Comment On The Hacking Of The CRU Website

As I am sure, the readers of my weblog are aware of the hacking of the CRU website (e.g. see Real Climate, The Blackboard, Roger Pielke Jr.’s Blog, The Examiner and Watts Up With That to name just a few sites). Since I am mentioned a number of times in the released e-mails, I will comment as appropriate on my specific reactions to these-mails. Today, I will address one of the issues raised by Real Climate.

On Real Climate today (under the header CRU Hack), there is a comment by “KTB” and reply by Gavin Schmidt that reads

KTB says:

It would be nice to get comments from the authors for lines like this. This can of course be understood in many ways…
I hope that posting of this small snippet doesn’t violate copyright, and I left the name out:

“I can’t see either of these papers being in the next IPCC report. Xxx and I will keep
them out somehow – even if we have to redefine what the peer-review literature is”

[Response: Bad papers clutter up assessment reports and if they don't stand up as science, they shouldn't be included. No-one can 'redefine' what the peer-reviewed literature is. - gavin]

The reply by Gavin Schmidt illustrates the gatekeeper aspect of the IPCC report which I documented in detail in my appendix to

Pielke Sr., Roger A., 2008: A Broader View of the Role of Humans in the Climate System is Required In the Assessment of Costs and Benefits of Effective Climate Policy. Written Testimony for the Subcommittee on Energy and Air Quality of the Committee on Energy and Commerce Hearing “Climate Change: Costs of Inaction” – Honorable Rick Boucher, Chairman. June 26, 2008, Washington, DC., 52 pp

and in

Documentation Of IPCC WG1 Bias by Roger A. Pielke Sr. and Dallas Staley – Part I

Documentation Of IPCC WG1 Bias by Roger A. Pielke Sr. and Dallas Staley – Part II

The challenge to the IPCC community, now that their duplicity has been exposed, is to communicate to all of us why the peer-reviewed papers that we documented, and that were available in time for the IPCC review process, were considered “bad papers” and thus ignored in the IPCC report.  A balanced assessment would comment on these papers, and provide the reason they disagree with their results.

The reply by Gavin Schmidt documents the control of the IPCC process by a few individuals (see also Climate Assessment Oligarchy – The IPCC).

Misrepresentation Of Scientific Consensus By The Leadership Of Professional Organizations

There is an article in the November 3 2009 issue of EOS titled “Science Organizations Remind Senators of the Consensus on Climate Change” by K. Chell [subscription required]. The letter is signed by the leadership of American Association for the Advancement of Science, American Chemical Society, American Geophysical Union, American Institute of Biological Sciences, American Meteorological Society, American Society of Agronomy, American Society of Plant Biologists, American Statistical Association, Association of Ecosystem Research Centers, Botanical Society of America, Crop Science Society of America, Ecological Society of America, Natural Science Collections Alliance, Organization of Biological Field Stations, Society for Industrial and Applied Mathematics, Society of Systematic Biologists, Soil Science Society of America, and the University Corporation for Atmospheric Research.

The letter reads

October 21, 2009

Dear Senator:

As you consider climate change legislation, we, as leaders of scientific organizations, write to state the consensus scientific view.

Observations throughout the world make it clear that climate change is occurring, and rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver. These conclusions are based on multiple independent lines of evidence, and contrary assertions are inconsistent with an objective assessment of the vast body of peer-reviewed science. Moreover, there is strong evidence that ongoing climate change will have broad impacts on society, including the global economy and on the environment. For the United States, climate change impacts include sea level rise for coastal states, greater threats of extreme weather events, and increased risk of regional water scarcity, urban heat waves, western wildfires, and the disturbance of biological systems throughout the country. The severity of climate change impacts is expected to increase substantially in the coming decades.

 
If we are to avoid the most severe impacts of climate change, emissions of greenhouse gases must be dramatically reduced. In addition, adaptation will be necessary to address those impacts that are already unavoidable. Adaptation efforts include improved infrastructure design, more sustainable management of water and other natural resources, modified agricultural practices, and improved emergency responses to storms, floods, fires and heat waves.

