Category Archives: Debate Questions

Further Discussion With Zhongfeng Xu On The Value Of Dynamic Downscaling For Multi-Decadal Predictions

In the post

Question And Answer On The Value Of Dynamic Downscaling For Multi-Decadal Predictions

two colleagues of mine and I discussed the significance of their new paper

Xu, Zhongfeng and Zong-Liang Yang, 2012: An improved dynamical downscaling method with GCM bias corrections and its validation with 30 years of climate simulations. Journal of Climate 2012 doi: http://dx.doi.org/10.1175/JCLI-D-12-00005.1

This post continues this discussion with  Zong-Liang Yang of the University of Texas in Austin and Zhongfeng Xu of the Institute of Atmospheric Physics of the Chinese Academy of Science.

Following is the comment by Zhongfeng, with my responses embedded.

Dear Roger,

Thank you for your interest to our paper.

In terms of your comments “their results show that they are not adding value to multi-decadal climate projections”. I think the comment is not accurate enough. We did not compare the climate changes simulated by IDD and TDD in the paper.

My Comment:

What you and Liang have very effectively documented are systematic errors in the observationally unconstrained model runs. You did not compare climate change, but you do show that the model results are biased. This bias is an impediment to skillful multi-decadal forecasts as it shows errors in the model physics and dynamics at that level. The elimination of these errors in the unconstrained runs is a necessary condition for skillful multi-decadal global model predictions.

Zhongfeng continues

So it’s too early to make conclusion whether IDD has adding value to climate change simulation.

My Response

To show skill, one has to show that changes in regional climate statistics between your control and your “future” are skillfully predicted. For model predictions in the coming decades, it is not enough to predict the same climate statistics, one must also skillfully predict changes to these statistics. Otherwise, the impact community could just as well use reanalyses.

Zhongfeng continues

 I guess it’s possible that IDD improves climate change projection when the GCM does a good job in producing climate change signals but producing a bad climatological means.

My Response

This cannot be correct. If the climatological means are in error, there are clearly problems in the model physics and dynamics. Also, what evidence do you have that the GCM does a good job in terms of multi-decadal predictions? [please see my post http://pielkeclimatesci.wordpress.com/2012/05/08/kevin-trenberth-is-correct-we-do-not-have-reliable-or-regional-predictions-of-climate/]

Zhongfeng continues

I will pay more attention to the IDD performance in climate change projection in our future study. I will keep you updated if we find some interesting results.

My Response

I look forward to learning more on your study. Thanks!

Zhongfeng continues

BTW: The IDD does significantly improve the projection of climatological mean. It’s still better than TDD which shows larger bias than IDD in projecting climatological means.

My Response

However, the global model multi-decadal predictions still are run with these biases. Even if you use IDD for the interior, the global model still has these errors meaning they have substantive physics and/or dynamic problems.

Zhongfeng’s comment

 Thank you for all your comments. They are very informative and make me thinking more about this dynamical downscaling study.  ^_^

My Reply 

I have also valued the discussion. I will add this as a weblog post follow-up. Your paper is a very important addition to the literature but the bottom line message is, in my view, documentation of why the impacts communities (e.g. for the IPCC assessments) should not be focusing on this methodology as bracketing the future of regional climates.

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Response From George Taylor On The Oregon Debate On Climate Science

In response to the post

Inadequate Poll Of Views On Climate Science By Scott Learn Of The Oregonian – But At Least An Opportunity To Debate The Climate Issue

George Taylor and I exchanged the e-mails below. George was in the debate in Oregon sponsored by the state chapter of the American Meteorological Society.  I am pleased that George is leading an effort for constructive debate on the climate issue.

George’s Comment On The Debate

Thanks, Roger. Good to hear from you. All in all it went well. There were over 500 people in attendance! I stated out loud that “human activities DO affect climate, in a variety of ways. CO2, in my opinion, exerts a relatively minor influence but there are many other human factors, such as land use change and particulate emissions, that influence climate. All in all, however, it is my opinion that natural variations, notably solar radiation and tropical Pacific SST, have exerted a greater influence on GLOBAL climate than have human activities.”

You were the one who influenced my thinking, years ago, on the multiplicity of human influences!

http://www.oregonlive.com/environment/index.ssf/2012/01/presentation_by_global_warming.html

George

My Reply

Hi George

It is good to hear from you!

Can I post your e-mail below on my weblog? In terms of global, I have concluded that the global average of surface temperature, etc, is almost a worthless metric, as what really matters is the extent (and if) large scale regional circulation patterns are changed. If we [convince] the IPCC (and AMS and AGU leadership) that they are looking at the wrong metrics, we might be able to make some progress. :-)

With Best Regards

Roger

P.S. Can I post your e-mail below on my weblog?

George’s Response

Absolutely. And I concur about “global temp” and said so last night. The McKitrick-Essex book has a chapter on the meaninglessness of that statistic, and I referred to that.

Sure, use my email!

GT

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Inadequate Poll Of Views On Climate Science By Scott Learn Of The Oregonian – But At Least An Opportunity To Debate The Climate Issue

UPDATE JANUARY 26 2012:  An update to the meeting is given at [h/t to Marc Morano]

Presentation by global warming skeptics draws big crowd in Portland

Don Bishop has alerted us to an article by Scott Learn of The Oregonian titled

*************************Original Post*****************************

Global warming skeptics to take center stage in Portland (poll)

The article refers to a meeting tomorrow evening in Portland. The article starts with the text [highlight added]

When it comes to global warming, the American Meteorological Society has strong views: “Human activities are a major contributor to climate change,” the society says, and “increases in greenhouse gases are nearly certain to produce continued increases in temperature.”

But at 7 p.m. Wednesday, the society’s Oregon chapter will give three opponents of those propositions their biggest stage, two hours before an expected audience of several hundred in a ballroom at the Portland Airport Shilo Inn.

The chapter’s invitation asks the question: “Is human caused global warming the greatest scientific myth of our generation?”

The article contains misinformation from some of those quoted; e.g.

Justin Sharp, a meteorologist for wind-power firm Iberdrola Renewables, declined to renew his membership in the local chapter. There are legitimate uncertainties to discuss about climate projections, he says.

“But devoting equal time on all subject matters just doesn’t make a lot of sense,” says Sharp, who adds that he is not speaking for Iberdrola. “If you had a panel with both sides represented in proportion to what the field believes, you’d have 900 scientists on one side and George (Taylor) on the other.”

Justin misses the critical point that there is a diversity of views on the climate issue, as illustrated by the article

Pielke Sr., R., K.  Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D.  Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E.  Philip Krider, W. K.M. Lau, J. McDonnell,  W. Rossow,  J. Schaake, J.  Smith, S. Sorooshian,  and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases.   Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American   Geophysical Union.

which was co-authored by only Fellows of the American Geophysical Union (and only 0.1% of the members receive this honor). George Taylor, who is a very well-respected climate scientist, is far from alone in his concerns is to how the climate issue is being misrepresented.

The news article has a poll with the following questions

Is human-caused global warming the greatest scientific myth of our generation?

  • Yes. Human-caused global warming is a myth.
  • No. Human-caused global warming is based in fact.
  •  I’ll take no formal position, like the Oregon Chapter of the American Meteorological Society.

This is a ridiculous poll as almost all climate scientists agree that the human addition of CO2 and other greenhouse gases into the atmosphere has a radiative warming effect. The substantive issues, however, that are naively ignored in these poll questions include, in terms of how weather patterns are affected, what is the effect of CO2 radiative forcing relative to other human and natural radiative forcings, as well as the role of negative and positive radiative feedbacks. Indeed, radiative forcing is just one of a range of climate forcings (e.g. the role human aerosol emissions on cloud and precipitation processes) as discussed in detail in

National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington,D.C., 208 pp.

