Monthly Archives: May 2010

How Independent Are Climate Models?

There is an excellent guest post by Ryan Meyer on May 27 2010  on my son’s weblog titled

The Significance of Climate Model Agreement: A Guest Post by Ryan Meyer

The post is based on their paper

Zachary Pirtle, Ryan Meyer, , and Andrew Hamilton, 2010: What does it mean when climate models agree? A case for assessing independence among general circulation models . Environmental Science & Policy. doi:10.1016/j.envsci.2010.04.004

The abstract of their paper reads

“Climate modelers often use agreement among multiple general circulation models (GCMs) as a source of confidence in the accuracy of model projections. However, the significance of model agreement depends on how independent the models are from one another. The climate science literature does not address this. GCMs are independent of, and interdependent on one another, in different ways and degrees. Addressing the issue of model independence is crucial in explaining why agreement between models should boost confidence that their results have basis in reality.”

I want to expand on this issue in this post.

As the Pirtle et al 2010 article discusses, agreement among models is often used to claim robustness in their predictions. However, it is actually quite easy to show that the model are actually very similar in their construction, and only differ in the details of how they are set up.

I decompose atmospheric models in my book

Pielke, R.A., Sr., 2002: Mesoscale meteorological modeling. 2nd Edition, Academic Press, San Diego, CA, 676 pp.

While the focus is on mesoscale atmospheric models, the set up for the atmospheric component of climate models uses the same framework.  These models have:

  • a fundamental physics part  which are the pressure gradient force, advection and gravity. There are no tunable constants or functions.
  • the remainder are parameterized physics (parameterized physics means that even if some of the equations of a physics formulation is used, tunable constants and functions inlcuded that are based on observations and/or more detailed models). These parameterizations are almost developed using  just a subset of actual real world conditions with the one-dimensional (column) representations yet then applied in the climate models for all situations!  The parameterized physics in the atmospheric model include long- and short-wave radiative fluxes; stratiform clouds and precipitation; deep cumulus cloud and associated precipitation; boundary layer turbulence; land-air interactions; ocean-air interactions).

The other components of the climate system (ocean, land, continental ice) each also have parameterized physics. The ocean component also has the fundamental physics of the pressure gradient force, advection and gravity.

All of the climate models  have this framework. They differ  in the grid spacing used, the numerical solution techniques, and the details of their parameterized physics.  The different results that they achieve are due just to these differences.

These models are also different from numerical weather prediction models. These NWP models are initialized with observed data. The predictions for different time periods into the future are compared with the observations at those time periods in order to evaluate prediction skill. The multi-decadal climate models, however, are not started from such observed real world initial conditions. Only recently has it proposed to run climate models in this manner; the so-called “seamless prediction” approach – see the post on this

Seamless Prediction Systems by Hendrik Tennekes

Comments On The Article By Palmer et al. 2008 “Toward Seamless Prediction: Calibration of Climate Change Projections Using Seasonal Forecasts”

There is further discussion of what the multi-decadal climate models involve in my post

Are Multi-Decadal Global Climate Simulations Hypotheses? Have They Been Tested, and, If So, Have the Hypotheses As Represented By the Models, Been Falsified?

In this post, there is an interesting statement by one of the lead authors on the WG1 IPCC report (David A. Randall) in an 1997 Bulletin of the American Meteorological Society paper:

“Measurements, Models, and Hypotheses in the Atmospheric Sciences” by David A. Randall, and Bruce A. Wielicki.

The abstract of the paper states,

‘Measurements in atmospheric science sometimes determine universal functions, but more commonly data are collected in the form of case studies. Models are conceptual constructs that can be used to make predictions about the outcomes of measurements. Hypotheses can be expressed in terms of model results, and the best use of measurements is to falsify such hypotheses. Tuning of models should be avoided because it interferes with falsification. Comparison of models with data would be easier if the minimum data requirements for testing some types of models could be standardized.”

Roy Spencer also has an  post on this topic titled

The Missing Climate Model Projections

Among his insightful comments, he writes

“Where the IPCC has departed from science is that they have become advocates for one particular set of hypotheses, and have become militant fighters against all others.”

