Global Warming: Does CO2 Heat The Atmosphere? No ….

Original post here: http://wattsupwiththat.com/2010/08/05/co2-heats-the-atmosphere-a-counter-view/

CO2 heats the atmosphere…a counter view

A guest post on Watts Up What With That by : Tom Vonk (Tom is a physicist and long time poster at many climate blogs.

The simplistic view of CO2 heat trapping

If you search for “greenhouse effect” in Google and get 1 cent for statements like…

“CO2 absorbs the outgoing infrared energy and warms the atmosphere” - or - “CO2 traps part of the infrared radiation between ground and the upper part of the atmosphere”

…you will be millionaire .

Even Internet sites that are said to have a good scientific level like “Science of doom” publish statements similar to those quoted above . These statements are all wrong yet happen so often that I submitted this guest post to Anthony to clear this issue once for all.

In the case that somebody asks why there is no peer reviewed paper about this issue , it is because everything what follows is textbook material . We will use results from statistical thermodynamics and quantum mechanics that have been known for some 100 years or more . More specifically the statement that we will prove is :

A volume of gas in Local Thermodynamic Equilibrium (LTE) cannot be heated by CO2.

There are 3 concepts that we will introduce below and that are necessary to the understanding .

  1. The Local Thermodynamic Equilibrium (LTE)

This concept plays a central part so some words of definition . First what LTE is not . LTE is not Thermodynamic Equilibrium (TE) , it is a much weaker assumption . LTE requires only that the equilibrium exists in some neighborhood of every point . For example the temperature may vary with time and space within a volume so that this volume is not in a Thermodynamic Equilibrium . However if there is an equilibrium within every small subvolume of this volume , we will have LTE .

Intuitively the notion of LTE is linked to the speed with which the particles move and to their density . If the particle stays long enough in a small volume to interact with other particles in this small volume , for example by collisions , then the particle will equilibrate with others . If it doesn’t stay long enough then it can’t equilibrate with others and there is no LTE .

There are 2 reasons why the importance of LTE is paramount .

First is that a temperature cannot be defined for a volume which is not in LTE . That is easy to understand . The temperature is an average energy of a small volume in equilibrium . Since there is no equilibrium in any small volume if we have not LTE , the temperature cannot be defined in this case.

Second is that the energy distribution in a volume in LTE follows known laws and can be computed .

The energy equipartition law

Kinetic energy is present in several forms . A monoatomic gas has only the translational kinetic energy , the well known ½.m.V² . A polyatomic gas can also vibrate and rotate and therefore has in addition to the translational kinetic energy also the vibrational and the rotational kinetic energy . When we want to specify the total kinetic energy of a molecule , we need to account for all 3 forms of it .

Thus the immediate question we ask is : “If we add energy to a molecule , what will it do ? Increase its velocity ? Increase its vibration ? Increase its rotation ? Some mixture of all 3 ?”

The answer is given by the energy equipartition law . It says : “In LTE the energy is shared equally among its different forms .

As we have seen that the temperature is an average energy ,and that it is defined only under LTE conditions , it is possible to link the average kinetic energy <E> to the temperature . For instance in a monoatomic gas like Helium we have <E>= 3/2.k.T . The factor 3/2 comes because there are 3 translational degrees of freedom (3 space dimensions) and it can be reformulated by saying that the kinetic energy per translational degree of freedom is ½.k.T . From there can be derived ideal gas laws , specific heat capacities and much more . For polyatomic molecules exhibiting vibration and rotation the calculations are more complicated . The important point in this statistical law is that if we add some energy to a great number of molecules , this energy will be shared equally among their translational , rotational and vibrational degrees of freedom .

Quantum mechanical interactions of molecules with infrared radiation

Everything that happens in the interaction between a molecule and the infrared radiation is governed by quantum mechanics . Therefore the processes cannot be understood without at least the basics of the QM theory .

The most important point is that only the vibration and rotation modes of a molecule can interact with the infrared radiation . In addition this interaction will take place only if the molecule presents a non zero dipolar momentum . As a non zero dipolar momentum implies some asymmetry in the distribution of the electrical charges , it is specially important in non symmetric molecules . For instance the nitrogen N-N molecule is symmetrical and has no permanent dipolar momentum .