A much better set of questions to ask tomorrow evening are:

  • Hypothesis 1: Human influence on climate variability and change is of minimal importance, and natural causes dominate climate variations and changes on all time scales. In coming decades, the human influence will continue to be minimal.
  • Hypothesis 2a: Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and involve a diverse range of first-order climate forcings, including, but not limited to, the human input of carbon dioxide (CO2). Most, if not all, of these human influences on regional and global climate will continue to be of concern during the coming decades.
  • Hypothesis 2b: Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and are dominated by the emissions into the atmosphere of greenhouse gases, the most important of which is CO2. The adverse impact of these gases on regional and global climate constitutes the primary climate issue for the coming decades.

The Pielke et al 2009 paper provides evidence why hypothesis 2a is the only one that has not been refuted. However, this would be a much more appropriate poll for the Oregonian to run than the poll that is in their newspaper. The paper however, should be commended for at least permitting a much needed debate on the climate issue.

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John Nielsen-Gammon and I Continue Our Discussion

John Nielsen-Gammon and I have continued our discussion that we started in the post

NBC Nightly News Regarding The Recent October Snowstorm And A Quote From John Nielsen-Gammon

With a few edits, with John’s permission, I have reproduced our e-mail communications below.

My Reply

Hi John. Thanks for the quick feedback. I will go ahead and post your reply.

I have this point of disagreement – you are (incorrectly in my view) equating global warming with the subset of warming caused by CO2 and a few other human inputs of greenhouse gases.

Response from John

Roger -

You might not agree with my numbers, but I do explicitly deal with “the issue of the relative contribution of greenhouse gases to global warming” in my comment, rather than equating the two. Thanks again!

- John

My Reply

I am then unclear on your text. You write

“I concluded (conservatively, I would say) that about a half degree to a degree was attributable to anthropogenic greenhouse gases.”

[which seems reasonable]

and also

“…summer temperatures would have been about  one half to one degree cooler without the increases in CO2 and other greenhouse gases.”

John’s Reply

so far so good…the two statements above say the same thing.

 My Response

But, you also write in your original post

“With the uncertainties over response times and feedbacks, the amount of observed warming over the past century plausibly attributable to anthropogenic increases in the concentration of greenhouse gases may be as small as 0.5F and may be as large as 2.0F, in my opinion. I picked 1.0F, but whatever the actual value is, it is unquestionably positive and enhanced the severity of the drought.”

“The actual summertime temperature was 86.8 F, so 4.0 F out of the 5.4 F of excess heat (74%) was a consequence of the drought itself.”

this leaves 1.4F from circulation effects and the other positive radiative forcings. I am assuming the “drought” effect means the greater sensible versus latent heat effect.

If there was no circulation effect, I can see how you could obtain 0.7F (i.e. 50% from CO2 as an upper bound) but certainly not 1F or 2F. Anyway, please clarify and I will add to the post.

I also would really like to see your analysis of the drought in terms of surface moist enthalpy. :-)

Best Regards

Roger

John’s reply

About the moist enthalpy, I could speculate…it’s faster…..presumably the sensible/latent effect partly mitigates moist enthalpy intensity vs. temperature intensity, but one other sensible/latent effects (decrease of cloud cover) means there should still be a moist enthalpy signal and a third effect (increased PBL height) probably works to decrease the moist enthalpy but I would guess not enough to overwhelm the cloud cover effect.

The 1.4F (+/- uncertainties in the 4.0F attribution) is what results from circulation effects and the combined effect of positive AND NEGATIVE radiative forcings.  Because much of the effect from CO2 and other anthropogenic greenhouse gas emissions will have been counteracted in part by negative forcings such as aerosols, the observed rise does not represent an upper bound on the anthropogenic greenhouse gas effect.

- John

 My Response

Hi John

“……You also have much more confidence in the IPCC modelling than I do. Their failure to properly predict the current cool-down, the one after 1998, etc should raise a concern that they do not properly handle circulation effects.  Even more clearly, they have no regional skill, which is what determines temperatures for Texas.

John’s Reply

Roger

In a strange way, I have much less confidence in the IPCC modelling than you do.  You seem to think that they should be able to predict the full atmospheric response to all future forcings as well as natural variability, since that’s what it would take to properly predict the full temperature (or OHC) variations over the past 13 years.  Since the AR4 model runs did not include 3-D initialization of the oceans, nor any predictions of solar activity, nor any predictions of volcanic activity, I do not expect them to be nearly as capable as you do.  I expect the AR4 runs to simulate a response to projected concentrations of CO2 and other GHG within scientifically plausible bounds of sensitivity in a dynamically self-consistent way, which they do.

My Response

With this assumption, you could claim that the CO2 effect covered ALL of the 1.4F (and more attribution).

However, there is no way to confirm this conclusion as in the real world we cannot separate out the effect of just one climate forcing.  Moreover,  I assume you are including the water vapor feedback into this number.

However, if the atmospheric water vapor does not increase (and in recent years it has not), there is no amplification of the CO2 radiative forcing (or any other positive or negative radiative forcing).  Your assumption is based on models which, as shown just a few days ago by Bob Tisdale

An Initial Look At The Hindcasts Of The NCAR CCSM4 Coupled Climate Model

http://bobtisdale.wordpress.com/2011/11/04/an-initial-look-at-the-hindcasts-of-the-ncar-ccsm4-coupled-climate-model/

is not able to skillfully predicting the behavior of the climate system during the last several decades.

Also, the issue of the role of added CO2 on the drought does not depend on what its maximum radiative forcing would be, but rather what fraction of the drought was a result of the added CO2 that was actually affecting the weather pattern. I do not see how we can answer that, as the  models have not shown such regional skill.

All we can say (as with any weather pattern) that the added CO2 had an effect.

John’s Reply

When driven by observed oceanic variability, the models do a great job simulating the atmospheric response.  With the present drought, it’s not a matter of predicting the oceans and atmosphere.  We know the present ocean temperature patterns, so we can estimate their contribution very well from both observations and models.  The models’ difficulty in simulating the statistics of ENSO itself is a red herring.

I also disagree with your philosophy/epistemology of attribution regarding weather patterns, but that’s a whole other issue.

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Exchange Of Viewpoints By Issac Held and Roger A. Pielke Sr.

On June 1 2011 I posted

A Different Interpretation Of Issac Held’s View Of Forced Climate Change

I also then alerted Issac of this post on his weblog under his title

Summer is warmer than winter.

Issac and I then had an informative exchange of viewpooints which I have reproduced below from the comments on his weblog. Issac Held is an internationally well-respected climate scientist, so his perspective on this subject is important to know and is influential. I also appreciate his willingness to engage in constructive dialog.

Roger A. Pielke Sr. says:

Hi Issac – I have posted on my weblog regarding your “Summer is warmer than winter” post. I look forward to a constructive discussion on our disagreement on this science issue.

My post is accessible at http://pielkeclimatesci.wordpress.com/2011/06/01/a-different-interpretation-of-issac-helds-view-of-forced-climate-change/.

Isaac Held says:

Roger: I prefer to call my anticipation that next summer will be warmer than the past winter a “prediction” (a very high confidence one, admittedly) and you don’t, and we could discuss this semantic point. But I think the substantive issue that we disagree on is simply the magnitude of the forced response to an increase in CO2 as compared to internal variability.