We in the scientific community offer our assistance to inform your deliberations as you seek to address the impacts of climate change.

Footnote to paragraph 2

The conclusions in this paragraph reflect the scientific consensus represented by, for example, the Intergovernmental Panel on Climate Change and U.S. Global Change Research Program. Many scientific societies have endorsed these findings in their own statements, including the American Association for the Advancement of Science, American Chemical Society, American Geophysical Union, American Meteorological Society, and American Statistical Association. We in the scientific community offer our assistance to inform your deliberations as you seek to address the impacts of climate change.

This statement (which was not voted on by the membership in the professional organizations that I am a member) contains a fundamental factual error in the view of a significant number of climate scientists. Specifically, the statements that “rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver. These conclusions are based on multiple independent lines of evidence, and contrary assertions are inconsistent with an objective assessment of the vast body of peer-reviewed science.”

Such a conclusion needs to be viewed as a hypothesis. If so , examples that refute the hypothesis is all that is need to reject its validity. This has been done, as has been discussed recently in several weblog posts; e.g. see

Further Evidence On The Breadth Of The Role Of Humans With Respect To Climate Change

Further Comments On The Article “Clean the Air, Heat the Planet?” By Arneth Et Al 2009

The reason that these professional organizations claim there is a consensus is that the very limited individuals who make these policy statements do not permit their membership to vote, or to present alternative viewpoints.  The Senators to whom this letter were addressed should reach out for a broader range of inputs with respect to the role of humans in the climate system.

As we concluded in our EOS article

Pielke Sr., Roger, Keith Beven, Guy Brasseur, Jack Calvert, Moustafa Chahine, Russ Dickerson, Dara Entekhabi, Efi Foufoula-Georgiou, Hoshin Gupta, Vijay Gupta, Witold Krajewski, E. Philip Krider, William K. M. Lau, Jeff McDonnell,  William Rossow,  John 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];

“[a]lthough 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”

and

“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.”

The claim in the Letter to the Senators that “rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver. These conclusions are based on multiple independent lines of evidence, and contrary assertions are inconsistent with an objective assessment of the vast body of peer-reviewed science” is incorrect, as documented above.

Land Use As Climate Change Mitigation by Brian Stone

Land Use as Climate Change Mitigation by Brian Stone [Associate Professor Center for City and Regional Planning Program at the Georgia Institute of Technology].

 One of the earliest journalistic accounts of climate change in the American media appears in a 1950’s edition of Popular Mechanics. While only a single paragraph in length, the piece is remarkable in at least two respects. First, the description of the basic workings of the global greenhouse effect is entirely consistent with our understanding of this phenomenon today, anticipating by more than half a century what has become the most significant policy challenge of our time. Second, and perhaps more telling in this regard, is the placement of the article. Appearing on the final pages of the magazine and following a piece titled, “Dutch entertainer rides tiny bike,” the editor’s positioning of the piece reflects accurately the light in which global warming would be viewed throughout much of the intervening period: more as a meteorological curiosity than as a problem worthy of a serious policy response.

Today, one could argue that the phenomenon of the urban heat island effect is generally regarded in the climate change literature in a similar light: as a meteorological anomaly occurring over a relatively small percentage of the Earth’s land surface, with few implications for larger scale climate phenomena.  However, as I argue in a forthcoming article in ES&T (http://pubs.acs.org/doi/pdf/10.1021/es902150g), the urban heat island effect can be understood to be only the most acute manifestation of a more geographically expansive mechanism through which land use change is altering climate at the regional to sub-continental scales.  Consistent with an established and growing body of evidence linking land use to regional scale climate changes, an analysis of temperature trends in the most populous U.S. cities since the 1950s suggests land use to be playing a role in urban climate change comparable in magnitude to that of greenhouse gas emissions.    

