Monthly Archives: February 2010

Fox Business Interview “Obama Backing the Wrong Climate Scientists?”

I was interviewed by Stuart Varney on Fox Business Network this morning. The interview is at Obama Backing the Wrong Climate Scientists?.

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Our Paper “Impacts Of Land Use Land Cover Change On Climate And Future Research Priorities” By Mahmood Et Al. 2010 Has Appeared

Our paper

Mahmood, R., R.A. Pielke Sr., K.G. Hubbard, D. Niyogi, G. Bonan, P. Lawrence, B. Baker, R. McNider, C. McAlpine, A. Etter, S. Gameda, B. Qian, A. Carleton, A. Beltran-Przekurat, T. Chase, A.I. Quintanar, J.O. Adegoke, S. Vezhapparambu, G. Conner, S. Asefi, E. Sertel, D.R. Legates, Y. Wu, R. Hale, O.W. Frauenfeld, A. Watts, M. Shepherd, C. Mitra, V.G. Anantharaj, S. Fall,R. Lund, A. Nordfelt, P. Blanken, J. Du, H.-I. Chang, R. Leeper, U.S. Nair, S. Dobler, R. Deo, and J. Syktus, 2010: Impacts of land use land cover change on climate and future research priorities. Bull. Amer. Meteor. Soc., 91, 37–46, DOI: 10.1175/2009BAMS2769.1

has appeared in print (see our earlier announcement about it) which I repeat with some added text from the article here

The paper starts with the text

“Human activities have modified the environment for thousands of years. Significant population increase, migration, and accelerated socio-economic activities have intensified these environmental changes over the last several centuries. The climate impacts of these changes have been found in local, regional, and global trends in modern atmospheric temperature records and other relevant climatic indicators.”

In our conclusions, we write

“As documented in this essay, we conclude that the finding of the National Research Council report (NRC 2005) that LULCC represents a first-order human climate forcing is a robust statement. LULCC effects must be assessed in detail as part of all future climate change assessments, including the forthcoming IPCC Fifth Assessment, in order for them to be scientifically complete. This includes not only climate effects in the regions where LULCC occurs, but also their role in altering hemispheric and global atmospheric and ocean circulations at large distances from the location of LULCC. We also conclude that a regional focus is much more appropriate in order to better understand the human effects on climate, including LULCC. It is the regional responses, not a global average, that produce drought, floods, and other societally important climate impacts.”

as well as make the following recommendations

“…..we recommend, as a start, to assess three new climate metrics:

1. The magnitude of the spatial redistribution of land surface latent and sensible heating (e.g., see Chase et al. 2000; Pielke et al. 2002). The change in these fluxes into the atmosphere will result in the alteration of a wide variety of climate variables including the locations of major weather features. For example, Takata et al. (2009) demonstrated the major effect of land use change during the period 1700-1850 on the Asian monsoon. As land cover change accelerated after 1850 and continues into the future, LULCC promises to continue to alter the surface pattern of sensible and latent heat input to the atmosphere.

2. The magnitude of the spatial redistribution of precipitation and moisture convergence (e.g., Pielke and Chase 2003). In response to LULCC, the boundaries of regions of wet and dry climates can change, thereby affecting the likelihood for floods and drought. This redistribution can occur not only from the alterations in the patterns of surface sensible and latent heat, but also due to changes in surface albedo and aerodynamic roughness (e.g., see Pitman et al. 2004; Nair et al. 2007).

3. The normalized gradient of regional radiative heating changes. Since it is the horizontal gradient of layer-averaged temperatures that force wind circulations, the alteration in these temperatures from any human climate forcing will necessarily alter these circulations. In the evaluation of the human climate effect from aerosols, for example, Matsui and Pielke (2006) found that, in terms of the gradient of atmospheric radiative heating, the role of human inputs was 60 times greater than the role of the human increase in the well-mixed greenhouse gases. Thus, this aerosol effect has a much more significant role on the climate than is inferred when using global average metrics. We anticipate a similar large effect from LULCC. Feddema et al. (2005), for example, have shown that global averages mask the impacts on regional temperature and precipitation changes. The above climate metrics can be monitored using observed data within model calculations such as completed by Matsui and Pielke (2006) for aerosols, as well as by using reanalyses products, such as performed by Chase et al (2000) with respect to the spatial pattern of lower tropospheric heating and cooling. They should also be calculated as part of future IPCC and other climate assessment multi-decadal climate model simulations.”