What this means is that multi-decadal  climate model predictions are just hypotheses. They can only be falsified by comparison with observed data which, of course, will not be available until these decades have passed.  Thus they are not only constructed with similar frameworks, but their predictive skill cannot yet even be tested.

Thus the real question regarding the climate models is how different are they in terms of what they really are –  scientific hypotheses. A start to answering this question is i) by  determining what climate forcings and feedbacks they leave out and ii) a comparison between each model of the specific details in (a) the fundamental physics part and (b) parameterizations of each physical, chemical and biological component of the models. 

What is already known, of course, is that all of the climate models have similar formulations and only differ in the details of the numerical solution scheme, grid mesh used and of the parameterizations.

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Comment On Real Climate’s Post By Gavin Schmidt – “Ocean Heat Content Increases Update”

There is a post by Gavin Schmidt  on Real Climate on May 21 2010 titled “Ocean heat content increases update” .

Gavin, unfortunately, does not comment about and question the odd jump in the warming earlier in the current decade that is seen in the plot of upper ocean heat data, the Lyman et al 2010 paper, and which he presents in his post. Indeed, the greater warming in the Lyman et al 2010 paper that he accepts unquestionably [which he writes is  “a greater warming than seen in the NODC data and more than even the models”] is due specifically to a short-term jump. Since this is the time that the Argo Network finally achieved global coverage the reason for this jump needs more exploration. However, this jump is not seen in the sea surface temperature data (see from Bob Tisdale’s weblog).

Here is Josh Willis’s response to my query to him on this jump, which is reproduced from my post of December 29 2009 titled

Comment From Josh Willis On The Upper Ocean Heat Content Data Posted On Real Climate

The text of this post is

Real Climate has a post titled  Updates to model-data comparisons which includes a plot of the variations in upper ocean content anomalies from the period 1955 through 2009 .  

I asked Josh Willis the following with respect to the plot in the Real Climate post

My question:

Real Climate has posted a plot of ocean heat content, which we have
 discussed before, that shows a sudden jump in the 2002-2003 time frame;

 This jump is not seen it other metrics, including the surface temperatures
 (which they show) or the lower tropospheric temperatures (e.g. see

 see Figure 7 TLT

 Can you comment on the realism of this jump? Would you be willing to let me
 post your reply, if you do comment?

 Most of their trend agreement with the models is due to this single jump.

Josh Willis’s reply [reproduced with his permission]

There is still a good deal of uncertainty in observational estimates of ocean heat content during the 1990s and into the early part of the 2000s. This is because of known biases in the XBT data set, which are the dominant source of ocean temperature data up until 2003 or 2004. Numerous authors have attempted to correct these biases, but substantial difference remain in the “corrected” data.  As a result, the period from 1993 to 2003 still has uncertainties that are probably larger than the natural or anthropogenic signals in ocean heat content that happen over a period of 1 to 3 years.  However, the decadal trend of 10 to 15 years seems to be large enough to see despite the uncertainties. Because Argo begins to become the dominant source of temperature data in about 2004, the period from 2000 to 2005 is especially worriesome because of the transition from an XBT-dominated estimate of ocean heat content.

You might also comment that there is another easily available estimate besides that of Levitus et al. (the one shown in this blog entry).  The other long-term estimate is from Domingues et al. and can be downloaded from CSIRO:

 What Gavin is also ignoring in his post is that  the rate of  heating has flattened since 2004 even in the Lyman et al 2010 paper. The NODC data even shows cooling.  This is the “missing heat” that Keven Trenberth has discussed (see).

This failure for Gavin to comment on other perspectives is evident in one of the comments on his post. There is an informative comment on May 24 2010 by Alex Harvey which reads

Gavin #60,

I am still left with the impression that you are evading the question of the meaning and significance of the Pielke/Willis/Trenberth exchange.