In light of this body of work, focused on the climate forcing effects of land use change within both urban and rural contexts, there is a need for national and international climate change management frameworks to employ land use mitigation strategies.  Such strategies would complement well existing frameworks for emissions mitigation and, within the U.S. context at least, capitalize on as of yet unharnessed governing capacities at the local and state levels of government.  With the potential for the upcoming Copenhagen talks to produce new binding agreements now greatly diminished, treaty negotiators should focus on augmenting established mitigation strategies with new approaches that can provide signatory nations with greater flexibility in meeting binding targets and facilitate more robust participation amongst developing economies.  Land use mitigation can advance both objectives.

Climate Change Survey Of Weathercasters

There is an interesting and quite informative survey of weathercasters that is published in the October 2009 issue of the Bulletin of the American Meteorological Society. It is by Kris Wilson and is titled

Opportunities and Obstacles for Television Weathercasters to Report on Climate Change

There are some remarkable findings including

“Almost two-thirds of this sample disagreed that “global climate models are reliable in their projections for a warming of the planet”

“Two-thirds of this sample also disagreed with the statement that “global climate models are reliable in their projections for local weather patterns”

and

“……this sample of AMS weathercasters repeatedly expressed their desire to have access to “independent,” “unbiased,” and “reputable” sources of data and information that present “both sides” of the issue.”

The full article with its survey results is worth reading.

I have also been informed of this new survey which is being distributed by the American Meteorological Society.

UPDATE: I have been e-mailed and informed that the two surveys are actually different surveys. The first one is open to all broadcast meteorologists, while the second were selected on known climate change work]

TV Meteorologists and News Directors Survey

“In early January, George Mason University will invite you to participate in a survey of TV meteorologists and news directors.  The research — which is funded by the National Science Foundation, and is being conducted in cooperation with AMS, NWA, and the Radio and Television Digital News Association — focuses on climate change beliefs and how climate change is addressed by TV meteorologists in their work.  Survey respondents will be given a $30 Amazon.com Gift Card to thank them for their participation.  This is an important opportunity to better understand how members of our professional community are responding to the issue of climate change. We urge you to participate in the survey.”

The invitation itself (from Dr. Katherine Rowan who is a  professor in the Communication Department at George Mason University in Fairfax, Virginia)  reads slightly differently and I have reproduced part of it below

“I write to invite you to participate in a research study.  This research is being conducted to understand how TV meteorologists educate their audiences about climate change.  If you agree to participate, we will schedule an in-person or telephone interview with you.  The interview will take approximately 60 minutes to complete.  After the interview, we will ask you to help us access examples of educational materials (or broadcasts) that you have used to educate audiences about climate change.  If you participate, you will be compensated $200 for your time in the form of a gift certificate from Amazon.

Because we would like to collect and share examples (on a website we will create) of your efforts to educate audiences about climate change, we are requesting that you participate as an identified participant.  We will ask your permission before posting anything you have said, or any educational material materials you have given us, on our website.  If you agree to the posting, we will credit you as the source by listing your full name and your current place of employment.

If you prefer, you may participate in this study on a confidential basis.  If you select that option, the data you contribute to this study will be kept confidential.  Your name and your contact information will be recorded only on the Informed Consent Form.  Your name will not appear with your answers to our questions, we will not use your name in our research, and we will not post any materials you give us on our website.

We appreciate your considering this invitation to be interviewed for this research.  There are no penalties for not participating.  If you do choose to participate, information you provide will be valuable our understanding of how climate change science is being communicated….”

I have no idea how objective this survey will be, but suspect it has been commissioned, at least in part, because the American Meteorological Society did not like the answers it received in the BAMS survey.