We also write

“With respect to surface air temperatures, for example, there needs to be an improved quantification of the biases and uncertainties in multi-decadal temperature trends, which remain inadequately evaluated in assessment reports such as from the Climate Change Science Program (CCSP 2006). We also recommend that independent committees (perhaps sponsored by the National Science Foundation) conduct these assessments.”

An important message from our paper is the number of  outstanding climate scientists who co-authored our recommendations.

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Air Pollution – A National Concern

I was reminded of a short essa  that I wrote in 1979 [thanks to Emmanuel Ekanem, a research student in the  United Kingdom for reminding me of it]. The article is

 Pielke, R.A. 1979: Air Pollution – A National Concern. Bull. Meteor. Soc., 78, 1461.

This article urged a broadening of the assessment of risks in weather to include air pollution as a threat.  In terms of threats from air pollution (without considering any climate effects), it causes more loss of life in the United States, than the other weather hazards.

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A Comment On Judy Curry’s Post On Her Weblog Titled “On the Credibility of Climate Research, Part II: Towards Rebuilding Trust”

Judith Curry of the Georgia Institute of Technology has published an insightful discussion on the climate science debate. It is titled “On the Credibility of Climate Research, Part II: Towards Rebuilding Trust” and is worth reading.

I only have one comment on her excellent post and this is respect to treating the climate issue as having just two “camps”. She writes (bold face added).

“And finally, the blogosphere can be a very powerful tool for increasing the credibility of climate research. “Dueling blogs” (e.g. versus and versus can actually enhance public trust in the science as they see both sides of the arguments being discussed.”

As we summarize in our 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

there are actually three perspectives in the climate science debate. The view that is most robust scientifically, yet has been generally ignored by policymakers and others, is that

“Although the natural causes of climate variations and changes are undoubtedly important, the human influencesare 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 infl uences on regional and global climate will continue to be of concern during the coming decades.”

We need more discussion on the blogs of this viewpoint, as it is well supported by the peer reviewed scientific literature (e.g. see).

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An Excellent News Article [But With One Very Important Error] In The Baltimore Sun By Timothy B. Wheeler Titled “A New Smokestack Cleans Baltimore’s Air”

There was an excellent news article on February 20 2010 in the Baltimore Sun titled “A new smokestack cleans Baltimore’s air” by Timothy B. Wheeler.  However, there is one very important error that the reporter makes. The article reads in part

“A new smokestack is not usually cause for celebration among environmentalists. But the 400-foot stack spouting white clouds at Brandon Shores power plant represents a quantum leap in cleaning Baltimore’s air, not another source of pollution.”

I have advocated throughout my career, including my tenure on the Colorado Air Quality Control Commission, on the need to improve air quality. This is a critical threat to human health, which is one of the five resource areas that we urge action on 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.

and in our focus on vulnerability as a policy framework (e.g. see also).

The single error, in the otherwise excellent article, is in the following paragraph [where I have bold-faced the error];

“Constellation Energy has just completed work on $875 million worth of pollution “scrubbers” at its 26-year-old coal-fired power plant on the Patapsco River. One of the plant’s two steam-generating units resumed operation with the new air-quality controls in December, and the second is cranking up now. The white clouds rising from the stack are almost entirely water vapor. A pair of 700-foot stacks nearby, which until recently belched toxic, acidic smoke from the power plant, are quiet.”

There is an other gas in this relatively clean effluent and it is carbon dioxide! I am unclear why this is not recognized in the article, but it is an important oversight.

The excerpts from the article given below present what are the positive benefits of the new scrubbers.

“But that’s likely to change with the installation of the twin scrubbers at Brandon Shores and pollution controls put in at Constellation’s other coal-burning plants in the area. The Baltimore-based power company has invested more than $1.5 billion to comply with Maryland’s Healthy Air Act, which when it was passed in 2006 was billed by state officials as the toughest power-plant pollution law on the East Coast.”

“Under the law, the state’s power plants were required to reduce harmful emissions by 70 percent to 80 percent by this year, and by 75 percent to 90 percent by 2013. Targeted are releases of nitrogen oxides, sulfur dioxide and mercury – byproducts of burning coal that contribute to environmental and health problems in the state.”

“Nitrogen oxides contribute to ground-level ozone pollution or smog that can make hot summer air difficult or painful to breathe. They harm water quality in the Chesapeake Bay as they drop from the air. Sulfur dioxide is a major source of fine-particle pollution that can cause breathing difficulties or premature death.”