If this signal/noise ratio is too small, than predicting climate anomalies a century from now will be analogous to the prediction of departures from the climatological seasonal cycle (for example, the phase of ENSO) many seasons in advance — and extremely difficult if not impossible due to the underlying chaos in the system. If this signal/noise ratio is large enough, as I am confident it is (I hope to explain my own personal basis for this confidence as these posts evolve) then predicting climate anomalies a century from now, given plausible CO2 trajectories, becomes possible. Almost all of the complexity of the atmosphere, including that inherent in the hydrological cycle and clouds that you mention, comes into play on the seasonal scale without making the seasonal cycle hopelessly complex. I find this encouraging.

Roger A. Pielke Sr.says:

Issac – Thank you for your reply.

In my view, there is a need to develop a way to test our two perspectives. My conclusion has been that, for the climate forcing of added CO2 and other greenhouse gases to be considered a forced boundary problem, the multi-decadal global model predictions

i) must first skillfully predict the current spatial and temporal statistics of the occurrence of ENSO events, the NAO, PDO etc with the “~current” atmospheric concentrations of these gases [say 1979 to the present]

and

ii) these models must also skillfully predict the changes in the statistics of these atmospheric/ocean features due to the added atmospheric concentrations of the greenhouse gases.

It is these climate circulations that have the most important influence on societally important events such as drought, floods, tropical cyclone tracks etc.

The challenge is that while requirement i) is testable today [and evidence on this would be welcome], but requirement ii) cannot be achieved until several decades from now, unless one can show the effect of added greenhouse gases for the period, for example, form 1979 to the present.

I suggest 1979 to the present as the global data quality and coverage became more homogeneous starting in 1979.

How do you see testing these requirements? What evidence do you have the requirements i) and ii) have been achieved?

Isaac Held says:

Roger — I think it is important to recognize that warming superposed on unchanged variability (ENSO, PDO, cyclone frequency) can be very significant. Think of heat waves — add 3C to summertime temperatures in Chicago and keep the pdf of temperatures fixed — that has consequences. You don’t need to make the case that some model adequately simulates the statistics of heat waves in Chicago. If you can make the case that you have such a model, then you can address the question of how the shape of the pdf might change — that’s great — but even without it, the implications of the conservative assumption of no change in pdf can still be very significant.

I would also emphasize that it is important not to lump all phenomena of relevance together and condemn modeling efforts because they cannot do everything. The ability of models to speak to different issues varies a lot across phenomena. I have included a couple of posts on the Atlantic hurricane issue. Post #2 describes the quality of some simulations of hurricane frequency in the post-1980 period. Post #10 then addresses the use of this model to study attribution of current trends and future projections (I think I will have to return to this, since several emails have indicated that I managed to confuse some readers). It think this is a very good case study for discussing how to evaluate a model/theory for use in projections. It’s a process, requiring an understanding of which model deficiencies future projections are most sensitive to, and whether past variability samples the space of possibilities adequately or if new physics comes into play as the climate warms.

Roger A. Pielke Sr.says:

Issac – We agree on this point – “…. that warming superposed on unchanged variability (ENSO, PDO, cyclone frequency) can be very significant.”. Indeed, we and others have shown that land use change (such as urbanization such as experienced in Chicago and elsewhere) can result in hotter weather even with unchanged large scale variability. Added CO2, while adding to the warming, may actually be a secondary influence as contrasted with this local land use change in this example.

Since land use change has occurred over such large areas of the globe, its affect on temperatures can ameliorate or amplify what occurs as a result of other climate forcings. The attribution of temperature changes as a boundary problem is much more complex than relating to just the radiative forcing of added CO2, and other greenhouse gases.

The issue that I have concluded is more fundamental, however, is the extent that added greenhouse gases, aerosols, and land use change alter regional and hemispheric circulation features. The question is the extent that these circulation featues are altered from what they would be in the absence of these human forcings, as I wrote in my earlier comment.

In our paper

Matsui, T., and R.A. Pielke Sr., 2006: Measurement-based estimation of the spatial gradient of aerosol radiative forcing. Geophys. Res. Letts., 33, L11813, doi:10.1029/2006GL025974. http://pielkeclimatesci.files.wordpress.com/2009/10/r-312.pdf,

for example, we found that the spatially variable forcing from the diabatic atmospheric heating from aerosols is large enough to alter regional pressure gradients in some regions. We wrote in our paper that

“This paper diagnoses the spatial mean and the spatial gradient of the aerosol radiative forcing in comparison with those of well-mixed green-house gases (GHG). Unlike GHG, aerosols have much greater spatial heterogeneity in their radiative forcing. The heterogeneous diabatic heating can modulate the gradient in horizontal pressure field and atmospheric circulations, thus altering the regional climate….”

Our paper, however, is only a start at answering this question, as we did not compare the relative role of this human forcing from aerosols with natural variability. To answer the question as to whether or not added greenhouse gases can be treated as a boundary problem cannot be adequately answered until both the role of other human climate forcings and of natural variability are quantitatively evaluated by using real world data in conjunction with the model predictions on multi-decadal time scales.

Tomorrow on my weblog, I am posting on the new paper

Fildes, R. and N. Kourentzes, 2011: Validation and forecasting accuracy in models of climate change. Journal of Forecasting. doi 10.1016/j.ijforecast.2011.03.008

which addresses the extent the IPCC type models have been adequately evaluted as tools to answer the questions such as you and I are discussing. Your comments on that paper in a post on your weblog would be very valuable.

Isaac Held says:

I don’t disagree with the argument that forcing with more horizontal structure is more efficient at generating changes in the mean atmospheric circulation than more uniform forcing of the same overall magnitude. I think it is very generally recognized that, for the same global mean forcing, aerosols perturb the mean precipitation field more than do the well-mixed greenhouse gases (WMGGs). So if, up to the present, anthropogenic aerosols and WMGGs have had comparable effects on regional precipitation, say, the WMGG effect will undoubtedly grow and will be essentially irreversible on the time scale of several centuries, in the absence of geoengineering, while the aerosol effect will likely be bounded by its current magnitude, and the WMGGs will dominate. The ozone hole vs WMGG effects on Southern Hemisphere circulation are analogous in this regard. I gather you feel that WMGG effects are so small that they will not dominate over other forcing agents for most phenomena of interest even as concentrations continue to grow over the next century. This is where we part ways if I understand your position correctly.

Roger A. Pielke Sr. says:

Issac – In terms of very long term effects, the aerosol influence continues even if the emissions were stopped (which is not likely to occur, unfortunately). Nitrogen emissions, as one example, do relatively quickly deposit on the Earth’s surface, but their effect on biogeochemistry of plants and other parts of the biosphere will persist long after the atmospheric concentrations would fall back to more natural levels. With respect to human land management (advertant and inadvertant), land use change will effect climate indefinitely.

I agree with you that the effect of added carbon dioxide will also persist indefinitely and it is a significant human climate forcing. I am actually more concerned about its biogeochemical effects than its radiative forcing, but both are important.

Where I see us disagreeing is that you conclude CO2 and a few other greenhouse gases will dominate climate change in the coming decades. However, as we summarize in

Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell, W. Rossow, J. Schaake, J. Smith, S. Sorooshian, and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union.
http://pielkeclimatesci.files.wordpress.com/2009/12/r-354.pdf

other human climate forcings are of at least as much importance on the time scale of decades. This broader perspective, including the recognition that natural climate variability is larger than simulated by the global models, makes the climate predicition problem much more difficult than suggested in your analogy to the annual cycle. We are too conservative if the focus is just on CO2 and a few other greenhouse gases as the dominate first order climate forcings.