Comments On Meehl Et Al 2009 On Trends In Record High And Low Temperatures

UPDATE November 18 2009: Bruce Hall has posted another valuable contribution on this subject at http://hallofrecord.blogspot.com/2009/11/non-linear-perspective-of-climate.html

The paper

Gerald A. Meehl, Claudia Tebaldi, Guy Walton, David Easterling, and Larry McDaniel, 2009: The relative increase of record high maximum temperatures compared to record low minimum temperatures in the U.S. Geophysical Research Letters. In press

has already been discussed in several excellent posts by others; e.g. see

http://hallofrecord.blogspot.com/2009/11/critique-of-october-2009-ncar-study.html

http://wattsupwiththat.com/2009/11/16/why-ncars-meehl-paper-on-highlow-temperature-records-is-bunk/

My post is to point out that the Meehl et al paper did not investigate and question the spatial representativeness of their results, as well as possible non-climatic effects on the data they have used.  We raised a number of issues of these bias and uncertainties in our paper

Pielke Sr., R.A., C. Davey, D. Niyogi, S. Fall, J. Steinweg-Woods, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, R. Mahmood, S. Foster, R.T. McNider, and P. Blanken, 2007: Unresolved issues with the assessment of multi-decadal global land surface temperature trends. J. Geophys. Res., 112, D24S08, doi:10.1029/2006JD008229

which need to be resolved before the Meehl et al study should be assumed to be a robust conclusion.  Why was our multi-authored peer-reviewed study not consulted in preparing their paper? Even if they reject our findings, they should not have ignored the issues we raised, but presented reasons for their rejection. Since I have considerable professional respect for the lead author, Jerry Meehl, I can only assume he (and the other co-authors) were not aware of our paper.

More recent papers raise the issue of attribution, even if these temperature records were spatially representative; e.g. see and see). Land use change clearly has a major effect on extreme temperatures, with urbanization, for example, limiting how cold it becomes at night.

In an earlier paper, we did look at the issue of temperature trends with respect to different temperature thresholds.

Pielke Sr., R.A., T. Stohlgren, L. Schell, W. Parton, N. Doesken, K. Redmond, J. Moeny, T. McKee, and T.G.F. Kittel, 2002: Problems in evaluating regional and local trends in temperature: An example from eastern Colorado, USA. Int. J. Climatol., 22, 421-434.

Our abstract reads

We evaluated long-term trends in average maximum and minimum temperatures, threshold temperatures, and growing season in eastern Colorado, USA, to explore the potential shortcomings of many climate-change studies that either: (1) generalize regional patterns from single stations, single seasons, or a few parameters over short duration from averaging dissimilar stations; or (2) generalize an average regional pattern from coarse-scale general circulation models. Based on 11 weather stations, some trends were weakly regionally consistent with previous studies of night-time temperature warming. Long-term (80 + years) mean minimum temperatures increased significantly (P <0.2) in about half the stations in winter, spring, and autumn and six stations had significant decreases in the number of days per year with temperatures ≤−17.8 °C (≤0 °F). However, spatial and temporal variation in the direction of change was enormous for all the other weather parameters tested, and, in the majority of tests, few stations showed significant trends (even at P <0.2). In summer, four stations had significant increases and three stations had significant decreases in minimum temperatures, producing a strongly mixed regional signal. Trends in maximum temperature varied seasonally and geographically, as did trends in threshold temperature days ≥32.2 °C (≥90 °F) or days ≥37.8 °C (≥100 °F). There was evidence of a subregional cooling in autumn’s maximum temperatures, with five stations showing significant decreasing trends. There were many geographic anomalies where neighbouring weather stations differed greatly in the magnitude of change or where they had significant and opposite trends. We conclude that sub-regional spatial and seasonal variation cannot be ignored when evaluating the direction and magnitude of climate change. It is unlikely that one or a few weather stations are representative of regional climate trends, and equally unlikely that regionally projected climate change from coarse-scale general circulation models will accurately portray trends at sub-regional scales. However, the assessment of a group of stations for consistent more qualitative trends (such as the number of days less than −17.8 °C, such as we found) provides a reasonably robust procedure to evaluate climate trends and variability.”