O=C=O is also symmetrical and has no permanent dipolar momentum . C=O is non symmetrical and has a permanent dipolar momentum . However to interact with IR it is not necessary that the dipolar momentum be permanent . While O=C=O has no permanent dipolar momentum , it has vibrational modes where an asymmetry appears and it is those modes that will absorb and emit IR . Also nitrogen N-N colliding with another molecule will be deformed and acquire a transient dipolar momentum which will allow it to absorb and emit IR .

In the picture left you see the 4 possible vibration modes of CO2 . The first one is symmetrical and therefore displays no dipolar momentum and doesn’t interact with IR . The second and the third look similar and have a dipolar momentum . It is these both that represent the famous 15µ band . The fourth is highly asymmetrical and also has a dipolar momentum .

What does interaction between a vibration mode and IR mean ?

The vibrational energies are quantified , that means that they can only take some discrete values . In the picture above is shown what happens when a molecule meets a photon whose energy (h.ν or ђ.ω) is exactly equal to the difference between 2 energy levels E2-E1 . The molecule absorbs the photon and “jumps up” from E1 to E2 . Of course the opposite process exists too – a molecule in the energy level E2 can “jump down” from E2 to E1 and emit a photon of energy E2-E1 .

But that is not everything that happens . What also happens are collisions and during collisions all following processes are possible .

  • Translation-translation interaction . This is your usual billiard ball collision .
  • Translation-vibration interaction . Here energy is exchanged between the vibration modes and the translation modes .
  • Translation-rotation interaction . Here energy is is exchanged between the rotation modes and the translation modes .
  • Rotation-vibration interaction … etc .

In the matter that concerns us here , namely a mixture of CO2 and N2 under infrared radiation only 2 processes are important : translation-translation and translation-vibration . We will therefore neglect all other processes without loosing generality .

The proof of our statement

The translation-translation process (sphere collision) has been well understood since more than 100 years . It can be studied by semi-classical statistical mechanics and the result is that the velocities of molecules (translational kinetic energy) within a volume of gas in equilibrium are distributed according to the Maxwell-Boltzmann distribution . As this distribution is invariant for a constant temperature , there are no net energy transfers and we do not need to further analyze this process .

The 2 processes of interest are the following :

CO2 + γ → CO2* (1)

This reads “a CO2 molecule absorbs an infrared photon γ and goes to a vibrationally excited state CO2*

CO2* + N2 → CO2 + N2⁺ (2)

This reads “a vibrationally excited CO2 molecule CO2* collides with an N2 molecule and relaxes to a lower vibrational energy state CO2 while the N2 molecule increases its velocity to N2⁺ “. We use a different symbol * and ⁺ for the excited states to differentiate the energy modes – vibrational (*) for CO2 and translational (⁺) for N2 . In other words , there is transfer between vibrational and translational degrees of freedom in the process (2) . This process in non equilibrium conditions is sometimes called thermalization .

The microscopical process (2) is described by time symmetrical equations . All mechanical and electromagnetical interactions are governed by equations invariant under time reversal . This is not true for electroweak interactions but they play no role in the process (2) .

Again in simple words , it means that if the process (2) happens then the time symmetrical process , namely CO2 + N2⁺ → CO2* + N2 , happens too . Indeed this time reversed process where fast (e.g hot) N2 molecules slow down and excite vibrationally CO2 molecules is what makes an N2/CO2 laser work. Therefore the right way to write the process (2) is the following .

CO2* + N2 ↔ CO2 + N2⁺ (3)

Where the use of the double arrow ↔ instad of the simple arrow → is telling us that this process goes in both directions . Now the most important question is “What are the rates of the → and the ← processes ?

The LTE conditions with the energy equipartition law give immediately the answer : “These rates are exactly equal .” This means that for every collision where a vibrationally excited CO2* transfers energy to N2 , there is a collision where N2⁺ transfers the same energy to CO2 and excites it vibrationally . There is no net energy transfer from CO2 to N2 through the vibration-translation interaction .