If I am correct, than the proposals to geoengineer away the radiative effect of added greenhouse gases is fraught with risk, as we would be just adding further to the complexity of how humans are altering the climate system.

Isaac Held says:

Some climate changes will be dominated by greenhouse gas increases on the time scale of several decades and others will not be due to the higher noise level. Table 11.1 in Ch. 11 of the WG1/AR4 provides estimates of the time it takes 20yr mean seasonal temperature and precipitation changes averaged over various sub-continental regions to emerge from internal variability, according to the CMIP3 ensemble of models (ie, given both their responses and their internal variability). I lean on the models a lot, plus I was one of the Lead Authors for this chapter, so this can be taken as a more explicit statement of my starting point for discussing this issue, at least for this subset of variables. The time required for these 20yr means to emerge from the model’s own noise varies a lot. Temperature responses emerge in most regions after 20 years — 20 year mean precipitation signals emerge in some regions in 30 years, some not for 100 years if then. Evidence that the model responses, or model internal variability levels, are biased one way or the other can then be brought to bear to criticize these numbers (and on a more minor point, one can question how the choice of regions and seasons affects the results) — but it helps to have a clear idea of the model results that one is then arguing should be modified.

Roger A. Pielke Sr. says:

Issac – Thank you for clearly clarifying our area of disagreement. In my view, the use of the CMIP3 ensemble of models (or other global climate models on this time scale) does not permit the testing of your hypothesis on the dominance of the added greenhouse gas relative to natural variability over multi-decadal time periods.

While I agree that models are very valuable tools, they are, however, just hypotheses. They must be tested against real world data. This means, for example, they need to show skill at predicting the statistics of large scale circulation features, and the change in these statistics due to human climate forcing.

As shown, however, in papers such as

Stephens, G. L., T. L’Ecuyer, R. Forbes, A. Gettlemen, J.‐C. Golaz, A. Bodas‐Salcedo, K. Suzuki, P. Gabriel, and J. Haynes (2010), Dreary state of precipitation in global models, J. Geophys. Res., 115, D24211, doi:10.1029/2010JD014532

the models still have a way to go to be accepted as robust predictive tools, in the similar manner as we accept numerical weather prediction model results.

The recent paper

Wyatt, Marcia Glaze , Sergey Kravtsov, and Anastasios A. Tsonis, 2011: Atlantic Multidecadal Oscillation and Northern Hemisphere’s climate variability Climate Dynamics: DOI: 10.1007/s00382-011-1071-8.

illustrates the type of variability that the global climate models must skillfully simulate.

The CMIP3 ensemble of models need to show that they can recreate this observed variability [in fully coupled ocean-atmosphere-land form] given initial conditions for the ocean, atmosphere, and land. Than the next step is to show they can skillfully predict changes in this variability due to added CO2 (and other human climate forcings) over the time period for which we have real world observations.

This is, in my view, a necessary condition to accept global climate predictions of regional climate in the coming decades.

Isaac Held says:

Model quality is one of the things that I hope to discuss, carefully and critically, on this blog

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Survey Of Climate Scientists Announced On Hans von Storch’s Weblog “Die Klimazwiebel”

A detailed survey of climate scientists has just been announced by Hans von Storch on his website Die Klimazwiebel in a post titled

CliSci Survey – results documented

The report, by Dennis Bray and Hans von Storch is titled

GKSS-Report 2010/9: CliSci2008: A Survey of the Perspectives of Climate Scientists Concerning Climate Science and Climate Change.

There is quite a lot of  useful survey information and I will comment on some of the results in a later post.

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Feedback On My Invitation On The Three Hypotheses Regarding Climate Forcings

UPDATE: July 14 2010: I have received a late feedback and have added to the end of this post.

On June 30 2010, I posted

Invitation On Assessing Three Climate Hypotheses

I have received excellent, insightful feedback and post them below. I will follow up in  a subsequent post with my response.

COMMENT [Graduate Student who requested anonymity]

Dear Professor Pielke,

Although I am but a humble engineering student, I would like to offer my thoughts on the question of these hypotheses. I only hope it is okay with you if I do not use my full name-I don’t wish to hind behind anonymity in a hostile way, though. I just don’t want too much attention.

It seems to me that the three hypotheses are perfectly well stated as a broad way of talking about different views of climate. I also suspect that very few scientists hold either hypothesis 1 or 2b as being true, although this is just my impression. Where I suspect a problem occurs is that the hypotheses as stated may encompass very different quantitative views although they are essentially qualitatively distinct. For example, one may hold the view that ” human influences are significant” but still think that most of, for example, twentieth century trends were mostly natural, or even 50-50. “Significant” may just be taken to mean “measurable outside of the range of error” in which case one may view human effects as significant, but marginally so, or almost completely dominant, and still adhere to hypothesis 2a, even though these two positions are quite different. Similarly, I suppose one could argue that, while other human forcings play a role, GHG’s are the largest and therefore most important ones-the others matter, but less so. But as long as that person believed that those effects were small enough to escape reliable detection, they would support 2b. At some threshold, they’d suddenly be supporting 2a, if they believe the other human effects are measurable, but only barely.

So I suppose the only criticism of the hypotheses that I would make is that they could benefit from being seen as categories of more specific hypotheses, and more specific views, rather than the hypotheses about climate. Other than that, I think that they are well posed.

COMMENT Mike Owens

Roger

I read your weblog frequently and although I do not agree with all you say (but most of it to be true), your logic is consistent and to be admired, as is your persistence and determination to resist the excesses and exaggeration of alarmism.

I am a semi retired scientist living in the UK, originally an industrial chemist converted to chemical engineering and subsequently to studies in technical safety, including computational fluid dynamics for modelling of fires and explosions and general risk analysis mostly for offshore oil and gas facilities. 

I feel that your original 2a implies that the natural forces are inferior to human influences. A more neutral 2a might be:-

Hypothesis 2a: The natural causes of climate variations and changes are undoubtedly important, but the human influences are also significant and involve a diverse range of first order climate forcings, including, but not limited to, the human input of carbon dioxide (CO2). Most, if not all, of these human influences on regional and global climate will continue to be of concern during the coming decades

If we are to retain 2a in its present wording, the proposed 2c below implies the opposite but, unlike hypothesis 1 still accepts that human influences are important:-

Hypothesis 2c: The natural causes of climate variations and changes are undoubtedly the most significant, but the human influences are also of some significance and involve a diverse range of significant climate forcings, including, but not limited to, the human input of carbon dioxide (CO2). Most, if not all, of these human influences on regional and global climate will continue to be of concern during the coming decades.

An alternative to 2c could be 1b i.e.:-

Hypothesis 1b: Human influence on climate variability and change is of some importance, but natural causes dominate climate variations and changes on all time scales. In coming decades, the human influence will continue to be less than that from natural causes, but still of some concern.

COMMENT [Bob Graza]

Roger,
   Appreciate your web site.  I have been visiting your site for a
   couple of years on a regular basis and find the presentation of
   material valuable and instructive.

   As far as the 3 hypotheses, they seem to capture well the  general positions held by those embroiled in the controversy.

   It appears Gavin is being a bit evasive.  He states, “…CO2
   emissions…are the dominant issue moving forward.”

   Hypothesis 2b states, “….human influences are significant & are dominated by….greenhouse gases, the most important of which is CO2.”

   Though he acknowledges the significance of other climate forcing mechanisms, so does hypothesis 2b.  Sounds like his position fits quite nicely into hypothesis 2b.

