Warming Caused by Soot, Not CO2
From the Resilient Earth
Submitted by Doug L. Hoffman on Wed, 07/15/2009 – 13:19
A new paper in Science reports that a careful study of satellite data show the assumed cooling effect of aerosols in the atmosphere to be significantly less than previously estimated. Unfortunately, the assumed greater cooling has been used in climate models for years. In such models, the global-mean warming is determined by the balance of the radiative forcings—warming by greenhouse gases balanced against cooling by aerosols. Since a greater cooling effect has been used in climate models, the result has been to credit CO2 with a larger warming effect than it really has.
This question is of great importance to climate modelers because they have to be able to simulate the effect of GHG warming in order to accurately predict future climate change. The amount of temperature increase set into a climate model for a doubling of atmospheric CO2 is called the model’s sensitivity. As Dr. David Evans explained in a recent paper: “Yes, every emitted molecule of carbon dioxide (CO2) causes some warming—but the crucial question is how much warming do the CO2 emissions cause? If atmospheric CO2 levels doubled, would the temperature rise by 0.1°, 1.0°, or by 10.0° C?”
Temperature sensitivity scenarios from IPCC AR4.
The absorption frequencies of CO2 are already saturated, meaning that the atmosphere already captures close to 100% of the radiation at those frequencies. Consequently, as the level of CO2 in the atmosphere increases, the rise in temperature for a given increase in CO2 becomes smaller. This sorely limits the amount of warming further increases in CO2 can engender. Because CO2 on its own cannot account for the observed temperature rise in the past century, climate modelers assume that linkages exist between CO2 and other climate influences, mainly water vapor (for a more detailed explanation of what determines the Global Warming Potential of a gas see my comment “It’s not that simple”).
To compensate for the missing “forcing,” models are tuned to include a certain amount of extra warming linked to carbon dioxide levels—extra warming that comes from unestablished feedback mechanisms whose existence is simply assumed. Aerosol cooling and climate sensitivity in the models must balance each other in order to match historical conditions. Since the climate warmed slightly last century the amount of warming must have exceeded the amount of cooling. As Dr. Roy Spencer, meteorologist and former NASA scientist, puts it: “They program climate models so that they are sensitive enough to produce the warming in the last 50 years with increasing carbon dioxide concentrations. They then point to this as ‘proof’ that the CO2 caused the warming, but this is simply reasoning in a circle.”
A large aerosol cooling, therefore, implies a correspondingly large climate sensitivity. Conversely, reduced aerosol cooling implies lower GHG warming, which in turn implies lower model sensitivity. The upshot of this is that sensitivity values used in models for the past quarter of a century have been set too high. Using elevated sensitivity settings has significant implications for model predictions of future global temperature increases. The low-end value of model sensitivity used by the IPCC is 2°C. Using this value results, naturally, in the lowest predictions for future temperature increases. According to the paper “Consistency Between Satellite-Derived and Modeled Estimates of the Direct Aerosol Effect” published in Science on july 10, 2009, Gunnar Myhre states that previous values for aerosol cooling are too high—by as much as 40 percent—implying the IPCC’s model sensitivity settings are too high also. Here is the abstract of the paper:
In the Intergovernmental Panel on Climate Change Fourth Assessment Report, the direct aerosol effect is reported to have a radiative forcing estimate of –0.5 Watt per square meter (W m–2), offsetting the warming from CO2 by almost one-third. The uncertainty, however, ranges from –0.9 to –0.1 W m–2, which is largely due to differences between estimates from global aerosol models and observation-based estimates, with the latter tending to have stronger (more negative) radiative forcing. This study demonstrates consistency between a global aerosol model and adjustment to an observation-based method, producing a global and annual mean radiative forcing that is weaker than –0.5 W m–2, with a best estimate of –0.3 W m–2. The physical explanation for the earlier discrepancy is that the relative increase in anthropogenic black carbon (absorbing aerosols) is much larger than the overall increase in the anthropogenic abundance of aerosols.