“Mercury is a toxic metal that, in small doses, can damage the brain, nervous system and other organs. It accumulates in fish tissue, prompting state health officials to warn against eating too many fish caught locally.”

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Seminar Announcement “From Hurricanes to Arctic Warming: Carbon Dioxide Or Multi-Decadal Climate Variability?” By Petr Chylek

From Hurricanes to Arctic Warming: Carbon Dioxide or Multi-Decadal Climate Variability?

 Thursday, March 4, 03:30 PM
David Skaggs Research Center, Room GC402 Boulder Colorado

Increasing strength of Atlantic hurricanes, disappearance of Arctic sea ice, melting of the Greenland ice sheet, six meters flooding in coastal cities; are these impending climate catastrophes supported by observations, or are they just results of imperfect climate modeling and the imagination of overeager climate politicians? I will present recent analysis of North Atlantic hurricane activities to show that there is no justification for claims that hurricane intensity or numbers have increased drastically with increasing atmospheric concentration of CO2.  Similarly, Greenland temperatures in the 1930s and 1940s were as high as they are today. Finally, I will argue that the current warming of the Arctic region is affected by multi-decadal climate variability more than by an increasing concentration of carbon dioxide. Thus we may spend hundreds of billions of dollars on curbing CO2 emissions without having a noticeable effect on the ongoing climate change in the Arctic.
Dr. Petr Chylek, currently a Remote Sensing Team Leader in the Space and Remote Sensing Group at Los Alamos National Laboratory and an Adjunct Professor at the NMSU Physics Department, held faculty positions at several US universities including SUNY Albany, Purdue University, and the University of Oklahoma. Before joining LANL in 2001 he was a Professor of Physics and the holder of a Senior Chair in Climate Research at Dalhousie University in
Halifax, Nova Scotia, Canada. He also spent several years as a visiting scientist at MIT, Harvard University, and NMSU. He is an author of over 100 peer-reviewed publications in the fields of light scattering, radiative transfer, remote sensing, and climate research. He is a LANL Fellow, as well as a Fellow of the American Optical Society and a Fellow of the American Geophysical Union.

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EPA Endangerment Finding: Comments On Non-Greenhouse Gas Forcings As Part Of The Climate System

There is a set of replies to comments in Volume 3 in the Endangerment and Cause or Contribute Findings for Greenhouse Gases under the Clean Air Act  which I am providing input on in this post. These are in Volume 3 on page 32 [see also for my comments on another one of the EPA Responses]
See volume 3, response to comments pdf (at bottom of page) and look around page 32.

The Comments are

Comment (3-30):

A commenter (3476.6) notes that there are a number of “first-order” anthropogenic radiative forcings that are not GHGs, namely aerosols (direct, indirect, and snow-albedo effects), nitrogen deposition, land use change, albedo effects, and water evaporation from land use and irrigation. Additionally, CO2 has an effect on plant growth changing water transpiration. The commenter claims that regional climate change will be dominated by regional forcings, not by global GHG forcings. Another commenter (3283.1) also objects that warming is the result of non-GHG anthropogenic factors as well as GHG factors but that the EPA’s endangerment finding seems to place all of the focus on anthropogenic GHG emissions. Several other commenters (3295.1, 3722, 4395) argue that variations in the amount of water vapor in the atmosphere are a principal driver of climate change.

Response (3-30):

The assessment literature discusses all of these additional forcings, and they are summarized in the TSD.
As stated in Forster et al. (2007):

“While most current GCMs [general circulation models] incorporate the trace gas RFs, aerosol direct effects, solar and volcanoes, a few have in addition incorporated land use change and cloud albedo effect. While LLGHGs [long-lived greenhouse gases] have increased rapidly over the past 20 years and contribute the most to the present RF (refer also to Figure 2.20 and FAQ 2.1, Figure 1), Figure 2.23 also indicates that the combined positive RF of the GHGs exceeds the contributions due to all other anthropogenic agentsthroughout the latter half of the 20th century.”