As we have seen that CO2 cannot transfer energy to N2 through the translation-translation process either , there is no net energy transfer (e.g “heating”) from CO2 to N2 what proves our statement .

This has an interesting corollary for the process (1) , IR absorption by CO2 molecules . We know that in equilibrium the distribution of the vibrational quantum states (e.g how many molecules are in a state with energy Ei) is invariant and depends only on temperature . For example only about 5 % of CO2 molecules are in a vibrationally excited state at room temperatures , 95 % are in the ground state .

Therefore in order to maintain the number of vibrationally excited molecules constant , every time a CO2 molecule absorbs an infrared photon and excites vibrationally , it is necessary that another CO2 molecule relaxes by going to a lower energy state . As we have seen above that this relaxation cannot happen through collisions with N2 because no net energy transfer is permitted , only the process (1) is available . Indeed the right way to write the process (1) is also :

CO2 + γ ↔ CO2* (1)

Where the use of the double arrow shows that the absorption process (→) happens at the same time as the emission process (←) . Because the number of excited molecules in a small volume in LTE must stay constant , follows that both processes emission/absorption must balance . In other words CO2 which absorbs strongly the 15µ IR , will emit strongly almost exactly as much 15 µ radiation as it absorbs . This is independent of the CO2 concentrations and of the intensity of IR radiation .

For those who prefer experimental proofs to theoretical arguments , here is a simple experiment demonstrating the above statements . Let us consider a hollow sphere at 15°C filled with air . You install an IR detector on the surface of the cavity . This is equivalent to the atmosphere during the night . The cavity will emit IR according to a black body law . Some frequencies of this BB radiation will be absorbed by the vibration modes of the CO2 molecules present in the air . What you will observe is :

  • The detector shows that the cavity absorbs the same power on 15µ as it emits
  • The temperature of the air stays at 15°C and more specifically the N2 and O2 do not heat

These observations demonstrate as expected that CO2 emits the same power as it absorbs and that there is no net energy transfer between the vibrational modes of CO2 and the translational modes of N2 and O2 . If you double the CO2 concentration or make the temperature vary , the observations stay identical showing that the conclusions we made are independent of temperatures and CO2 concentrations .

Conclusion and caveats

The main point is that every time you hear or read that “CO2 heats the atmosphere” , that “energy is trapped by CO2” , that “energy is stored by green house gases” and similar statements , you may be sure that this source is not to be trusted for information about radiation questions .

Caveat 1

The statement we proved cannot be interpreted as “CO2 has no impact on the dynamics of the Earth-atmosphere system” . What we have proven is that the CO2 cannot heat the atmosphere in the bulk but the whole system cannot be reduced to the bulk of the atmosphere . Indeed there are 2 interfaces – the void on one side and the surface of the Earth on the other side . Neither the former nor the latter is in LTE and the arguments we used are not valid . The dynamics of the system are governed by the lapse rate which is “anchored” to the ground and whose variations are dependent not only on convection , latent heat changes and conduction but also radiative transfer . The concentrations of CO2 (and H2O) play a role in this dynamics but it is not the purpose of this post to examine these much more complex and not well understood aspects .

Caveat 2

You will sometimes read or hear that “the CO2 has not the time to emit IR because the relaxation time is much longer than the mean time between collisions .” We know now that this conclusion is clearly wrong but looks like common sense if one accepts the premises which are true . Where is the problem ?

Well as the collisions are dominating , the CO2 will indeed often relax by a collision process . But with the same token it will also often excite by a collision process . And both processes will happen with an equal rate in LTE as we have seen . As for the emission , we are talking typically about 10ⁿ molecules with n of the order of 20 . Even if the average emission time is longer than the time between collisions , there is still a huge number of excited molecules who had not the opportunity to relax collisionally and who will emit . Not surprisingly this is also what experience shows .

http://wattsupwiththat.com/2010/08/05/co2-heats-the-atmosphere-a-counter-view/

Global Warming: Climate Gate – Mann’s Hockey Stick Findings Refuted – Irrelevant To Accurate Warming Predictions – Annals of Applied Statistics

From:

Watts Up With That? -  New paper makes a hockey “sticky wicket” of Mann et al 98/99/08

Sticky Wicket – phrase, meaning: “A difficult situation”.

http://wattsupwiththat.com/2010/08/17/breaking-new-paper-makes-a-hockey-sticky-wicket-of-mann-et-al-99/

Now, there’s a new look to the familiar “hockey stick”.

