Category Archives: RA Pielke Sr. Position Statements

Comments On Numerical Modeling As The New Climate Science Paradigm

UPDATE MAY 3 2010: I e-mailed each author of the Navarra et al 2010 paper and invited them to respond to my post; as of today’s date they have not replied to even acknowledge receipt of my e-mail.

Dick Lindzen has presented a summary of how climate science has changed over the last decade or so (see). In his article he writes [h/t to David L. for posting on Climate Audit]

“In brief, we have the new paradigm where simulation and programs have replaced theory and observation, where government largely determines the nature of scientific activity, and where the primary role of professional societies is the lobbying of the government for special advantage.”

There is an article in the March 2010 issue of the Bulletin of the American Meteorological Society which exemplifies the first of the issues that have been raised by Dick Lindzen.  The article is

A. Navarra, J. L. Kinter III, J. Tribbia, 2010: Crucial Experiments in Climate Science. Bulletin of the American Meteorological Society. Volume 91 Issue 3. 343–352.

I have provided excerpts from this article and will provide comments after each indicating points of agreement and disagreement.

There is a delicate web of interactions among the different components of the climate system. The interplay among the time scales is quite intricate, as the fast atmosphere interacts with the slow upper ocean and the even slower sea ice and deep-soil and groundwater processes. Spatial scales are tightly connected too, as small-scale cloud systems, for instance, affect the large-scale energy balance. Furthermore, everything is connected by water in its various forms. Water flows easily from place to place and exchanges energy with the environment every time it changes phase. Evaporation, condensation, freezing, and melting processes must be taken into account and evaluated as accurately as possible. The past 40 years of climate simulation have made it apparent that no shortcut is possible; every process can and ultimately does affect climate and its variability and change. It is not possible to ignore some components or some aspects without paying the price of a gross loss of realism.

This summary is a much-needed ,belated recognition of the accuracy of the 2005 NRC report [uncited in the Navarra et al 2010 BAMS article]

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.

Figure 1-1 in the NRC report [reproduced below] schematically illustrates what is written in the Navarra et al paper.

The Navarra et al 2010 article then has the text

A strict application of the scientific method requires a process of isolation of constituent subsystems and experimental verification of a hypothesis. For the climate system, this is only possible by using numerical models. Such models have become the central pillar of the quantitative scientific approach to climate science [emphasis added] because they allow us to perform “crucial” experiments under the controlled conditions that science demands. Sometimes crucial experiments are recognized as such at the design phase, like the quest for the Higgs boson currently going on at the European Organization for Nuclear Research [Conseil Européen pour la Recherche Nucléaire (CERN)]. Other times it is only in historical perspective that some experiments are recognized as truly “crucial.” This was the case of the 1887 test by Michelson and Morley that rejected the hypothesis of the existence of the “luminiferous aether” (Tipler and Llewellyn 2003), an undetected medium through which light was deemed to propagate (see Fig. 1 on title page; http://quantumrelativity. Their result led to a reformulation of a physical theory of electromagnetic radiation and to special relativity and the invariance of the speed of light. “Crucial” experiments test competitive theories and the most successful one is finally selected.

This text seeks to equate climate modeling with the development of fundamental concepts in basic physics. However, these are not the same. Whereas fundamental physical constants such as the speed of light were the focus of the Michelson and Morley study, climate modeling relies on tunable parameters and functions in their parameterizations of clouds, precipitation, vegetation dynamics, etc in the construction of the models. Climate models are engineering code not basic physics. Only advection, the pressure gradient force and gravity provide the fundamental physics in climate model. The combination of a fundamental component of the model with an engineering component (in which the physics is tuned) results in engineering code, not basic physics.

I summarized the types of climate models in my post

What Are Climate Models? What Do They Do?

There are three basic classes: process studies; diagnosis; and prediction.  As I discuss in that post, the IPCC assessment models are actually process studies, although they have been marketed by the IPCC as predictions.  With respect to the  Navarra et al paper, their proposed modeling framework, in reality, is to develop a more comprehensive climate process assessment tool. The models hypotheses.