Both the IPCC and CCSP agree that these effects can be locally important. CCSP (2008e) examines the effects of climate change on agriculture, land resources, water resources, and biodiversity in the United States and concludes that global climate change effects will be superimposed on and modify those resulting from land use and land cover patterns in ways that are as of yet uncertain. Karl et al. (2009) find that the anthropogenic land use activities such as cutting and burning forests, replacement of natural vegetation with agriculture and cities, and large-scale irrigation can cause local (and even regional) warming or cooling, but that globally the net effect of these changes has probably been a slight cooling over the last 100 years. Karl et al. also discuss the possibility that the Dust Bowl of the 1930s was the result of an interaction between poor agricultural practices removing native vegetation that had maintained soil moisture, and variations in ocean temperatures that disrupted wind patterns and therefore rainfall. While these local and regional variations can lead to differing trends in the short term, in the long term the continued accumulation of GHGs will lead to a global forcing that will exceed the short-term, local variability.

The TSD has been updated to address water evaporation from land use. We have added the following statement to Section 4a: “Irrigation and deforestation both have small, poorly understood effects on humidity, in opposite directions, and the IPCC concluded that radiative forcing from these sources of tropospheric water vapor was smaller than their non-radiative effects (such as evaporative cooling).” On the other hand, water vapor changes resulting from changes in the global climate are significant, and are included in the models as a feedback (but not a forcing). For further detail on water vapor, see the responses on the percent contribution in the atmosphere in Volume 2, and on the contribution of emissions from irrigation and combustion in Volume 9, of this Response to Comments document.

The EPA reply ignores recent research that refutes their conclusion that

“While these local and regional variations can lead to differing trends in the short term, in the longterm the continued accumulation of GHGs will lead to a global forcing that will exceed the short-term, local variability.”

Our EOS 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

In this paper we presented the three hypotheses

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 signifi cant and involve a diverse range of fi rst- order climate forcings, including, but not limited to, the human input of carbon dioxide (CO2). Most, if not all, of these human infl uences 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 signifi cant 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.

We concluded that

“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.

Therefore, the cost- benefit analyses regarding the mitigation of CO2 and other greenhouse gases need to be considered along with the other human climate forcings in a broader environmental context, as well as with respect to their role in the climate system. Because hypothesis 2a is the one best supported by the evidence, policies focused on controlling the emissions of greenhouse gases must necessarily be supported by complementary policies focused on other first- order climate forcings.”

The peer reviewed papers that are referenced in our EOS article, and which were ignored in the EPA Reposnse are

Flanner, M. G., C. S. Zender, J. T. Randerson, and P. J. Rasch (2007), Present- day climate forcing and
re sponse from black carbon in snow, J. Geophys. Res., 112, D11202, doi: 10.1029/ 2006JD008003.

Galloway, J. N., et al. (2004), Nitrogen cycles: Past, present, and future, Biogeochemistry, 70(2), 153–226, doi:10.1007/s10533- 004- 0370- 0.

Rosenfeld, D., U. Lohmann, G. B. Raga, C. D. O’Dowd, M. Kulmala, S. Fuzzi, A. Reissell, and M. O. Andreae (2008), Flood or drought: How do aerosols affect precipitation?, Science, 321(5894), 1309–1313, doi:10.1126/science.1160606.

Takata, K., K. Saito, and T. Yasunari (2009), Changes in the Asian monsoon climate during 1700–1850 induced by preindustrial cultivation, Proc. Natl. Acad. Sci. U. S. A.,106, 9570–9575, doi:10.1073/pnas.0807346106.

This are just a sample of the studies that refute the EPA Findings.

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News Article On Fox News With Respect To The Appointment Of Thomas Karl As The Head Of A New Climate Office

There is a news article today by Ed Barnes of Fox News titled “New Climate Agency Head Tried to Suppress Data, Critics Charge“. The article accurately summarizes issues associated with the appointment of  Thomas Karl as the head of a new Climate office. As reported in the article, he

 “has been criticized for trying to suppress contradictory scientific data on climate change.”

I documented the process by which Tom Karl excluded other viewpoints in my Public Comment

Pielke Sr., Roger A., 2005: Public Comment on CCSP Report “Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences“. 88 pp including appendices.

which I wrote after I resigned from the CCSP  Committee (not the IPCC Committee as given in the article).

Excerpts from the Executive Summary of my report read

“The process for completing the CCSP Report excluded valid scientific perspectives under the charge of the Committee. The Editor of the Report [Tom Karl] systematically excluded a range of views on the issue of understanding and reconciling lower atmospheric temperature trends. The Executive Summary of the CCSP Report ignores critical scientific issues and makes unbalanced conclusions concerning our current understanding of temperature trends”


“The process that produced the report was highly political, with the Editor taking the lead in suppressing my perspectives, most egregiously demonstrated by the last-minute substitution of a new Chapter 6 for the one I had carefully led preparation of and on which I was close to reaching a final consensus. Anyone interested in the production of comprehensive assessments of climate science should be troubled by the process which I document below in great detail that led to the replacement of the Chapter that I was serving as Convening Lead Author.

