Guest commentary from Ben Santer
Part 2 of a series discussing the recent Guardian articles
A recent story by Fred Pearce in the February 9th online edition of the Guardian (“Victory for openness as IPCC climate scientist opens up lab doors”) covers some of the more publicized aspects of the last 14 years of my scientific career. I am glad that Mr. Pearce’s account illuminates some of the non-scientific difficulties I have faced. However, his account also repeats unfounded allegations that I engaged in dubious professional conduct. In a number of instances, Mr Pearce provides links to these allegations, but does not provide a balanced account of the rebuttals to them. Nor does he give links to locations where these rebuttals can be found. I am taking this opportunity to correct Mr. Pearce’s omissions, to reply to the key allegations, and to supply links to more detailed responses.
Another concern relates to Mr. Pearce’s discussion of the “openness” issue mentioned in the title and sub-title of his story. A naïve reader of Mr. Pearce’s article might infer from the sub-title (“Ben Santer had a change of heart about data transparency…”) that my scientific research was not conducted in an open and transparent manner until I experienced “a change of heart”.
This inference would be completely incorrect. As I discuss below, my research into the nature and causes of climate change has always been performed in an open, transparent, and collegial manner. Virtually all of the scientific papers I have published over the course of my career involve multi-institutional teams of scientists with expertise in climate modeling, the development of observational datasets, and climate model evaluation. The model and observational data used in my research is not proprietary – it is freely available to researchers anywhere in the world.
The 1995 IPCC Report: The “scientific cleansing” allegation
Mr. Pearce begins by repeating some of the allegations of misconduct that arose after publication (in 1996) of the Second Assessment Report (SAR) of the Intergovernmental Panel on Climate Change (IPCC). These allegations targeted Chapter 8 of the SAR, which dealt with the “Detection of Climate Change, and Attribution of Causes”. The IPCC SAR reached the historic finding that “The balance of evidence suggests a discernible human influence on global climate”. Information presented in Chapter 8 provided substantial support for this finding.
I served as the Convening Lead Author (CLA) of Chapter 8. There were three principal criticisms of my conduct as CLA. All three allegations are baseless. They have been refuted on many occasions, and in many different fora. All three allegations make an appearance in Mr. Pearce’s story, but there are no links to the detailed responses to these claims.
The first allegation was that I had engaged in “scientific cleansing”. This allegation originated with the Global Climate Coalition (GCC) – a group of businesses “opposing immediate action to reduce greenhouse gas emissions”.
In May 1996, a document entitled “The IPCC: Institutionalized ‘Scientific Cleansing’?” was widely circulated to the press and politicians. In this document, the Global Climate Coalition claimed that after a key Plenary Meeting of the IPCC in Madrid in November 1995, all scientific uncertainties had been purged from Chapter 8. The GCC’s “scientific cleansing” allegation was soon repeated in an article in Energy Daily (May 22, 1996) and in an editorial in the Washington Times (May 24, 1996). It was also prominently featured in the World Climate Report, a publication edited by Professor Patrick J. Michaels (June 10, 1996).
This “scientific cleansing” claim is categorically untrue. There was no “scientific cleansing”. Roughly 20% of the published version of Chapter 8 specifically addressed uncertainties in scientific studies of the causes of climate change. In discussing the “scientific cleansing” issue, Mr. Pearce claims that many of the caveats in Chapter 8 “did not make it to the summary for policy-makers”. This is incorrect.
The Summary for Policymakers (SPM) of the IPCC SAR is four-and-a-half pages long. Roughly one page of the SPM discusses results from Chapter 8. The final paragraph of that page deals specifically with uncertainties, and notes that:
“Our ability to quantify the human influence on global climate is currently limited because the expected signal is still emerging from the noise of natural variability, and because there are uncertainties in key factors. These include the magnitude and patterns of long term natural variability and the time-evolving pattern of forcing by, and response to, changes in concentrations of greenhouse gases and aerosols, and land surface changes”.
Contrary to Mr. Pearce’s assertion, important caveats did “make it to the summary for policy-makers”. And the “discernible human influence” conclusion of both Chapter 8 and the Summary for Policymakers has been substantiated by many subsequent national and international assessments of climate science.
There were several reasons why Chapter 8 was a target for unfounded “scientific cleansing” allegations. First, the Global Climate Coalitions’s “scientific cleansing” charges were released to the media in May 1996. At that time, Cambridge University Press had not yet published the IPCC Second Assessment Report in the United States. Because of this delay in the Report’s U.S. publication, many U.S. commentators on the “scientific cleansing” claims had not even read Chapter 8 – they only had access to the GCC’s skewed account of the changes made to Chapter 8. Had the Second Assessment Report been readily available in the U.S. in May 1996, it would have been easy for interested parties to verify that Chapter 8 incorporated a fair and balanced discussion of scientific uncertainties.
Second, the “pre-Madrid” version of Chapter 8 was the only chapter in the IPCC Working Group I Second Assessment Report to have both an “Executive Summary” and a “Concluding Summary”. As discussed in the next section, this anomaly was partly due to the fact that the Lead Author team for Chapter 8 was not finalized until April 1994 – months after all other chapters had started work. Because of this delay in getting out of the starting blocks, the Chapter 8 Lead Author team was more concerned with completing the initial drafts of our chapter than with the question of whether all chapters in the Working Group I Report had exactly the same structure.
The reply of the Chapter 8 Lead Authors to the Energy Daily story of May 22, 1996 pointed out this ‘two summary’ redundancy, and noted that:
“After receiving much criticism of this redundancy in October and November 1995, the Convening Lead Author of Chapter 8 decided to remove the concluding summary. About half of the information in the concluding summary was integrated with material in Section 8.6. It did not disappear completely, as the Global Climate Coalition has implied. The lengthy Executive Summary of Chapter 8 addresses the issue of uncertainties in great detail – as does the underlying Chapter itself.”
The removal of the concluding summary made it simple for the Global Climate Coalition to advance their unjustified “scientific cleansing” allegations. They could claim ‘This statement has been deleted’, without mentioning that the scientific issue addressed in the deleted statement was covered elsewhere in the chapter.
This was my first close encounter of the absurd kind.
The 1995 IPCC Report: The “political tampering/corruption of peer-review” allegation
The second allegation is that I was responsible for “political tampering”. I like to call this “the tail wags the dog” allegation. The “tail” here is the summary of the Chapter 8 results in the IPCC Summary for Policymakers, and the “dog” is the detailed underlying text of Chapter 8.
In November 1995, 177 government delegates from 96 countries spent three days in Madrid. Their job was to “approve” each word of the four-and-a-half page Summary for Policymakers of the IPCC’s Working Group I Report. This was the report that dealt with the physical science of climate change. The delegates also had the task of “accepting” the 11 underlying science chapters on which the Summary for Policymakers was based. “Acceptance” of the 11 chapters did not require government approval of each word in each chapter.
This was not a meeting of politicians only. A number of the government delegates were climate scientists. Twenty-eight of the Lead Authors of the IPCC Working Group I Report – myself included – were also prominent participants in Madrid. We were there to ensure that the politics did not get ahead of the science, and that the tail did not wag the dog.
Non-governmental organizations – such as the Global Climate Coalition – were also active participants in the Madrid meeting. NGOs had no say in the formal process of approving the Summary for Policymakers. They were, however, allowed to make comments on the SPM and the underlying 11 science chapters during the first day of the Plenary Meeting (November 27, 1996). The Global Climate Coalition dominated the initial plenary discussions.
Most of the plenary discussions at Madrid focused on the portrayal of Chapter 8’s findings in the Summary for Policymakers. Discussions were often difficult and contentious. We wrestled with the exact wording of the “balance of evidence” statement mentioned above. The delegations from Saudi Arabia and Kuwait argued for a very weak statement, or for no statement at all. Delegates from many other countries countered that there was strong scientific evidence of pronounced a human effect on climate, and that the bottom-line statement from Chapter 8 should reflect this.
