Strong Negative Feedback from the Latest CERES Radiation Budget Measurements Over the Global Oceans
By Dr. Roy W. Spencer, Ph. D.
Arguably the single most important scientific issue – and unresolved question – in the global warming debate is climate sensitivity. Will increasing carbon dioxide cause warming that is so small that it can be safely ignored (low climate sensitivity)? Or will it cause a global warming Armageddon (high climate sensitivity)?
The answer depends upon the net radiative feedback: the rate at which the Earth loses extra radiant energy with warming. Climate sensitivity is mostly determined by changes in clouds and water vapor in response to the small, direct warming influence from (for instance) increasing carbon dioxide concentrations.
This can be estimated from global, satellite-based measurements of natural climate variations in (1) Earth’s radiation budget, and (2) tropospheric temperatures.
These estimates are mostly constrained by the availability of the first measurement: the best calibrated radiation budget data comes from the NASA CERES instruments, with data available for 9.5 years from the Terra satellite, and 7 years from the Aqua satellite. Both datasets now extend through September of 2009.
I’ve been slicing and dicing the data different ways, and here I will present 7 years of results for the global (60N to 60S) oceans from NASA’s Aqua satellite. The following plot shows 7 years of monthly variations in the Earth’s net radiation (reflected solar shortwave [SW] plus emitted infrared longwave [LW]) compared to similarly averaged tropospheric temperature from AMSU channel 5.
Simple linear regression yields a net feedback factor of 5.8 Watts per sq. meter per degree C. If this was the feedback operating with global warming, then it would amount to only 0.6 deg. C of human-caused warming by late in this century. (Use of sea surface temperatures instead of tropospheric temperatures yields a value of over 11).
Since we have already experienced 0.6 deg. C in the last 100 years, it would also mean that most of our current global warmth is natural, not anthropogenic.
But, as we show in our new paper (in press) in the Journal of Geophysical Research, these feedbacks can not be estimated through simple linear regression on satellite data, which will almost always result in an underestimate of the net feedback, and thus an overestimate of climate sensitivity.
Without going into the detailed justification, we have found that the most robust method for feedback estimation is to compute the month-to-month slopes (seen as the line segments in the above graph), and sort them from the largest 1-month temperature changes to the smallest (ignoring the distinction between warming and cooling).
The following plot shows, from left to right, the cumulative average line slope from the largest temperature changes to the smaller ones. This average is seen to be close to 10 for the largest month-to-month temperature changes, then settling to a value around 6 after averaging of many months together. (Note that the full period of record is not used: only monthly temperature changes greater than 0.03 deg. C were included. Also, it is mostly coincidence that the two methods give about the same value.)
A net feedback of 6 operating on the warming caused by a doubling of atmospheric CO2 late in this century would correspond to only about 0.5 deg. C of warming. This is well below the 3.0 deg. C best estimate of the IPCC, and even below the lower limit of 1.5 deg. C of warming that the IPCC claims to be 90% certain of.
How Does this Compare to the IPCC Climate Models?
In comparison, we find that none of the 17 IPCC climate models (those that have sufficient data to do the same calculations) exhibit this level of negative feedback when similar statistics are computed from output of either their 20th Century simulations, or their increasing-CO2 simulations. Those model-based values range from around 2 to a little over 4.
These results suggest that the sensitivity of the real climate system is less than that exhibited by ANY of the IPCC climate models. This will end up being a serious problem for global warming predictions. You see, while modelers claim that the models do a reasonably good job of reproducing the average behavior of the climate system, it isn’t the average behavior we are interested in. It is how the average behavior will CHANGE.
And the above results show that not one of the IPCC climate models behaves like the real climate system does when it comes to feedbacks during interannual climate variations…and feedbacks are what determine how serious manmade global warming will be.
“Correct! Since Dr. Spencer is directly observing cause and effect”
Afraid not. It takes much longer than a month to see the full effect of a forcing, so again this only shows it takes a lot of energy to heat water.
Is that so. Then why does stay below freezing all through the summer?
Just for reference, I have been experimenting with the MODTRAN line-by-line atmospheric transmission calculator tool recommended by Willis Eschenbach. I am using the tool as-is with no documentation. For a nominal radiated output power, Iout, of 292.993 W/m2 at 70 km up in clear tropical air (no cloud feedback effects,) I note that this tool indicates about 30 percent of the radiated energy from the ground would be blocked by other gases even if there were no CO2 were in the atmosphere.