The complex influence of atmospheric aerosols on the climate system and the influence of humans on aerosols are among the key uncertainties in the understanding recent climate change. Rated as one of the most significant yet poorly understood forcings by the IPCC there has been much activity in aerosol research recently (see Airborne Bacteria Discredit Climate Modeling Dogma and African Dust Heats Up Atlantic Tropics). Some particles absorb sunlight, contributing to climate warming, while others reflect sunlight, leading to cooling. The main anthropogenic aerosols that cause cooling are sulfate, nitrate, and organic carbon, whereas black carbon absorbs solar radiation. The global mean effect of human caused aerosols (in other words, pollution) is a cooling, but the relative contributions of the different types of aerosols determine the magnitude of this cooling. Readjusting that balance is what Myhre’s paper is all about.
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Discrepancies between recent satellite observations and the values needed to make climate models work right have vexed modelers. “A reliable quantification of the aerosol radiative forcing is essential to understand climate change,” states Johannes Quaas of the Max Planck Institute for Meteorology in Hamburg, Germany. Writing in the same issue of Science Dr. Quaas continued, “however, a large part of the discrepancy has remained unexplained.” With a systematic set of sensitivity studies, Myhre explains most of the remainder of the discrepancy. His paper shows that with a consistent data set of anthropogenic aerosol distributions and properties, the data-based and model-based approaches converge.
Myhre argues that since preindustrial times, soot particle concentrations have increased much more than other aerosols. Unlike many other aerosols, which scatter sunlight, soot strongly absorbs solar radiation. At the top of the atmosphere, where the Earth’s energy balance is determined, scattering has a cooling effect, whereas absorption has a warming effect. If soot increases more than scattering aerosols, the overall aerosol cooling effect is smaller than it would be otherwise. According to Dr. Myhre’s work, the correct cooling value is some 40% less than that previously accepted by the IPCC.
Not that climate modelers are unaware of the problems with their creations. Numerous papers have been published that detail problems predicting ice cover, precipitation and temperature correctly. This is due to inadequate modeling of the ENSO, aerosols and the bane of climate modelers, cloud cover. Apologists for climate modeling will claim that the models are still correct, just not as accurate or as detailed as they might be. Can a model that is only partially correct be trusted? Quoting again from Roy Spencer’s recent blog post:
It is also important to understand that even if a climate model handled 95% of the processes in the climate system perfectly, this does not mean the model will be 95% accurate in its predictions. All it takes is one important process to be wrong for the models to be seriously in error.
Can such a seemingly simple mistake in a single model parameter really lead to invalid results? Consider the graph below, a representation of the predictions made by James Hansen to the US Congress in 1988, plotted against how the climate actually behaved. Pretty much what one would expect if the sensitivity of the model was set too high, yet we are still supposed to believe in the model’s results. No wonder even the IPCC doesn’t call their model results predictions, preferring the more nebulous term “scenarios.”
Now that we know the models used by climate scientists were all tuned incorrectly what does this imply for the warnings of impending ecological disaster? What impact does this discovery have on the predictions of melting icecaps, rising ocean levels, increased storm activity and soaring global temperatures? Quite simply they got it wrong, at least in as much as those predictions were based on model results. To again quote from David Evans’ paper:
None of the climate models in 2001 predicted that temperatures would not rise from 2001 to 2009—they were all wrong. All of the models wrongly predict a huge dominating tropical hotspot in the atmospheric warming pattern—no such hotspot has been observed, and if it was there we would have easily detected it.
Once again we see the shaky ground that climate models are built on. Once again a new paper in a peer reviewed journal has brought to light significant flaws in the ways models are configured—forced to match known historical results even when erroneous values are used for fundamental parameters. I have said many times that, with enough tweaking, a model can be made to fit any set of reference data—but such bogus validation does not mean the model will accurately predict the future. When will climate science realize that its reputation has been left in tatters by these false prophets made of computer code?
Be safe, enjoy the interglacial and stay skeptical.
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ADDENDUM BY ANTHONY
I’d like to add this graph showing CO2’s temperature response to supplement the one Doug Hoffman cites from IPCC AR4. here we see that we are indeed pretty close to saturation of the response.
The “blue fuzz” represents measured global CO2 increases in our modern times.
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I think Scenario A and B are the same with the a different volcanic forcing. I think Hansen said “B” was “most likely”.
I would guess that due to the movements of the air circulation systems and the patchy geographical operation of the hydrological cycle the rate of energy transfer from air to space is irregular.
