures change as heat moves from your cold fridge to your warm kitchen.
If you know how a fridge works, why do you not accept related physics at work in the atmosphere?
HaroldW
A small bet as illustration. I'm getting too decripit to do the maths myself, but I would bet that an Otto style calculation using 1980s or 1990s data would give a higher climate sensitivity than one using the 2000s.
HaroldW
A small bet as illustration. I'm getting too decripit to do the maths myself, but I would bet that an Otto style calculation using 1980s or 1990s data would give a higher climate sensitivity than one using the 2000s.
Entropic
Energy transport within the workings of a refrigerator is commonly performed by mechanical work. It is not performed by direct radiative transfer from the interior to the kitchen. Your analogy is a false one and if you believe it not to be so then I understand why you find yourself able to cling so ardently to Cli-Phy. I shall trouble you no more on that topic.
ssat
Perhaps you should read this.
http://scienceofdoom.com/2010/10/07/amazing-things-we-find-in-textbooks-the-real-second-law-of-thermodynamics/
Entropic Man (9:54/11:03 PM) -
You'd lose the bet, I'm afraid. Take the figures in Table S1 of Otto et al.'s supplement, and their equation 1:
(1) ECS = F2x * ΔT / (ΔF – ΔQ)
The central estimate for ECS obtained from this equation comes to:
2000s: 1.98
1990s: 1.92
1980s: 1.86
1970s: 1.40
1970-2009: 1.92
Your forfeit for losing the bet -- it is you who must rescue the Eloi with your time machine !
P.S. By the way, thanks for the question. When I went to check the link to the SI, I noticed that Otto had filed an update, of which I had previously been unaware.
HaroldW
Well argued. You win this one. :-) Weena, here I come.
Goodnight.
Entropic man
Dang. Weena was beautiful. I should have kept that job for myself.
Entropic
Yes I am aware of the conclusion in the link you cite, I entirely agree with it (my post at 7:19) as does conventional physics on which it draws. What it does not support is the Cli-Phy version of energy flow (flux) and which none of your replies has been able to support yet to which you cling so ardently.
Let me be clear, I entirely agree with the conclusion that additions to the atmosphere of the radiative gas that is CO2 will reduce the rate of heat loss (the outgoing radiative flux) from the surface.