Navarra et al 2010 continue with the text

There have been no revolutionary changes in numerical models of climate since their advent over 30 years ago. The models make use of the same dynamical equations, with improved numerical methods, and have comparable resolution and similar parameterizations. Over the past 30 years, computing power has increased by a factor of 106. Of the millionfold increase in computing capability, about a factor of 1,000 was used to increase the sophistication of the model. Model resolution, the inclusion of more physical and biogeochemical processes, and more elaborate parameterizations of unresolved phenomena have all been modestly improved.

This is an accurate summary.  An interesting and important oversight, however, is any discussion on improvements in the predictive skill of the models on different time scales (i.e. seasonal; annual, multi-year; decadal). Of course, the absence of this discussion reflects the general lack of a demonstration of predictive skill beyond a few months at most by the IPCC or anyone else.

Navarra et al 2010 write

These trends indicate that the problem of weather and climate modeling can be organized in terms of four dimensions: resolution, complexity, integration length, and ensemble size.

There is an interesting oversight here. There is no mention of observational verification of the model skill.

Increasingly, century-long climate projection will become an initial-value problem requiring the current observed state of all components of the Earth system: the global atmosphere, the world oceans, cryosphere, and land surface (including physical quantities, such as temperature and soil moisture, as well as biophysical quantities, such as leaf area index, etc.) to produce the best projections of the Earth system and also giving state-of-the-art decadal and interannual predictions. The shorter time scales and weather are known to be important in their feedback on the longer-time-scale behavior. In addition, the regional manifestations of longer-time-scale changes will be felt by society mainly through the changes in the character of the shorter time scales, including extremes.

This is an accurate summary of the challenges in climate prediction. The admission that climate prediction is an initial value problem was ignored by the 2007 IPCC assessments.  See, for example, my recent post

Comments On A New Paper “A Unified Modeling Approach to Climate System Prediction” By Hurrell Et Al 2009

which refers to my paper

Pielke, R.A., 1998: Climate prediction as an initial value problem. Bull. Amer. Meteor. Soc., 79, 2743-2746. {with respect to my Comments on the Hurrell et al paper that was sent to BAMS last year, it was only sent out for review in the past month!].

Navarra et al 2010 further write

The era of industrial computing. The changes that we have described will usher in a new era of calculation on such a large scale that it will be comparable to the transition from the artisan shop to the modern factory: it will be the era of industrial computing. Issues like quality control, procedure certifications, and data integrity will no longer be the subject of discussions by researchers, but they will be matters of procedural control and monitoring. It will free climate scientists from much of the engineering work that is now necessary in the preparation of the experimental apparatus they are using in their laboratory but that is hardly necessary to the core of climate science.

It will also create some new problems. It is unclear at this point if the field is going to need more software engineers and programmers or fewer as the computing power is concentrated in larger and fewer centers. A new professional figure may emerge who will maintain the laboratory and the experiment as the routine day-by-day simulations, developing along well-planned lines, may stretch for months or years. Questions about how such professionals will be trained arise without obvious answers.

This is a remarkable proposal for a new approach in climate modeling as it removes the climate modeller  from working with the real world data.  This exemplifies what Dick Lindzen stated

“we have the new paradigm where simulation and programs have replaced theory and observation….”. 

The Navarra et al article concludes with the text

The discussions conducted for the simulations needed for the IPCC assessments have already gone in this direction, but they are still examples of a loose coordination, rather than the tight coordination that will be required by the petascale machines. The transition is similar to what happened in astronomy when that community went from coordinating observations at different telescopes to creating a consortium for the construction of one larger instrument. Industrial computing and numerical missions will rely on that capability even more to allow climate science to address problems that have never before been attempted.

The global numerical climate community soon will have to begin a proper discussion forum to develop the organization necessary for the planning of experiments in the industrial computing age.

The proposal put forth in Navarra et al 2010, if adopted, would concentrate climate modeling into a few well-funded institutions, as well as focus the use models for multi-decadal predictions of the real climate system (in which we do not, of course have observational validation data), rather than as a tool to test scientific hypotheses against real world observations. Policy decisions will be made from these unvalidated model predictions (has they have already been made based on the global-average and regional scale from the IPCC multi-decadal model forecasts).

This is a path that will likely lead to the eventual discrediting of the climate science community who participates in this activity if, as I expect, the regional multi-decadal regional (and even global average forecasts) generally fail to show skill in the coming years.

