APS members comment on climate change statement

by Judith Curry

The battle over the American Physical Society draft Statement on Climate Change is heating up.


In 2007, the APS issued a very controversial Statement on Climate Change.  These statements expire after 5 or so years, and they need to be reratified, revised, or dropped.  The process got off to a good start with a fascinating Workshop summarized in my post APS reviews its climate change statement.

The text of the new draft statement is (cited on my previous blog post, after it was reproduced on Reddit):

On Climate Change:
Earth’s changing climate is a critical issue that poses the risk of significant disruption around the globe. While natural sources of climate variability are significant, multiple lines of evidence indicate that human influences have had an increasingly dominant effect on the climate warming observed since the mid-twentieth century. Although the magnitudes of future effects are uncertain, human influences on the climate are growing. The potential consequences of climate change are great and the policies of the next few decades will determine human influences on the climate for centuries.

On Climate Science:
As summarized in the 2013 report of the Intergovernmental Panel on Climate Change (IPCC), there continues to be significant progress in climate science. In particular, the connection between rising concentrations of atmospheric greenhouse gases and the increased warming of the global climate system is more certain than ever. Nevertheless, as recognized by Working Group 1 of the IPCC, scientific challenges remain to our abilities to observe, interpret, and project climate changes. To better inform societal choices, the APS urges sustained research in climate science.

On Climate Action:
The APS reiterates its 2007 call to support actions that will reduce the emissions, and ultimately the concentration, of greenhouse gases, as well as increase the resilience of society to a changing climate. Because physics and its techniques are fundamental elements of climate science, the APS further urges physicists to collaborate with colleagues across disciplines in climate research and to contribute to the public dialogue.

In my post on the Draft APS Statement on Climate Change.  I wrote:

Well, their paragraph on Climate Science is a rather astonishing take on the APS Workshop. Their paragraph on Climate Change seems to come from the Guardian. Their statement on Climate Action reiterates their rather crazy statement in 2007.

Here is my real problem with this statement. This is an egregious misuse of the expertise of the APS. Their alleged understanding of issues like spectroscopy and fluid dynamics are not of any direct relevance to the issues they write about in this statement.

There is some additional backstory in this Scientific American Article: Physicists battle over the meaning of ‘incontrovertible’ in the global warming fight.

Request from APS members

In response to my post on the draft APS statement, on April 8 I received an email from a group of APS members requesting that I create a thread on Climate Etc. where APS members could post their comments publicly, so that they could be discussed and so that it would be more difficult for the APS to ignore these comments.  This thread is the result of this email discussion.

The comments that I have received so far are appended below:

Roger Cohen

What a craven and scientifically misguided statement this is. It wreaks of slogans, exaggeration, and distortions. For example: “In particular, the connection between rising concentrations of atmospheric greenhouse gases and the increased warming of the global climate system is more certain than ever.” You do not mention that the accumulating evidence is that this ‘connection’ is far smaller than we have been told by IPCC, that it has been revised DOWNWARD, and that any future warming will be correspondingly much smaller.

Let’s take another: “…there continues to be significant progress in climate science.” Really? Then why is it that, as revealed in the Koonin group framing document, there has been no progress whatsoever in narrowing the uncertainty in the critical Climate Sensitivity parameter during the 25 years of IPCC existence? This is despite the billions wasted on climate models that are known to be materially deficient and downright wrong in their projections.

Then there are significant developments that you choose to ignore because they do not fit your Agenda. You do not mention that increased CO2 in the atmosphere is beneficial and that greening of the earth has already been observed by satellites. You do not mention that there has been no global warming for nearly two decades, in opposition everything we have been told would happen. You do not mention that even IPCC finds no significant evidence of increased extreme weather.

Any knowledgeable reader who looks through the Koonin group’s framing document  or the workshop transcript will find that this material is at odds with the conclusions presented in the draft Statement.

Physics is a quantitative science that makes progress through debate and weighing of the evidence. But you have abandoned this tradition in favor of politically correct slogans and talking points. You do not present a whit of evidence to support your conclusions. In fact the inputs collected by APS are at odds with its conclusions. As the now clearly obvious climate truths become more widely known and acknowledged, future generations of APS leaders will come to regard this Statement and the fabricators that produced it as embarrassing reminders of how readily the Science Project could be corrupted.

Roger W. Cohen, Fellow, American Physical Society

David Douglass

The APS should let the prior 2007 statement expire — i.e. let it die.

Physics to me has always meant the search for scientific truth. Guidance in this pursuit is given in the motto of the Royal Society: ‘Nullius in verba’ (take nobody’s word for it). This is embodied in the scientific method in which belief in any model/theory/ hypothesis must be supported by experiments/observations. This goes back at least to Galleo.

That there there is some global warming due to the increase in CO2 is generally agreed to as has been described by Richard Lindzen. However, The claim of enhancement of “global warming” by positive feedback comes entirely from computer models. This is only a hypothesis with no creditable observational evidence.

In fact, the observational evidence goes against this hypothesis. For the past 15 years the concentration of CO2 has been increasing while the Earth “refuses” to warm.

The problems and errors in the APS POPA statement are documented in detail by APS members Judith Curry and Roger Cohen. I will not repeat these here. I strongly agree with what they say.

Do not issue a new climate statement! Let the issue die!

David Douglass, Fellow APS

William Happer 

History will not look kindly on APS for its 2007 Climate Change Statement, with its supposedly “incontrovertible” science. A little more than a year ago, I was encouraged by the excellent APS workshop on the status of climate science, organized by Steve Koonin. I had hoped that a POPA review, guided by the results of the workshop, would lead to a sensible climate statement. But the draft POPA statement does not even mention the Koonin workshop. It includes silly pontifications like “the connection between rising concentrations of atmospheric greenhouse gases and the increased warming of the global climate system is more certain than ever.” Who ever doubted that greenhouse gases cause warming? The issue has always the magnitude of the warming caused by a doubling the amount of CO2 in the atmosphere. As the Koonin workshop makes clear, the magnitude is less certain than ever, and it may well be so small that increasing CO2 will benefit the planet. And the new draft goes beyond the old statement with a call for “Climate Action.” Is the APS a society for the advancement of physics or is it a propaganda organ for a cause?

I urge the APS Council to let the previous statement expire naturally and to issue no new statement. This was the solution chosen by the Geological Society of Australia in 2014. It worked for them, and it would work for us.