At a nominal pre-industrial era CO2 level of 280 ppm, MODTRAN indicates the blocked radiation rises to about 37 percent. That means only 63 percent of the total power radiated from the ground would make it out (up to 70 km.) According to this on-line tool, all we seem to have done since that time is add enough CO2 to reduce transmission from the surface by about 0.4 percent and perhaps increase the ground temperature another half a degree K.
MODTRAN does seem to indicate rapidly increasing logarithmic sensitivity as the CO2 concentration rises above about 7200 ppm — almost 20 times our current concentration. Perhaps this is a radiation window pinch-off effect or an artifact of noise in the spectrum data at such high CO2 concentration settings.
Dr Spencer you always succeed in ‘warming’ the level of the discussion and increasing grey matter reactions. Outstanding! Now, perhaps, more will think before they speak –on both sides of the aisle.
Arctic ice has not grown substantially in the last 3 years. And it has not recovered. Unfortunately many on this blog post don’t understand the basics of Arctic science and that is unfortunate. Winter ice extent shows little changes in 33 years (trends around -2 to -3%/decade). And it’s not expected to, not in terms of the physics that govern the extent of the winter ice cover, nor in model simulations of future temperatures. Any suggestion that ice has recovered shows a lot of ignorance. (btw—winter ice extent thisyear was less than the previous 2 winters, which you wouldn’t know from all the references to this years ice being back to normal).
The ice is even thinner this winter than last winter, and low and behold, the ice extent is taking a nose dive. Who would have thought? Wonder how that fits with many arguments on this site that suggest more ice this year than last, a shift towards colder temperatures for decades to come, etc. This site seems no better than RC. You don’t critique folks like Roy Spencer, but all other climate scientists. And you don’t seem to understand that most climate scientists are not alarmists, because they understand what the real uncertainties are in the climate system and what the limitations are on model predictions.
I do find it interesting thought that for a LONG time now, these models have been forecasting changes to come, and now all of a sudden the observations are matching the models predictions. So the models haven’t been entirely useless.
BTW—7 years of observational data is not enough to draw the conclusions stated in Roy’s post. Just like 7 years of sea ice extent data does not tell you how the system will continue to respond in the future. And comparisons of 7 years of observational data with climate models is not accurate either. Each climate model would be in their own phase of natural climate variability and can be showing decreases or increases during 7 years. There are not currently enough climate model simulations to tease out natural vs forced changes in temperature or the real climate sensitivity.
Willis Eschenbach says:
May 8, 2010 at 3:00 am
So I assume from your statistical analysis that 7 years of sea ice extent data versus annual air temperature for example (which shows a strong correlation greater than 0.7) would also be a valid method for predicting the future response of sea ice to air temperatures? Or sea ice versus CO2 which Johanneson tried to publish on a few years ago to say that CO2 causes the sea ice loss, and that in the future there will be no sea ice as CO2 increases? I rejected the paper because it was based on simple correlation rather than including the physics of the system.
I’m sorry but I believe junk science is that which is based on statistical analysis w/out inclusion of the physical processes, and trying to make statements on a few years of data and extrapolating to the future.
BTW…Dr. Spencer has been wrong before. Remember the UAH data? Frank Wentz at RSS showed Dr. Spencer’s method to compute the temperature trends was in error and that he was off by a factor of 2 in his trend (i.e. 0.09C/decade versus 0.19C/decade). I believe UAH did correct their data based on analysis by Wentz.
[REPLY – Sure he has been wrong before. And the error was discovered BECAUSE THE DATA WAS MADE AVAILABLE. That is the primary difference between skeptics and the others.Skeptics have many varying theories. They can’t all be right! But how can anyone place even a modicum of trust in any scientist who refuses to divulge data and methods? ~ Evan]
barefootgirl;
BTW—7 years of observational data is not enough to draw the conclusions stated in Roy’s post. Just like 7 years of sea ice extent data does not tell you how the system will continue to respond in the future>>
Once again we have confusion between modeling and data. Dr Spencer was not drawing conclusions regarding trends, nor did he propose any, nor was he proposing a model. What he said was in point form:
1. The models are based on CO2 causing an energy imbalance of X.
2. The measured imbalance is 0.2X
If the models were to be corrected in accordance with the actual measured imbalance, they would have different results. The climate might be cyclical, but the laws of physics aren’t. Your complaint about only 7 years of data is like measuring the force of gravity and then saying we should measure it again next year to see if it changed. Unless you can propose some physical change that would affect the results, the force of gravity will be the same next year. So will the imbalance.
barefootgirl says:
May 8, 2010 at 12:14 pm (Edit)
Willis Eschenbach says:
May 8, 2010 at 3:00 am
If you “assume” that the results of one analysis can automatically be extended to another analysis of a another dataset of the same length,then you don’t have even a basic understanding of statistical analysis. Whether or not a correlation is significant depends on the characteristics of the individual datasets used. For some datasets, seven years is more than enough data. For others, twenty years is nowhere near enough.