Given the intense interest in Chapter 8, Sir John Houghton (one of the two Co-Chairs of IPCC Working Group I) established an ad hoc group on November 27, 1996. I was a member of this group. Our charge was to review those parts of the draft Summary for Policymakers that dealt with climate change detection and attribution issues. The group was placed under the Chairmanship of Dr. Martin Manning of New Zealand, and included delegates from the U.S., the U.K., Canada, Kenya, the Netherlands, and New Zealand. Sir John Houghton also invited delegates from Saudi Arabia and Kuwait to participate in this ad hoc group. Unfortunately, they did not accept this invitation.
The ad hoc group considered more than just the portions of the Summary for Policymakers that were relevant to Chapter 8. The Dutch delegation asked for a detailed discussion of Chapter 8 itself, and of the full scientific evidence contained in it. This discussion took place on November 28, 1996.
On November 29, 1996, I reported back to the Plenary on the deliberations of the ad hoc group. The Saudi Arabian and Kuwaiti delegations – who had not attended any of the discussions of the ad hoc group, and had no first-hand knowledge of what had been discussed by the group – continued to express serious reservations about the scientific basis for the detection and attribution statements in the Summary for Policymakers.
On the final evening of the Madrid Plenary Meeting, debate focused on finding the right word to describe the human effect on global climate. There was broad agreement among the government delegates that – based on the scientific evidence presented in Chapter 8 – some form of qualifying word was necessary. Was the human influence “measurable”? Could it be best described as “appreciable”, “detectable”, or “substantial”? Each of these suggested words had proponents and opponents. How would each word translate into different languages? Would the meaning be the same as in English?
After hours of often rancorous debate, Bert Bolin (who was then the Chairman of the IPCC) finally found the elusive solution. Professor Bolin suggested that the human effect on climate should be described as “discernible”.
Mr. Pearce – who was not present at the Madrid Plenary Meeting – argues that the discussion of human effects on climate in the IPCC Summary for Policymakers “went beyond what was said in the chapter from which the summary was supposedly drawn”. In other words, he suggests that the tail wagged the dog. This is not true. The “pre-Madrid” bottom-line statement from Chapter 8 was “Taken together, these results point towards a human influence on climate”. As I’ve noted above, the final statement agreed upon in Madrid was “The balance of evidence suggests a discernible human influence on global climate”.
Is “suggests” stronger than “points towards”? I doubt it. Is “The balance of evidence” a more confident phrase than “Taken together”? I don’t think so.
The primary difference between the pre- and post-Madrid statements is that the latter includes the word “discernible”. In my American Heritage College Dictionary, “discernible” is defined as “perceptible, as by vision or the intellect”. In Merriam-Webster’s Online Dictionary, one of the three meanings of the verb “discern” is “to recognize or identify as separate and distinct”. Was the use of “discernible” justified?
The answer is clearly “yes”. Chapter 8 of the IPCC’s Second Assessment Report relied heavily on the evidence from a number of different “fingerprint” studies. This type of research uses rigorous statistical methods to compare observed patterns of climate change with results from climate model simulations. The basic concept of fingerprinting is that each different influence on climate – such as purely natural changes in the Sun’s energy output, or human-caused changes in atmospheric levels of greenhouse gases – has a unique signature in climate records. This uniqueness becomes more apparent if one looks beyond changes averaged over the entire globe, and instead exploits the much greater information content available in complex, time-varying patterns of climate change.
Fingerprinting has proved to be an invaluable tool for untangling the complex cause-and-effect relationships in the climate system. The IPCC’s Second Assessment Report in 1995 was able to draw on fingerprint studies from a half-dozen different research groups. Each of these groups had independently shown that they could indeed perceive a fingerprint of human influence in observed temperature records. The signal was beginning to rise out of the noise, and was (using Merriam-Webster’s definition of “discern”) “separate and distinct” from purely natural variations in climate.
Based on these fingerprint results, and based on the other scientific evidence available to us in November 1995, use of the word “discernible” was entirely justified. Its use is certainly justified based on the scientific information available to us in 2010. The “discernible human influence” phrase was approved by all of the 177 delegates from 96 countries present at the Plenary Meeting – even by the Saudi and Kuwaiti delegations. None of the 28 IPCC Lead Authors in attendance at Madrid balked at this phrase, or questioned our finding that “the balance of evidence suggests a discernible human influence on global climate”. The latter statement was cautious and responsible, and entirely consistent with the state of the science. The much more difficult job of trying to quantify the size of human influences on climate would be left to subsequent IPCC assessments.
Mr. Pearce’s remarks suggest that there is some substance to the “political tampering” allegation – that I was somehow coerced to change Chapter 8 in order to “reflect the wording of the political summary”. This is untrue. There was no political distortion of the science. If Mr. Pearce had been present at the Madrid Plenary Meeting, he would have seen how vigorously (and successfully) scientists resisted efforts on the part of a small number of delegates to skew and spin some of the information in the Summary for Policymakers.
The key point here is that the SPM was not a “political summary” – it was an accurate reflection of the science. Had it been otherwise, I would not have agreed to put my name on the Report.
A reader of Mr. Pearce’s article might also gain the mistaken impression that the changes to Chapter 8 were only made in response to comments made by government delegates during the Madrid Plenary Meeting. That is not true. As I’ve mentioned above, changes were also made to address government comments made during the meeting of the ad hoc group formed to discuss Chapter 8.
Furthermore, when I first arrived in Madrid on November 26, 1995, I was handed a stack of government and NGO comments on Chapter 8 that I had not seen previously. I had the responsibility of responding to these comments.
One reason for the delay in receiving comments was that the IPCC had encountered difficulties in finding a Convening Lead Author (CLA) for Chapter 8. To my knowledge, the CLA job had been turned down by at least two other scientists before I received the job offer. The unfortunate consequence of this delay was that, at the time of the Madrid Plenary Meeting, Chapter 8 was less mature and polished than other chapters of the IPCC Working Group I Report. Hence the belated review comments.
The bottom line in this story is that the post-Madrid revisions to Chapter 8 were made for scientific, not political reasons. They were made by me, not by IPCC officials. The changes were in full accord with IPCC rules and procedures (pdf). Mr. Pearce repeats accusations by Fred Seitz that the changes to Chapter 8 were illegal and unauthorized, and that I was guilty of “corruption of the peer-review process”. These allegations are false, as the IPCC has clearly pointed out.
The 1995 IPCC Report: The “research irregularities” allegation
The third major front in the attack on Chapter 8 focused on my personal research. It was a two-pronged attack. First, Professor S. Fred Singer claimed that the IPCC’s “discernible human influence” conclusion was entirely based on two of my own (multi-authored) research papers. Next, Professor Patrick Michaels argued that one of these two papers was seriously flawed, and that irregularities had occurred in the paper’s publication process. Both charges were untrue.
On July 25, 1996, I addressed the first of these allegations in an email to the Lead Authors of the 1995 IPCC Report:
“Chapter 8 references more than 130 scientific papers – not just two. Its bottom-line conclusion that “the balance of evidence suggests a discernible human influence on global climate” is not solely based on the two Santer et al. papers that Singer alludes to. This conclusion derives from many other published studies on the comparison of modelled and observed patterns of temperature change – for example, papers by Karoly et al. (1994), Mitchell et al. (1995), Hegerl et al. (1995), Karl et al. (1995), Hasselmann et al. (1995), Hansen et al. (1995) and Ramaswamy et al. (1996). It is supported by many studies of global-mean temperature changes, by our physical understanding of the climate system, by our knowledge of human-induced changes in the chemical composition of the atmosphere, by information from paleoclimatic studies, and by a wide range of supporting information (sea-level rise, retreat of glaciers, etc.). To allege, as Singer does, that “Chapter 8 is mainly based on two research papers” is just plain wrong”.
In the second prong of the attack, Professor Michaels claimed that a paper my colleagues and I had published in Nature in 1996 had been selective in its use of observational data, and that our finding of a human fingerprint in atmospheric temperature data was not valid if a longer observational record was used. Further, he argued that Nature had been “toyed with” (presumably by me), and coerced into publishing the 1996 Santer et al. Nature paper one week prior to a key United Nations meeting in Geneva.