Robert Knox

One of the APS climate statement FAQs argues that physics is important to climate science. It is, and certainly physicists are contributing to it, but as climate science is now practiced (concerning global temperatures and other global properties) its epistemology is wholly distinct from that of physics. An astounding level of uncritical credence is afforded to the output of large models. For example, results most divergent from observations are typically not discarded. They are averaged in with all others. Try this philosophy with your favorite unexplained physical measurement.

Do large percentages of scientists actually agree with global warming predictions? They may say they do in surveys, but it is very likely that a majority are not qualified to judge. Only a few at the top of the modeling profession are truly competent to know whether model feedback parameterizations, the treatment of clouds, etc., are adequate. Having read many papers that predict bad consequences for flora or fauna, or for humanity, I feel that those who conclude “climate change is bad” have done perfectly good deductions within their field of expertise but have taken some model warming prediction as a primary premise. This unwarranted premise is critical to their results and is usually unmentioned as such.

Rather than calling out the questionable epistemology — or better yet remaining silent on the entire issue — POPA and APS have joined those who promulgate the model predictions of dangerously rising temperatures as if they were settled science. It is a shameful situation that is amplified by the calamity-hungry popular press. The majority of APS members are not equipped to meaningfully assess the science behind the predictions; a blatantly political statement, developed by “consensus building that has resulted in a solid, science-based statement,” as the POPA chair has said, will ultimately tarnish the reputation of the Society.

I urge APS Council, of which I am a former member as DBP representative, to withdraw the 2007 statement and cease this climate change statement effort.

Robert S. Knox,  Fellow APS, Professor of Physics Emeritus, University of Rochester

Hugh Kendrick

This statement is pathetically unworthy of a high school physics project much less of an organisation of physicists whose hallmark ought to be quantitative analysis, not an ignorant ideological polemic like this that tramples the scientific method. The original theory of catastrophic anthropogenic global warming (CAGW) has morphed into the generic “climate change” so that any weather event can be blamed on human intervention. None of the hysterical claims of CAGW has materialised. That APS would be a party to such deliberate mendacity is shameful and not worthy of a scientific society.

This statement relies on a sole resource, the IPCC, whose mandate is restricted to human contributions to risks from climate change. So it ignores a vast body of independent research into natural causes of climate change, and the findings of the benefits of increased CO2 concentrations that are greening the planet, and the reduction of the adverse human health effects of cold weather.

It fails to acknowledge, to borrow from the discredited 2007 statement, that the “evidence is incontrovertible”; global warming stopped more than 18 years ago. So it is wrong to say the connection between rising CO2 and warming is more certain. Climate sensitivity, including feedbacks originally assumed large and positive by IPCC, has continuously had to be scaled back as the divergence between all model projections and real data increases. Research ignored here shows feedbacks to be small and likely negative, undermining the whole premise of CAGW. Moreover, none of the theories that attempt to explain this 18+ year “hiatus”, as the IPCC calls it, has any supporting data.

It ignores its own Workshop and the summary of it by Chair Dr Koonin. Not only is it not settled, but climate science is beset by uncertainties as revealed by any fair reading of the Workshop transcript. It ignores that even the IPCC acknowledges no connection between rising CO2 and extremes of weather.

This statement is an embarrassment to the APS and unrepresentative of its talented body of physicists.

Franco Battaglia

I’m sorry to say that the above statement would challenge the authority that the APS has so far gained on science issues. I would NOT approve the statement as it is.

  • The sentence «multiple lines of evidence indicate that human influences have had an increasingly dominant effect on the climate warming observed since the mid-twentieth century» does not reflect the emergence of any risk: assuming (and it is NOT so) that any climate change that the planet has experienced since the mid-twentieth century is due to human responsibility, has not been more severe than climate changes experienced in the past centuries and millennia. Human responsibilities (admitting they exist) appear to be a background noise over a ever changing climate due to natural causes.
  • The sentence «Although the magnitudes of future effects are uncertain, human influences on the climate are growing» is self-contradicting (if the effects are uncertain, how can they be growing?) and contrary to the evidence: the global mean temperature has not increased during the last 10 years or so, although the GHG emission have restlessly increased.
  • It is not clear why the IPCC – a politically-constructed organization – is considered an authority on the matter. If it is, why would the APS need to make its own statement parroting the statement of another organization? In any case, the sentence «the connection between rising concentrations of atmospheric greenhouse gases and the increased warming of the global climate system is more certain than ever» does not appear to be true: a) the global temperature has been rising since the exit from the last glacial period; has fallen several times (the last time during what the geologists call the Little Ice Age (1500-1700 AD); and started to rise again since the middle of the Seventieth century, when GHG emissions could not be responsible); finally, during the years of steadily increasing GHG emissions, the temperature of the planet has NOT steadily increased (see the last 10 years or so).

In conclusion: I think that the above statement is more political than scientific: it would jeopardize the credibility of a community – the APS – whose authoritativeness has been founded on scrupulous scientific grounds. Of course I agree on the statement that encourages continuous research on climate science.

Franco Battaglia, Professor of Chemical Physics, University of Modena, Italy

Laurence Gould


I am a member of the Forum of Physics and Society and also a member of the topical Group on Climate Physics. I have been studying the subject of “climate change/global warming” for the past decade.

In your Report you mentioned that “It [the subcommittee of POPA] will be informed by such parts of the Fifth Assessment Report [AR5] of the Intergovernmental Panel on Climate Change (IPCC) as are available at the time. The most relevant part for POPA purposes is the report of Working Group I, which is concerned with the physical science basis of the assessment…” This seems to indicate that the AR5 is will be the main source of information. However there have been a number of scientific criticisms of the AR5 that have been detailed in the NIPCC Report — “Climate Change Reconsidered II: Physical Science”

That NIPCC Report (there have been others in past years) is, to my knowledge, the only one that looks critically and comprehensively — from a scientific standpoint that includes many peer-reviewed references — at the arguments put forth in the AR5.  I call this Report to your attention because — although it may seem harsh to criticize the IPCC’s AR5 — the NIPCC Report appears to have valid scientific justifications for its claims.

Although it is understandable why there have been past issues about the APS Statement on “climate change/anthropogenic global warming”  I hope that the full scientific method — plus whatever is germane from the attachments — can be brought to bear in formulating the new statement by the APS.

… In view of the difficult scientific issues pertaining to climate, as well as issues of scientific integrity, I am also glad that the Climate Change Statement is being revisited (hopefully with the result that the Statement will be rescinded).


Laurence I. Gould, Past Chair (2004), New England Section of the APS

JC message to APS members: You can submit your comments by pasting them into the comments box at the bottom of the thread.  Alternatively, you can email them to me at curryja at eas.gatech.edu and I will post them for you.  APS members can also discuss other comments or aspects of the process in general by submitting comments.