The “infamous Hockey Stick” below:

Multiproxy reconstruction of Northern Hemisphere surface temperature variations over the past millennium (blue), along with 50-year average (black), a measure of the statistical uncertainty associated with the reconstruction (gray), and instrumental surface temperature data for the last 150 years (red), based on the work by Mann et al. (1999). This figure has sometimes been referred to as the hockey stick. Source: IPCC (2001).

McShane and Wyner re-examine and replot the data below …

Backcast from Bayesian Model of Section 5. CRU Northern Hemisphere annual mean land temperature is given by the thin black line and a smoothed version is given by the thick black line. The forecast is given by the thin red line and a smoothed version is given by the thick red line. The model is fit on 1850-1998 AD and backcasts 998-1849 AD. The cyan region indicates uncertainty due to t, the green region indicates uncertainty due to β, and the gray region indicates total uncertainty.

“Not only are the results stunning, but the paper is highly readable, written in a sensible style that most laymen can absorb, even if they don’t understand some of the finer points of bayesian and loess filters, or principal components. Not only that, this paper is a confirmation of McIntyre and McKitrick’s work, with a strong nod to Wegman. I highly recommend reading this and distributing this story widely.”

http://wattsupwiththat.com/2010/08/17/breaking-new-paper-makes-a-hockey-sticky-wicket-of-mann-et-al-99/

The original paper submitted by McShane and Wyner to Annals of Applied Statistics here: A Statistical Analysis of Multiple Temperature Proxies: Are Reconstructions of Surface Temperatures Over the Last 1000 Years Reliable?

EXCERPT:

On the one hand, we conclude unequivocally that the evidence for a ”long-handled” hockey stick (where the shaft of the hockey stick extends to the year 1000 AD) is lacking in the data … Consequently, the long flat handle of the hockey stick is best understood to be a feature of regression and less a reflection of our knowledge of the truth… Climate scientists have greatly underestimated the uncertainty of proxy based reconstructions and hence have been overconfident in their models…  

Global Warming: IPCC Global Warming Model Used To Predict Temp Changes Overstates Warming By 60% – American Meteorological Society

Abstract

The observed increase in global mean surface temperature (GMST) over the industrial era is less than 40% of that expected from observed increases in long-lived greenhouse gases together with the best-estimate equilibrium climate sensitivity given by the 2007 Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Possible reasons for this warming discrepancy are systematically examined here. The warming discrepancy is found to be due mainly to some combination of two factors: the IPCC best estimate of climate sensitivity being too high and/or the greenhouse gas forcing being partially offset by forcing by increased concentrations of atmospheric aerosols; the increase in global heat content due to thermal disequilibrium accounts for less than 25% of the discrepancy, and cooling by natural temperature variation can account for only about 15%. Current uncertainty in climate sensitivity is shown to preclude determining the amount of future fossil fuel CO2 emissions that would be compatible with any chosen maximum allowable increase in GMST; even the sign of such allowable future emissions is unconstrained. Resolving this situation, by empirical determination of the earth’s climate sensitivity from the historical record over the industrial period or through use of climate models whose accuracy is evaluated by their performance over this period, is shown to require substantial reduction in the uncertainty of aerosol forcing over this period.

Why Hasn’t Earth Warmed as Much as Expected?

 

Stephen E. Schwartz Brookhaven National Laboratory, Upton, New York

Robert J. Charlson University of Washington, Seattle, Washington

Ralph A. Kahn NASA Goddard Space Flight Center, Greenbelt, Maryland

John A. Ogren NOAA/Earth System Research Laboratory, Boulder, Colorado

Henning Rodhe Department of Meteorology, Stockholm University, Stockholm, Sweden

http://journals.ametsoc.org/doi/abs/10.1175/2009JCLI3461.1

The full PDF of the  paper can be viewed here: http://journals.ametsoc.org/doi/pdf/10.1175/2009JCLI3461.1

Shame on Wikipedia: Web Site Allows RealClimate.Org To “Doctor” or “Delete” 5,428 climate articles –

The National Post exposes Wikipedia over climate information

Watts Up With That?
December 21, 2009

UPDATED: see stats below the “read more” line.