Even more importantly, they are unlikely to be useful to most of the actual needs of resource stakeholders in their plans to reduce the vulnerability to climate and other environmental and social threats; e.g. see Table E.7 in

 Pielke, R.A. Sr., and L. Bravo de Guenni, 2004: Conclusions. Chapter E.7 In: Vegetation, Water, Humans and the Climate: A New Perspective on an Interactive System. Global Change – The IGBP Series, P. Kabat et al., Eds., Springer, 537-538.

 While I support the use of climate models to examine climate processes, they must be solidly based on observational validation. It also must not be forgotten that climate models (and indeed all models) are hypotheses. Real world observations must be the standard to test the climate models.

The Navarra et al conclusion that

“Such models have become the central pillar of the quantitative scientific approach to climate science because they allow us to perform “crucial” experiments under the controlled conditions that science demands”

is not how climate science should proceed. The “central pillar” must be the real-world observations.

The American Meteorological Society, as represented by the Editor-in-Chief of the Bulletin of the AMS, Jeff Rosenfeld, agrees with the view with models as the central pillar of the quantitative scientific approach to climate science. He writes in his “Letter From The Editor” [which, unfortunately is not online at the BAMS website]

“If climate science develops the way Navarra et al suggest will this be proof that the age of numerical experimentation has matured? Perhaps so. A science shaped by Franklin and Lorenz’s critical experiments is now a critical experiment itself – a test of the viability of science when it is dependent on numerical modeling for methodology. For better or worse, the result of this grand experiment – the very state of climatology – will forever be ingrained in popular consciousness.”

Dick Lindzen’s perceptive statement that “simulation and programs have replaced theory and observation” accurately (and unfortunately) represents the current  position of the leadership of the American Meteorological Society.

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The Significance of the E-Mail Interchange with Kevin Trenberth and Josh Willis

On Friday of last week, and Monday and Tuesday of this week, I presented the following posts:

Further Feedback From Kevin Trenberth And Feedback From Josh Willis On The UCAR Press Release

Comments On Two Papers By Kevin Trenberth On The Global Climate Energy Budget

Is There “Missing” Heat In The Climate System? My Comments On This NCAR Press Release

My son had the post

The Missing Heat

I want to summarize today what are the main conclusions from this exchange of perspectives:

  • First, when colleagues who differ can interact in a constructive manner, we all benefit by an improved understanding of the science issues and the way forward to resolve remaining uncertainties.
  • In terms of climate science, a very substantive conclusion from this interchange of perspectives is that we do not need to continue to use the global average surface temperature trend (with its unresolved biases and uncertainties) to diagnose global warming. The trends in the upper ocean heat content, which has been accurately measured since at least 2005, and will for the foreseeable future, should be adopted as the primary metric to monitor global warming.

This second finding does not mean continued analyses of surface temperatures and their anomalies are not needed [they certainly are for length of growing season, heating degree days, etc], but for the specific metric of global warming (and cooling), it is an inadequate metric compared with ocean heat content changes.

We need near-real time plots of the ocean heat content changes over time, such as given in the figure in

Pielke Sr., R.A., 2008: A broader view of the role of humans in the climate system. Physics Today, 61, Vol. 11, 54-55.

Four-year rate of the global upper 700 m of ocean heat changes in Joules at monthly time intervals. One standard error value is also shown. (Figure courtesy of Josh Willis of NASA’s Jet Propulsion Laboratory).

It will be illuminating and informative to see how NCDC (Tom Karl), GISS (Jim Hansen), and CRU (Phil Jones)  respond to this recognition that it is time to move past the surface temperature trend as the “gold standard” of global warming.

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Roger A. Pielke Sr.’s Position On Climate Change

As a result of the New York Times article on December 6 2009 which I posted on yesterday (see), I have been e-mailed by several colleagues who are unclear of my perspective on the science of climate change. I am writing this e-mail to make sure my viewpoint is abundantly clear.

I have concluded that of three possible hypotheses of the role of humans in the climate system, the only one that has not been refuted is

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.

This consequences of this finding include the following:

1.  The human addition of carbon dioxide to the atmosphere by human activities is a signficant contributor to climate change. Its effect is both radiative and biogeochemical.

2. However, there are also other human contributions to the climate system that are as, or are more important, than the addition of CO2. These include The influence of human-caused aerosols on regional (and global) radiative heating the effect of aerosols on clouds and precipitation, the influence of aerosol deposition (e.g. soot; nitrogen) on climate, and the effect of land cover/ land use on climate.