JC message to Denizens:  This thread is open only to APS members.  I’ve created a parallel thread  APS discussion thread, for general comments and discussion.  Note, comments aren’t due until May 6, so comments may be a bit slow to accumulate.

25 responses to “APS members comment on climate change statement

  1. Pingback: APS members comment on climate change statement | Enjeux énergies et environnement

  2. This is a political statement and not a scientific statement. I find both the process and the content inappropriate for the APS. On January 8, 2014 Steven Koonin hosted a Climate Change Statement Workshop at NYU. The complete 573 page transcript of that meeting has been available for quite some time. The Workshop was an excellent give-and-take between 6 climate experts and members of an APS subcommittee. Subsequent to that meeting, Dr. Koonin resigned from POPA, and wrote a balanced, thoughtful essay on Climate Science which was published on Sept. 19, 2014 in the Wall Street Journal. This essay discusses the difficulties that climate scientists have in modeling the interactions of the atmosphere with the oceans and the landmasses, especially the complexities of radiation transport through the clouds and the consequent precipitation cycles. The mean temperature of the lower troposphere has been flat for about 18 years. This is not understood and the models have generally not predicted it.
    If POPA wants to publish a statement on climate science that reflects the views, ideas and expertise of the APS Membership, it should be considerably longer and thoughtful. A starting point for such an effort would be studying the 573 page Workshop transcript. The draft statement seems to ignore the process begun by Koonin at NYU. Why? Members of POPA who have not studied the Workshop transcript should not sign their names to the statement. The authors of the statement should explicitly sign their names to the document.
    Surely, the full collection of these comments should be made available to the APS Membership and the Public in general.

    Samuel A. Werner, APS Fellow
    Curators’ Professor of Physics Emeritus, University of Missouri-Columbia
    & Guest Researcher in the Neutron Physics Group, NIST

  3. Comment received via email:

    To APS members:

    I am so pleased that physicists are engaging on the topic of climate change. My purpose for writing to this blog is to urge all current APS members so inclined to comment on the APS draft statement on climate change before the deadline of May 6th. The APS will be well served by your input. You have received a unique link by email. Also, if you find this topic fascinating and are not yet a member of the Topical Group on the Physics of Climate, please consider joining. We are growing fast and seek to provide a forum where physicists from all fields may find a place for their expertise in some aspect of the climate system. There is still so much to understand, and a huge variety of skills are needed to make the climate problem tractable.

    To the technically inclined public:

    I strongly recommend the free online courses below. They are excellent, technical yet accessible introductions to the complex science that is climate change:

    David Archer, University of Chicago

    Dan Cziczo, Kerry Emanuel, and David McGee, MIT


    Morgan O’Neill
    Executive Committee, Member-at-Large, APS Topical Group on the Physics of Climate

  4. Email message from Dave Rutledge:

    Hi Judy,

    I have known Steve Koonin for more than 20 years, and I have had many occasions to observe his integrity in matters large and small. His background makes him uniquely suited for leading the discussion on an APS statement on climate change. If it is true that he has been pushed out of the process, then the process has likely been compromised by politics. It would be best in this circumstance to let the 2007 statement lapse.

    Dave Rutledge

  5. Like Lilly Tomlin, I am finding it increasingly difficult to be cynical enough. After having read the climate workshop documents, I had some hopes that the new statement might reflect some of the realities of what we know for sure about climate. The new expression of increased confidence in the connection between global warming and human activities bears no resemblance to the current reality in which the climate models are increasingly divergent from the pattern of actual warming. The new statement is an embarrassment to all actual physicists.
    Stan Robertson

  6. Here are the comments I submitted to APS nearly two weeks ago. I chose to comment within the limits imposed by the original statement rather than insist on scrapping or totally rewriting it.

    “I am concerned that the APS statement contains language that is unduly alarmist and not well motivated by current science.

    Saying that changing climate is a “critical issue” suggests an urgency that hardly seems justified. Calling it an “important issue” would be sufficient. Likewise, human influence shouldn’t be called a “dominant effect.” Only climate models suggest dominance and they don’t rise to the level of “evidence.” In fact, the two middle sentences of the statement on climate change are redundant and could be replaced by a single sentence. Something along the following lines would be appropriate: “While natural sources of climate variability are significant, multiple lines of evidence indicate that human influences on the climate are growing, especially in their contribution to warming temperatures.” Finally, potential consequences should be said to be “substantial” instead of “great” and policies “may” determine influences on climate. Saying “will” implies an efficacy to policy that is simply unjustified. It is unclear that any politically achievable policy is capable of having a measurable impact on temperatures.

    In the statement on climate science, it is crucial to acknowledge the growing gap between all temperature data sets (surface, satellite, and balloon) and all climate models. It is hardly debatable that this gap implies the existence of significant systematic errors in either the data or models or both. The ability to formulate effective policy is handicapped by these systematic errors. The primary task of climate science, then, should be to resolve them.

    The statement on action should be explicit that, because of substantial uncertainties implied by climate science, the APS can only support actions that provide net benefits beyond the climate issue. Examples might include policies to increase the % of low-carbon energy sources, such as solar and nuclear, to diversify our energy portfolio and guard against oil shocks, or to make buildings more storm resistant as means of reducing the cost of damages and loss of human life we already incur without climate change.”

  7. I told the APS that the new statement is much better than the old one. I agree with a lot of the points above, but nonetheless still think the new statement is at least an improvement. I agree with statements above that there are exaggerations in the new statement, but at least they don’t have such a gross exaggeration as “incontrovertible”. And the new statement mentions both reducing emissions and increasing resilience (and additional research) in the call to action, which is better than before. I did also mention that I don’t think the APS needs to have a call to action since it is a scientific organization, not a political one.

    Michael Wilson, APS member

  8. Professor Curry – Thank you very much for taking on the task of providing a more public forum for comments. In the following submission which I made, I tried to stick to the actual text of the draft statement in hopes that it might lead to more temperate language.

    Kindest regards,

    Arthur G. Tweet, Fellow, APS

    On Climate Change:
    Earth’s changing climate is a critical issue that poses the risk of significant disruption around the globe. While natural sources of climate variability are significant, multiple lines of evidence indicate that human influences have had an IMPORTANT effect on the climate warming observed since the mid-twentieth century. Although the magnitudes of future effects are uncertain, human influences on the climate are growing. The potential consequences of climate change are great and the policies of the next few decades will determine human influences on the climate for centuries.