Lawrence Solomon at the National Post writes about a topic that WUWT readers have known about for a long time: How Wikipedia’s green doctor rewrote 5,428 climate articles.

We’ve known for some time that Wikipedia can’t be trusted to provide unbiased climate information. Solomon starts off by talking about Climategate emails.

The emails also describe how the band plotted to rewrite history as well as science, particularly by eliminating the Medieval Warm Period, a 400 year period that began around 1000 AD.

The Climategate Emails reveal something else, too: the enlistment of the most widely read source of information in the world — Wikipedia — in the wholesale rewriting of this history.

He then focuses on RealClimate.org co-founder William Connolley, who has “touched” 5,428 Wikipedia articles with his unique brand of RC centric editing:

All told, Connolley created or rewrote 5,428 unique Wikipedia articles. His control over Wikipedia was greater still, however, through the role he obtained at Wikipedia as a website administrator, which allowed him to act with virtual impunity. When Connolley didn’t like the subject of a certain article, he removed it — more than 500 articles of various descriptions disappeared at his hand. When he disapproved of the arguments that others were making, he often had them barred — over 2,000 Wikipedia contributors who ran afoul of him found themselves blocked from making further contributions. Acolytes whose writing conformed to Connolley’s global warming views, in contrast, were rewarded with Wikipedia’s blessings. In these ways, Connolley turned Wikipedia into the missionary wing of the global warming movement.

The Medieval Warm Period disappeared, as did criticism of the global warming orthodoxy. With the release of the Climategate Emails, the disappearing trick has been exposed. The glorious Medieval Warm Period will remain in the history books, perhaps with an asterisk to describe how a band of zealots once tried to make it disappear.

Wikipedia suffers from the same problem that climate science in general suffers from now. A few determined zealots have influenced the vast majority of the published information.

IMHO it is time for Connolley to step aside from Wikipedia, one person should not have so much influence over so many articles. At the same time, the number two person, almost as influential, is Kim Dabelstein Peterson. Here’s a National Review article on the kind of things Petersen has been doing in similar to the work of Connolley.

Additionally, there are many Wikipedia editors and contributors that do so anonymously, and I think that is terribly wrong. There’s no accountability, no quality control, and no recourse to people who falsify information, or mold it to fit a personal agenda. Wikipedia relies upon an honor system, and as we’ve seen from the Climategate emails, there’s no honor in some circles of climate science.

Here is another example:

The Opinionator

Posted: May 03, 2008, 2:53 AM by Lawrence Solomon

Connolley is not only a big shot on Wikipedia, he’s a big shot at Wikipedia — an Administrator with unusual editorial clout. Using that clout, this 40-something scientist of minor relevance gets to tear down scientists of great accomplishment. Because Wikipedia has become the single biggest reference source in the world, and global warming is one of the most sought after subjects, the ability to control information on Wikipedia by taking down authoritative scientists is no trifling matter.

One such scientist is Fred Singer, the First Director of the U.S. National Weather Satellite Service, the recipient of a White House commendation for his early design of space satellites; the recipient of a NASA commendation for research on particle clouds — in short, a scientist with dazzling achievements who is everything Connolley is not. Under Connolley’s supervision, Singer is relentlessly smeared, and has been for years, as a kook who believes in Martians and a hack in the pay of the oil industry. When a smear is inadequate, or when a fair-minded Wikipedian tries to correct a smear, Connolley and his cohorts are there to widen the smear or remove the correction, often rebuking the Wikipedian in the process.

Wikipedia founder Jimmy Wales recently put out an appeal for donations here. He writes:

I believe in us. I believe that Wikipedia keeps getting better. That’s the whole idea. One person writes something, somebody improves it a little, and it keeps getting better, over time. If you find it useful today, imagine how much we can achieve together in 5, 10, 20 years.