We all know, of course, Trenberth’s now famous behind the scenes remark that it is a travesty that we can’t account for the lack of recent global warming, and his exclamation that the observing system must be inadequate (which I guess is reference to the satellite radiation budget measurements?). Trenberth later claimed that there is heat missing and that it must lie beneath >700m in the deep ocean and that it may come back “to haunt us”. But Willis then agreed with Pielke that it is probably impossible and that it’s unlikely we’ll find any missing heat below 700m. Pielke Jr spelt it out for us the next day that this means the “missing heat” is probably missing because it has been radiated out into space, or in layman’s terms, because it’s just not there.

Now a few weeks later we find ocean heat has been adjusted upwards by Lyman et al. and we find Josh Willis one of the coauthors. Yet Willis already agreed that he thought the existing measurements were pretty good. Pielke has used Willis’s data to show a decline in OHC since 2003 which doesn’t appear in this the new Lyman et al analysis. (In fact, it looks like Willis has frankly got his own name on two of the curves in your diagram, both the NODC data and the Lyman et al data. Is that right?)

So what is the conclusion for this? There is missing heat below 700M or there isn’t?

Best, Alex

[Response: There is clearly some heating going on below 700m. But this discussion of ‘missing’ heat is very confused. The satellite records are not good enough to say what the year-to-year imbalance is and so are not able to say whether any heat is missing or not. So what is the ‘missing’ idea based on? Model estimates – but as I showed above, the estimates of OHC change are in line with the models, and so I don’t see why anyone thinks that any heat is missing. If the satellite data were better, there might be something to this, but right now the issues are all in the noise, and thus pretty unresolvable. – gavin]

What Gavin does not comment on is that the upper ocean heat data is a more robust metric to diagnose the global average radiative imbalance than the estimates of the radiative fluxes from satellites. This was shown as early as in the paper

Ellis et al. 1978: The annual variation in the global heat balance of the Earth. J. Climate. 83, 1958-1962

 I discussed the consequences in terms of diagnosing the radiative forcing in

Pielke Sr., R.A., 2003: Heat storage within the Earth system. Bull. Amer. Meteor. Soc., 84, 331-335.

Gavin also ignores the excellent paper

Douglass, D.H. and R. Knox, 2009: Ocean heat content and Earth’s radiation imbalance. Physics letters A.

What Gavin Schmidt has done is to present an uncritical assessment of the Lyman et al 2010 paper without questioning the robustness of its findings. I am pleased that at least one commenter on Real Climate recognized  (and was permitted to post) this lack of scientific balance in Gavin’s post.

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Excellent Post On The Economist On Water As “The World’s Most Valuable Stuff”

In the May 22 2010 issue of the Economist, there is an excellent article titled

The world’s most valuable stuff 

with the subheading

“Mostly because of farming, water is increasingly scarce. Managing it better could help”

This article effectively presents the vulnerability view that is consistent with what we urged in our paper

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

where we wrote

“The impact on water quality and water quantity, for example, is a critically important societal concern. The water cycle is among the most significant components of the climate system and involves, for example, cloud radiation, ice albedo, and land use feedbacks [NRC, 2003]. Regional and local variations in water availability, water quality, and hydrologic extremes (floods and droughts) affect humans most directly.”

We recommend that the next assessment phase of the IPCC (and other such assessments) broaden its perspective to include all of the human climate forcings. It should also adopt a complementary and precautionary resource- based assessment of the vulnerability of critical resources (those affecting water, food, energy, and human and ecosystem health) to environmental variability and change of all types.


“We ….. propose that one should not rely solely on prediction as the primary policy approach to assess the potential impact of future regional and global climate variability and change. Instead, we suggest that integrated assessments within the framework of vulnerability, with an emphasis on risk assessment and disaster prevention, offer a complementary approach [Kabat et al., 2004].”

as well as in posts on my weblog; e.g. see where I wrote

“There are 5 broad areas that we can use to define the need for vulnerability assessments : water, food, energy, health and ecosystem function. Each area has societally critical resources. The vulnerability concept requires the determination of the major threats to these resources from climate, but also from other social and environmental issues. After these threats are identified for each resource, then the relative risk from natural- and human-caused climate change (estimated from the GCM projections, but also the historical, paleo-record and worst case sequences of events) can be compared with other risks in order to adopt the optimal mitigation/adaptation strategy.”