    On Climate Science:
    As summarized in the 2013 report of the Intergovernmental Panel on Climate Change (IPCC), there continues to be significant progress in climate science. In particular, the connection between rising concentrations of atmospheric greenhouse gases AND THE GLOBAL CLIMATE SYSTEM DESERVES FURTHER EXPERIMENTAL AND THEORETICAL STUDY, INCLUDING COMPUTER MODELING. Nevertheless, as recognized by Working Group 1 of the IPCC, scientific challenges remain to our abilities to observe, interpret, and project climate changes. To better inform societal choices, the APS urges sustained research in climate science.

    On Climate Action:
    The APS reiterates its 2007 call to support actions that will reduce the emissions, and ultimately the concentration, of greenhouse gases, as well as increase the resilience of society to a changing climate. Because physics and its techniques are fundamental elements of climate science, the APS further urges physicists to collaborate with colleagues across disciplines in climate research and to contribute STRICTLY SCIENTIFIC INPUT to the public dialogue. I ALSO SUGGEST SOMETHING ABOUT PEER-REVIEWED JOURNALS GIVING UNBIASED ATTENTION TO SERIOUS TECHNICAL MSS. WHICH DISAGREE WITH THE IPCC SUMMARY REPORT OF 2013.

  9. received via email:
    Dear Professor Curry:

    I have submitted the following feedback on the proposed climate statement to the APS:

    “The proposed APS statement on climate change is inappropriate for a physics society, and should be abandoned.

    One principal problem is that the IPCC uses the Clausius-Clapeyron equation to determine the amplification of the direct heating effect of greenhouse gases. This is plausible starting point, but the absence of a correct treatment of clouds and precipitation yields predictions of the rate of climate change which are much larger than reality, as shown by satellite and balloon measurements (which are in reasonable agreement with each other and disagree with IPCC’s models, as has been presented by Roy Spencer). The difference is very important because it determines whether manmade effects are dominant or if natural causes are dominant. Since the measurements agree with the latter case, only Don Quixote would find it useful to attempt to change the outcome.

    Even if the IPCC predictions were correct (which they are not), have the advocates of ceasing manmade greenhouse gas production seriously considered how they would be personally impacted by doing so, given today’s technologies? Nuclear power would be a viable option if poiiticians stopped cancelling waste repositories. Without nuclear power and with the limited available hydroelectric power, how will houses be heated or cooled? What will you use for a form of transportation? How will you fly to global warming conferences? How will energy intensive industry continue to operate? First bankruptcy, then a stone age existence appear to be the logical outcomes of trying to follow this avenue. Adapting to the changing climate seems like a much better investment of resources.”

    Ronald Sundelin, Fellow, American Physical Society

  10. I think that the APS draft statement is a bit unclear in some places, and could do with a little tweaking in others, but is nevertheless a reasonable summary of the current state of the science, and in accord with much of the discussion at the NYU climate workshop (and of course, the other scientific evidence available to the drafting committee). I hope that it or something similar will be adopted.

    In particular, the NYU workshop reflected a diversity of viewpoints, all from capable scientists with impressive reputations in the physics of climate. All participants surely had every opportunity to make their case. I thought that Drs. Collins, Held, and Santer made the more persuasive case, and that there is a good deal of additional evidence that points in the same direction, albeit with considerable uncertainties about the details. The writers of the APS draft seem to have agreed.

    A good bit of that evidence, as I read it, does not rely on general circulation models.

    For what it may be worth, I am a physicist, an APS member, and a member of the APS Topical Group on climate. Although my research is in the history of physics, I am interested in the physics of climate and try to keep up with it. I have read the transcript of NYU climate workshop. I respect the viewpoints of those who do not think the evidence supports the APS draft. Some of them–Dr. Curry is an prominent example–have considerable expertise and well-deserved reputations, and views that must command respect. Nevertheless, it is my impression that among physicists, geophysicists, oceanographers, and the like whose expertise and published research is in the physics of climate and related areas, a substantial majority read the evidence along the same lines as I do, and as reflected in the APS draft statement.

    I do think that the diversity of viewpoints reflected in the NYU workshop will play out chiefly in the published literature. It can be entertaining and, to be fair, sometimes informative to read the often energetic and occasionally overwrought statements (on all sides) that one sees in Internet posts and opinion pieces, but the real action is elsewhere.

    Clayton Gearhart

  11. Received via email from APS member Roy Clark:

    APS Comment Submitted

    Over the last 200 years or so, the atmospheric concentration of CO2 has increased by approximately 120 ppm. This has produced an increase in downward LWIR flux at the surface of approximately 2 W per sq. meter. When this flux increase is added to the time varying surface heat flux it is too small to have any measurable effect on surface temperature. The surface solar flux can very from zero to over 1000 W per sq. meter each day.

    There is simply no evidence in the climate record to support any role for CO2 induced climate change or any CO2 induced increase in ‘extreme weather’. Small changes in solar flux are sufficient to heat the oceans and changes in CO2 concentration follow the ocean temperatures. The penetration depth of LWIR radiation into the oceans is 100 micron or less. It is simply impossible for the small increase in LWIR flux from CO2 to couple below the ocean surface and heat the ocean underneath.
    The troposphere acts as an open cycle heat engine. The dominant tropospheric heat transfer process is by moist convection, not LWIR flux. The Earth’s climate is determined mainly by ocean thermal storage and rate limited evaporation of water from the oceans, not by small changes in LWIR flux. The so called ‘greenhouse effect temperature’ of 33 K is a result of the cooling produced as the air ascends through the troposphere from the surface to the cold reservoir of the tropospheric heat engine at an altitude near 5 km.

    The climate models are completely fraudulent and have been since the mid 1960s. The fundamental error is the underlying equilibrium assumption. There is no such thing as an equilibrium average climate that can be analyzed using perturbation theory. The assumptions used to build the first climate models must by definition produce global warming as a mathematical artifact of the modeling constraints applied. The flux equations are computational climate fiction. The radiative forcing constants used by the IPCC are nothing more than empirical pseudoscience. The climate models were ‘calibrated’ by using changes in ocean surface temperatures. The Earth stopped warming some 18 years ago and is now starting to cool back towards another Little Ice Age.
    In addition to fraudulent climate models, the process of ‘homogenization’ and averaging used to produce the global climate averages from the weather station data has been used to create additional ‘warming’ in the climate record. At least half of the surface temperature ‘warming’ is a result of fraudulent ‘homogenization’. This is a complete disgrace.