My colleagues and I immediately addressed the scientific criticism of our Nature paper by Michaels and his colleague Chip Knappenberger. We demonstrated that this criticism was simply wrong. Use of a longer record of atmospheric temperature change strengthened rather than weakened the evidence for a human fingerprint. We published this work in Nature in December 1996. Unfortunately, Mr. Pearce does not provide a link to this publication.
Since 1996, studies by a number of scientists around the world have substantiated the findings of our 1996 Nature paper. Such work has consistently shown clear evidence of a human fingerprint in atmospheric temperature records.
Disappointingly, Professor Michaels persists in repeating his criticism of our paper, without mentioning our published rebuttal or the large body of subsequently published evidence refuting his claims. Michaels’ charge that Nature had been “toyed with” was complete nonsense. As described below, however, this was not the last time I would be falsely accused of having the extraordinary power to force scientific journals to do my bidding.
A Climatology Conspiracy? More “peer-review abuse” accusations
Mr. Pearce also investigates a more recent issue. He implies that I abused the normal peer-review system, and exerted pressure on the editor of the International Journal of Climatology to delay publication of the print version of a paper by Professor David Douglass and colleagues. This is not true.
The Douglass et al. paper was published in December 2007 in the online edition of the International Journal of Climatology. The “et al.” included the same Professor S. Fred Singer who had previously accused me of “scientific cleansing”. It also included Professor John Christy, the primary developer of a satellite-based temperature record which suggests that there has been minimal warming of Earth’s lower atmosphere since 1979. Three alternate versions of the satellite temperature record, produced by different teams of researchers using the same raw satellite measurements, all indicate substantially more warming of the Earth’s atmosphere.
The focus of the Douglass et al. paper was on post-1979 temperature changes in the tropics. The authors devised what they called a “robust statistical test” to compare computer model results with observations. The test was seriously flawed (see Appendix A in Open Letter to the Climate Science Community: Response to A “Climatology Conspiracy?”). When it was applied to the model and observational temperature datasets, the test showed (quite incorrectly) that the model results were significantly different from observations.
As I have noted elsewhere, the Douglass et al. paper immediately attracted considerable media and political attention. One of the paper’s authors claimed that it represented an “inconvenient truth”, and proved that “Nature, not humans, rules the climate”. These statements were absurd. No single study can overturn the very large body of scientific evidence supporting “discernible human influence” findings. Nor does any individual study provide the sole underpinning for the conclusion that human activities are influencing global climate.
Given the extraordinary claims that were being made on the basis of this incorrect paper, my colleagues and I decided that a response was necessary. Although the errors in Douglass et al. were easy to identify, it required a substantial amount of new and original work to repeat the statistical analysis properly.
Our work went far beyond what Douglass et al. had done. We looked at the sensitivity of model-versus-data comparisons to the choice of statistical test, to the test assumptions, to the number of years of record used in the tests, and to errors in the computer model estimates of year-to-year temperature variability. We also examined how the statistical test devised by Douglass et al. performed under controlled conditions, using random data with known statistical properties. From their paper, there is no evidence that Douglass et al. considered any of these important issues before making their highly-publicized claims.
Our analysis clearly showed that tropical temperature changes in observations and climate model simulations were not fundamentally inconsistent – contrary to the claim of Douglass and colleagues. Our research was published on October 10, 2008, in the online edition of the International Journal of Climatology. On November 15, 2008, the Douglass et al. and Santer et al. papers appeared in the same print version of the International Journal of Climatology.
In December 2009, shortly after the public release of the stolen emails from the University of East Anglia’s Climatic Research Unit, Professors David Douglass and John Christy accused me of leading a conspiracy to delay publication of the print version of the Douglass et al. paper. This accusation was based on a selective analysis of the stolen emails. It is false.
In Mr. Pearce’s account of this issue, he states that “There is no doubt the (sic) Santer and his colleagues sought to use the power they held to the utmost…” So what are the facts of this matter? What is the “power” Fred Pearce is referring to?
- Fact 1: The only “power” that I had was the power to choose which scientific journal to submit our paper to. I chose the International Journal of Climatology. I did this because the International Journal of Climatology had published (in their online edition) the seriously flawed Douglass et al. paper. I wanted to give the journal the opportunity to set the scientific record straight.
- Fact 2: I had never previously submitted a paper to the International Journal of Climatology. I had never met the editor of the journal (Professor Glenn McGregor). I did not have any correspondence or professional interaction with the editor prior to 2008.
- Fact 3: Prior to submitting our paper, I wrote an email to Dr. Tim Osborn on January 10, 2008. Tim Osborn was on the editorial board of the International Journal of Climatology. I told Dr. Osborn that, before deciding whether we would submit our paper to the International Journal of Climatology, I wanted to have some assurance that our paper would “be regarded as an independent contribution, not as a comment on Douglass et al.” This request was entirely reasonable in view of the substantial amount of new work that we had done. I have described this new work above.
- Fact 4: I did not want to submit our paper to the International Journal of Climatology if there was a possibility that our submission would be regarded as a mere “comment” on Douglass et al. Under this scenario, Douglass et al. would have received the last word. Given the extraordinary claims they had made, I thought it unlikely that their “last word” would have acknowledged the serious statistical error in their original paper. As subsequent events showed, I was right to be concerned – they have not admitted any error in their work.
- Fact 5: As I clearly stated in my email of January 10 to Dr. Tim Osborn, if the International Journal of Climatology agreed to classify our paper as an independent contribution, “Douglass et al. should have the opportunity to respond to our contribution, and we should be given the chance to reply. Any response and reply should be published side-by-side…”
- Fact 6: The decision to hold back the print version of the Douglass et al. paper was not mine. It was the editor’s decision. I had no “power” over the publishing decisions of the International Journal of Climatology.
This whole episode should be filed under the category “No good deed goes unpunished”. My colleagues and I were simply trying to set the scientific record straight. There was no conspiracy to subvert the peer-review process. Unfortunately, conspiracy theories are easy to disseminate. Many are willing to accept these theories at face value. The distribution of facts on complex scientific issues is a slower, more difficult process.
Climate Auditing – Close Encounters with Mr. Steven McIntyre
Ten days after the online publication of our International Journal of Climatology paper, Mr. Steven McIntyre, who runs the “ClimateAudit” blog, requested all of the climate model data we had used in our research. I replied that Mr. McIntyre was welcome to “audit” our calculations, and that all of the primary model data we had employed were archived at Lawrence Livermore National Laboratory and freely available to any researcher. Over 3,400 scientists around the world currently analyze climate model output from this open database.
My response was insufficient for Mr. McIntyre. He submitted two Freedom of Information Act (FOIA) requests for climate model data – not for the freely available raw data, but for the results from intermediate calculations I had performed with the raw data. One FOIA request also asked for two years of my email correspondence related to these climate model data sets.
I had performed these intermediate calculations in order derive weighted-average temperature changes for different layers of the atmosphere. This is standard practice. It is necessary since model temperature data are available at specific heights in the atmosphere, whereas satellite temperature measurements represent an average over a deep layer of the atmosphere. The weighted averages calculated from the climate model data can be directly compared with actual satellite data. The method used for making such intermediate calculations is not a secret. It is published in several different scientific journals.
Unlike Mr. McIntyre, David Douglass and his colleagues (in their International Journal of Climatology paper) had used the freely available raw model data. With these raw datasets, Douglass et al. made intermediate calculations similar to the calculations we had performed. The results of their intermediate calculations were similar to our own intermediate results. The differences between what Douglass and colleagues had done and what my colleagues and I had done was not in the intermediate calculations – it was in the statistical tests each group had used to compare climate models with observations.
The punch-line of this story is that Mr. McIntyre’s Freedom of Information Act requests were completely unnecessary. In my opinion, they were frivolous. Mr. McIntyre already had access to all of the information necessary to check our calculations and our findings.
When I invited Mr. McIntyre to “audit” our entire study, including the intermediate calculations, and told him that all the data necessary to perform such an “audit” were freely available, he expressed moral outrage on his blog. I began to receive threatening emails. Complaints about my “stonewalling” behavior were sent to my superiors at Lawrence Livermore National Laboratory and at the U.S. Department of Energy.