Put that on top of the longer term irregularity and patchy geographical variation of the rate of emission of energy from oceans to air and there is plenty of scope for discontinuities in the energy flow through the depth of the air.
As per my general climate description the oceans introduce irregularities in the energy flow from sun to ocean to air.
It is then left to the air to try to arrange that energy leaving the system in radiated longwave is much the same as energy coming in as solar shortwave.
Irregularities in the rate of energy transfer from air to space work to smooth out irregularities in the rate of energy transfer from oceans to air.
The mechanism is the latitudinal positions of the air circulation systems which in turn controls the speed of the hydrological cycle. As a fortuitous by product that mechanism also neutralises the climate effect of ANY changes in the composition of the air alone whether it be CO2, water vapour, other GHGs or indeed aerosols.
It must be so for oceans of water on our planet to exist at all. If any significant imbalance were ever to have occurred then the oceans would have long gone.
Nothing in current climatology considers irregular flows of energy between sea and air and between air and space underpinned by another level of irregularity in solar input. The models currently work backwards from meteorolgical observations rather than forward from measurements of net energy flow in and out of the different sections (oceans and air) of the system. It’s like trying to work out how a car engine works by watching the driver.
I am suggesting an entirely new perspective.
I think I’ve nailed it but the Earth will verify or rebut what I say over time now that everyone’s attention is so closely focused on these issues.
The work of Arrhenius, Tyndall et al relates only to the air in isolation. It has no climate significance because the equilibrium temperature is set by the oceans and not by any characteristic of the air. Indeed the air circulation systems always work back towards ensuring that the surface air temperature matches the sea surface temperatures whatever attempts are made by ANY changes in the air to cause a divergence.
Their work has been misapplied to the climate system as a whole so that our models are entirely out of synchronisation with reality.
@ur momisugly geo (08:24:11) :
There are three scenario’s, A, B, and C. A had an increasing rate of CO2 emissions, B had constant rate of CO2 emissions, whereas scenario C had reduced CO2 emissions rate from 1988 levels into the future.
And guess what, the global (even GISS) are below the prediction made for scenario C wich is pretty amazing since we are still following scenario A when it comes to CO2-emissions.
@geo
Hansen’s Scenario A was expected an ‘exponential’ rise on CO2 levels, (or at least higher rise than what is really happening). Scenario B shows a linear rise on CO2 levels, more or less similar to what really happened (with CO2 rise, not temperature rise) and Scenario C shows stagnant or slow declining CO2 levels.
As a set-up, the experiment was nicely designed, it reminds the Goldilocks tale, one scenario shows what the models say if the CO2 levels rise too much, the other if the CO2 levels don’t go up, and the middle one turned out just right.
geo (08:24:11)
“If people are saying that we’re really on “Scenario B” now, isn’t that the same as admitting there has already been significant effective reduction of the growth of C02 in the atmosphere?”
Only measured against predicted growth – i.e. the prediction was wrong. Actual growth in CO2 has been steady.
The point being that CO2 has continued to grow at “business as usual” levels and tempratures have not. By a long way.
Stephen Wilde (09:22:55) : I have seen people claim that air currents determine ocean currents. I don’t see how that’s possible given the difference in density between air and water. It seems the two systems would be mostly independent WRT movement. The spinning of the Earth will put into play forces on the oceans just as it does the air. The effect of the spinning will affect each system independently. Then, warming from the Sun will affect both systems. There will be some interaction between the two WRT heat, but how can wind drive the ocean currents?
WRT to high altitude CO2, it is very sparse. It seems photons of any frequency could escape that upper layer. Then there is the line broadening due to pressure for lower CO2. The photons from the “wings” won’t even get absorbed by the upper level CO2 which will have narrow absorption band.
I just don’t understand the great emphasis by climatologists on the upper atmosphere CO2 – there’s just not much of it per unit volume due to the low pressure.
I don’t know why DJ chose an 8 year old paper, so much has been learned between now and then, perhaps some AGW believers just feel like it’s convienent to think it’s just CO2 warming the climate without any other variables.
Since getting CO2 to 1000 PPM (greenhouse levels) isn’t going to cause much of a rise in temps. maybe we should get it there and cap the level there, imagine all the increased plant productivity 😉
It seems like the reported study that aerosols cause much less cooling than believed really does seem to damage the AGW based argument of the 1970’s global cooling scare.