The strength of the correlation is not what is at issue. It is the statistical significance of the correlation. For example, the two series {2, 4, 8} and {3, 6, 12} have a correlation of 1.0 … but it is not statistically significant.
I guess I missed the part where Dr. Spencer extrapolated to the future, would you be so kind as to point it out?
And as to whether there is a physical process involved, Dr. Spencer and I have both suggested possible physical mechanisms which would lead to negative cloud feedback. In addition, negative cloud feedback is supported by e.g. the ERBE measurements. On the other hand, all of the models show positive cloud feedback … perhaps you could explain to us what might be the physical process leading to positive cloud feedback …
barefootgirl says:
May 8, 2010 at 12:21 pm
OMG, a scientist was wrong, stop the presses!
Yes, Dr. Spencer was wrong. And like any good scientist (and unlike say Michael Mann or a host of other AGW supporting “scientists”) he acknowledged the error and corrected his work. Since he and Dr. Christy were the first ones to use the MSU data to extract temperatures, and the process of doing so is quite complex, it would have been shocking if errors in their work had not been found … so?
The mark of a good scientist is not that he/she is never wrong. It is that when the error is pointed out, the scientist admits it and corrects the work in question. You seem to think that makes their work less solid, but that’s just how science progresses. The UAH MSU analysis has been very carefully examined, and all known errors have been removed … which makes their work more solid, not less solid.
Given that the annual cycle in forcing due to the elliptical orbit is 14 W/m2, and that the response to this would be more than 3 degrees, but is reduced by the earth’s thermal inertia, of course you would see a negative feedback. It is just due to the fact that the temperature amplitude is not the forced amplitude (and is also lagged). If you want to see a much bigger negative feedback, try the same calculation for the diurnal cycle.
In summary, Dr. Spencer has rediscovered the annual cycle and thermal inertia, which would be obvious if he displayed his data as a time series of the two variables.
jeff brown says: (May 7, 2010 at 3:54 pm
“Dirk at the summer solstice the north pole receives more incoming solar energy than anyplace else on earth.”
Please explain this. At the summer solstice the Sun is directly overhead at 23.5 degrees N, the Tropic of Cancer. It is daylight there for approx 14 hours. Although the north pole receives 24 hours of daylight, wouldn’t the Sun be too low on the horizon for most of that time to allow the total solar energy to be higher than at the Tropic of Cancer?
Tom in Florida
Please explain this. At the summer solstice the Sun is directly overhead at 23.5 degrees N, the Tropic of Cancer. It is daylight there for approx 14 hours. Although the north pole receives 24 hours of daylight, wouldn’t the Sun be too low on the horizon for most of that time to allow the total solar energy to be higher than at the Tropic of Cancer?>>
http://wattsupwiththat.com/2010/02/28/sense-and-sensitivity/
Espen
May 8, 2010 at 9:17 am
“Far north temperatures are very volatile, they were in the same range as now in the thirties and forties. In addition, temperatures in winter are extremely sensitive to siting issues, and unfortunately too many of the stations still in use are now located at airports.”
Well, could be that natural variation and siting problems explain everything, but Klotzbach et al suggested the surface/satellite discrepancy is mostly related to changes in the non-turbulent air layer near the surface, not siting problems. Lots of published work suggest that warming from 1975 on has been greater at high northern latitudes, and this is seen pretty clearly in the satellite data ( http://www.remss.com/data/msu/graphics/plots/MSU_AMSU_Channel_TLT_Trend_Map_v03_2.png ). The satellite data doesn’t show quite as much warming as the land surface measurements, but clearly shows significant warming. Siting biases in ground data can’t influence satellite data. So it could be all this warming is completely natural, but if so, a mechanism remains to be identified.
R Gates
Since you are aware of the change in minimum extent over the last three years, you’re being intellectually dishonest in pointing the ice extent at this present date. There is very little year to year variability in ice extent for this time of year.
DavidMHofer,
from the link,
“As a side note, one thing that is not generally recognized is that the poles during summer get the highest daily average insolation of anywhere on earth. This is because, although they don’t get a lot of insolation even during the summer, they are getting it for 24 hours a day. This makes their daily average insolation much higher than other areas. But I digress …)”
So, explain why this does not translate into no ice every summer??