The Economist article includes the perceptive and very important text

“Nature has decreed that the supply of water is fixed. Meanwhile demand rises inexorably as the world’s population increases and enriches itself. Homes, factories and offices are sucking up ever more. But it is the planet’s growing need for food (and the water involved in producing crops and meat) that matters most. Farming accounts for 70% of withdrawals.”

“Although the supply of water cannot be increased, mankind can use what there is better—in four ways. One is through the improvement of storage and delivery, by creating underground reservoirs, replacing leaking pipes, lining earth-bottomed canals, irrigating plants at their roots with just the right amount of water, and so on. A second route focuses on making farming less thirsty—for instance by growing newly bred, perhaps genetically modified, crops that are drought-resistant or higher-yielding. A third way is to invest in technologies to take the salt out of sea water and thus increase supply of the fresh stuff. The fourth is of a different kind: unleash the market on water-users and let the price mechanism bring supply and demand into balance. And once water is properly priced, trade will encourage well-watered countries to make water-intensive goods, and arid ones to make those that are water-light.”

“Even if the world manages to limit depletion, many water-related problems will persist. About 1 billion people are still without access to a decent water supply, while others suffer from flooding, pollution and poor sanitation. Yet if man wants to solve these problems, he can. He has applied far more money and know-how to issues far less important than the shortage of water. And if he does tackle them successfully, the big causes of human suffering—disease and poverty—will be automatically alleviated. Investing more thought and cash in the better use of the world’s most valuable commodity is surely worthwhile.”

The entire article is worth reading!

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Excellent Posts On The Weblog Of Bob Tisdale On Near Real-Time Ocean Surface Temperature Anomalies

In my post

Lack Of A Trend In The Ocean Surface Temperature Since 2000 – Its Significance

I wrote

“What is missing from the otherwise excellent website (refering to website, of course, are time plots of the global average sea surface temperatures, as well as averages for different subregions of the oceans.  With that information, we could more readily track the ocean contribution to the global average surface temperature trend, as well as anomalies within the subregions.”

Bob Tisdale on his weblog has alerted us to his excellent weblog presentation with monthly updates of SST anomalies globally, and for hemispheric and ocean basin basins. His information is accessible at

The global average anomaly is currently well above average, but unless this positive anomaly continues for the coming months, the absence of a clear long term trend since 1998 remains (although the interannual variations are remarkably large).

As Bob writes

“NINO3.4 SST anomalies are dropping but El Niño conditions remained during April in the central tropical Pacific (Monthly NINO3.4 SST Anomaly = +0.68 deg C). Weekly data has fallen into ENSO-neutral ranges (+0.30 deg C). Global SST anomalies increased slightly again during April (0.017 deg C). On a hemispheric basis, the rise was limited basically to the Northern Hemisphere, since the increase in the Southern Hemisphere was negligible (0.002 deg C). And looking at the major ocean basins, the North Pacific, South Atlantic, Indian Ocean, and the East Indian-West Pacific Ocean datasets all show drops this month, but they were not strong enough to outweigh the rises in the North Atlantic and South Pacific.”

Bob also provides mid-month updates of NINO3.4 and global data using the weekly OI.v2 SST anomaly data, aka Reynolds SST data at He writes

“NINO3.4 SST anomalies for the week centered on May 19, 2010 show that central equatorial Pacific SST anomalies are below zero and continuing their decline. Presently they’re at -0.21 deg C, which is in ENSO-neutral levels.”


 “Weekly Global SST anomalies are still elevated, but they may have peaked for this El Nino. They are starting to show signs of a drop in response to the decline in central equatorial Pacific temperatures, but the global weekly data is much too variable to tell for sure.”

I recommend bookmarking this excellent, much needed weblog!