    The APS has been fooled by climate astrology and bribed to abandon the Second Law of Thermodynamics in favor of environmental alchemy.

    All of the IPCC reports should be rejected and a scientific and criminal fraud investigation conducted into the IPCC. Global warming/ climate change/ climate disruption is a multi-trillion dollar fraud.

    For further discussion see:
    Clark, R., 2013a, Energy and Environment 24(3, 4) 319-340 (2013) ‘A dynamic coupled thermal reservoir approach to atmospheric energy transfer Part I: Concepts’
    Clark, R., 2013b, Energy and Environment 24(3, 4) 341-359 (2013) ‘A dynamic coupled thermal reservoir approach to atmospheric energy transfer Part II: Applications’
    and the other papers in this special E&E climate issue [24(3,4)].

  12. Responding to Roger Cohen’s invitation, here are the comments I submitted to the APS regarding the draft climate change statement.

    Bill Burdett, APS member for over 40 years

    APS Draft Climate Statement Comment

    The draft APS statement is self-contradictory. The conclusive assertions in the first paragraph (e.g., “…human influences have had an increasingly dominant effect on the climate warming observed since the mid-twentieth century”) do not comport with the call in the second paragraph for “…sustained research in climate science” and the urging in the third paragraph for “…physicists to collaborate with colleagues across disciplines in climate research…”. Following good scientific practice, let the ongoing research reach evidence-based conclusions regarding the dynamics of climate change. The APS statement should not predetermine the outcome of that research.

    Because the “potential consequences of climate change are great”, the APS statement should state that science will serve the public good by not allowing the poorly validated climate models available today to govern the allocation of limited public resources in the near future. For example, if natural sources of climate variability prove to be dominant, public policy should encourage investments in societal resilience rather than costly and futile efforts to alter the course of climate change.

    Bottom Line: The statement should focus on the need for objective, high-quality collaborative research in climate science that will gain the confidence of the public and guide the implementation of policies that will be truly effective in the coming decades.

  13. I submitted my statement. Not sure it will fit here:
    For years I also believed that man was the primary cause of
    changes to earth’s climate. Eventually an ethanol company
    needed a business plan and asked me to analyze the problem from
    the point of view of “will the US government continue to
    provide ethanol subsidies?” After reading the literature I
    found the evidence for alarming alteration of the climate to be
    very weak.

    The essential problem with the climate is that it has always
    been extremely variable. To avoid that variation, you need to
    be able to either (a) understand it so well that you can
    predict it, or (b) gather data for such a long time that the
    natural cycles are integrated out. As far as (a), the problem
    of predicting the climate will be solved after the problem of
    predicting the weather is solved. As far as (b), the climate
    cycles on the order of 10 degrees C over time periods of about
    100,000 years. Because of these inherent problems, it is not
    now possible to predict what the effect of CO2 on the climate
    is. We can say it will result in warming but cannot make a
    theoretical calculation that shows that it is significant. And
    we can model the warming but only with respect to temperatures
    that have oscillated wildly for many millions of years. And
    that means that the error bars on our estimates have to be
    incredibly large.

    The basic problem with climate science is that it is a very
    young science and has not yet learned the humbling lessons of
    older science. Every major branch of physics has gone through
    this transition. Early work can be characterized by naive use
    of statistics with a great deal of work published that reflects
    the biases of the authors. An example is the discovery of
    gravitational waves by Joe Weber. Compare his use of statistics
    with those now used by LIGO and you will see the difference
    between climate science now and what climate science needs to be.

    But when Joe Weber repeatedly saw impossible gravitational
    waves the only result was the expenditure of a few million
    dollars in experiments.

    What the APS statement is supporting implies trillions of
    dollars in changes to the world’s economy. What you are asking
    for is that we avoid the present CO2 experiment, which is
    likely to make small positive improvements to the world
    climate. After thirty years of failed predictions of imminent
    major climate effects is it any surprise that there is so
    little political support for a huge experiment in the world’s
    economy? I’m reminded of the physics predictions of the 1950s
    that it would take 20 years for fusion to bring the cost of
    electricity to zero. CO2 rises but world production of food
    continues to grow, snow continues to fall.

    But the situation is worse than that. In addition to bad
    science, it is clear that the core of climate science has been
    politicized by emotional arguments about the environment and
    corrupted by the distribution of government money. The
    temperature record has been changed to accent recent highs. And
    the perversion of the peer review process, etc. All this came
    out in the “climategate” emails.

    If you want to make a positive and fair APS statement on
    climate change, put it up to a vote. Let the same 6 experts
    that testified at Koonin’s workshop put together (up to) 6
    climate statements and their arguments in favor of their
    statements. Let the APS membership read the statements and vote
    on the one they prefer. Then publish the vote totals. Are 97%
    of your members scared of CO2? Let’s find out.

  14. I favor repealing the incorrect and embarrassing APS public statement on global warming and replacing it with nothing. The proposed update is as harmful to the reputation of the APS as the original statement.

    Based on spectroscopic calculations of air molecules, the literature shows that the zero-feedback climate sensitivity (≡ temperature increase due to doubling CO2 from 300 ppm) is initially about 1 deg C. A variety of atmospheric, ocean, and biological responses will then either add more warming (positive feedback) or add some cooling (negative feedback) to this initial direct heating. Almost all relevant published data indicate that the feedback is mildly negative, on several time scales. Hence the warming due to doubling CO2 will be less than 1 deg C.

    The geological record (e.g., ice and ocean sediment cores) shows that CO2 is not correlated to temperature over tens of millions of years. Over a shorter timescale of hundreds of thousands of years they are correlated, but CO2 follows (not leads) temperature by about 500 years. These data support the idea that temperature controls CO2 concentration (not vice versa). However, water vapor and clouds do have a much larger and dominating effect on global temperature. This argument unequivocally refutes the popular and deceitful story of global warming proponents who speculate that the feedback is positive, huge warming will occur, and disaster is just around the corner due to human fossil fuel usage.
    Ironically a slightly warmer Earth, with double the present CO2 concentration, would improve the human condition on the planet by enabling more food crop production and lowering the well-documented excess human death rate in winter.