3. All of these human climate contributors affect the climate on local, regional and global scales.

4. Atmospheric and ocean circulation variability and changes result from these climate forcings. Since it is these circulations which cause our weather patterns, including drought, floods, tropical cyclones, and blizzards,  circulation pattern changes are a much more appropriate metric to monitor with respect to climate change, than a focus on global average radiative forcing changes.

5.  For this reason, climate change involves very much more than global climate system heat changes (global warming or cooling).

5.  The 2007 IPCC report, the Copenhagen meeting currently underway, and the EPA Endangerment Finding are based on a scientific hypothesis which is straightforward to refute (e.g. see).  Inadequate, and likely seriously flawed policy inevitable will result.

6. The released CRU e-mails documents that a culture in the leadership of the climate science community to suppress and/or ignore viewpoints which differ from the 2007 IPCC view. This has resulted in a failure of the science community to properly present to policymakers the actual diversity of viewpoints on climate science.

UPDATE: I have been asked my viewpoint on policies related to greenhouse gas emissions.  As I wrote in my post yesterday (see),

“Thus the plans being made in Copenhagen will necessarily be inadequate to address the diversity of the climate issues that society and the environment face in the coming decades.  What are needed is a multiple pronged approach to address the different types of natural and human climate forcings as articulated in one of my son’s posts (see) where he wrote

“As the community begins to realize these significant, multi-faceted and hideous complexities, it would not be a surprise to learn that a policy framework design 20 years ago is now somewhat out of step with current scientific understandings. The upshot is that as presently designed, international climate policy is both too complex and too simplistic. It is too simplistic because it is built upon a set of scientific perspectives on climate change that are increasingly seen as outdated and appropriate only for dealing with a narrow set of very important human influences — long-lived greenhouse gases. It is too complex because in trying to deal with added complexity it has become unwieldy and clearly impractical from the standpoint of not just implementation but the politics of even reaching an agreement about implementation.

Climate policy can be improved by reconstructing climate policy from the bottom up. This process should begin by recognizing that no single policy instrument will ever deal with “climate change” (human caused or otherwise). An approach to climate policy that is decentralized and more focused in its elements will be better able to adjust as science evolves (and it will continue to evolve, to be sure) and allows for progress to be made incrementally along a set of parallel paths. The all-or-nothing approach to climate policy that dominates the present agenda is incapable of keeping pace with evolving scientific understandings as they relate to policy implementation, and from a pragmatic perspective, pretty much guarantees the “nothing” outcome.”

For further discussion of my views on this issue, please see, for example,  RA Pielke Sr. Position Statements and Summary Of Roger A. Pielke Sr’s View Of Climate Science.

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Interview By Andy Revkin At Dot Earth Titled “Critic Of ‘Climate Oligarchy’ Defends Case For CO2-Driven Warming”

In addition to the excellent Pajamas Media interview,  I recommend the also well done interview by Andy Revkin titled Critic of ‘Climate Oligarchy’ Defends Case for CO2-Driven Warming at Dot Earth [although the more complete and accurate title would be “Critic of ‘Climate Oligarchy’ Defends Case For Human Driven Climate Change”].

My answer to Andy’s questions start with

“The  C.R.U. is only one of several groups who are analyzing the long term global average surface temperature trends drawing from mostly the same raw observed data. Even if their data analysis is excluded, it does not alter the findings that were reported in the 2007 I.P.C.C. report with respect to  the surface temperature trends, since these other analyses provide a redundant check of their analyses over the last century. Over the last 100 years or so this surface data clearly documents a long-term warming.

There are remaining problems with the quantitative accuracy of these surface temperature data sets, however, as we have presented in several multi-authored recent papers. For example, most recently in  Klotzbach et al 2009, we find a significant divergence between the lower tropospheric and surface temperature trends, which can be explained in part by the more limited vertical sampling of temperature trends using just the surface temperature data. This indicates that the long-term surface temperature trends overstate the warming relative to warming through a deeper depth of the troposphere.

In any case, the surface temperature trends are not the most appropriate metric to assess global warming (or cooling) as it is the oceans, which are the largest component of heat changes, as I discussed most recently in my Physics Today paper. This is an issue that I agree with Jim Hansen on. Since mid-2003 through the latest data that I have seen, there has been no annual average warming or cooling in the upper oceans. I recommend you contact  Josh Willis for the latest information. For future assessments, this should be the metric to use to monitor (and seek to predict) global warming.