COMMENT [Michael Lenaghan]

I’ve attached a revised schematic which (I think) ties it a little
more closely to your original statements. (I don’t really care about attribution one way or the other.)

I think it would help to define what “significant” and “dominant” mean.

COMMENT [ Graham Long]

Dear Professor Pielke

The comments below are rather lengthy - this is because I think there are some tricky issues raised. If the comments are of any use, feel free to chop them down for inclusion.

I have no expertise in climate science at all – I teach political theory. Though it might be hard to believe given the length, these comments are very rough and ready, and many caveats apply…

Hypotheses 2a and 2b
I can see what you’re driving at here, but I did think there’s scope for dispute on the part of realclimate, in respect of both important parts of 2a and 2b: I too wasn’t clear, at first sight, whether these were mutually exclusive.

(1)     Human influences: 2a says `involve a diverse range of first order climate forcing’ 2b says `dominated by the emissions into the atmosphere of greenhouse gases’. One natural reading is that an event can `involve a diverse range’ of contributing causes but causation can still be `dominated’ by one of them.

(2)    Influences continuing to be of concern: 2a says `most will continue to be of concern’, 2b says that the adverse impact of greenhouse gases will be `the primary climate issue’. Again, it seems possible for one issue to be primary, but a variety of issues to still be of concern.

You might dispute whether influences really can be said to involve a diverse range but simultaneously be dominated by one, and whether a range of influences can be of concern, but one be truly primary. Does this hinge, I wonder, on an account of “forcing” or “influence”? On your reading, is it the case that one influence being dominant precludes there being a range of influences (since if one influence did by far the most of the work, the others could not by definition be influences)? I think realclimate are maintaining that there is nothing contradictory in holding one amongst these many is dominant, while still recognising the many.

The second, more “action-guiding” parts of 2a and 2b both seem to follow from the first, `descriptive’ parts ? I skimmed the article, and in this context, the final part of both hypotheses did seem to imply different views of the policy required.  I took what you’re saying in the article to be that actually many people are wedded to an untenable hybrid of (a) and (b). The climate science supports a range of significant forcings (early 2a), but disproportionate policy attention is being directed at GHG ( later 2b)?
But they also don’t seem to be directly comparable in some respects. In 2a, I wondered if the qualification `most, if not all’ and the expression `continue to be of concern’ was making a point about these human influences not going away any time soon. I wondered if this wasn’t really the concern of the end of 2b, which sounds much more concerned with what should be the focus of policy attention. Relatedly, is “issue” or “concern” a question of policy action, or further research, or “keeping an eye on”?

My suggestion would be that the two hypotheses (a) be made more clearly mutually exclusive as a way of (partly - see below) circumventing the first, messy, issue, and (b) that the ideas in the final section of 2a be separated out a little. As a first stab, which hopefully serves to highlight some of these issues:

Hypothesis 2a: Although the natural causes of climate variations and changes are undoubtedly important, the human influences involve a diverse range of significant first order climate forcings, including but not limited to, the human input of carbon dioxide (C02). Most, if not all, of these human influences on regional and global climate will continue during the coming decades. These continuing influences should, together, be the focus of climate policy and research.

Hypothesis 2b: Although the natural causes of climate variations and changes are undoubtedly important, the human influences are clearly dominated by the emissions into the atmosphere of greenhouse gases (the most important of which is CO2), in comparison to which other human forcings are insignificant. Though most, if not all, of these human influences on regional and global climate will continue during the coming decades, the adverse impact of greenhouse gases on regional and global climate should be the focus of climate policy and research.

Well, these new versions of 2a and 2b are mutually exclusive, I take it. I’ve messed around with the placement of “significance” here, and this might destroy your sense, but there’s probably another way to achieve the same effect. But these hypotheses still bring in several issues, so we have to expect people to reject both and affirm other hypotheses which, for example, agree with early 2a, but later 2b, or are subtly different in their view of regional and global factors, or of research and policy. For example, it might not be crazy for someone to reject 2a and 2b, and affirm 2d.

Hypothesis 2d: Although the natural causes of climate variations and changes are undoubtedly important, the human influences involve a diverse range of significant first order climate forcings, including the human input of carbon dioxide (CO2). Most, if not all, of these human influences on regional and global climate will continue during the coming decades. Nevertheless, on balance greenhouse gas emission is the largest single global influence and should therefore be the primary contemporary focus of climate policy.

There might be merit in ditching the final sentence in 2a and 2b, and picking up the policy implications elsewhere? In summary, I thought this was trickier stuff than it might appear at first sight…

COMMENT [Sean Wise]

Dr. Pielke,

I have been reading your blog for several years now so am quite familiar with your three hypothesis.  The more polar hypotheses 1 and 2b not only reflect the polarization of the political/scientific debate but probably also seem more global in their applicability.  Hypothesis 2a while more nuanced, is more regional in its cause and effects.  Considering that most
climate modeling is done on 500 km grid cells and larger, regional or local nuances are almost completely washed out of the analysis.  (I’ve often wondered if GHG’s have become the whipping boy of climate science simply because their effects occur only on a very large scale so are broad enough to model.)

That said, I must also tell you that the most interesting things I read on your site these days are your “keeping score” discussions.  Everyone is well aware of the noise in the temperature record as well as biases that creep in due to changes in environment around monitoring stations.  These two facets of the temperature record mean that the surface temperature record and the trends will be debated for the next 50 years–without conclusion.  But you have featured articles and even started a bit of debate on the total ocean heat content.  You even got Kevin Trenbreth and Roy Spenser talking over the same graphs.  You’ve got people talking about a metric that is stable and precise enough that it is probably the best way to track the climate trends on the earth.  That coupled with the radiative satellite measurements, both low wave and short wave, is really going to move the debate forward.

COMMENT Phil Cartier

Dear Dr. Pielke,

I am an independent science and engineering consultant.

I’d suggest the following hypotheses:

1)  We do not know enough about the functioning of the climate system to evaluate what are actually the most critical elements to study.  We need to start with the basics- Milankovitch cycles, how the sun affects the earth beyond the obvious of effect of solar radiation intensity and what causes the cyclic ebb and flow of glaciers.  Until we understand the dynamics of the switch from glaciation to the interglacial periods we cannot really study other less basic variations in the climate.

2) The overall climate of the earth is controlled by the basic energy in/energy out flow of radiation from the sun and re-radiated from earth.  Human activity may have significant effects on what happens in between- the transfer of energy within the atmosphere and ocean.  We need to understand the magnitude of these effects and whether or not they can affect the overall climate or whether they are limited to regional effects.

COMMENT Steven Geiger

Dr. Pielke – My idea for hypothesis 2c.

Although the natural causes of climate variations and changes are
undoubtedly important, the human influences are significant and involve a
diverse range of first order climate forcings, including, but not limited
to, the human input of carbon dioxide (CO2).   Greenhouse gases (GHGs), of which CO2 is the most important based on mans influence and projected
concentrations, is a first order forcing that has the most wide-spread
(global) impact.  Other first order forcings, such as LULC changes, are
important–and potentially the most important–forcing in more limited
areas of the globe where their effects act in concert with those from GHGs.
Most, if not all, of these human influences on regional and global climate
will continue to be of concern  during the coming decades.

COMMENT Robb Randall

 I read your post yesterday on the Climate Hypotheses and decided to add
my 2 cents.  I realize that you and your co-authors are highly respected
climate scientists and I’m very new to the community, so please take my
comments with that in mind and if I am not interpreting the question or
paper properly I apologize up front.