About Sea Level rise caused by man-made water displacement, that may have a grain of truth, considering the ocean being full of stuff like super-tankers displacing the water, it’s like when you put a boat in your bathtub and the water rises.
>>>Observations of noctilucent clouds come in from
>>>all over the world (dimming?)
I was flying back across Europe just three days ago, and the noctilucent clouds were so bright they made midnight zulu look like a pre-dawn glow.
Not seen high-level cloud cover like this for a long time.
Methinks the AGW’ers doth protest too much about their ABC’s to make sure we don’t read this little jewel:
“As Dr. David Evans explained in a recent paper: “Yes, every emitted molecule of carbon dioxide (CO2) causes some warming—but the crucial question is how much warming do the CO2 emissions cause? If atmospheric CO2 levels doubled, would the temperature rise by 0.1°, 1.0°, or by 10.0° C?”
—-
OK. so the democrats’ ENTIRE 1.6 trillion dollar global socialist boondoogle for the UN consists of:
Assume a forcing multiplier (a constant) for a doubling of CO2.
Assume a future CO2 trend.
Extrapolate that CO2 trend 1000 years.
Multiply.
Plot a graph for the next 100 years based on an old 30 year trend from 1970 to 1998.
Extrapolate the graph for 600, 800, or 1000 years as required.
Assume xxx or yyy (very bad) effect from the extrapolated temperatures.
Promote assumed zzzz and wwww (very bad) results of the (very bad) effect from the extrapolated temperature based on the extrapolated graph based on the assumed constant for the assumed CO2 extrapolated for 400, 600, or 800 years.
Propagandize the wwww and zzzzz results for all to see, but allow nobody to criticize or debate your process.
Allow 2 hours to pass an incomplete, unread bill regulating the country’s economy for 800 years, because you have to leave for a four week vacation.
—
From his comments, Hansen’s actual “program” merely consists of assigning that single assumed forcing variable for CO2, assigning the assumed constant for aerosols and soot to fit the 1940-1970 downward temperature trend, then printing a temperature rise for the next few years.
Jim (06:19:16) : In clouds water is ionized, as OH- H+. When there is CO2 it reacts with water, in an endothermic (sucking heat in) reaction forming H2CO3 (carbonic acid). SO2 it is also as SO2-, when reacting with ionized water in clouds form H2SO3, sulphurous acid. Both after reacting are already droplets which not having electric charge cannot “float” any longer in clouds and fell down.
BTW : I would like to see if someone, any world environmental organization can impose or enforce any penalties or sanctions whatsoever or even close a VOLCANO for breaking environmental laws.
Any Volcano can produce trillions more SO2, even HCl (as last year a chilean volcano) than all world refineries taken together.
Well I’d like to start by giving both Doug Hoffman, and Anmthony a full pardon for the material in both the paper Doug presents,a nd Anthony’s graph.
You two chaps are held quite blameles; and earn kudos for exposing this chicanery.
Lets get rid of that silly CO2 triple graph first. Note that it starts at 255Kelvins at zero CO2 in the atmosphere, and also note that absolutely nobody has ever observed the mean global temperature whent he atmospheric CO2 was 250 ppm or lower; I’m being generous; I could go up to 280 ppm.
So that puts the global temperature at 285K.
Now that 255K for zero CO2 just happens to be the equilibrium black body temperature for an object at earth’s orbital location, with no atmospheric warming. I believe the normal earth 0.357 or whatever albedo is assumed.
So that zero CO2 starting point is also for zero water vapor.
So clearly those three curves, are computations and not observations and they obviously are total Balderdash; because water vapor on its own is going to run the temperature up to that 285Kelvin mark, with no CO2 or any other form of GHG.
The earth is in its present comfortable temperature range because of water vapor; not because of 250 ppm of CO2. If you look at the atmospheric absortion bands; even the Wiki ones at:
http://upload.wikimedia.org/wikipedia/commons/7/7c/Atmospheric_Transm,ission.png you will see that water is alread absorbing in the same spectral locations as CO2, and a whole bunch of other places as well.
So Nyet to that triple CO2 graph; it’s a total phony.