    The data-based argument that global warming by CO2 is not a problem is obvious to many accomplished leaders in the science community (Freeman Dyson [Princeton and co-inventor of QED], Ivar Giaever [Nobel Prize], Robert Laughlin [Nobel Prize], Edward Teller [co-inventor of the hydrogen bomb], Fred Hoyle [co-inventor of stellar nucleosynthesis], Frederick Seitz [past president of the National Academy of Sciences], Robert Jastrow [co-founder of NASA GISS], William Nierenberg [past director Scripts Institute of Oceanography], William Happer [Princeton and past presidential science advisor], Hal Lewis [past physics chair at U. Calif. S. B.], Richard Lindzen [MIT], John Christy and Roy Spencer [two principal investigators for satellite-based global temperature measurements], Burt Rutan [designer of Voyager and SpaceShipOne], Henk Tennekes [past director, Royal Dutch Meteorological Service], and Harrison Schmitt [NASA geologist and astronaut]).

    The argument against dangerous global warming is so obvious that even the general public (e.g. Patrick Moore, co-founder of Greenpeace) can see through the charade. This public statement is damaging the credibility of APS, and could prevent the public from listening to the important advice of the physics community at a future date when a true threat faces humanity.

    Gregory C. Herring (April 2015)

  15. Underlying the APS statement there are two unstated assumptions:
    1. Climate models have good predictive power.
    2. The effects of increased atmospheric CO2 concentration are all negative.
    These assumptions are controversial at best and arguably false.

    Regarding the first assumption, the recent divergence between observations and model predictions is strong evidence that climate models have limited forecasting skill. This problem was anticipated by Hendrik Tennekes in 2009 (A Skeptical View of Climate Models), long before the divergence was as clear as it is today. This is important because any call for action to reduce emissions, as is contained in the APS statement, is predicated on model predictions. If the models have overestimated the effects of greenhouse gas emissions, the benefits of reducing them are overstated. It is impossible to weigh the costs and benefits of a policy of the benefits are uncertain.

    Furthermore, the APS statement does not account for the benefits of increased CO2 concentration in the atmosphere. The IPCC Assessment Reports focus on the possible effects on climate caused by greenhouse gases. However, changes in CO2 concentration have consequences that are beneficial, including the well-documented effects on plant growth. By implicitly assuming that the only effect of CO2 emissions is on climate (and deleterious), the APS statement fails to take a comprehensive view of the issue. To make informed policy choices, all the costs and benefits of any action (or inaction) must be considered.

    In 2007, the APS issued an intemperate climate change statement containing unscientific exaggeration of the certainty of climate science understanding and predictions. This statement was so ill advised and poorly considered that a lengthy explanation was appended in 2010 to the original statement in an attempt to correct some of the errors. The new statement contains much of the same alarmism and immoderate language as the 2007 statement.

    I urge the APS to step out of this controversy until there is less uncertainty lest we find ourselves repeating the mistakes of the past. The APS has no business taking an official position on this topic at this time. At the very least, the APS should eliminate any call to action, which is a political recommendation, and stick to scientific issues.

    Gabriel Lombardi

  16. (slightly modified from the version I submitted to APS)

    I wish to respond constructively to the Draft APS Statement on Earth’s Changing Climate. I have invested a lot of time working for APS on this issue for the last five years (I am an APS fellow, was a member of the 2010 APS Presidential Panel on Climate Change, then one of the organizers of the Topical Group on the Physics of Climate, and a member of the GPC Executive Committee through 2014), in addition to many other roles within the society. Let me be blunt: this statement will damage APS at least as much as the first one did. I will suggest two specific changes below that I think would be widely recognized as serious improvements.

    Let me begin by acknowledging the honest efforts of many people in creating this statement, and the very positive act of sending it to the membership for review. The 2007 statement from POPA, as approved by the APS Council, seriously damaged the reputation of APS. For this reason, my preference from the beginning has been to let the 2007 statement die without a replacement. There is no statement you can write that will be uncontroversial, climate change research cannot viewed as a core specialty of APS members as a whole, and climate “action” or policy certainly does not reflect any special APS expertise. However, we may well be past that point now: not approving some statement will also effectively be making a statement.

    You will receive plenty of strongly worded comments about the science. I will not join that group, as I think the science statements are at least defensible, although I hardly think they reflect a consensus among APS members. Rather, I would ask a more important question:

    Who is the target audience?

    It surely is not the APS membership: you will only succeed in getting people angry. I hope it is not the other professional societies: they will not be impressed to see yet another dragged-out fight here, and will not view this statement as giving any insight.

    In the end, I see only one important target audience: policy makers. In that case, the “climate action” statement is comically bad. Politics is the art of the possible, and the statement suggests an extreme policy without evaluating costs and benefits. Today, almost any serious scientist would conclude that evaluation is essentially impossible. Even if you take the IPCC AR5 document as revealed truth, you have a factor of three range (1.5-4.5C) for climate sensitivity (and, in fact, there is plenty of recent evidence that both the lower and upper limits are too high). The economic impacts are highly nonlinear (small positive changes are almost certainly of net benefit), so for any given amount of total emissions, even the IPCC numbers give about a factor of 10 uncertainty as to societal cost, and that is probably an underestimate.

    The possible benefit (avoiding this cost) must be weighed against cost estimates for extreme reduction strategies, which are also vague, but numbers in the trillions per year are thrown about-equivalent to the income of the poorest two billion people. That money would essentially eradicate worldwide extreme poverty. Of course that money would not otherwise be handed to them-but anyone who doesn’t realize that, in the end, the poorest will bear a disproportionate share of the costs, has not followed much economic and political history.

    So my first suggested change is very simple: change the first sentence of the climate action statement to

    “The APS supports cost-effective actions that will reduce the emissions of greenhouse gases, as well as increase the resilience of society to a changing climate.”

    That statement says, in effect, do the smart things first. With that statement, you might even get a Republican presidential candidate or two to agree.

    I also believe that you are giving up an important opportunity to do something useful, taking advantage of expertise that is within APS: understanding the scientific method. Very simply, “climate science” is so poisoned by politics, on both sides of the arguments, that efforts to understand climate physics are severely compromised. There is a long list of prominent scientists on both sides who are behaving very badly. Dueling editorials, direct attacks on scientists by politicians, lawsuits intended to silence debate, and campaigns to impugn the integrity of anyone who presents a different result or perspective are all incredibly destructive. These efforts are funded by deep-pocketed political groups, and egged on by news media anxious to create interesting stories (without much concern for truth).

    This problem you can address, with at least a chance of a positive impact, by turning the last sentence of “On Climate Science” (which, by itself, just looks like the usual plea for money) into the following paragraph:

    “To better inform societal choices, the APS urges sustained research in climate science. It also notes that the intimate mingling of climate science with climate politics, common across the spectrum of opinions, greatly damages efforts to achieve our common goal, a quantitative understanding of the risks and costs associated with carbon dioxide emissions and the benefits of reduction strategies. Money spent on those strategies will not be spent on other urgent needs, so improving our understanding of the tradeoffs ranks among the highest priorities in modern science.”