 As I read your paper it appears to present only two possibilities,
either natural causes are dominate or human influences are dominate
(either multiple influences (2a) or CO2 (2b)).   If there is something
missing it would be the possibility of having some human influences and
natural causes on the same order magnitude of influence.

 This perception may be due to the wording used in the paper.  1a states
that natural causes are “dominate”, but 2a and 2b state natural causes
are “important” with human influences “significant”.  This wording may
lead some to confusion (as it did for me).

 If, however, you and your co-authors meant to include in 2a and 2b that
the combination of influence from humans and nature could range from

1.)    “dominate” human influence (whether co2 or multiple)   to

2.)    Equal influence from nature and human influence

 Then I believe the paper is correct as stated. (But it may need to be
clarified as such)

 So to restate (hopefully to clarify what I’m thinking)

 I think that the following possibilities should be considered:

1.       Dominate natural influence

2.       Dominate human influence

a.       Multiple

b.      CO2

3.       Equal (or something close in forcing magnitude) of natural and
human influence

 Your current Hypotheses may actually encompass these three, but the
wording may lead some to confusion and in their current wording it
appears that my (3) above is not considered in your paper’s Hypotheses.

 Thanks for your invite to comment and I will talk to you soon.

 Robb

COMMENT from Dan Hughes

Hello Professor Pielke,

I do not have any suggestions for additional or different distinct hypotheses.  Instead I have general comments as follows.

The fundamental basis for human influences on climate variability is that a disruption of the energy-balanced, equilibrium state of the planet will ( or has ) obtained.  This being the case, the hypotheses should be statements about the energy states of Earth’s climate systems and the theoretical aspects of an energy-balanced equilibrium state for the entire planet.

I am not interested in theoretical falsification of stated hypotheses in the sense of philosophy.  Instead, the focus are hypotheses that potentially can be validated by comparisons with measured data.  Unfortunately, the energy-balance state of Earth cannot be known for the distant past, so new or additional hypotheses can only be applied to the recent past and future states going forward in time.

The critical key is that the hypotheses can be validated by comparisons with measured data.  In general, this basis seems to be the only way to ensure that the hypotheses are in accord with the actual energy-balance state of the Earth.  Use of some kind of global-average temperature of only parts of the Earth’s climate systems leaves open the possibility that a seemingly correct result has been obtained when in fact it has not.

An energy-balanced equilibrium state has been the focus of research for decades.  The important natural physical phenomena and processes that can affect this balance have been known for about 150 years.  Yet, to this day, these critically important phenomena and processes, directly affecting the energy balance, remain among those that are the least understood from both theoretical and empirical basis.  Additionally, they are among those that are the most crudely represented in mathematical models of the climate’s systems.  And they are also among those that are used to ‘tune’ the models whenever hindcasts are carried out with the models.  It is not a good situation that the fuzziest numbers are used to effect changes in less-than-completely understood yet critically important aspects of the complete problem.

In engineering work it is common to early identify the critically important phenomena and processes that control the response of materials and systems to imposed conditions.  If it is also determined that these are not sufficiently well established and well known for proper specification of solutions of the problem of interest, experimental and theoretical investigations, focused like a laser on just these, will be developed and carried out.  Focused mathematical models based on the fundamental equations for these phenomena and processes can also be studied for insights into coupling these detailed models and methods with the additional parts that comprise the models of the climate systems.

In the case of the Earth’s climate systems, this approach would basically focus on development and deployment of instruments that can measure the energy in-coming to and out-going from the climate systems and the interactions of these energy transports with components of the systems.  While we can’t change the states of the Earth’s climate systems so as to obtain wide ranges of conditions for which to make the measurements, the possibility that large-scale, integrated, coupled-effects experiments could be devised should not be simply dismissed out of hand.  I think this approach has been used in studies of the transport of a trace gas from a mixture of gases into a liquid.  Transport of CO2 from the atmosphere into the oceans, and other large bodies of liquid, for example, has been studied on spatial scales ranging from laboratory bench to real-world flows in the environment.

Such approaches are very costly.  However, if the problem of interest is of sufficient importance work on other aspects has to be scaled back or eliminated until a sufficient understanding of the controlling aspects has been firmly obtained and validated.  In the case of an engineering solution, if the required focused work cannot be justified, or is simply too hard to resolve, the solution space is moved to other regions by changing the designs of the proposed solutions.

Given the enormous spatial and temporal heterogeneities that humans experience in the Earth’s climate, the ramifications of changes in the energy content and transport of the systems due to human and natural activities should be stated on a local, or regional, basis.  All natural physical phenomena and processes are solely functions of the local states of the interacting matter; none respond to global-average states of the entire planet.  All humans have adapted to local climate conditions; none to global-average conditions.

Establishment of changes in the energy balance on local or regional scales very likely will prove to be extremely difficult.  Maybe impossible, but I don’t like to use that characterization.

Thank you for taking time to consider this notes.
Dan Hughes

COMMENT Bill Kerr

hi roger pielke snr

wrt
http://pielkeclimatesci.wordpress.com/2010/06/30/invitation-on-assessing-three-climate-hypotheses/

<http://pielkeclimatesci.wordpress.com/2010/06/30/invitation-on-assessing-three-climate-hypotheses/>I
think the hypotheses are good as they are
affiliation: I’m not an expert, I’m a secondary school teacher in science,
maths, IT

I did post a comment to John Cook’s blog, which does seem to make an honest attempt to evaluate evidence, about your invitation
http://www.skepticalscience.com/A-Scientific-Guide-to-the-Skeptics-Handbook.html#comments
comment 32

thank you for your ongoing expert efforts to go against the ipcc “consensus”
tide and open up things for reasoned discussion

cheers,
 Bill Kerr

COMMENT FROM A Scientific Guide to the ‘Skeptics Handbook’

32.billkerr at 11:11 AM on 2 July, 2010
hi John,
Have you considered the choice b/w Pielke snrs invitation and hypotheses 2a and 2b? (Invitation On Assessing Three Climate Hypotheses) You seem to support 2b judging by your handbook’s CO2 emphasis but 2a may be a better fit for the evidence

Hypothesis 2a: Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and involve a diverse range of first order climate forcings, including, but not limited to, the human input of carbon dioxide (CO2). Most, if not all, of these human influences on regional and global climate will continue to be of concern during the coming decades.

Hypothesis 2b: Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and are dominated by the emissions into the atmosphere of greenhouse gases, the most important of which is CO2. The adverse impact of these gases on regional and global climate constitutes the primary climate issue for the coming decades.

Response: I hadn’t seen Pielke’s hypotheses. It seems to me 2a and 2b aren’t mutually exclusive – any climate scientist would agree that CO2 is not the only driver of climate and that we need to take into account all forcings. The reason for the emphasis on CO2 is because it is the most dominant and fastest rising forcing. The emphasis on CO2 in the Scientific Guide is also necessary as the ‘Skeptics Handbook’ fails to recognise the many lines of evidence that more CO2 forces up temperature – this is a somewhat more extreme stance than the more nuanced views of Roger Pielke Snr.

billkerr at 10:03 AM on 3 July, 2010
#32 and #33

John,
When you say “The reason for the emphasis on CO2 is because it is the most dominant and fastest rising forcing” you are supporting Pielke snrs hypothesis 2b and rejecting 2a. They are mutually exclusive by my reading.

Doug and John,
The Real Climate discussion that Doug links to predates Pielke snrs invitation for people to improve the wording of the hypotheses if they feel the wording is inadequate, as claimed by Eric in the Real Climate discussion. This Pielke snr post, which also predates the invitation, condenses the different viewpoints.