There is also a question of attribution. First, it needs to be better recognized that global warming (i.e., climate system heat changes) is only a subset of climate change. Humans are altering the climate in diverse ways, a variety of human climate forcings are significant, and the effects of these forcings need to be responded to, even if the climate did not warm.”

See the full interview for the rest of my comments.

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Interview By Charles Martin At Pajamas Media Titled “Climategate Emails Just A Small Sample Of A Broad Issue”

As reported at my son’s weblog yesterday (see) I was interviewed by Charles Martin at Pajamas Media “Climategate Emails Just a Small Sample of a Broad Issue”.

The interview starts with the text

PJM: The release of the purloined emails and files from the UEA Climatic Research Unit has been a shock that still reverberates in the world of climate science, and among the critics of the current state of climate science. On the one hand, it has led some people to denounce “global warming” as a “hoax”; on the other, apparently dismisses it as a tempest in a teacup. In your opinion, how important are these revelations?

Pielke: Both those who denounce “global warming” as a hoax and RealClimate’s claim that this is a “tempest in a teapot” are incorrect. With respect to the role of humans in the climate system, there is incontrovertible evidence that we exert both warming and cooling effects. The warming occurs through the emission of carbon dioxide and other greenhouse gases and certain aerosols, and cooling [occurs due to] other types of aerosols. Land use change due to human land management also effects warming and cooling forcings.

With respect to the RealClimate dismissal of the emails, however, there are serious issues exposed by the emails — including the goal of these scientists to prevent proper scientific disclosure of their data, as well as to control what papers appear in the peer reviewed literature and climate assessments. The IPCC assessment, with which major policy decisions are being made, involves the individuals in the emails who have senior leadership positions.

See the rest of the interview for the other questions and answers.

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New Article “Climate Change: The Need to Consider Human Forcings Besides Greenhouse Gases” In EOS

UPDATE: See also

We have a Forum article that appeared today in the American Geophysical Union publication EOS. It is

Pielke Sr., Roger, Keith Beven, Guy Brasseur, Jack Calvert, Moustafa ChahineRuss Dickerson, Dara Entekhabi, Efi Foufoula-Georgiou, Hoshin Gupta, Vijay Gupta, Witold Krajewski, E. Philip Krider, William K. M. Lau, Jeff McDonnellWilliam RossowJohn Schaake, James Smith, Soroosh Sorooshian,  and Eric Wood: 2009: “Climate Change: The Need to Consider Human Forcings Besides Greenhouse Gases“. Eos, Vol. 90, No. 45, 10 November 2009, page 413.  This paper was published by AGU EOS [subscription required for the version as it appears in EOS – Copyright (2009) American Geophysical Union].

All of the authors are Fellows of the American Geophysical Union.

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My Early View (1980s) On The Role Of Humans In The Climate System

In the early 1980s, I presented my viewpoint on climate in an annual publication of Encyclopedia Britannica. I have decided to post on my early views to document how they have stood up over time.  They are in

Pielke, R.A., 1984: Earth sciences: Atmospheric sciences – 1983, Encyclopedia Britannica Yearbook of Science and the Future, 279-281 where I wrote

“Concern regarding the impact of the steady increases of carbon dioxide on the Earth’s atmosphere continued in 1983. The U.S. Environmental Protection Agency released reports in the fall which suggested that by 2100 the average global temperature could increase by 5°C (9°F) with an associated rise in global sea level of between 144 cm (4.8 ft) and 217 cm (7 ft) as a result of the increased levels of carbon dioxide and other trace gases put into the atmosphere primarily through the burning of fossil fuels. These gases act to reduce the emission of long-wave radiation out into space yet still permit solar radiation to teach the Earth’s surface. This mechanism of heat increase is referred to as the “greenhouse effect.” At about the same time the U.S. National Research Council (NRC) issued a somewhat more conservative report on the same subject, which emphasized the remaining uncertainties in estimating the effect of carbon dioxide and other trace gases on climate. The report concluded, for instance, that if deforestation has contributed significantly to the increase in carbon dioxide during recent decades, then existing models that project future atmospheric concentrations based on man-made sources may overpredict the fraction of carbon dioxide remaining airborne. The NRC report concluded that existing evidence does not support a change away from fossil fuels but did suggest that some priority be given to the enhancement of long-term energy options that do not involve the combustion of such fuels.