Back to Doug’s SCIENCE paper; I have SCIENCE piled all over my desk looking at other rubbish so I will have to find this paper too.
There’s a lot of information in there; and a lot of information that is not in there but hidden between the lines.
Am I the only one who thinks these “Scientists” are just making stuff up as they go along.
Did you notice how they explained in so much detail, how “aerosols” and particulates such as black soot, and dust, and microbes too, act as nucleation centers for water droplets to form clouds; no they waffle on about how thoise things scatter the sunlight to cause cooling, and then absorb it to cause warming; but nary a word about cloud formation. Now I don’t know a lot about cloud chemistry; I’m not a chemist, and I know it is a complex subject; but just go bacl and take a peek at that beautiful Volcanic eruption cloud of dust and black soot, and aerosols of all kinds; and the beautiful cloud forming right on top of the volcanic muck; not to mention the beautiful fairy circle burnbed in the clouds by the hot gases escaping from the mountain; hey I have it as my screen wall paper.
Every member of the US Congress should be forced to read this paper that Doug has exposed to us; and then they should be asked to write a four page essay, on what they leasnred about the state of “climate science”, or what passes for science in theis weird world where ancient astrology and economic science are close neighbors.
Thanks Doug, and Anthony; it’s a great way to start my day with a great laugh. If it wasn’t such a seriosu matter; it would be hilarious.
I don’t thin ther’s enough room on my hard drive for me to write a full criticism of the gobbledegook in this revelation that doug presents here.
It’s time for some of the big names in “Climatology” like Prof Lindzen, Roy Spencer etc to start screaming for this so-called science discipline to clean up its act, and start creating models that mimic the laws of Physics, instead of curve fitting a bunch of highly suspect and controversial raw “data”
George
PS for those who don’t read Scientific American Magazine; be informed that Anthony Watts hit the big time, and got a whole article written about him and his phony owl box expose.
Sorry I didn’t bring this latest issue in but they are reall y trying to do the CYA job; and failing badly; they try to excuse away the phony ice and temperature data that Anthony has been alerting us too, and essentially vclaim that fudging the data is pretty much normal operating procedure. Way to go Anthony !
REPLY: Hi George. I don’t see anything on the SciAm website. Is this the print edition only? If they wrote an article about me, I’m unaware of it. You’d think if they had any journalism skills they would at least call me and ask a question or two first. – Anthony
One question about soot, which the paper declares causes warming. Hey it may warm the soot by absorbing solar energy; but then that energy doesn’t reach the ground so it would cool the fround; And by catching the solar energy high in the atmosphere, those black partilces can then radiate IR from the upper atmosphere, and send that energy back into space.
I know I have read articles that were all over the place around the last Olympic Games that claimed that China is experienceing globale cooling (for their part of the globe) because of all of their dirty coal fired power plants, they put out so much soot that it swamps any CO2 caused warming.
That’s waht these articles claimed.
Soot it is not an areosol properly, these are carbon particles suspended which as soon as there is enough wind or rain fell down to ground.
DJ (01:51:27) :
“Hansen published 3 scenarios (http://www.pnas.org/content/103/39/14288.full). Why show just one which is FAR too high in its CO2 emissions? This tactic has been used before”
So why did Hansen show it? Scare tactic?
I’m not sold that Hansen’s Scenario A isn’t what is happening, or worse. If the rate of increase was ‘exponential’ on the order of 1.5%/yr (doing a quick BOE calculation) — if the amount of CO2 added to the atmosphere (if you are willing to assume 100% of it is anthropogenic in origin) in 1988 was 1.5ppm then an increase of 1.5%/yr means that by 2006 the amount would be around 1.94ppm/yr, which is right about where we were in 2006.
So I think we are closer to scenario A than B.
While I think Dr Hansen is correct in that that rate of increase is not sustainable over the long run, I think that the continued increase in CO2 generation by India and China will keep it close for the next 10 years or so.