COMMENT FROM David [last name withheld by request]

I realized I am slow in responding to your invitation for comments on your three climate hypotheses and understand if you find them a bit frustrating.  Your many valuable contributions to climate science and opinions are respected and you are certainly much better informed on climate matters than I.

I ask that you not disclose to others anything more than my first name (Dave) to minimize potential targeting by aggressive global warming advocates my views tend to energize.  I am/was an economist by training and occupation (before retirement) rather than physical science professional.  My interest in climate science flows from strong concern about public policy proposals advocated to counter what I discern as significantly exaggerated potential for global warming caused by human use of fossil fuels, and the adverse impact implementation of such policy proposals would have on children, grandchildren and the national interest.
   _Hypothesis 1:_ Human influence on climate variability and change
    is of minimal importance, and natural causes dominate climate
   variations and changes on all time scales. In coming decades, the
   human influence will continue to be minimal.

   _Hypothesis 2a: _Although the natural causes of climate variations
   and changes are undoubtedly important, the human influences are
   significant and involve a diverse range of first order climate
   forcings, including, but not limited to, the human input of carbon
   dioxide (CO2). Most, if not all, of these human influences on
   regional and global climate will continue to be of concern  during
   the coming decades.

   _Hypothesis 2b:_ Although the natural causes of climate variations
   and changes are undoubtedly important, the human influences are
   significant and are dominated by the emissions into the atmosphere
   of greenhouse gases, the most important of which is CO2. The
   adverse impact of these gases on regional and global climate
   constitutes the primary climate issue for the coming decades.
Reading the three alternatives, I basically come away with the overall impression they postulate two scenarios – 1) humans have minimal effect on climate and 2) humans impacts dominate natural forces in determining climate.  I read 2a and 2b as variations on the relative magnitude and modalities of human impacts versus natural forces.  Addition of a 1b postulating dominance of natural forces, exacerbated and/or attenuated
by a diverse range of climate forcings and regional environmental impacts might help clarify scenario difference.

To date, I have not seen strong evidence the full range of natural forces bearing on climate have been adequately considered in theoretical or quantitative models.  Phenomena likely warranting further study and consideration include submarine geothermal heat, seismic generated thermal and kinetic energy release, tropospheric cloud dynamics and distribution, solar wind impacts, and effects of interplanetary magnetic field fluctuations.

I have no doubt humans are affecting local and regional environments and likely contribute to extent and timing of climate changes.  But, I am truly skeptical about the climate impact of human CO2 emissions – skeptical that they are a major contributor to global warming and skeptical that they are not.

respectfully,

David *****

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My Further Response To Real Climate’s Gavin Schmidt and Eric Steig

I continue to be amazed at how Gavin Schmidt and Eric Steig are so convinced of their viewpoints, that they fail to see that their autocratic tenor and tone is turning off many of their colleagues. In my engagement with them at Real Climate, apparently, I never learn either (see). :-)

Here are the latest comment/replies on the Real Climate weblog reproduced below

Eric – Please elaborate, however, on why hypotheses 2a and 2b are not sufficiently distinct. The 19 authors of our 2009 EOS paper concluded that they are. Hypothesis 2b is clearly the emphasis of the 2007 IPCC reports.

As we wrote in our article

“The evidence predominantly suggests that humans are significantly altering the global environment, and thus climate, in a variety of diverse ways beyond the effects of human emissions of greenhouse gases, including CO2. Unfortunately, the 2007 Intergovernmental Panel on Climate Change (IPCC) assessment did not sufficiently acknowledge the importance of these other human climate forcings in altering regional and global climate and their effects on predictability at the regional scale.”

Also, you state that Hypothesis 2a is not original. Please refer us to where this perspective is discussed in the IPCC (and CCSP) reports.

[Response: Eric can speak for himself, but other forcings are discussed in WG1 Chapter 2, section 2.3, 2.4, 2.5, through most of chapter 6, and all of chapter 7. The dominance of CO2 among the greenhouse gases is seen in fig 2.20 and fig 2.21 as well as the diversity of other forcings. - gavin]

[Response: To answer your question about hypotheses 2a and 2b, it simply depends on what aspect of the climate system you are talking about. In many land areas, deforestation has a huge impact on the local climate, certainly larger than CO2, so far (Hypothesis 2a). In the central Pacific, it is certainly not land use that dominates; CO2 probably does (Hypothesis 2b). To suggest these are mutually exclusive is just wrong.
--eric]

Response #1: June 25 2010

It appears that Eric, although he apparently does not want to admit it (perhaps even to himself), provides evidence to reject Hypothesis 2b. If in parts of the climate system, non-CO2 human climate forcings are more important than CO2 radiative forcing, than Hypothesis 2b must be rejected. 

We do need to better define what aspects of the climate system are important to society and the environment. In the 2005 NRC report

National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C., 208 pp.

it is written

Despite all these advantages, the traditional global mean TOA radiative forcing concept has some important limitations, which have come increasingly to light over the past decade. The concept is inadequate for some forcing agents, such as absorbing aerosols and land-use changes, that may have regional climate impacts much greater than would be predicted from TOA radiative forcing. Also, it diagnoses only one measure of climate change—global mean surface temperature response—while offering little information on regional climate change or precipitation. These limitations can be addressed by expanding the radiative forcing concept and through the introduction of additional forcing metrics. In particular, the concept needs to be extended to account for (1) the vertical structure of radiative forcing, (2) regional variability in radiative forcing, and (3) nonradiative forcing.

In our 2009 EOS article, we concluded

In addition to greenhouse gas emissions, other first- order human climate forcings are important to understanding the future behavior of Earth’s climate. These forcings are spatially heterogeneous and include the effect
of aerosols on clouds and associated precipitation [e.g., Rosenfeld et al., 2008], the influence of aerosol deposition (e.g., black carbon (soot) [Flanner et al. 2007] and reactive nitrogen [Galloway et al., 2004]), and the role of changes in land use/land cover [e.g., Takata et al., 2009]. Among their effects is their role in altering atmospheric and ocean circulation features away from what they would be in the natural climate system [NRC, 2005]. As with CO2, the lengths of time that they affect the climate are estimated to be on multidecadal time scales and longer.

Apparently, Eric has chosen to ignore this broader view of the human role in the climate system, which necessarily requires that Hypothesis 2b be rejected.

 Response #2: June 25 2010

Gavin – You accept Hypothesis 2b. Thank you for answering clearly. Our EOS paper concluded otherwise, and it is informative to have a discussion by your readers of the three hypotheses on Real Climate. I look forward to reading them.

[Response: Please do not put words into my mouth. First of all, I do not recognise your statements as hypotheses in any useful sense. Secondly, I see no contradiction in accepting that there are multiple sources of anthropogenic influences on climate (I think we will have over a dozen independent effects in the AR5 simulations we are doing), and acknowledging that because of the rate of the rise and the perturbation lifetime of CO2 emissions that they are the dominant issue moving forward. However that does not imply that only CO2 emission cuts are useful, and if you look at any of our recent policy-related work (Shindell et al, 2009; Unger et al, 2009), you will see a portfolio approach to calculating the impact of specific policies and sectors. See also this piece in Physics World. Thus neither 2a nor 2b properly encompass my views. Other forcings are neither negligible nor is CO2 just one issue among the rest. - gavin]

 Gavin fails (deliberately?) to accurately present what our three hypotheses actually state. In Hypothesis 2b, we do not state that the other human climate forcings are negligible, just that the dominant human climate forcing is the radiative forcing from CO2, as is assumed by the IPCC. When Gavin writes

 “acknowledging that because of the rate of the rise and the perturbation lifetime of CO2 emissions that they are the dominant issue moving forward”

this is a rejection by Gavin of Hypothesis 2a [whose rejection conflicts with what Eric has written in his response].