    Even with those two changes, count on the statement being controversial. But I believe that a majority of APS members could then at least agree that you are doing something constructive.

  17. Dear APS POPA,

    I have read the new statement carefully, as well as numerous blog postings on all sides of the issue. One most upsetting fact learned is that the Topical Group on the Physics of Climate was not formally, and apparently not even informally, consulted by POPA on the new proposed statement. How, then, can the APS credibly assert as fact that “human influences have had an increasingly dominant effect on the climate warming observed since the mid-twentieth century” without this group’s imprimatur? I, and surely many others, joined this group after the first statement was released, as a hopeful alternative to resigning from the APS immediately.

    As this point I can recommend only two options for proceeding that would ensure my continued membership: 1) withdraw both the original and the proposed new statement, i.e. get the APS quietly back to its original and only mission, physics; 2) withdraw the proposed new statement, and close the activity, leaving the original statement in place, in permanent testimony to the foolishness of even physicists, as it becomes even more ridiculous as time passes. In the absence of either of these choices, I will let my membership expire.

    David W. Norcross, APS Fellow

  18. I was indeed disappointed to read this draft statement, but anticipated something in this direction. It could well have been written by Holdren himself, specially noting words like “disruption” in the text – a word he seems to have invented.

    In reality there is nothing so far in existing climate-related observations that point to anything beyond natural climate and weather variability. At the same time one notes very clearly that the CLIMATE MODEL outcomes (the sole basis for alarmism) deviate more and more from actual observations.

    But the IPCC board instead is cited to claim that “the connection between rising concentrations of atmospheric greenhouse gases and the increased warming of the global climate system is more certain than ever”… What utter NONSENSE!

    No, this whole process has been a politically orchestrated farce from the beginning, and the scientific community and also APS members are the losers in the long run.

    Short-perspective objectives like hoping to raise research funding via fraud (like manipulated series of temperature data or suitably tampered model runs) will backfire for sure, and the whole idea is anyway utterly unethical from a scientific truth-seeking perspective.

    Also, most of the statement text is made up of POLITICAL buzz words rather than SCIENTIFIC statements.

    It should be rewritten from scratch.

    Peter Stilb

  19. I am very disappointed in the draft APS climate statement. This statement, in my opinion, undermines the “anchor[s]” of “the success and credibility of science.” (http://www.aps.org/policy/statements/99_6.cfm)

    The January 8, 2014 Workshop sponsored by the APS Panel on Public Affairs presented evidence and opinions consistent with a systematic gathering of knowledge, testing theories, exposing results, and reconsidering conclusions in the face of additional evidence – exactly as suggested by the APS Ethics and Values statement 99.6 “What Is Science.” This draft appears to ignore that workshop entirely, instead using language evoking concern and alarm beyond that suggested by the data.

    For example, global temperatures have undergone a “stasis” for over 15 years, as described in the Workshop. This falls below the model predictions, which are known to be incomplete. Given the extreme complexity of the climate system, future predictions should be given a more appropriate uncertainty, rather than the small and decreasing uncertainties of each IPCC report. As a result, it is inappropriate to say “the connection between rising concentrations of atmospheric greenhouse gases and the increased warming of the global climate system is more certain than ever.” It was never “certain,” it is not now, and temperatures of the past 15 years have decreased the evidence for CO2 as the primary driver of climate.

    A number of words and phrases appear more emotional than scientific: “critical issue,” “significant disruption,” “more certain than ever,” etc. This is in sharp contrast to the more balanced discussion of the 2014 Workshop. Additionally, the “APS reiterates its 2007 call to support actions…” appears to endorse its 2007 statement and its overly certain suggestions that “The evidence is incontrovertible: Global warming is occurring… We must reduce emissions of greenhouse gases beginning now.” It seemed largely agreed among the 2014 Workshop panelists that statements like these, and the initial sentence of the draft “On Climate Action” section, are inappropriate.

    My primary concern: to much of the public, climate science is the most public face of science. If its predictions don’t come to pass, many will see science as just another form of opinion, rather than being grounded in reality. So, statements of confidence and severity should reflect only objective evidence, not opinion or precaution. Over the long term, advocating a position beyond the evidence will do more harm than good, since not all predictions can be correct. Each failure of a “certain” prediction leads more of the public to abandon their trust in science as a method for seeking truth.


    Steve Carabello

  20. Comment on Draft APS Statement on Earth’s Changing Climate by Vladislav Bevc

    On Climate Change: Earth’s climate has been changing for billions of years. Significant changes have been occurring long before the advent of humanity. Changes, such as warming have occurred well before the industrial civilization and were generally beneficial to agriculture and other economic activities.

    On Climate Science: IPCC supported and generated theoretical predictions of global warming and climate change have so far not been confirmed by experimental evidence. Human generated carbon dioxide does not represent a significant amount of the total carbon dioxide in the atmosphere and is not likely to cause a significant rise in global temperature.

    On Climate Action: It is inappropriate to recommend actions requiring reducing emissions of the so- called greenhouse gases in absence of experimental evidence (as opposed to theoretical estimates). Such actions are damaging the economies of technically advanced countries, reduce the general standard of living, and result in no general benefit.

    A professional society such as APS should refrain from making statements on controversial issues such as climate change because such statements, regardless of their nature, will be abused by political entities expecting to represent them as support of their actions.

  21. Dr. Walter B. Paul

    I object to this statement.

    I do not believe it represents the views of the membership, which have yet to be polled on this topic. It is cleverly worded to be mostly literally true while strongly suggesting scientifically unjustified alarmism. In fact, since 2007, the case for catastrophic anthropogenic warming has grown weaker. So the “potential consequence may be great” but they are increasingly improbable.

    The statement about the connection between greenhouse gases and increased warming is false. It is not “more certain than ever.” The decrease in the estimated cooling effect of aerosols, along with “the pause” is strong evidence of a lower ECS as partially reflected in the change in this estimate between IPCC AR4 and AR5. The models, which assume this connection has large positive feedback, have been running too warm for nearly twenty years.

    Does the APS support ALL actions “that will reduce emissions”, regardless of cost and efficacy? Wind and solar will always be expensive as long as they require conventional backup. Why not advocate for R&D in energy storage technologies or mention the increased safety of 4th gen nuclear?