A little over a month after receiving Mr. McIntyre’s Freedom of Information Act requests, I decided to release all of the intermediate calculations I had performed for our International Journal of Climatology paper. I made these datasets available to the entire scientific community. I did this because I wanted to continue with my scientific research. I did not want to spend all of my available time and energy responding to harassment incited by Mr. McIntyre’s blog.
Mr. Pearce does not mention that Mr. McIntyre had no need to file Freedom of Information Act requests, since Mr. McIntyre already had access to all of the raw climate model data we had used in our study (and to the methods we had used for performing intermediate calculations). Nor does Mr. Pearce mention the curious asymmetry in Mr. McIntyre’s “auditing”. To my knowledge, Mr. McIntyre – who purports to have considerable statistical expertise – has failed to “audit” the Douglass et al. paper, which contained serious statistical errors.
As the “Climategate” emails clearly show, there is a pattern of behavior here. My encounter with Mr. McIntyre’s use of FOIA requests for “audit” purposes is not an isolated event. In my opinion, Mr. McIntyre’s FOIA requests serve the purpose of initiating fishing expeditions, and are not being used for true scientific discovery.
Mr. McIntyre’s own words do not present a picture of a man engaged in purely dispassionate and objective scientific inquiry:
“But if Santer wants to try this kind of stunt, as I’ve said above, I’ve submitted FOI requests and we’ll see what they turn up. We’ll see what the journal policies require. I’ll also see what DOE and PCDMI administrators have to say. We’ll see if any of Santer’s buddies are obligated to produce the data. We’ll see if Santer ever sent any of the data to his buddies”
(Steven McIntyre; posting on his ClimateAudit blog; Nov. 21, 2008).
My research is subject to rigorous scrutiny. Mr. McIntyre’s blogging is not. He can issue FOIA requests at will. He is the master of his domain – the supreme, unchallenged ruler of the “ClimateAudit” universe. He is not a climate scientist, but he has the power to single-handedly destroy the reputations of exceptional men and women who have devoted their entire careers to the pursuit of climate science. Mr. McIntyre’s unchecked, extraordinary power is the real story of “Climategate”. I hope that someone has the courage to tell this story.
Benjamin D. Santer
John D. and Catherine T. MacArthur Fellow
San Ramon, California
February 22, 2010*
*These remarks reflect the personal opinions of Benjamin D. Santer. They do not reflect the official views of Lawrence Livermore National Laboratory or the U.S. Department of Energy. In preparing this document, I would like to acknowledge the assistance of Tom Wigley, Myles Allen, Kristin Aydt, Graham Cogley, Peter Gleckler, Leo Haimberger, Gabi Hegerl, John Lanzante, Mike MacCracken, Gavin Schmidt, Steve Sherwood, Susan Solomon, Karl Taylor, Simon Tett, and Peter Thorne.
Rod B. A blackbody spectrum is just the equilibrium distribution of a gas of photons at a particular temperature.
Question: Photons don’t interact with each other, so how can that come into equilibrium?
Answer: They have to interact with the matter around them, and the matter and the photon gas come into equilibrium with each other and so each is also in equilibrium with itself. If you have a deficit of photons in a spectral range, gas molecules will collide and excite each other and decay radiatively. You will get more radiative decays that radiative excitations and so, you get more photons to make up the deficit.
The thing is that matter can only absorb/emit where it has allowed energy transitions. An atom or molecule can’t exist in a forbidden energy, right? So in reality, you get emission in lines (for a low-pressure gas), broadened lines (high-pressure gas and liquids) and bands (solids). That is why a gas in a vapor lamp emits light at spectral lines (e.g. sodium, mercury…). The thing is if you drew a blackbody curve at the right energy, it would bound the intensities of the spectral lines. What you have is a slice of a blackbody spectrum determined by the material.
Thomas: “Game over!”
BPL: Thomas, go look up what the cake said to Alice.
[edit – explanations are fine, insults are not. It’s really not that hard]
What IS hard is spending 10 minutes coming up with an explanation and then have it thrown out either because the site is failing and being coy about it or someone is throwing it away.
[Response: We are not being ‘coy’ – comments that are one or two line accusations that a commenter is being prissy, or is an idiot or is too stupid to look stuff up are completely pointless and not wanted here. Do not bother (for even 10 seconds) to submit comments like that, they will not be posted. Instead, take 10 minutes (or more) and provide an explanation and a link. Instead of 10 one-liners, try writing one substantive post that has a paragraph. More reflection in your comments will improve both their tone and their likelihood of passing moderation. – gavin]
[Response: We are not being ‘coy’…]
No, not YOU being coy.
Sometimes this site gives a “Internal Server Error” and then go back and click Send and it works. Sometimes it only *says* it works.
***IT*** is being coy, in as much as an inanimate program manages to be coy, since programs don’t like to be anthropormophised.
[Response: Sometimes the site gets busy and in those cases you should resubmit. We will generally catch duplicates if that occurs by mistake. – gavin]
CFU,
I mean no disrespect, but maybe the question that you need to ask yourself is what your reason for posting a comment is. If it is merely to vent your frustrations, then this might not be the most effective venue.
If you are seeking to persuade or to educate, there are more effective strategies. Speaking as someone whose tongue is as sharp as anyone’s and who is as frustrated with the [edit] disinformation campaign of the ideologues, I share your frustration. However, would it not be more efficacious to vent your spleen at the most pernicious elements of that campaign–those spreading unsubstantiated calumny?
The problem is not that people are incorrect. The problem is that they are incorrect because they are being lied to. To insult them after the fact is to injure them twice. Maybe hold fire until they insist on repeating the lie multiple times.
Ray –
You say “The thing is if you drew a blackbody curve at the right energy, it would bound the intensities of the spectral lines. What you have is a slice of a blackbody spectrum determined by the material.”
Do you happen to have a pointer to a reference with a good explanation of this connection? This seems to be an important key to interpreting intensity vs. wavenumber plots (like those generated by Archer’s MODTRAN tool) so I’d like to understand it in some detail.
Hey, guess what, BobFJ, let’s assume for now that I was wrong about the skin being able to detect infrared. I don’t think so, but it was just the first handwaving notion I suggested trying, before using instruments, when someone back there posted the old ‘saturation’ notion. The band isn’t saturated.
I suggested ways to start thinking about it. Then you got all excited. OK, I don’t have clear proof of the sensitivity in human skin. Beetles, perhaps more favored and gifted than humans, can do it:
http://dx.doi.org/10.1016/S1095-6433(00)00322-6
How would _you_ test whether the CO2 bands are saturated? You can look it up in Spencer Weart’s book, and in topics here at RC.
More air blocks more infrared (as well as more blue — you can tell that’s missing from sunset light, eh?).
My handwaving suggestion there was hardly scientific,
So, if you want to detect infrared, and don’t like handwaving, what will you use? Prism and thermometer? Infrared photocell? Those worked for the Herschels measuring incoming sunlight.
But Eli points out the band of infrared coming up from Earth is lower-energy photons than the infrared coming in. Someone up there posted the old mistake, claimed that band is saturated. How can you tell whether that’s saturated, besides relying on the scientific work or looking at Modtran?
How about a satellite in orbit looking down in the relevant infrared bands? That’s been done.
http://ams.confex.com/ams/Annual2006/techprogram/paper_100737.htm
The results match the theory: the band isn’t saturated, more CO2 blocks more heat coming up from the surface. (I suggest reading the topics on the subject again if you doubt this.)
[Response: Sometimes the site gets busy and in those cases you should resubmit. We will generally catch duplicates if that occurs by mistake. – gavin]
Problem is I don’t think this one is anywhere near 100% reliable. Probably not even 50-50.
The website itself is having problems.
This is not a *fault* of someone, but a *fact* of what we have here now.