While our study was for a limited geographic area, the approach of examining each observation site in detail in order to seek to explain each of the observed trends is an approach that should have been adopted in the Meehl et al 2009 study.

For example, the reduction in the number of the coldest days for the stations we examined in Colorado is consistent  with the Meehl et al study. However, the fractional contribution to this temperature change from long-term local and/or region land use change, changes in local and regional atmospheric aerosols, change in cloud cover, large-scale  circulation changes, etc., and from non-climatic siting issues (e.g. see), and as well as from a large-scale radiative effect from human-added greenhouse gases,  needs further quantitative examination.

Comment On James Annan’s Post “Klotzbach ad nauseam 2009″

There is a post by James Annan title Klotzbach ad nauseam 2009 which has a number of substantive errors, which I will respond to below. Interestingly, despite these errors and the statements that our paper if flawed, Annan actually confirms that there is a bias in the surface temperature trends if they are to be used to interpret tropospheric temperature changes through a deeper depth of the atmosphere!  He writes

“Gavin’s value knocks off half of the claimed discrepancy at a stroke.”

Thus, James is still admitting that a discrepancy remains.

On his factual errors, the surface and tropospheric temperature trends remain unreconciled as clearly seen in Kltozbach et al (2009) even without using any amplification.  Moreover, in the follow up with Ross McKitrick (see), an amplification remains.

On the recognition of Urs Neu on the error he found in my interpretation of the Lin et al (2007)  paper, he was acknowledged in a post titled Error Identified by Urs Neu in one of my Interpretations of the Results in Lin et al. 2007.  In the constructive e-mail exchange I had with Urs, Urs and I did agree the use of a temperature at one level to diagnose a  temperature trend through a deeper layer of the troposphere can introduce a bias. [it would be constructive if James would also adopt Urs's constructive dialog approach].

In that post, with respect to our papers, I  also wrote

“In summary, the error in my interpretation of the Lin et al lapse rate trends does not alter the conclusions in Pielke and Matsui 2007 and Klotzbach et al. 2009. We present scientific evidence that any effect which reduces the slope of the vertical  temperature profile within a stably stratified surface boundary layer will introduce a warm bias, while any process that increases the magnitude of the slope of the vertical  temperature profile in a stably stratified surface boundary layer will introduce a cool bias, remains a robust finding based on boundary layer dynamics. “

James Annan, I note, ignored commenting on the science of this conclusion in his most recent post [probably because he did not want to repeat his presenting his lack of fundamental knowledge of  atmospheric boundary layer dynamics, as I documented in several posts earlier this Fall (e.g. see Remarkable Admission By James Annan On The Klotzbach Et Al (2009) Paper)].

Indeed, Annan has apparently decided that dissing research papers without scientific conclusions based on his own research is okay. Having worked with him on our survey (see), I am disappointed to see him assume this lack of scientific rigor.  After all, he still accepts that “half of the claimed discrepancy” remains, yet ignores following up on the significance of this finding. The Santer et al (2000) paper [see for the correct citation] remains a valid approach to investigate the issues we raised in our paper.

He has also ignored other evidence that supports the Klotzbach et al (2009) paper; e.g.

Further Support for Klotzbach et al. 2009 – Observational Evidence of a Change of Surface Radiative Forcing in a Paper: Philipona et al. 2004

Another Very Important Paper Which Illustrates Major Problems With Using Minimum Land Temperatures As Part Of The Diagnosis of Global Warming and Cooling: “Vertically Integrated Sensible-Heat Budgets For Stable Nocturnal Boundary Layers By Nakamura and Mahrt 2006

Support For Klotzbach Et Al (2009) In The 1997 Easterling Et Al Science Paper “Maximum And Minimum Temperature Trends For The Globe”

Illustration Of The Sensitivity In The Minimum Overnight Temperature To Even Small Changes In Land Surface Processes

As we invited Gavin Schmidt, James Annan is welcome to collaborate with us to address the issue of the descrepancy between the surface and tropospheric temperature data.  Alternatively, he could submit a Comment to JGR on our paper, which we would be pleased to Reply to.  