Increased levels of aerosols in the upper atmosphere and lower stratosphere that are associated with high levels of industrial activity could counter the greenhouse effect of high levels of carbon dioxide. This possibility was not adequately examined in either of the studies. These aerosols appear to be ejected into the upper atmosphere and stratosphere via deep cumulus clouds, a process that is referred to as cloud venting.”

and in Pielke, R.A., 1985: Earth sciences: Atmospheric science – 1984. Encyclopedia Britannica Yearbook of Science and the Future, 284-287, where I wrote

“Concern continued with respect to the potential impact on  climate of the increase of carbon dioxide in the atmosphere.  Additions of carbon dioxide to the atmosphere as a result of the combustion of fossil fuel can retard radiational cooling to space, thereby causing a net warming at the Earth’s surface.  Unless mitigated by other results of human activities, such as reduced sunlight at the ground due to additions of aerosols to the upper atmosphere, this warming could result in major changes in climate patterns.  In 1984, as part of the continued study of this phenomenon, NOAA used aircraft to estimate how much carbon dioxide is transferred from the atmosphere into the North Atlantic during winter storms when the cold ocean waters are most efficient in absorbing carbon dioxide. “

What we know in 2009 is that the role of humans within the climate system includes the issues reported above.  However, the effect of humans is even more diverse and significant than I reported in the 1980s. Aerosols are now recognized to have a large range of effects (e.g. see), while land use/land cover change has been demonstrated to be a first order climate forcing (e.g. see).

The 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

remains the best overview of the diversity of human climate forcings.


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My 1991 View of “Overlooked Scientific Issues In Assessing Hypothesized Greenhouse Gas”

In 1991 I published a paper which had my views on the issue of the GCM modeling of global warming. This weblog revisits the topics I raised at that time.

Pielke, R.A., 1991: Overlooked scientific issues in assessing hypothesized greenhouse gas warming. Environ. Software, 6, 100-107.

I summarized the focus of my article in the text

“Numerical models of the global atmosphere and ocean circulations (referred to as general circulation models -GCMs) have been used to investigate the impact on climate of an increase in these trace gases [which include carbon dioxide, methane, chlorofluorocarbons, and nitrous oxide]. The Environmental Protection Agency (EPA) concluded in 1983 based on these models, for example, that an increase of the average global temperatures of 5°C by the year 2100 with an incrcase or sea level up to around 2 meters will result because of the global enhancement of these gases. The World Meteorological Organization has concluded that greenhouse gas cause warming could cause a global warming of 1.5°C to 4°C by the middle of the next century.

The purpose of this paper is to discuss a number of serious shortcomings in the GCM model simulations which produced these conclusions regarding climate change, These limitations, which are either inadeqately handled or not represented at all in GCMs are summarized in this paper.”

The following are the issues that I have raised, and what has been accomplished since the appearance of this paper:


Biogeochemisty and biogeography are now recognized as first order climate effects [e.g see NRC, 2005].


Even though the models now have finer spatial resolution, The IPCC community still fails to recognize that they must test the ability to faithfully simulate weather features (i.e. they need to be run in a numerical weather prediction mode). This is a necessary test in order to evalute the dynamics and thermodynamics in the GCMs.


The issue still requires futher investiagation. I would welcome urls of peer reviewed papers that have looked at this specific issue  [which is directly related to the spatial resolution in the ocean part of the global climate models, as well as both the physical temperature effect and the biogeochemical (carbon assimilation) effect on ocean biomass].


This climate forcing is now recognized as a major effect on the climate system [NRC, 2005]. Its complexity, however, and the microphysics spatial scales in which this occurs, continue to challenge skillful modeling of this process.


This effect is included in the 2007 IPCC report.


This has been one of my major research areas, and it has been elevated to a first order climate effect (e. g. see NRC, 2005), although the 2007 IPCC failed to adequately discuss it.


As with #4,  this climate forcing is now recognized as a major effect on the climate system [e.g, see NRC, 2005]. Clouds and precipitation process are not seen, however, as an even more difficult modeling issue than in the early 1990s (e. g. see Table 2-2 in NRC, 2005).