In a perfect world, maybe. In a perfect world unicorns frolic in the park, free money falls from the sky, and people are honest and without bias 100% of the time. But when you have Wikibullies, such as Connolley and Peterson, your honor system goes up in smoke. Fact is Jimmy, your honor system is as corrupted as the peer review process is for climate science these days. In my view, don’t give Wikipedia another dime until they make some changes to provide for a more responsible information environment.

Making free reference information available to the public shouldn’t be a battle of wills between Wikibullies with an agenda and the rest of society.

Here’s where to write to complain to Wikipedia:

Wikimedia Foundation

Postal address

Wikimedia Foundation Inc.
149 New Montgomery Street, 3rd Floor
San Francisco, CA 94105
USAPhone: +1-415-839-6885
Email: info@wikimedia.org
Fax: +1-415-882-0495 (note: we get a large number of calls; email or fax is always a better first option)

UPDATE: I’ve located Solomon’s source of information, an independent Wikipedia author tracker. Here is Connolley’s base statistics:

media  The National Post exposes broad trust issues over Wikipedia climate information

Click image for full report

http://www.sodahead.com/united-states/the-national-post-exposes-wikipedia-over-climate-information/blog-219897/

Shame on The IPCC: Climate Change Consensus Was Phoney – Climate Gate Continues

NATIONAL POST.COM

(The National Post is Canada’s largest english language national newspaper. The Post exposes how an ‘Editor” at Wikipedia “rewrote” 5,248 climate articles – http://www.sodahead.com/united-states/the-national-post-exposes-wikipedia-over-climate-information/blog-219897/). 

The IPCC consensus on climate change was phoney, says IPCC insider

 

Claims that 2500 scientists agreed were "disingenuous"

The UN’s Intergovernmental Panel on Climate Change misled the press and public into believing that thousands of scientists backed its claims on manmade global warming, according to Mike Hulme, a prominent climate scientist and IPCC insider.  The actual number of scientists who backed that claim was “only a few dozen experts,” he states in a paper for Progress in Physical Geography, co-authored with student Martin Mahony.

“Claims such as ‘2,500 of the world’s leading scientists have reached a consensus that human activities are having a significant influence on the climate’ are disingenuous,” the paper states unambiguously, adding that they rendered “the IPCC vulnerable to outside criticism.”

Hulme, Professor of Climate Change in the School of Environmental Sciences at the University of East Anglia –  the university of Climategate fame is the founding Director of the Tyndall Centre for Climate Change Research and one of the UK’s most prominent climate scientists. Among his many roles in the climate change establishment, Hulme was the IPCC’s co-ordinating Lead Author for its chapter on ‘Climate scenario development’ for its Third Assessment Report and a contributing author of several other chapters.

Hulme’s depiction of IPCC’s exaggeration of the number of scientists who backed its claim about man-made climate change can be found on pages 10 and 11 of his paper, found here.

Additional quotes taken from his paper:

Consensus and Uncertainty

Understanding consensus as a process of ‘truth creation’ (or the more nuanced ‘knowledge production’) which marginalizes dissenting voices – as has frequently been portrayed by some of the IPCC’s critics does not do justice to the process {the process of scientific investigation} ….

Consensus-building in fact serves several different goals. As Horst and Irwin have explained, seeking consensus can be as much about building a community identity – what Haas refers to as an epistemic community – as it is about seeking the ‘truth’.

Pielke and Sarewitz agree that the IPCC has failed in its role as an ‘honest-broker’ and has moved towards being an ‘issue advocate’ in Pielke’s terminology, or even on some occasions a ‘stealth issue advocate’.

Without a careful explanation about what it means, this drive for consensus can leave the IPCC vulnerable to outside criticism.

 Claims such as ‘2,500 of the world’s leading scientists have reached a consensus that human activities are having a significant influence on the climate’ are disingenuous. { –adjective lacking in frankness, candor, or sincerity; falsely or hypocritically ingenuous; insincere: Her excuse was rather disingenuous}.