Finally, statements by Eric such as

Response: To use an overused metaphor, you are basically asking “Do you still beat your wife, sir?”. The point is that the “AGW” mainstream (at least, as represented by the IPCC) is not in conflict with Pielke’s position, at least not the way it is expressed by you. As I note above the real problem with his position is that it is a false dicotomy. Both 2a and 2b are correct depending on what part of the system you are talking about. Pielke Sr. makes it sound like the ‘mainstream’ is missing something when they aren’t. Hence the definition of a loaded question: one that presupposes something that has not been proven or accepted by all the people involved. If Pielke Sr. gets classified as a skeptic, or contrarian, or whatever, it is due to this sort of misleading rhetoric. It may not purposefully intend to mislead, but it is misleading nevertheless, and in quite substantive ways (because it implies that the mainstream view that we probably ought to cut CO2 emissions is based on faulty science). Note, however, this none of this has anything to do with Anderegg et al., except that, if in fact he gets classified as a ‘denier’ in their analysis, this is probably why. –eric]

and

[Response: Being listed on our blogroll does not constitute endorsement. In general, the sites we do list — whether they are run by scientists or not — tend to get the science right much of the time, and hence are consistent with our mission. Being not-listed could mean that a) we haven’t heard of the site, b) that it is uninteresting or unimportant, or c) that we consider it dishonest or disingenuous with respect to the science. Pielke Jr, Blackboard, and ClimateAudit all fall squarely into the latter category.–eric

illustrate their continued use of ad hominem labels to attempt to promote their viewpoint rather than constructively engage in the discussion of the science. Unfortunately, this also means that when they (and those colleagues who agree with them) review one of my proposals or papers (and those others with whom Gavin and Eric disagree), they likely are going to provide biased reviews. This is why the term “black list” is so appropriate.

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Further Comment On The Dot Earth Post On “Climate Data, Trends and Peer Review”

Yesterday I posted a blog titled

A Myth About The Surface Temperature Record Analyses Perpetuated On Dot Earth By Andy Revkin.

To his credit, despite my criticism, Andy presented a rebuttal by Michael Schlesinger on his website. I have reposted Michael’s response below in its entirety, and then I follow with my comment.

POST FROM DOT EARTH

Roger Pielke, Sr., of Colorado State strongly criticized Michael Schlesinger’s assessment of the temperature data — http://wattsupwiththat.com… and Dr. Schlesinger sent this reply:

I have been expecting this comment, not from anyone in particular, but from someone – and here it is. Of course we have only one raw dataset comprised of all the world’s surface temperature measurements.

How could it be otherwise?

The different groups that have analyzed this single raw dataset have made different decisions in their analyses. For example, whether the station data should be averaged as is, or whether they should first be area-weighted for the region of their coverage.

It is because of the differences in analysis methods that the results of the 4 groups are not identical.

That is healthy.

So, one set of raw temperature data, of needs be, and several different decisions about how to analyze these raw data, all lead to the same conclusion – the Earth’s near-surface temperature has warmed by about 0.9°C (1.6°F) during the past 150 years.

The case of detecting climate change is closed, period, RPS or any other climate skeptic notwithstanding.

The next task is to attribute these detected changes in near-surface temperature to their causes, natural or not – us (and U.S.).

This can be done only with a climate model, either the simple one that I and Natasha Andronova applied in our year-2000 paper, referenced in my cotribution to Andy Revkin’s blog today, or with climate science’s most comprehensive climate models, our coupled atmosphere-ocean general circulation models.

As documented in the IPCC AR4, it is not possible to replicate the observed warming due to natural causes – the sun and volcanoes – alone. Such replication can be done only by including the effects of the human-generated increase in the concentrations of greenhouse gases.

Thus the case of the causes of the observed climate change is closed, period – RPS or any other climate skeptic notwithstanding.

What remains is to decide what to do about this, bury our collective heads in the sand and pretend that reality is otherwise, or take on the hard task before us of making the transition this century from the fossil-fuel age to the post fossil-fuel age.

As I am an engineer as well as a scientist, I challenge humanity to this great and singular task.

I will not be here much longer, so I can at most see only the beginning of this voyage.

But my 3 children and 6 grandchildren will be here to see whether or not we now behave in a responsible way to them and their progeny, and to our one-and-only planet.

To not do so would be to condemn billions of human beings, now and in the future, to death by climate.

THIS WE MUST NOT DO!

Michael

MY RESPONSE

First,  I am pleased that Michael Schlesinger has confirmed what I have reported; in that

“…we have only one raw dataset comprised of all the world’s surface temperature measurements.”

However, what this means is that the  0.9°C increase in the global average surface temperature during the last 150 years is guaranteed to be closely replicated by each of the research centers that are analyzing the data.  This close agreement was reported on in the CCSP 1.1 report as I reproduced in my post  

An Erroneous Statement Made By Phil Jones To The Media On The Independence Of The Global Surface Temperature Trend Analyses Of CRU, GISS And NCDC

An excerpt from the CCSP 1.1. report, as I reproduced in my post,  reads

“While there are fundamental differences in the methodology used to create the surface data sets, the differing techniques with the same data produce almost the same results (Vose et al., 2005a).”

Michael introduces another broader issue, however, in his  statement

“The case of detecting climate change is closed, period, RPS or any other climate skeptic notwithstanding.”

This statement is a further example of the narrow and closed viewpoint illustrated in the released CRU e-mails. I agree with Michael that we have detected human climate forcing effects. To label me as a skeptic, however,  is completely wrong (as Andy knows; e.g. see and see)

More importantly, I am disappointed in his failure to discuss the fundamental scientific issue that remains which is which of the two hypotheses below are correct:

  • Hypothesis 2a: Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and involve a diverse range of first- order climate forcings, including, but not limited to, the human input of carbon dioxide (CO2). Most, if not all, of these human influences on regional and global climate will continue to be of concern during the coming decades. 
  •  

  • Hypothesis 2b: Although the natural causes of climate variations and changes are undoubtedly important, the human influences are significant and are dominated by the emissions into the atmosphere of greenhouse gases, the most important of which is CO2. The adverse impact of these gases on regional and global climate constitutes the primary climate issue for the coming decades.
  •  

     Hypothesis 2b was rejected in our joint paper (of which all of the authors are AGU Fellows)

    Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell,  W. Rossow,  J. Schaake, J. Smith, S. Sorooshian,  and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. An edited version of this paper was published by AGU. Copyright (2009) American Geophysical Union

     Michael Schlesinger clearly accepts Hypothesis 2b.  I invite him to discuss why he rejects Hypothesis 2a, since only one of these hypotheses can be correct.

     

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    Filed under Advocacy Masking As Science, Climate Change Forcings & Feedbacks, Debate Questions

    Recommended Reading – A Post On The Washington Post Capitol Weather Gang Website By Matt Rogers

    There is a concise very knowledgable summary of a number of climate issues at the Washington Post Capitol Weather Gang website. The post by Matt Rogers is A Skeptical Take on Global Warming [h/t to Tom Fuller's Examiner.com weblog for alerting us to it!].  Matt’s post is worth reading.

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    Filed under Climate Science Reporting, Debate Questions