But the site does its best to make posting detailed accounts worthless. Even when the post does not disappear because of temporary issues (and these have happened when the site sees it as “waiting for moderation” but after a later posting gets a squiff, that “waiting for moderation” post has gone away), each post as it approaches a detailed length approaches the spam shot horizon: the system will assert that something somewhere in that message (no message about where) is marked as spam.
Especially when you talk about a detailed and technical issue where the people who work in that narrow tecnhical field has a name that is flagged as spam.
So one liners are more likely to go through.
Since people like Rod B have asked time and time again about planck radiation, a detailed rebuttal is not going to do anything. It never has before.
So not only is it more likely to get through, it’s less of a waste both on the putative recipient and in retyping in the fairly common (if low as a fraction) failure of the site to accept messages.
Ray, I hear what you’re saying but Rod is not being misled.
This conversation about LTE and so on has happened before.
Just to close the circle–it’s the same physics involved in both the greenhouse gases and the infrared receptors in, e.g., beetles:
“A variety of thermoreceptors are present in animals and insects…. Melanophila pit organs are thermomechanical receptors, which convert IR electromagnetic radiation …. Chitin contains C-H, N-H, and O-H bonds which are bonds that have stretch resonances in the range of 3 um. When IR radiation comes in contact with these bonds their vibrational energy is converted into translational energy producing heat by non-radiative de-excitation processes.”
Micron 33 (2002) 211-225
Biological infrared imaging and sensing
Campbell, Naik, Sowards, Stone
Air Force Research Laboratory, Wright-Patterson AFB
http://web.neurobio.arizona.edu/gronenberg/nrsc581/thermo/biologicalinfraredsenses.pdf
David Warkentin,
Hmm, that sounds like a question for that Wascally Wabett. Me, I’m just a dumb physicist who assumes that equipartition will apply. It’s usually a pretty good assumption in the near-equilibrium world.
CFU,
I know we’ve been over this before, but the arguments I’ve constructed so far haven’t clicked for Rod. It’s a challenge for me to do better.
Ray Ladbury #955
I’ve always been impressed by how you are unfailingly polite and informative in the face of sometimes unremitting mendacity by other posters here, and elsewhere.
You’re doing a great job, keep it up – to any outsider it’s always clear who is on the side of reason.
David W (946), Everything is quantized in the purest sense. You and textbooks don’t say it is for precisely the same reason I’ve been trying to tell CFU — in 99.9999% of the time it has no effect on or relevance to anything.
Mr. David Warkentin writes on the 10 of March 2010 at 10:46 AM
“Ray –
You say “The thing is if you drew a blackbody curve at the right energy, it would bound the intensities of the spectral lines. What you have is a slice of a blackbody spectrum determined by the material.
Do you happen to have a pointer to a reference with a good explanation of this connection? ”
The wikipedia article at
http://en.wikipedia.org/wiki/Atomic_spectral_line
has a relation between the Planck curve, Einstein coefficients, oscillator strengths, and absorption cross section.
Ray Ladbury, I think I agree with what you say in #951 but might have a quarrel with words. I understand what is meant by a gas of photons reaching equilibrium (and this is a common helpful use of the phrase), but in pure physics I’m not sure what it is. A blackbody at a discrete temperature will emit photons across a wide spectral range of wavelengths and energy levels covering from UV to far IR. In this large pile of photons most (all?) are different from any siblings. In this context the photons are not in any equilibrium. However, the distribution of the photons across many energy levels will be exactly the same for any blackbody at the same temperature. Is this what is meant by “photon gas being in thermal equilibrium?” [In which case I assume one can not assign the character of temperature to any one photon.]
Getting back to the original discussion [I think :-) ], you say,
Right only in the precise purest sense, but not right in what is being implied. A molecule or atom has very narrow allowed energy levels (ergo large forbidden energy zones) as it applies to bond vibration, molecular rotation, or bound electrons. A free electron or whole atomic/molecular movement of translation or vibration has, for all practical purposes, infinite allowed energy levels. The former gives rise to our sodium lamp spectra (bound electrons) and the IR emission/absorption by a gas. These emissions have very precise frequencies with very few extremely narrow — almost a single line — bandwidths, and, technically, they ARE NOT Planck-type blackbody emissions. The latter can and do move and vibrate at an infinite number of frequencies covering a wide bandwidth. If any of these movements involve an accelerating charge, and they mostly do within a matter of nano/microseconds, radiation is emitted (or absorbed in a reverse sequence). This emission is in a virtually continuous spectrum with varying power levels and IS Planck-type blackbody emission.
The true Planck-type blackbody-type emission can and does have variances in its spectrum and in the emitted power levels by virtue of the material’s overt physical characteristics (again, for all practical discussion purposes), but NOT by virtue of the material’s bound electron status or whether a molecular bond vibration level is filled or not, for example. Ergo, CO2’s emission of IR at 15um IS NOT Planck’s blackbody type.
However, physicists can (and do) correctly assume that the mathematics of Planck blackbody radiation can be accurately applied to CO2 emission, by conveniently applying emissivities to narrow the emitted bandwidth. This mathematical construct seems to work accurately and is extremely helpful for the analysis. It is what’s done. Or as you said,
But, my point is that it is still a mathematical construct, not actual physics.
Maybe this is an academic exercise and not helpful. But this physics is at the heart of GW. If all of this is a simple semantic shortcut used by the scientists it won’t matter in the end. But (and this is hard to fathom) it is not 100% obvious here that the physics is precisely understood in all of its finite detail. That would be a problem.
> it is not 100% obvious here that the physics is precisely
> understood in all of its finite detail. That would be a problem.
Wonderful cartoon caption there. Imagine the conditions under which someone might be saying that.
Mr. Rod B says in reply to Mr. Ray Ladbury
‘ “The thing is if you drew a blackbody curve at the right energy, it would bound the intensities of the spectral lines. What you have is a slice of a blackbody spectrum determined by the material.
But, my point is that it is still a mathematical construct, not actual physics.’
I disagree. The mathematics is derived from stat mech and quantum theory. Please read the link I posted earlier.
http://en.wikipedia.org/wiki/Atomic_spectral_line
sidd
Rod B., OK, you are getting close.
You say: “A free electron or whole atomic/molecular movement of translation or vibration has, for all practical purposes, infinite allowed energy levels.”
OK, now if you move an atom or molecule–even if you accelerate it–it won’t radiate, because it is a neutral particle, right? And if you accelerate an electron, it will radiate either at the frequency of the force or according to a Bremmstrahlung or Cerenkov spectrum, right? Neither of these is blackbody, right? So this can’t be where the blackbody radiation comes from either, right?
Rod, the blackbody radiation distribution is determined by the properties of an aggregation of photons. Once the photon gas has assumed the blackbody distribution, it will continue to interact with the molecules/atoms of and within the container, but the distribution won’t change (at least not much. That is what we mean by equilibrium. Up to that point, the longer the photon gas interacts with its surroundings at temperature T, the closer it will come to a blackbody distribution.
The thing is that real matter is never a perfect blackbody–it can’t absorb/emit at any and all frequencies, but rather only at those where there are allowed transitions. So, the text books tell us that you never get a perfect blackbody spectrum. They go on to say that the closest you can get is a cavity at temperature T where the gas (photon and material) has had a very long time to come to equilibrium. The longer the equilibration time, the more chance there is for very improbable interactions where a photon is absorbed or emitted at the extreme edge of an absorption band/line (e.g. due to collisional broadening, etc.). These fill in the spaces between lines somewhat, but a true blackbody is always an approximation.
It is, however, a very useful approximation, and it allows us to understand a variety of physical phenomena–including greenhouse heating. Does that make more sense, Rod?
VeryTallGuy,
Thank you. Do you want to try and convince my wife? ;-)
sidd (967) you make a valid point. I think my basic premise re Planck-type radiation still holds, but my mathematical construct statement was too sweeping. Much of the mathematics stems directly from the discrete vibration, rotation, and bound electronic radiation physics, or radiation in general.
Rod (963) – You keep saying “everything is quantized”, but why do you think that? If it isn’t in textbooks – if, in fact, textbooks flatly state that the energy of bound particles is quantized but that of unbound particles “can have any value” (Eisberg and Resnick) – how did you come to think differently?
sidd (964) – Thanks for the link; that looks helpful.