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Lack Of A Trend In The Ocean Surface Temperature Since 2000 – Its Significance

In the Lyman et al 2010 paper [that I have discussed in two posts; see and see], there is the interesting statement that

“…sea surface temperatures have been roughly constant since 2000…”

This finding is based on the section of the paper State of the Climate in 2008 by Peterson and Baringer (2009) titled

Knight, J. et al. Global oceans: do global temperature trends over the last decade falsify climate predictions? Bull. Am. Meteorol. Soc. 90, S56–S57 (2009).

Figure 3.4 top  in this article is presumably the data  that Lyman et al 2010 are referring to. The tropical ocean average anomalies in Figure 3.4 5th figure also shows an absence of further warming since 1998 although, as with the global average, it remains above the long term average (1950 to 2008).

There are important consequences of this lack of a continued global average ocean surface temperature increase:

  • since an increase of atmospheric water vapor is required to amplify the radiative heating from added CO2 and other human inputs of greenhouse gases, the absence of continued ocean surface warming suggests this water vapor feedback to radiative forcing is more muted than predicted by the IPCC multi-decadal model predictions. This more muted response in the real world  is consistent with what has been reported in the study De-Zheng Sun, Yongqiang Yu, and Tao Zhang, 2009: Tropical Water Vapor and Cloud Feedbacks in Climate Models: A Further Assessment Using Coupled Simulations Journal of Climate, Volume 22, Issue 5 (March 2009) pp. 1287–1304.
  • The claims that warming is continuing  (e.g. see) is, therefore, based on the land portion of the surface temperature record  [warm equatorial ocean temperature anomalies in recent years, particularly in the Atlantic, are offset elsewhere in the ocean].  With respect to the land surface temperature trends, we have documented a warm bias as we report in our paper Klotzbach, P.J., R.A. Pielke Sr., R.A. Pielke Jr., J.R. Christy, and R.T. McNider, 2009: An alternative explanation for differential temperature trends at the surface and in the lower troposphere. J. Geophys. Res., 114, D21102, doi:10.1029/2009JD011841.

Of course, as I and others, including Kevin Trenberth, have repeatedly urged (e.g. see and see) we need to move to the use of the ocean heat content change as the metric to assess global warming and cooling. Ocean heat content changes provide a much more robust metric than surface temperature trends as the metric to assess global warming and cooling (e.g. see and see).

A further assessment of the ocean surface temperature trends is available from the excellent website

I have presented two analyses of ocean surface temperature anomalies below; one for mid May 2010 (top) and one for mid May 1997 (bottom). The format has changed and the center point of geography is different (which makes it harder to compare the two figures], but what stands out is not a clear difference in the ocean average, but the remarkably large spatial variations in the anomalies. It is these anomalies that have a much greater effect on the climate that society and the environment experience (e.g. drought, floods, hurricanes, etc) than a global average trend (which has not even been evident for several years).

What is missing from the otherwise excellent website, of course, are time plots of the global average sea surface temperatures, as well as averages for different subregions of the oceans.  With that information, we could more readily track the ocean contribution to the global average surface temperature trend, as well as anomalies within the subregions.

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My Perspective On The Nature Commentary By Kevin Trenberth

As readers of my weblog know, there are a set of posts giving e-mails among Kevin Trenberth, Josh Willis and I, and blog posts by Roy Spencer, on the issue of “missing heat” in the climate system. These posts can be viewed at

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

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

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

Article On The “Missing Heat” In The April 16 Issue of

Further Comment By Kevin Trenberth

Roy Spencer’s Response To Kevin Trenberth, April 26, 2009

April 26 2010 Reply By Kevin Trenberth

Earths Missing Energy: Trenberth’s Plot Proves My Point

There is now a new contribution by Kevin on Nature (it is actually not new in one sense, since Kevin (and J. Fasullo) recently posted a commentary on the same subject at Science magazine. Nature soliciting the same person (no matter how qualified) to write a comment is not expanding our perspective on this issue (Roy Spencer, for example, would have been a good choice as he has a different viewpoint than Kevin expressed in his Science comment).