 

Further Comments On The Article “Clean the Air, Heat the Planet?” By Arneth Et Al 2009

There is an interesting statement in the article

Arneth, Almut , Nadine Unger, Markku Kulmala, Meinrat O. Andreae, 2009: Clean the Air, Heat the Planet? Science 30 October 2009: Vol. 326. no. 5953, pp. 672 - 673 DOI: 10.1126/science.1181568

in which the following text was written

“Like many others in the climate debate, we have focused on surface temperature, but other aspects of climate change especially the amount, distribution, and intensity of rainfall—are at least as important to human well-being. Changing aerosol burdens may alter local and regional cloud cover and precipitation, change the intensity or timing of the monsoon circulation, and even shift precipitation across national borders… Changes in cloud cover and precipitation will also feed back on the photochemistry and rainout of short-lived species … These issues must be considered if aerosol emissions are to become part of climate policy.”

While land use change is conspicuously absent in this statement, the need to broaden out beyond a focus on carbon dioxide as a human climate forcing, as we have urged in the Arneth et al 2009 article further supports the perpsective in our new contribution

Pielke Sr., Roger, Keith Beven, Guy Brasseur, Jack Calvert, Moustafa Chahine, Russ Dickerson, Dara Entekhabi, Efi Foufoula-Georgiou, Hoshin Gupta, Vijay Gupta, Witold Krajewski, E. Philip Krider, William K. M. Lau, Jeff McDonnell, William Rossow, John 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.

Bias In News Reporting

UPDATE: November 14 2009 There is a very informative discussion of my post at http://cruelmistress.wordpress.com/2009/11/14/bias-in-reporting/.  The issues that are raised in that post are valid; hopefully, my post will encourage a rigorous scientific assessment of this question.

There is a press release on a paper yesterday from NCAR titled Record High Temperatures Far Outpace Record Lows Across U.S.

I plan to post on the paper on which this news article is based next week ( it has major problems, as already identified at Watts Up With That). However, today, I want to just compare the news exposure of three press releases, one of which supports a surface temperature changes from the human addition of CO2 and other greenhouse gases (the NCAR press release), and two others which present other explanations for at least part of the surface temperature increases.

The NCAR press release as of 10am EST November 13 2009 has 95 links (under the lead author) at google news.

The other two press releases are

“Study gives clearer picture of how land-use changes affect U.S. climate”  from Purdue which has 3 links (under any of the co-authors) in google news where the press relase has the text

“What we highlight here is that a significant trend, particularly the warming trend in terms of temperatures, can also be partially explained by land-use change,” said Dev Niyogi, a Purdue earth and atmospheric sciences and agronomy professor, and the Indiana state climatologist.”

New Idea offered to fight climate change  from Georgia Tech which has 6 links (under the author’s name) in google news where the press release has the text

“Across the (United States) as a whole, approximately 50 percent of the warming that has occurred since 1950 is due to land use changes (usually in the form of clearing forest for crops or cities) rather than to the emission of greenhouse gases,” Stone said. “Most large U.S. cities … are warming at more than twice the rate of the planet as a whole — a rate that is mostly attributable to land use change.”

The news community clearly has a bias in its reporting.

Further Evidence In Support Of Klotzbach Et Al 2009

A research study has been communicated in Boulder this week which further support the findings in

Pielke Sr., R.A., and T. Matsui, 2005: Should light wind and windy nights have the same temperature trends at individual levels even if the boundary layer averaged heat content change is the same? Geophys. Res. Letts., 32, No. 21, L21813, 10.1029/2005GL024407.