That particular consensus judgment, as are many others in the IPCC reports, is reached by only a few dozen experts ….. questions about the status of climate change knowledge synthesized by the IPCC remain less widely investigated, questions which emerge from the agendas raised by the new geographers of science ……….knowledge that is claimed by its producers to have universal authority is received and interpreted very differently in different settings. …………

 http://fullcomment.nationalpost.com/2010/06/13/the-ipcc-consensus-on-climate-change-was-phoney-says-ipcc-insider/

Minority report: 50 year warming due to natural causes: 06/08/10 By Roy W Spencer, PhD

Minority report: 50 year warming due to natural causes

Minority report: 50 year warming due to natural causesPosted on June 7, 2010 by Anthony Watts  http://wattsupwiththat.com/2010/06/07/minority-report-50-year-warming-due-to-natural-causes/

Warming in Last 50 Years Predicted by Natural Climate Cycles

by Roy W. Spencer, Ph. D.

One of the main conclusions of the 2007 IPCC report was that the warming over the last 50 years was most likely due to anthropogenic pollution, especially increasing atmospheric CO2 from fossil fuel burning.

But a minority of climate researchers have maintained that some — or even most — of that warming could have been due to natural causes. For instance, the Pacific Decadal Oscillation (PDO) and Atlantic Multi-decadal Oscillation (AMO) are natural modes of climate variability which have similar time scales to warming and cooling periods during the 20th Century. Also, El Nino — which is known to cause global-average warmth — has been more frequent in the last 30 years or so; the Southern Oscillation Index (SOI) is a measure of El Nino and La Nina activity.

A simple way to examine the possibility that these climate cycles might be involved in the warming over the last 50 years is to do a statistical comparison of the yearly temperature variations versus the PDO, AMO, and SOI yearly values. But of course, correlation does not prove causation.

So, what if we use the statistics BEFORE the last 50 years to come up with a model of temperature variability, and then see if that statistical model can “predict” the strong warming over the most recent 50 year period? That would be much more convincing because, if the relationship between temperature and these 3 climate indicies for the first half of the 20th Century just happened to be accidental, we sure wouldn’t expect it to accidentally predict the strong warming which has occurred in the second half of the 20th Century, would we?

Temperature, or Temperature Change Rate?
This kind of statistical comparison is usually performed with temperature. But there is greater physical justification for using the temperature change rate, instead of temperature. This is because if natural climate cycles are correlated to the time rate of change of temperature, that means they represent heating or cooling influences, such as changes in global cloud cover (albedo).

Such a relationship, shown in the plot below, would provide a causal link of these natural cycles as forcing mechanisms for temperature change, since the peak forcing then precedes the peak temperature.
                                                                     

Predicting Northern Hemispheric Warming Since 1960
Since most of the recent warming has occurred over the Northern Hemisphere, I chose to use the CRUTem3 yearly record of Northern Hemispheric temperature variations for the period 1900 through 2009. From this record I computed the yearly change rates in temperature. I then linearly regressed these 1-year temperature change rates against the yearly average values of the PDO, AMO, and SOI.

I used the period from 1900 through 1960 for “training” to derive this statistical relationship, then applied it to the period 1961 through 2009 to see how well it predicted the yearly temperature change rates for that 50 year period. Then, to get the model-predicted temperatures, I simply added up the temperature change rates over time.

The result of this exercise in shown in the following plot.

What is rather amazing is that the rate of observed warming of the Northern Hemisphere since the 1970’s matches that which the PDO, AMO, and SOI together predict, based upon those natural cycles’ PREVIOUS relationships to the temperature change rate (prior to 1960).

Again I want to emphasize that my use of the temperature change rate, rather than temperature, as the predicted variable is based upon the expectation that these natural modes of climate variability represent forcing mechanisms — I believe through changes in cloud cover — which then cause a lagged temperature response.

This is powerful evidence that most of the warming that the IPCC has attributed to human activities over the last 50 years could simply be due to natural, internal variability in the climate system. If true, this would also mean that (1) the climate system is much less sensitive to the CO2 content of the atmosphere than the IPCC claims, and (2) future warming from greenhouse gas emissions will be small.

http://wattsupwiththat.com/2010/06/07/minority-report-50-year-warming-due-to-natural-causes/

The Great Global Warming Swindle – The Video Produced By WAGTV For The BBC

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