Hank Roberts says: 10 March 2010 at 10:47 AM
Hey, guess what, BobFJ, let’s assume for now that I was wrong about the skin being able to detect infrared. I don’t think so, but it was just the first handwaving notion I suggested trying…
How about a simple experiment in human sensitivity to IR, handwaving included?
— If you have a portable hotplate, turn it on, set it so that you can’t see any incandescence in the dark.
— Rotate the hotplate 90 degrees from horizontal, so that convecting air will move more or less vertically yet not impinge on an object a short distance perpendicularly from the surface of the hotplate.
— Now, wave your hand a few inches or so from the hotplate.
— Feel any heat?
Handwaving science…
“963
Rod B says:
10 March 2010 at 2:54 PM
David W (946), Everything is quantized in the purest sense.”
So why do you say that Plank Radiation is a new sort of radiation because it’s continuous as you did in post 944?
Ray: “It’s a challenge for me to do better.”
In the same way as perfection is an option, ray.
Education does rather require that both sides (the teacher and the student) wish to learn.
Take a look at thse spurious claims!
“In the atmosphere, on average, water vapor is about 4000 ppmv (0.4%), which is 10 times the concentration of CO₂. H₂O varies in the atmosphere more than CO₂, and it drops off considerably in the stratosphere, but its concentration is still, on average, 5 times greater than CO₂ in the lower stratosphere.
The hydroxyl bond in the H₂O molecule absorbs very strongly in thermal infrared wavelengths, and it has unique properties which allow it to absorb a very broad range of the thermal infrared spectrum. CO₂ also absorbs strongly in the thermal infrared region, but in a much narrower band. So, any given molecule of H₂O in the atmosphere is slightly less than twice as likely to absorb and re-emit a photon in the thermal infrared spectrum as a molecule of CO₂.
H₂O overlaps with CO₂ on all bands of thermal infrared radiation (wavelengths between 8 and 15 microns) that CO₂ absorbs, as can be clearly seen in the graph below. And any bands that CO₂ now absorbs at 100% (most of the bands it absorbs) are irrelevant, because this means that increased concentration of CO₂ will not result in increased absorption in these bands.
What is relevant are the narrow bands where CO₂ and H₂O overlap, but neither currently absorb at 100%. This is the region of the Thermal Infrared Radiation (TIR) spectrum where the warming potential is.
There is also an issue with “pressure spreading”, or something like that, where the band of TIR that CO₂ absorbs gets broader due to conditions in the atmosphere, but that is complex, and everything I know about molecular physics suggests that it would only “spread” to longer wavelengths, where H₂O absorbs very well.
So, since CO₂ and H₂O overlap in the bands where neither absorbs 100% of TIR, this means that they “fight” over the available photons (radiation) in this band, and for the reasons I gave above, H₂O is going to win this fight every time, especially since global warming theory says that atmospheric water vapor increases exponentially with a slight warming from CO₂.
The point is that exactly how much radiation is absorbed by each molecule in these narrow bands is not known, but it is known that the warming potential from CO₂ alone is very limited.
So, the statement that “added C02 will always = added heat energy” defies the laws of physics. Even assuming that man-made CO₂ produced most of the observed 20th century warming trend (which is a big assumption), then the most warming that any additional CO₂ emissions can produce is still only ~ 1° C. (more on this later, if anyone is interested)
**Note: The band of thermal infrared radiation is from 8 to 15 µm (microns). That range is close to centered on the 10 µm mark on the X-axis, now follow that range up to the absorption patterns for CO₂ and H₂O.”
Uggghh……
957, Hank Roberts
I don’t know whether you’ll check back, but thanks for the link. I downloaded the PDF. It looks real good.
“The point is that exactly how much radiation is absorbed by each molecule in these narrow bands is not known, but it is known that the warming potential from CO₂ alone is very limited. ”
Except above the tropopause where there’s little water.
If CO2 cannot manage it, please explain Venus. After all, it 100% overlaps with CO2 bands, yet Venus has shown little sign of that being a problem to increasing insulation.
Doug Bostrom (972),
I’m no scientist but I enjoy some basic science. In your experiment with a hot plate on its side, how about you return it to level, and get Hank to wave his hand above it again? Will not his hand feel hotter than before, but not just from infra red, but also from convection? How does Hank think he can distinguish the infra red? Now turn up the heat till it glows bright. When he waves his hand this time, he may go ouch, but how does he tell which part of the ouch is infra red?
David Warkentin (946, 971), a typical pendulum with one joule of energy can easily have that energy quantized into 10^33 separate quanta. It’s not hard to find texts and lecture notes discussing this, but it is very infrequent because it is continuous for all useful purposes and has no effect; including it in classes would only complicate and make the course less effective, and confuse the student all for zero benefit (unless they are specifically studying this.) BTW, the formula is (roughly) E = nhf with n the number of discrete levels allowed. A sample site is http://science.exeter.edu/ssaltman/quantum/quantum.htm
Ray Ladbury (968, et al), et al:
Sorry I’m slow; I’ve been away.
A quick related clarification to David Warkentin’s #946: The electron energy levels in every one of your 10^17 atoms will be exactly the same. So if one has a level at A it will emit a photon at a precise frequency associated with the energy quanta change. Every other atom, no matter how many atoms you have, will emit at the exact same frequency in the same circumstances. You will never get a broadband spectrum from this physics mechanism.
Ray says, “…if you move an atom or molecule–even if you accelerate it–it won’t radiate, because it is a neutral particle, right?”
Therein lies a rub. NOT RIGHT. Most texts, papers, lectures (of the limited set I’ve perused) simply do not address the physical details of this Planck function radiation. It is usually one of those magic happens steps. However, a few talk about it. The broadband spectra created by colliding free-free electrons is easy to understand, While this can be significant, as you say, it doesn’t seem to be greatly prevalent at normal temperatures. Most at normal temperatures comes from atomic and molecular collisions — either as vibrations in crystalline solids or individual translation collisions in liquids, plasma, or gases. The charge acceleration can stem from polarized molecules; most comes from neutral molecules or atoms with the charge coming from the electron cloud surrounding the molecule/atom. As one source ( http://galileo.phys.virginia.edu/classes/252/black_body_radiation.html — provided by Hank, I think) states, “…heat was known to cause the molecules and atoms of a solid to vibrate, and it was known that the molecules and atoms were themselves complicated patterns of electrical charges…. when a body was heated, the consequent vibrations on a molecular and atomic scale included some oscillating charges…. then these oscillating charges would radiate, presumably giving off heat and light.”
It’s true that the familiar continuous blackbody spectrum is usually modified by the change in emissivity as a function of wavelength. However this is variations over a large bandwidth or maybe sharp narrowband but numerous variations spread throughout the blackbody spectrum. Blackbody emissivity that is zero everywhere except 14.771 um where it is 1.0 is nonsensical.
Secondly, although a really torturous explanation is possible, it’s hard to accept CO2 vibrational emissions as a Planck-type function. For example how do you handle Wien’s displacement law where the wavelength (um) at the peak radiation = 2897/T? CO2 has radiation at one very precise wavelength no matter what the temperature?
I do agree with your other descriptions. But the question at hand is: does the radiation emitting from a change in a molecule’s vibration energy stem from the same physical process, and follows the same Planck-type function as what we commonly call blackbody radiation (but really mean radiation from the heat/temperature of matter)? I say no. Among other things it has virtually no direct relevance to temperature. (There is an indirect function that relates the probability of a vibration level being filled to the temperature of the surroundings.)
You finally say, “It is… a very useful approximation, and it allows us to understand a variety of physical phenomena–including greenhouse heating. Does that make more sense, Rod?”
That makes eminent sense, and I agree. I have said all along that the mathematics of Planck functions can lend itself very well to vibrational radiations, and it’s the easiest and best we have. I’m simply saying the radiations do not have the same genesis. And there might be areas in the details where the mathematical application does not work very well. I don’t know if there is or if they’re important. But we need to stay aware. Just like with any model.