How about cold ocean and high albedo even with melted ice due to the low angle of the insolation to the surface…
DavidMHofer,
You may also want to consider cloud cover. During the 2007 extreme there was an abnormal high pressure zone sitting over the north pole that created a record low for clouds also. Insolation truly was high during that exceptional event.
RE: kuhnkat (May 8, 2010 at 7:06 pm) “During the 2007 extreme there was an abnormal high pressure zone sitting over the north pole that created a record low for clouds also. Insolation truly was high during that exceptional event.”
Very interesting. I have not seen any information about the typical formation of seasonal stationary high or low pressure areas in the Arctic region. It seems to me that the high-pressure cell you described could also have a strong Chinook or ‘ice eating’ region at its central core caused by descending dry air.
Excellent analysis and I cannot wait for it to be published so I can add it to the list,
700 Peer-Reviewed Papers Supporting Skepticism of “Man-Made” Global Warming
0.5 deg. C of warming by the end of this century? Is that all? Batten down the hatches for another !
evanmjones says:
May 7, 2010 at 2:33 pm
One can conclude from this that CO2 may be a thumb on the scale, but it doesn’t appear to be a primary driver.
How much proof will be needed before undue attention on co2 ends? Money is the thumb on that scale.
Dr Roy Spencer
You wrote,
Simple linear regression yields a net feedback factor of 5.8 Watts per sq. meter per degree C. If this was the feedback operating with global warming, then it would amount to only 0.6 deg. C of human-caused warming by late in this century.
Is it by accident that your 0.6 deg C warming per century is identical to the linear warming of 0.6 deg C per century in this chart:
http://wattsupwiththat.files.wordpress.com/2010/04/orssengo3.png
And any observed global warming rate above 0.06 deg C per decade is due to the cyclic component of the global mean temperature?
Girma Orssengo
Dr Roy Spencer
You wrote,
Simple linear regression yields a net feedback factor of 5.8 Watts per sq. meter per degree C. If this was the feedback operating with global warming, then it would amount to only 0.6 deg. C of human-caused warming by late in this century.
How do you get 0.6 deg C per century from 5.8 Watts per Sq. meter per Degree C?
Is there a formula for it? What is it?
Girma Orssengo
barefootgirl says:
May 8, 2010 at 12:14 pm
“Or sea ice versus CO2 which Johanneson tried to publish on a few years ago to say that CO2 causes the sea ice loss, and that in the future there will be no sea ice as CO2 increases? I rejected the paper because it was based on simple correlation rather than including the physics of the system.”
Do you mean this press article from last year: http://translate.google.com/translate?js=y&prev=_t&hl=en&ie=UTF-8&layout=1&eotf=1&u=http%3A%2F%2Fwww.vg.no%2Fnyheter%2Futenriks%2Fklimatrusselen%2Fartikkel.php%3Fartid%3D542650&sl=no&tl=en
Here, Johannessen suggests that the Arctic will be ice free in winter by 2100, based on extrapolation of a correlation between CO2 and ice extent, where CO2 is assumed to cause 90% of the ice loss.
The most appalling about this isn’t the assumption that correlation equals causation, nor the linear extrapolation into the distant future of his trivial calculations, but the fact that some of these “climate scientists” don’t even understand the basic physics of the phenomenon they are researching. In this case, Johannessen doesn’t seem to understand that sea water freezes at -2C, and that it would require a temperature rise of about 30C to prevent sea water from freezing in the Arctic winter. Neither do some of these scientists seem to understand or accept that there are other “forcings” than man-made CO2 induced atmospheric temperature rise that influence climate and sea ice extent.
“Unfortunately many on this blog post don’t understand the basics of Arctic science and that is unfortunate.”
I think most people here are well educated and scientifically literate people, although only few may have any professional expertise in Arctic or atmospheric sciences. And yes, people here make mistakes and use wrong assumptions, sometimes leading to erroneous conclusions. But the people here aren’t the ones demanding that the entire world population change their lifestyles, reduce their living standards, give up their livelihoods, pay trillions in extraordinary “climate” taxes, and give up their democratic rights for an unelected world governance under UN rule. These are the demands of the alarmists and their supporting “climate scientists.”
The most appalling is when alarmists and “climate scientists” that make such demands, do not understand the basic physics of their own “science.”
Skye,
You list out a number of climate sensitivity estimates (ignoring the one by Schwartz which is at the low end of your range) and ask how Dr. Spencer’s results compare to them. Most of these estimates are based on surface temp records by CRU or GISS. If these surface temp records have a warming bias, as Anthony’s SurfaceStations.org project suggests they might, then the estimates of climate sensitivity will be hugely exaggerated. Spencer’s work is based on tropospheric temps as measured by satellites. I hope this helps.