    Why does the POPA get to speak for the APS? Why not actually poll the membership. Put out this statement along with links to supporting material along with an alternate statement drafted by say Curry/Happer/Dyson/Lindzen and just let us vote? Why do the results of Steve Koonin’s workshop seem to have disappeared down the rabbit hole? BTW are you going to publish an anonymized version of these comments, so that the membership gets some idea of what other members think?


    6 May 2015

    I would like to focus my comment on your draft statement “On Climate Science”.

    You refer to “significant progress in climate science” which neglects the factor of three uncertainty in the IPCC Equilibrium Climate Sensitivity. This century-old uncertainty in the global surface temperature response to increased atmospheric CO2 persists despite three decades of intensive research.

    It is particularly difficult to accept a tight connection between the clearly rising anthropogenic concentration of the greenhouse gas CO2 and the lack of increase in the Global Mean Surface Temperature during the last sixteen years, despite the strong warming accompanying the CO2 rise from 1980-1998.

    It seems to me that the APS could substantially improve the accuracy of its science statement.

    William Duffy Jr.

    Member APS and APS GPC

    • Brian G Valentine

      Remember when your lab reports had to include an error analysis?

      The IPCC ushered in a new era of “non-error science.”

      Actually, I don’t blame them.. I blame the hand that feeds them

  23. I have read through the APS Climate Statement several times. The more that I read it, the more I unhappy I became.

    The last sentence of the second paragraph contradicts much that precedes it.
    Hence I most strongly believe that the material that is in contradiction with this last sentence must be removed, leading the revised statement that I have
    written below. This altered version or something similar to it must be used.
    In my view, not doing so would place the APS in a position of scientific

    In addition to the self-contradictory character of the statement which should be
    sufficient to make the changed statement written below, I believe that much that
    I have removed is not supported by the evidence. For example, the sentence “… the connection between … and the increased warming …” is not supported by the
    fact that the temperature at the earth’s surface has had no significant increase
    in the last 15 years or so.

    Lowell Brown

    On Climate Change:
    Earth’s changing climate is a critical issue that poses the risk of significant disruption around the globe. While natural sources of climate variability are significant, multiple lines of evidence indicate that human influences have had an increasingly dominant effect on the climate warming observed since the mid-twentieth century. Although the magnitudes of future effects are uncertain, human influences on the climate are growing. As recognized by Working Group 1 of the Intergovernmental Panel on Climate Change, scientific challenges remain to our abilities to observe, interpret, and project climate changes. To better inform societal choices, the APS urges sustained research in climate science.
    On Climate Action:
    The APS reiterates its 2007 call to support actions that will reduce the emissions, and ultimately the concentration, of greenhouse gases, as well as increase the resilience of society to a changing climate. Because physics and its techniques are fundamental elements of climate science, the APS further urges physicists to collaborate with colleagues across disciplines in climate research and to contribute to the public dialogue.

  24. I vote against the 2015 (and 2007) APS Climate Statements

    I strongly object to the “2015 APS Revised Climate Statement”. In my opinion, its primary assertion regarding the alleged “connection between rising concentrations of atmospheric greenhouse gases and the increased warming of the global climate system” has not been demonstrated. In particular, I assert that the overwhelmingly dominant term in the energy balance equations for the earth’s heating and cooling has been neither identified nor quantified. The dominant term arises from the seemingly random but nonetheless enormous radiant energy loss attributable to cloud reflectivity (backscatter) back into outer space of incident sunlight. I contend that this latter process is enormously important, indeed dominant, and that it has neither been accurately modeled nor even barely mentioned. It thus qualifies as an “ignored elephant in the room”.
    The 2003 NRC – National Academy report “Understanding Climate Change Feedbacks” (p26) notes that “…Clouds also reflect solar radiation very effectively, which reduces the amount of solar energy reaching the surface of the earth…”, and that “…A relatively modest change in cloud properties can have a significant effect on Earth’s energy balance.” … “If the structure or area coverage of clouds change with climate, they have the potential to provide a very large feedback and greatly increase or decrease the response of climate to human-caused warming. At this time both the magnitude and sign of cloud feedback effects on the global mean response to human forcing are uncertain.”
    Despite this brief mention of a possibility of a strong cloud reflectivity / cloud-area coverage feedback mechanism, there is no further mention or discussion of this important and, I contend, totally dominant mechanism. Instead, the report concentrates on water vapor feedback, noting that “…water vapor is the most important greenhouse in the earth’s atmosphere…”. The 2003 report further notes that (p.21) “Cloud feedback and its association with water vapor feedback and lapse rate feedback appear to be the largest contributors to uncertainty in climate sensitivity and therefore one of the key uncertainties in projections of future climates.” That 2003 report, and indeed all subsequent reports including the 2007 IPCC report, the 2014 National Academy / Royal Society report and the 2013 IPCC Summary for Policymakers virtually ignore any quantification of any feedback mechanism associated with sunlight reflection by clouds.
    A very strong negative feedback mechanism associated with solar energy reflection by clouds, modulated in turn by cloud area coverage is not hard to find. A reduced cloud coverage causes increased solar energy input to the oceans, in turn causing a greater evaporation rate, in turn causing increased cloud area coverage, whereupon strong negative feedback results. This simple and seemingly obvious mechanism is the “elephant in the room” nowhere mentioned in any of the reports.
    Also, the associated “radiative forcing” order of magnitude of reflection by clouds, in turn, modulated by cloud area coverage is easy to estimate. All that one needs to do is watch the change in output of a solar panel when a fluffy white cloud passes over and shadows it. Typically, the output drops to about one half. Since clouds contain only pure water, which only negligibly absorbs sunlight, then the clouds can only reflect the incident sunlight back into space. A fifty percent reflection of the solar constant (~ 1361 W m-2) gives a reflection of ~ 681 W m-2. For our order of magnitude estimate, one also may crudely estimate (from typical satellite imagery) the earth’s cloud coverage as varying from about 1/3 to 2/3 of its surface area on say a weekly time scale. This seemingly random variation then represents ~ 227 W m-2 random radiative forcing when referenced to the earth’s frontal area (i.e. its energy absorbing area), and ~ 57 W m-2 random radiative forcing when referenced to the earth’s total surface area (i.e. its energy reradiating area). Both of these numbers totally dwarf the 1.13 to 3.33 W m-2 radiative forcing attributed by the 2013 IPCC Summary for Policy makers to anthropogenic effects. Hence, I must conclude that the IPCC and National Academy reports have misidentified the dominant mechanism responsible for climate change.

    John F. Clauser, APS member since 1966