> RodB
The first quote you use says:
> the molecules and atoms of a solid to vibrate
Then you say
> it’s hard to accept CO2 vibrational emissions as a Planck-type function. …
> no matter what the temperature?
The first quote is describing solids.
Freeze a block of CO2 solid.
What do you think you’ll get if you measure a spectrum from it?
Look at spectra from a star. You see discrete emissions from iron, carbon, and many other elements — because you’re dealing with gases.
Rod, I’m guessing you’re having trouble with the ‘ultraviolet catastrophe’ — sound familiar?
http://galileo.phys.virginia.edu/classes/252/black_body_radiation.html
“… (As long ago as 1877, Maxwell had pointed out that hot gases emit light at particular frequencies. The frequencies do not change with temperature, so the oscillations must be simple harmonic—but such an oscillator would surely also be excited by collisions at low temperatures, so why was energy not being fed into this mode?) …”
OK Rod (979), I think I see the problem – you haven’t made the connection that a pendulum’s energy is quantized precisely because it _is_ bound. Free particles aren’t bound, and their energy is not quantized. (The book I cited earlier shows how this difference arises from the form of the Schroedinger equation.)
Furthermore, this:
“A quick related clarification to David Warkentin’s #946: The electron energy levels in every one of your 10^17 atoms will be exactly the same. So if one has a level at A it will emit a photon at a precise frequency associated with the energy quanta change. Every other atom, no matter how many atoms you have, will emit at the exact same frequency in the same circumstances. You will never get a broadband spectrum from this physics mechanism.”
is also quite fundamentally wrong. Atoms which are bonded together do _not_ have the same allowable electron energy levels as atoms which are separate. This page on molecular orbital diagrams: http://en.wikipedia.org/wiki/MO_diagram#Dihydrogen_MO_diagram
illustrates how the 1s orbitals of two separate hydrogen atoms combine to form two molecular orbitals of H2 with distinctly different energy levels. Further down on that page there’s a diagram showing how the 2s and 2p atomic orbitals of C and O combine to form molecular orbitals at six different energy levels in the CO2 molecule.
(If you’re interested in learning more about this sort of thing, MIT has put videos of the lectures for 3.091 Introduction to Solid State Chemistry online here:
http://ocw.mit.edu/OcwWeb/Materials-Science-and-Engineering/3-091Fall-2004/CourseHome/index.htm)
For a microgram of metal with 10^17 atoms bonded together, the resulting energy levels will be very numerous and very closely spaced – I think my conjecture that natural broadening causes transitions between them to appear as a continuous spectrum is quite plausible.
Rod B.
If the second law of thermodynamics is never invalidated (in statistically-significant populations, and except for small fluctuations of the sort expected from such populations), then there must be such a thing as the Planck function for blackbody radiation. For local thermodynamic equilibrium (among non-photon matter), as the emission weighting function traced back over an isothermal path (including all the branchings and diffusions that may occur by reflection, scattering) approaches 1, for a given direction, frequency, polarization, the intensity of radiation (per unit of the frequency spectrum, per unit of the ‘polarization spectrum’);must approach the blackbody value for that temperature (allowing for that being a function of index of refraction at that location as well as temperature and frequency).
IF this were not true, it would be possible to devise a perpetual motion machine.
In full thermodynamic equilibrium (among photons and non-photons), non-photon matter must be emitting as much energy as it is absorbing, and the intensity of radiation that must be present for the absorption to equal emission is the blackbody value. This also must be true seperately for all directions, frequencies, and polarizations, so that the same energy transitions happen in the forward and reverse directions at the same rate; otherwise there would be a net flow of energy from one population of states to another, which is not characteristic of thermodynamic equilibrium (but is, if the inflows and outflows are balanced (for at least some of these, a time average) for a defined system, characteristic of climatic equilibrium, ecological equilibrium, homeostasis, etc.), where each chemical and physical reaction occurs in the forward and reverse directions at the same rate.
(Thermalization of energy, the process by which energy is redistributed among forms toward a thermodynamic equilibrium, is sufficiently rapid (setting aside kinetic barriers to chemical and physical reactions reactions, which needn’t disrupt LTE in so far as photon emission and absorption are concerned) for most of the mass of the atmosphere to be near LTE in spite of net cooling, heating, or balance from inflows and outflows that are in different forms.)
“which needn’t disrupt LTE in so far as photon emission and absorption”
With the exception of photons emitted directly from chemical reactions, as opposed to the enthalpy they might release; this (and other non-LTE emissions, like the aurora) is not a significant contributor to atmopsheric radiation, in terms of energy.
… okay, a bit OT from the original point, but in other words, with exceptions to this not making significant changes to the climate system’s energy budget, ***in so far as I know***, chemical and physical disequilibrium (nuclear, too) can be set aside for the purposes of evaluating LTE for radiation processes, with LTE relevant to radiation being determined by the distribution of internal energy, given the composition and physical state of the matter – because the relevant chemical and physical reactions either occur quite slowly (CH4 oxydation) and/or do not directly emit or absorb photons but do so via changes in internal energy (for the most part).
Where can I find data/research papers on how C02 migrates above the troposphere and how its measured? How do miniscule amounts play such a large role in the energy imblance at high altidues? Can you point me in the right direction?
Rod, you aren’t thinking this through. First, CO2 is a neutral molecule, correct? The carbon and oxygen atoms are bound, correct? If so, then the energy it radiates is quantized. PERIOD! That is not to say that it is a delta function. Spectral lines always have width–or more specifically, a distribution over which they absorb and emit radiation. That spread, too, is defined by quantum mechanics.
I’ve asked before where you think the radiation in the blackbody spectrum between spectral lines comes from. All you have given is vague, handwaving argumenst. No references, no math, no specifics. The reason: because there are no sources of radiation between the spectral lines. This is most evident when looking at a gas–that is why I keep emphasizing the sodium vapor lamp. The spectrum becomes more continuous when dealing with a liquid, and even more so in a solid. Even so, if you are looking at the spectrum in detail, you will see spectral lines that allow you to identify the material.
Ask yourself, why is it that blackbody radiation has the same spectrum independent of the radiator? It is because the spectrum is not a property of the material, but of the photon gas–it is the energy distribution such a gas would have at equilibrium. The issue is that photons do not interact with each other, so the only way they can come to equilibrium is to interact with matter around them. OK, so here’s the question: How does a photon interact with matter when the matter has no allowed transition corresponding to the photon’s energy?
The best blackbody approximators are materials with carbon nanotubes. Why? Because with all those carbon bonds, there is a near continuum of energy states to absorb photons. Now, why given your view would a gas be so much worse of a blackbody radiation?
> Adam
> Where can I find
Upper left corner of the page, click “Start Here”
Hank (981), I never claimed that both/many types of radiation can’t be occurring at the same time. The Sun is obviously simultaneously radiating blackbody Planck function type over a broadband and narrow (line) spectral radiation stemming from changing electron energy levels in H, He, etc. The two physical processes are neither identical nor mutually exclusive.
David Warkentin (983), free vs bound has nothing to do with it. All (that’s “all”, as in all…) things are quantized. The 1st energy level of a Hydrogen (H) atom’s electron above its base is exactly (that’s “exactly” as in exactly…) the same for every single H atom in the known universe. How in the hell do we identify H as a component of the sun through spectrographic analysis if each H emits a different frequency?? You’re using different energy levels and orbitals to describe electron bound levels.
Accept it or not. I thought I was helping, but evidently not.
Rod – Perhaps we’ve reached an impasse on the question of what is and is not quantized. I’ve provided an authoritative reference (included on the reading list for MIT’s 8.04 Quantum Physics I, as it happens) that explicitly contradicts you, and I understand enough about the form of the Schroedinger equation to see why free and bound particles have different wave function solutions. Unless you care to provide something more than your own say-so, I think I’ll continue to not accept your idiosyncratic claim that the energy of free particles is quantized.