Moderator – can you add this to my previous comment — thanks if you can
“”” bill (08:20:57) :
One should remember that the spectral absorption lines are much narrower than potrayed in most of these. CO2 absorbs at many discrete wavelengths not just a block for example from 4 to 5 um A more detailed transmissio plot of the atmosphere is given below:
http://img151.imageshack.us/img151/278/atmtransmwave.jpg
A research paper showing the narrowness of the bands for water/ch4/co2 is available here:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA039380&Location=U2&doc=GetTRDoc.pdf
Note that as pressure increases absorption increases (i.e. more nearer ground)
Note that as temp changes from 245 to 310 the absoption peak changes from 13.86um to 13.89um which will mean high level co2 will absorb a different wavelength to ground level. As DJ said in DJ (01:51:27) : CO2 is not saturated. it is nearing saturation! “””
Bill, are those absorption spectra you linked to actual measured atmospheric transmission spectra, or are they calculated theoretical spectra ?
All the data sources I have on such spectra, which are for military equipment IR purposes, have only calculated spectra, and they say that Doppler and Collision broadening end up smudging the real world spectra into continuous bands.
As for the temperature shift going from 13.86 up to 13.89 microns for CO2, I think you will admit, that that shift of the actual molecular resonance, is totally negligible compared to the very much larger Wien’s displacement shift in the thermal emission spectrum of the atmosphere, with temperature.
For the earth’s surface temperature range from -90C to +60C, the emission specrum peak shifts from about 15 microns down to 8.6 microns; so the CO2 temperature effect is irrelevent.
George
George E. Smith (10:30:23) : More and more, I appreciate your comments. One difference between CO2 and H2O is the liquification point. CO2 is a gas even at the poles, so it is always in the atomosphere to add some heat. I have wondered if CO2 isn’t like a pilot light on a gas water heater whose function is mainly to keep the air hot enough to keep water vapor in play. I wonder what would happen if there were no green house gasses. Would water liquify, then the entire Earth turn into a Snowball? Maybe we could model it?? 🙂
Nick Stokes (00:44:05) :
Have you now been tasked with commenting on non-pro AGW blogs in the run-up to Copenhagen?
How come the graph contains only scenario A and not scenario B which was the one the greenhouse forcing followed more closely. Why omit the correct line? Doesn’t this throw the rest of the article into doubt. I can’t trust it now on matters I don’t know much about when a matter I do know about isn’t presented correctly.
“”” MattN (05:55:02) :
Can anyone tell me if solar activity increases, will the energy availible in the band that CO2 absorbs also increase? If so, could *that* be what we’re seeing? “””
Matt, there is very little interraction between CO2 and the solar spectrum.
The lowest CO2 band is at about 1.9-2.0 microns, and the total solar energy longer than that wavelength is only a few percent, and only a small piece of that is taken out by CO2 There’s a 2.9 micron CO2 band bu5t only about 1% of solar energy is longer than that and the 2.9 band is quite narrow so doesn’t get much of that.
Besides, anything that absorbs some incoming solar energy results in cooling, because that energy doesn’t reach the ground; and the higher up in the atmosphere it gets absorbed, the quicker it can be radiatied back into space.
Nogw (10:22:42) : I find it hard to believe all the water in a cloud is ionized. The only thing necessary for the cloud particles to stay aloft would be a small particle size. Updrafts hold some larger particles up. Do you have a reference for the assertion that the water in a cloud is completely ionized? I wouldn’t think it would be even .001% ionized.
Murray Carpenter (05:33:17) : Jimmy Haigh (07:36:47) :
“half a brick”
Consider too sedimentation from the major rivers. At least in the USA this would have increased with settlement and farming practices. Also, consider levees along the Mississippi and tributaries that send more of the sediment into the Gulf. Then there are the channels cut through the Gulf coastal areas causing additional erosion. Forestry and construction in California, Oregon, and Washington states have added major sediment loads to the rivers flowing to the Pacific Ocean.
Now, maybe, you have a full brick.
Jim (09:55:35) :
Stephen Wilde (09:22:55) : I have seen people claim that air currents determine ocean currents. I don’t see how that’s possible given the difference in density between air and water. It seems the two systems would be mostly independent WRT movement. The spinning of the Earth will put into play forces on the oceans just as it does the air. The effect of the spinning will affect each system independently. Then, warming from the Sun will affect both systems. There will be some interaction between the two WRT heat, but how can wind drive the ocean currents?
It is called waves? Transferubg kinetic energy?
I hear that in the oceans they can be ten meters high and worse. Surface currents can be and are set up by steady winds. So things are not as independent as you are guessing,