This warming has occured in the Arctic (and, while there is disagreement), it has not warmed in the Antarctic region at the same level. 


The 2007 IPCC continued to perpetuate the view that the models can skillfully predict the climate in the coming decades despite their own admission that the GCMs do not even have all of the first order climate forcings (see the caption to figure SPM.2).

I summarized my recommendations are follows

“Since climate change is a natural feature of the earth, we need to husband our resources even if there were no man-caused changes (e.g. Schneider). With respect to man’s potential influence on climate, the “path-of least- regret” is that we should immediately adopt policies which mitigate man’s impact providing there are no deleterious economic, environmental, or political effects of these policies. Even better, of course, is if these policies result in positive benefits to mankind. Conservation of fossil fuel resources, for example, and utilization of renewable energy resources represent examples of beneficial activities which should be promoted by government policy makers regardless of the direction of climate change. Recommendations by Rosenfeld and lIafemeister represent definite steps which could be taken to achieve this goal. Policies which require significant hardship, are  in this writer’s opinion premature.”

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“Don’t Rely On Computer Models To Judge Global Warming” – A Christian Science Monitor Op-Ed By Roger A. Pielke Sr. In 1994

In response to a recent request, I was reminded of an op-ed I completed in 1994. Its message is still true in 2009.

Christian Science Monitor (Boston, MA) August 24, 1994, Wednesday

Don’t Rely on Computer Models to Judge Global Warming By Roger A. Pielke Sr.

HIGHLIGHT: Predicting the climate in the 21st century – when events will happen and, most important, why – is not yet possible

Scientific controversy over ”global warming” continues. The great global-warming debate has taken shape around those who say the science is too uncertain to justify action and those who warn that we cannot afford the luxury of waiting for science to answer all our questions. Such controversy need not block sensible actions, however.

One area of controversy has to do with the reliability of computer models of the global climate system. Can they accurately predict future climate change?

At this point, the answer is no. Predicting the climate of the next century with precision is impossible. Scientists and the news media must take care to better educate policymakers about the process of science, and in that effort, scientists must also be careful about the words they use. Policymakers must beware those who talk about ”climate predictions;” no one knows how to accurately predict climate.

Computer simulations of the climate, referred to as ”general circulation models” (GCMs), can be used to assess the sensitivity of climate to changes that might result from increased greenhouse gases. However, because physical feedbacks between Earth’s atmosphere (including clouds), the ocean, and the biosphere remain incomplete in the models, their use as a tool is limited.

For instance, T. Palmer, a scientist at the European center for medium-range weather forecast, writes in the journal ”Weather” that climate predictions using GCMs could be grossly misleading because the computer simulations may be unable to accurately predict long-term changes in the frequency of weather patterns. A separate report in the Journal of Climate by Australian atmospheric scientist J. Garratt found significant errors in GCM estimates of incoming solar radiation. The errors were four times larger than the assumed impact of man-made greenhouse gases, a fact that seriously compromises the integrity of the computer model.

While GCMs provide a powerful and valuable scientific tool to improve our understanding of climate physics, they have not demonstrated an ability to accurately predict long-term climate changes.

The overselling of climate predictions can result in less funding for more-immediate concerns. Some of these include urban air pollution, indoor air pollution, and toxic and hazardous waste disposal. The preservation of wilderness areas as a means to promote species diversity and regions of pristine air and water is also vital. The allocation of financial resources toward reducing greenhouse gas emissions could significantly reduce the number of dollars available to remedy these other threats to environmental health.

Atmospheric and other climate-change scientists need to meet regularly to discuss and debate what is known and what remains to be discovered about climate change. Atmospheric scientists need to better communicate their concerns and needs with policymakers. Policymakers need to use the knowledge from the scientists to develop programs that benefit the environment and economy. For example, we could prepare for both short- and long-term changes of weather and climate while we continue to investigate the ecological and societal effects of atmospheric fluctuations, both natural and man-caused. Droughts, floods, hot spells, and cold waves will continue to occur irregularly. Over longer time periods, global warm and cold cycles have naturally occurred and undoubtedly will again.

The current state of knowledge of atmospheric science leaves us with uncertainty about the future. But this does not mean that effective policies to meet the challenges of global change cannot be formulated. Effective policies in the face of scientific uncertainty need to be decentralized, small-scale, and short-term.