As for the energy levels of all hydrogen atoms being the same: you’re right – for _monatomic_ hydrogen, which is what we see in the solar atmosphere. But when atoms are bonded together, they don’t maintain the same energy levels that they did when they were separate, independent atoms. The H2 _molecule_ will have electron energy levels that are not the same as those of separate, independent H _atoms_. By extension, a conglomeration of a large number of atoms bonded together in a solid will have a huge number of closely spaced electron energy levels which are not the same as those that the constituent atoms have separately. This the foundation of whole concept of electronic band structure in solids (see http://en.wikipedia.org/wiki/Electronic_band_structure or the 3.091 lectures I linked to); last time I checked semiconductors still work, so I think I’m on pretty firm ground here, too.
Patrick 027, LTV is not directly relevant to the discussion Ray, et al and I are having. But I do agree with your apt description of LTV ala blackbody radiation. I think Ray said essentially the same thing. Thanks.
Ray (988), I try to describe in my words what I understand certainly better equipped physicists have said. A molecule has a (maybe funny shaped) cloud of charged electrons surrounding a core (maybe in 2 or 3 spots) of oppositely charged protons. While the molecule is overall neutral it none the less presents a slight electric field to the outside, depending (I suppose) somewhat on the orientation of the outside. This molecule is calmly strolling through the medium — nothing happens. It then crashes into another molecule and gets knocked backwards (more or less) — that tiny cloud charge accelerates greatly for a moment and, walla, emits a photon based on the exact amount of overt charge and the exact amount of momentary acceleration. All of the other molecules are doing the same thing but at an almost random spectrum of accelerations. All of those different accelerations cover a wide range but with virtually no delta from one to the next — looks and for all useful purposes is a continuous spectrum. They are not quantized other than in the purely academic sense that David W. and I have been discussing. This is one of the ways of generating Planck function blackbody radiation. [This might not be rigorously exact from a physics viewpoint but the essence is accurate and sufficient to make my point.]
Now we look at a CO2 molecule (which could also be doing the above). It’s just laying on the beach quietly soaking up the rays (pun intended). Then a ray of 2.031 x10^13 HZ with 1.325×10^-20 joules happens to hit it and for the first time gives it a jolt. Its bonds between the C and the two O atoms absorb the energy and start vibrating at a very precise frequency depending on the atomic weights and bond strengths, e.g. After a while it tires of this and relaxes by releasing another ray (photon) of exactly the same energy — a radiation emission.
The above two paragraphs describe two entirely different physical mechanisms of generating radiation. They also describe two very different characteristics of the two radiation mechanisms. One is broadband, given a large enough pool of molecules/atoms; the other is narrow band and for all practical purposes requires only one molecule. One has a range of energies that depend on an independent function, namely temperature; the other releases only a very precise and discrete energy packet which depends on squat from other factors. That’s it. [For clarity it is understood that additional characteristics of the two “different” radiations might be similar or exactly the same.]
I did so give you a reference in #980. Another is a NASA/JPL document in a chapter called The Mechanisms of Electromagnetic Emissions (I don’t have its URL) put out for basic level understanding. An excerpt: ” …the molecules are continuously vibrating (if a solid) or bumping into each other (if a liquid or gas), sending each other off in different directions and at different speeds. Each of these collisions produces electromagnetic radiation [how they don’t say…] at frequencies all across the electromagnetic spectrum. [my emphasis] However, the amount of radiation emitted at each frequency (or frequency band) depends on the temperature of the material producing the radiation.” I also said rigorous explanations of any kind have been difficult to find. I’m not sure why, but it ain’t my fault.
You said, “…because there are no sources of radiation between the spectral lines.”
Give me a break!. Please explain solar radiation and insolation. A little doppler action on the H atoms line spectrum perhaps??!!?
David Warkentin, H2 molecules might have different bound electron energy levels than H atoms. But ALL H2 levels are EXACTLY the same for each and every H2 molecule. If you are saying if there is a mixture of many/all elemental atoms and molecules, and put all of their individual bound electron energy levels on a list, that list might look almost continuous… maybe so; I’ve never done that. I’m not sure what helpful relevance is there, though. But none of this has anything to do with the quantizing of, say, free electrons. Nor does it have anything above a teensy bit to do with semiconductor operation — LEDs excepted.
Go sic your MIT guys on Saltman at Phillips Exeter (my reference).
Er, ah, Rod, would you accept Einstein’s opinion on the subject?
“… Einstein took the next step: he conjectured that all oscillators are quantized, for example a vibrating atom in a solid…..”
As David points out, in a solid there are vastly many interactions.
In a solid, each possible electron whatsis pattern bond field arrangement individually can act as an oscillator with a characteristic emission, emitting a photon, a quantum of energy. The result of all of them viewed together will look like a smooth spectrum curve, with a peak that depends on the temperature.
In a gas, the electrons of an atom or molecule have only a few possible oscillations, each of those with a characteristic emission, and those look like lines on the spectrum _because_it_is_a_gas_ and so each individual atom or molecule isn’t enmeshed in the kind of interactions it would be in a solid.
I await correction, noting that without the mathematics, this can be at best nothing more than an attempt at a poetic description of what’s happening.
http://galileo.phys.virginia.edu/classes/252/black_body_radiation.html
PS, why is it worth persisting?
Because this is what it takes for understand how visible light impinging on the surface of the planet can be depositing energy; how that turns into heat in the solid and liquid; how the solid and liquid emitting infrared photons across a wide range, varying with temperature; how that infrared warms the atmosphere; how the greenhouse gases in the atmosphere, while moving around, returns some of the heat back to the surface of the planet.
And when you get that clear, the energy flow diagrams make sense:
http://www.cgd.ucar.edu/cas/Trenberth/Presentations/CC07_UWis.pdf
And you can understand why you can take your little infrared thermometer out
http://mynasadata.larc.nasa.gov/P18.html
and meter the night sky at different angles and different weather conditions, and meter clouds in the sky, and get different readings.
—–
Rod, try an analogy.
Take a dozen balls of each of a dozen different weights, and hang each ball from a rubber band, picking from a dozen different sizes of rubber band.
You get a huge variety of possible oscillators, each unique. Each one will bounce and swing in a predictable way. You can poke just one of them, and only that one will move–each time in a predictable way. It’s (like) a gas.
Now, take those and criss-cross the rubber bands in a net or cat’s cradle, with the various weights hanging down at various places from the maze of rubber bands of different sizes.
Check how each of the weights behaves, once all those rubber bands are woven together. Does each weight still have a characteristic, predictable motion? Can you poke just one of them and have only one of them move?
It’s (like) a solid or liquid.
Rod, your colliding atoms/molecules: Are the the constituents bound or free? If they are bound, then please explain how they absorb/emit at an energy other than an alowed transition. If free, then how does the atom/molecule get ionized?
Yes, a line can be broadened by a collision, but it is still a narrow energy line. And if your picture is general, then why does the sodium vapor lamp emit only in the lines of the sodium atom?
And there is nothing in Saltman that supports your view.
Mr. Rod B writes om the 14th of March 2010 at 4:42 PM:
“start vibrating at a very precise frequency depending on the atomic weights and bond strengths, e.g. After a while it tires of this and relaxes by releasing another ray (photon) of exactly the same energy — a radiation emission.”
That is not the only way out. the vibrational energy state can be excited and deexcited by collisions. The populations in these states are coupled to surrounding gas. The coupling constants are often specified as lifetimes against collisional and radiative decay.
Rod (995), I agree all H atoms are identical (deuterium and tritium aside), and that all H2 molecules are identical. The point is that the energy levels of H2 molecules are not the same as those of individual H atoms – and similarly, the energy levels of a piece of solid matter consisting of a large number of atoms bonded together are not the same as those of individual atoms.
What I’m saying is this:
which you would have seen had you looked here: http://en.wikipedia.org/wiki/Electronic_band_structure . And contrary to your suggestion, this has everything in the world to do with semiconductor operation. (You really should consider checking out those materials science lectures.)
I agree that this is a different issue than your claim that “everything is quantized”. No need, I think, to call down the wrath of MIT on Phillips Exeter; I read the page you linked to, and found nothing to support your “everything is quantized” position. Can you point to a specific passage which you think does?