Karl’s narrow and incorrect view of the climate issues is illustrated yet again in the quote from the Fox News article where it is written

“Responding to the criticism, Karl told the Washington Post, “the literature doesn’t show [Pielke's] ideas about the importance of land use are correct.”

This statement, if he was quoted correctly, shows just one example of why he is ill-suited to serve as head of a new climate office. 

The literature is extensive on the major role of land surface change within the climate system as documented, for example, in the multi-authored assessment reports

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


Kabat, P., Claussen, M., Dirmeyer, P.A., J.H.C. Gash, L. Bravo de Guenni, M. Meybeck, R.A. Pielke Sr., C.J. Vorosmarty, R.W.A. Hutjes, and S. Lutkemeier, Editors, 2004: Vegetation, water, humans and the climate: A new perspective on an interactive system. Springer, Berlin, Global Change – The IGBP Series, 566 pp

and summarized most recently 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.

For Tom Karl to cavalierly dismiss the peer-reviewed evidence of the major role of land surface processes documents his inaccurate narrow view on the climate issue.

It is disappointing that he has chosen to use his position to promote this particular perspective, as well as deliberately worked to exclude other views. 

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Guest Post By Ben Herman “Conservation in Radiative Transfer Calculations”

Guest Post by Professor Ben Herman

 I was just reading over the question from  Dan Hughes on this  site dated Feb. 9, 2010. The question  asked whether instrumentation having sufficient spatial and temporal coverage and measurement accuracy will ever be available to validate the expected TOA  radiative energy balance.It was, as you stated on your blog,a very good question. A similar question could be raised with respect to theoretical calculations of the TOA outgoing irradiance.

 We are looking for effects to cause temperature trends on the order of 0.1 deg C per decade. I will limit the following discussion to the transfer of solar energy only. Years ago when we were developing our radiative transfer models, we required solar energy conservation from a model to within about 0.1%, with  no solar absorption by the atmosphere.

 To accomplish this degree of conservation required an angular grid of 108 angles, and an optical depth increment of 0.01 for the numerical integrations of the relevant equations. Since it was necessary to also include polarization to avoid errors of up 10%, this introduced a 4×4 matrix into the calculations, increasing the number of equations by a factor of 16.

 For a nominal optical depth of 0.1, this made 10 levels, so there was  a system of about 16,000 simultaneous,highly coupled equations to  solve.  We assessed the resulting degree of energy conservation by summing the outgoing irradiance at the top and bottom of the atmosphere with the incoming solar at the top. This was with  model that I would guess, and I stress the word guess, was much more accurate than what  they use in the climate models. Now, if we assume that there was an absorption of solar energy in addition to scattering, we could not assess the accuracy because the irradiances at the top and bottom no longer equal the incoming solar due to internal losses from absorption.

Now,this was with a flat atmosphere model. With a more realistic spherical atmosphere, for various reasons due to the complexity of the  model, it was very difficult to check for conservation of energy but undoubtedly, the conservation was not as good as with the simpler one dimensional flat atmosphere. We could check for programming errors in the spherical model by letting the radius of the sphere get very large (approximating a flat atmosphere) and comparing results to the flat atmosphere model. The agreement was very good but not exact (I can’t recall the deviations). The small differences between conservation and model results were due to numerical errors.The transfer equations must be solved numerically and this leads to the errors.

The above was for one wavelength. Now, to integrate over wavelength, other approximations are made which introduce additional errors. Other uncertainties due to the addition of aerosols with unknown composition, number density, shape effect, vertical profile, optical depth, complex index of refraction, etc have been well discussed and I will not go into that here. We have also assumed no clouds. The above applies just to the solution of the transfer equation, assuming all of the quantities  mentioned above are known. While all of these errors may be quite small (some are undoubtedly not small) are they small when trying to predict resulting temperature trends of 0.1 deg C/per decade as I stated above? I don’t know but they certainly cannot be dismissed without careful consideration. The equations are non-linear in optical depth so the trends themselves will also have errors if the irradiances are incorrect.

The above applies primarily to transfer in the solar spectrum. In the IR, where scattering (except by clouds and precipitation) can be ignored, the problem is less complex, but the integration over wavelength is still a major issue. Again, I will not go into that here, but I believe I have raised some questions which could be of importance in obtaining the accuracies required for climate change issues.