The Nature comment is

Kevin E. Trenberth, 2010: The ocean is warming, isn’t it? Nature 465, 304-304 (19 May 2010) doi:10.1038/465304a News and Views

The abstract reads

“A reappraisal of the messy data on upper-ocean heat content for 1993–2008 provides clear evidence for warming. But differences among various analyses and inconsistencies with other indicators merit attention.”

The Trenberth commentary is in response to the paper (which I posted on this past Friday; see)

John M. Lyman, Simon A. Good, Viktor V. Gouretski, Masayoshi Ishii, Gregory C. Johnson, Matthew D. Palmer, Doug M. Smith, Josh K. Willis, 2010: Robust warming of the global upper ocean. Nature 465, 334-337 (20 May 2010) doi:10.1038/nature09043 Letter

The abstract of the Lyman et al paper reads

A large (~1023 J) multi-decadal globally averaged warming signal in the upper 300 m of the world’s oceans was reported roughly a decade ago and is attributed to warming associated with anthropogenic greenhouse gases. The majority of the Earth’s total energy uptake during recent decades has occurred in the upper ocean, but the underlying uncertainties in ocean warming are unclear, limiting our ability to assess closure of sea-level budgets, the global radiation imbalance and climate models. For example, several teams have recently produced different multi-year estimates of the annually averaged global integral of upper-ocean heat content anomalies (hereafter OHCA curves) or, equivalently, the thermosteric sea-level rise. Patterns of interannual variability, in particular, differ among methods. Here we examine several sources of uncertainty that contribute to differences among OHCA curves from 1993 to 2008, focusing on the difficulties of correcting biases in expendable bathythermograph (XBT) data. XBT data constitute the majority of the in situ measurements of upper-ocean heat content from 1967 to 2002, and we find that the uncertainty due to choice of XBT bias correction dominates among-method variability in OHCA curves during our 1993–2008 study period. Accounting for multiple sources of uncertainty, a composite of several OHCA curves using different XBT bias corrections still yields a statistically significant linear warming trend for 1993–2008 of 0.64 W m-2 (calculated for the Earth’s entire surface area), with a 90-per-cent confidence interval of 0.53–0.75 W m-2.

Unfortunately, Kevin (nor the Lyman et al paper which includes Josh Willis as one of the co-authors)  includes any of the discussion in the e-mails that I posted where there is no evidence of significant heat being accumulated in recent years at depths lower than 700m. However, Kevin does acknowledge a “slowdown since 2003” of heating.

Kevin’s statement

“Moreover, methods of analysis and interpolation of gaps in space and time should take account of the warming climate, and care is needed not to bias results towards background values”

however, is puzzling as it implies that heat has to be added to the analysis even if it is not directly measured! The background (i.e. measured values) are what should be used.

While it is unfortunate that he did not use the Nature commentary to include the perspective that Josh Willis provided to him in the e-mail exchanges and Roy Spencer provided in his blog posts, Kevin does agree with us that

“More robust indicators of a warming planet come from evidence of increasing ocean heat content and associated sea-level rise.”


“As the relevant analytical methods mature, ocean heat content is likely to become a key indicator of climate change.”

Both of these conclusions are what I proposed in my paper

Pielke Sr., R.A., 2003: Heat storage within the Earth system. Bull. Amer. Meteor. Soc., 84, 331-335

where the abstract reads

“The assessment of heat storage and its changes over time should be a focus of international climate monitoring programs.”

with the conclusion reading

In conclusion, there are several major reasons that the assessment of the earth system’s heat budget is so valuable.

• The earth’s heat budget observations, within the limits of their representativeness and accuracy, provide an observational constraint on the radiative forcing imposed in retrospective climate modeling.

• A snapshot at any time documents the accumulated heat content and its change since the last assessment. Unlike temperature, at some specific level of the ocean, land, or the atmosphere, in which there is a time lag in its response to radiative forcing, there are no time lags associated with heat changes.