Decentralization allows for different responses in various contexts. Policies that are small-scale limit the costs of being wrong about what’s going to happen or what to do about it. Short-term policies also allow for rapid feedback into the policy process. In this manner, society can avoid placing all its eggs in one basket based on a scenario that may or may not occur.

Similarly, effective policies on greenhouse gas emissions should emphasize using fossil-fuel energy more efficiently and cleanly. We also need to make effective use of solar and wind energy. These practices would be beneficial on their own. We need not rely exclusively on predictions generated by GCMs in order to justify sensible actions.

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Transcript of My Talk “Considering the Human Influence on Climate” At The George C. Marshall Institute

The Transcript of my presentation “Considering the Human Influence on Climate” by Dr. Roger A. Pielke, Sr. May 14, 2009 is now available, courtesy of the George C. Marshall Institute.  The transcript also includes questions from the audience along with my answers. The overview of the talk is also available.

Dr. Mike Macracken and I both have discussed the talk in weblogs (see and see).

Excepts from the transcript include the discussion on vulnerability where, I said

So what is my suggestion? There is no doubt in my mind that there are multiple types of human climate forcings. CO2 is important and we need to look at it, but there is a range of other forcings. Policymakers should look for win-win policies in order to improve the environment that we live in. The costs and benefits of the regulation of the emissions of CO2 into the atmosphere need to be evaluated together with all other possible environmental regulations. The goal should be to seek politically and techno-logically practical ways to reduce the vulnerability of the environment and society to the entire spectrum of human-caused and natural risks.

I want to give an example here. Figure 28 is from some work that I published about a year ago8 with respect to a Colorado report on climate change. In that report they took the IPCC model assessments and were trying to tell the water managers in Colorado and other parts of the west what the weather conditions are going to be for the next twenty, thirty, forty and fifty years into the future. I was asked to write a short essay, because they knew I disagreed with taking the IPCC models and using them on a regional scale. I said, “Let’s look at the natural variation in the past.” This is work by Connie Woodhouse at the University of Arizona. The graph in Figure 28 is tree ring data and is basically a measure of dryness in the western part of the United States go-ing back to about 800 A.D. What you see is that it goes up and down and the message of this data is that there were more serious droughts in the natural record prior to European settlement than there have been in the 20th century. That means that we are already at risk and we don’t know whether human disturbance of the climate system pushes us toward or away from having more frequent droughts. The bottom line is that because they have happened in the past, we need to be prepared for droughts anyway. That is a bottom-up, resource-based perspective; it is not one you can drive by changing CO2. I think this is a message that needs to be communicated.

I asked one of the IPCC authors whether his model results fall inside or outside of this envelope. He said it falls inside of the envelope. The bottom line is that in spite of what the IPCC models state, we need to do something. In fact, if you are a strong advocate of the IPCC models, factor that into your vulnerability assessment, but don’t consider that is the universe of what could happen in the future, because that is not what has happened in the past. You can also see this is a very chaotic signal and it never repeats itself. We have a different environment now with different CO2, land use, and aerosols. We do not know our trajectory, and here is how I propose that we move forward: we need a bottom-up, resource-based focus rather than relying on downscaling from global climate models. I have done a lot of work on downscaling and showed that you are not really adding anything with downscaling. I can talk about that at another time, if you like. The IPCC focus is top down, meaning you take a global model and downscale it and give it to the resource people and say, “this is what is going to happen in 2030 or 2040.” I think that is a mistake. What we need to do is look at the risks that the resources face.

Figure 29 shows one example of that: water resource vulnerability. How can we reduce our vulnerability to problems with water quality and water quantity? Obviously in the west that is a major issue. There are a variety of threats: natural landscape change, land management changes, long-term weather variability and change, human population demands, animal and insect dynamics, industrial and vehicular emissions and so forth, and they all interact with each other. We should look at our vulnerability to risk with today’s society and what we anticipate the society might be ten, twenty, or thirty years from now and try to make our system more robust to these resources. We should make our system robust to risk from the environment and from human activity, rather than relying on these IPCC models to tell us what is going to happen to the future and assuming that we can actually control climate, which I think is hubris. We can’t say that we have to prevent human intervention in the climate system; we are already intervening in the climate system.”

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