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An Important Study On The Role Of Station Siting On Surface Temperatures – “Effects Of Simulated Grazing On Soil Temperature, Moisture, And Respiration On A Shortgrass Steppe In Northeastern Colorado” By Jennifer Wolchansky

There is a very important research contribution that is relevant to the effect of the siting of surface temperature instrumentation with respect to the assessment of spatially representative long-term trends.  The implications of her study goes beyond that of cattle grazing, as this is the first study, to my knowledge, of the effect on surface temperatures of vegetation/soil patterns on the scale of a few meters. This, of course, assures that the overlying atmosphere is essentially identical such that any differences in the soil temperatures, and other climate metrics are due to the details of the immediate land surface characteristics.

The study is in an M.S. thesis (which is a peer reviewed contribution) under the direction of Peter D. Blanken of the University of Colorado in Boulder.

The thesis is

Wolchansky, Jennifer E. (M.A., Geography)
Effects of Simulated Grazing on Soil Temperature, Moisture, and Respiration on a Shortgrass Steppe in Northeastern Colorado. University of Colorado, 2005.

The abstract reads

“Cattle grazing, a common form of land use on grasslands, could alter the climate at the surface. This study focused on how physical landscape changes associated with grazing could have a significant impact on soil temperature and moisture, and subsequently on soil respiration on a shortgrass steppe in northeastern Colorado.

Using micrometeorological data, the objective of this research was to discern the connections between energy, water, carbon and land use, particularly grazing.

 To achieve this objective, the research was divided into two sections, each with its own objectives and results, yet both related to the overall objective. The first section examined the impacts of simulated grazing on soil temperature and moisture. Plots with varying fractions of bare ground were used to simulate grazing density. Results indicated that both soil temperature and soil moisture increased with an increase in the fraction of bare ground. In addition, this section investigated the effects of the arrangement of bare ground on soil temperature and moisture. Soil temperature was found to be similar under contiguous and mosaic patches of bare ground while soil moisture was found to differ.

The second section of the research expanded upon the results found in the first section. Having found the relationship between the fraction of bare ground, and soil temperature and moisture, simulated cattle grazing was indirectly linked to changes in soil respiration. Soil respiration increased with an increase in soil temperature, until a critical threshold temperature was reached. An increase in soil moisture resulted in a decrease in soil respiration.

Because grasslands cover nearly half of the earth’s terrestrial surface, it is important to understand how land management on these grasslands can affect the ecosystem. In addition, determining how grazing can influence the release of CO2 to the atmosphere is crucial at such a time when there is growing concern about global climate change.”

One of the predictions which she confirmed in her study was that

“Configuration of patchiness will impact spatial variation of soil temperature and moisture. An increase in soil temperature and a decrease in upper profile soil moisture is expected with distance from vegetation. Therefore, a plot of half bare ground and half vegetation will have a higher maximum temperature and lower minimum soil moisture than that of a randomly arranged plot.”

An excerpts in the conclusion, that is directly relevant to the issue of spatial representativeness of long-term temperature trends read

“The first phase of this research found that while Ts under bare ground was generally greater than that under vegetation, more importantly, Ts values increased as the fraction of bare ground increased under both bare and vegetated cover throughout the full period. Essentially, because there is a positive correlation between grazing density and the fraction of bare ground (Teague et al. 2004, Metzger et al. 2005), these results imply that an increase in grazing density will increase Ts. Additionally, greatest differences in Ts between bare ground and vegetated cover were found in the plot with roughly half vegetation, half bare ground. Although recommended grazing densities generally result in 15-20% bare ground (Justin Derner, personal communication), this result indicates that if an area were overgrazed enough to produce 50% bare ground, then implications would be great. Such a significant difference in Ts between the bare and vegetated cover could influence surface heat fluxes and, in turn, could affect atmospheric conditions.”

In terms of station siting, the spatial assessment completed by Jennifer Wolchansky and Peter Blanken can be interpreted as what occurs if a single location undergoes these local land surface changes over time. The effect on the surface temperature trends as more bare ground is gradually exposed for whatever reason would result in a warming trend that can be misinterpreted as a larger scale surface temperature trend. Similarly, a gradual reduction in bare soil coverage due to revegetation, would result in a cooling trend, which could similarly be misinterpreted as a larger scale cooling.

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