• Since the surface temperature is a two-dimensional global field, while heat content involves volume integrals, as shown by Eq. (1), the utilization of surface temperature as a monitor of the earth system climate change is not particularly useful in evaluating the heat storage changes to the earth system. The heat storage changes, rather than surface temperatures, should be used to determine what fraction of the radiative fluxes at the top of the atmosphere are in radiative equilibrium. Of course, since surface temperature has such an important impact on human activities, its accurate monitoring should remain a focus of climate research (Pielke et al. 2002a).”

There is also an interesting statement in the Lyman et al 2010 paper

“…sea surface temperatures have been roughly constant since 2000…”

which I will discuss further in an upcoming post since this means any global average surface temperature increase since 2000 must have occurred on land (yet, as we have seen (e.g. see), there is a warm bias in the land surface temperature trend assessments presented by NCDC, GISS and CRU).

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A New Paper “Global Warming Advocacy Science: A Cross Examination” By Jason Scott Johnston

A very important, much needed new research paper has appeared. It is

Global Warming Advocacy Science: A Cross Examination by Jason Scott Johnston who is the Robert G. Fuller, Jr. Professor of Law and Director, Program on Law, Environment and Economy of the University of Pennsylvania – Law School.

His short biographical vita reads

“Jason Scott Johnston has published dozens of articles in American law journals, such as the Yale Law Journal,and in peer-reviewed economics journals, such as the Journal of Law, Economics and Organization. He is currently working on books about the law and economics, corporate environmentalism, global warming policy, and the comparative law and economics of environmental federalism. He has served on the Board of Directors of the American Law and Economics Association and on the National Science Foundation’s Law and Social Science grant review panel. He won Penn Law’s Robert A. Gorman Award for Teaching Excellence in 2003.”

The abstract reads

Legal scholarship has come to accept as true the various pronouncements of the Intergovernmental Panel on Climate Change (IPCC) and other scientists who have been active in the movement for greenhouse gas (ghg) emission reductions to combat global warming. The only criticism that legal scholars have had of the story told by this group of activist scientists – what may be called the climate establishment – is that it is too conservative in not paying enough attention to possible catastrophic harm from potentially very high temperature increases.

This paper departs from such faith in the climate establishment by comparing the picture of climate science presented by the Intergovernmental Panel on Climate Change (IPCC) and other global warming scientist advocates with the peer-edited scientific literature on climate change. A review of the peer-edited literature reveals a systematic tendency of the climate establishment to engage in a variety of stylized rhetorical techniques that seem to oversell what is actually known about climate change while concealing fundamental uncertainties and open questions regarding many of the key processes involved in climate change. Fundamental open questions include not only the size but the direction of feedback effects that are responsible for the bulk of the temperature increase predicted to result from atmospheric greenhouse gas increases: while climate models all presume that such feedback effects are on balance strongly positive, more and more peer-edited scientific papers seem to suggest that feedback effects may be small or even negative. The cross-examination conducted in this paper reveals many additional areas where the peer-edited literature seems to conflict with the picture painted by establishment climate science, ranging from the magnitude of 20th century surface temperature increases and their relation to past temperatures; the possibility that inherent variability in the earth’s non-linear climate system, and not increases in CO2, may explain observed late 20th century warming; the ability of climate models to actually explain past temperatures; and, finally, substantial doubt about the methodological validity of models used to make highly publicized predictions of global warming impacts such as species loss.

Insofar as establishment climate science has glossed over and minimized such fundamental questions and uncertainties in climate science, it has created widespread misimpressions that have serious consequences for optimal policy design. Such misimpressions uniformly tend to support the case for rapid and costly decarbonization of the American economy, yet they characterize the work of even the most rigorous legal scholars. A more balanced and nuanced view of the existing state of climate science supports much more gradual and easily reversible policies regarding greenhouse gas emission reduction, and also urges a redirection in public funding of climate science away from the continued subsidization of refinements of computer models and toward increased spending on the development of standardized observational datasets against which existing climate models can be tested.

Keywords: Climate change, greenhouse effect, ghg emission reductions, catastrophic risk, comparative scientific analysis, open scientific questions, size and direction of feedback effects, inherent non-linear temperature changes, methodological validity of climate models, gradual and reversible policy choices.

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