Walters, J. T., R. T. McNider, X. Shi, W. B Norris, and J. R. Christy (2007): Positive surface temperature feedback in the stable nocturnal boundary layer, Geophys. Res. Lett., 34, L12709, doi:10.1029/2007GL029505 [see also the guest post on this subject by Dick McNider]

and

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.

that there is a warm bias in the land surface temperatures, if they are used as a diagnostic to assess deeper layer atmospheric temperature trends. In the Klotzbach et al paper, we wrote

“……any positive forcing such as additional greenhouse gases destabilizes the boundary layer, increases its depth, and mixes warm air aloft to the surface. Thus, the warming is amplified at the surface but represents a redistribution of heat rather than accumulated heat from the additional forcing. Use of surface data in which minimum temperatures are included in the data set then leads to a direct warm bias if interpreted as a heat accumulation from both the column depth dependency and the destabilization.”

There is new information in a seminar to be presented at the David Skaggs Research Center, Room 1D403 on Wednesday, November 18, 2:00 PM by Imtiaz Rangwala of the Western Water Assessment and UCAR VSP (Visiting Scientist Program) Postdoctoral Fellow.  The talk is titled

“Influence of Increasing Surface Humidity on Winter Warming at High Altitudes through the 21st Century”

The abstract reads

“This presentation will review the late 20th century climate change over the Tibetan Plateau. Studies, including this one, suggest an elevation dependent warming on the plateau, i.e. higher warming at higher elevation. I will present analyses of observed climate variables (1961-2000) and a GCM output to discuss some of the mechanisms responsible for this phenomenon. In particular, I will focus on the localized greenhouse effect of water vapor increases in the boundary layer, which will be referred as surface water vapor feedback (SWVP). SWVP appears to be the major cause of surface warming during winter, particularly at higher elevations, in the model. This is supported by greater increases in downward longwave radiation relative to outgoing longwave radiation at surface during winter. This difference is greater at higher elevations. Seasonally, observations show largest warming trend in winter when there are much greater increases in the minimum temperatures relative to the maximum temperatures. These differences are also greater at higher elevations. Cloud cover, which can significantly influence the downward longwave flux, show decreasing trends in both observations and the modeled results. Between 1950 and 2100, the model shows an elevation dependent warming trend during winter and spring. We find that (1) increases in downward longwave radiation influenced by increases in surface specific humidity during winter, and (2) increases in absorbed solar radiation influenced by decreases in snow cover extent during spring are, in part, the reasons for a large warming trend over the plateau in the model.”

The relevant text with respect to the warm bias include

“In particular, I will focus on the localized greenhouse effect of water vapor increases in the boundary layer, which will be referred as surface water vapor feedback (SWVP). SWVP appears to be the major cause of surface warming during winter, particularly at higher elevations, in the model.”

“….observations show largest warming trend in winter when there are much greater increases in the minimum temperatures relative to the maximum temperatures.”

We look forward to the appearance of this paper in the literature.

New Paper Accepted “Temperature And Equivalent Temperature Over The United States (1979 – 2005) by Fall Et Al 2009

We have a new paper accepted. It is

Fall, S., N. Diffenbaugh, D. Niyogi, R.A. Pielke Sr., and G. Rochon, 2009: Temperature and equivalent temperature over the United States (1979 – 2005). Int. J. Climatol., accepted.

The abstract reads

“Temperature (T) and equivalent temperature (TE) trends over the United States from 1979 to 2005 and their correlation to land cover types are investigated using National Centers for Environmental Prediction (NCEP) North American Regional Reanalysis (NARR) data, the Advanced Very High Resolution Radiometer (AVHRR) land use/cover classification, the National Land Cover Database (NLCD) 1992-2001 Retrofit Land Cover Change, and the Normalized Difference Vegetation Index (NDVI) derived from AVHRR.

Even though most of the magnitude of TE is explained by T, the moisture component induces larger trends and variability of TE relative to T. The contrast between pronounced temporal and spatial differences between T and TE at the near-surface level and minor to no differences at 300 mb – 200 mb is a consistent pattern. This study therefore demonstrates that in addition to temperature, atmospheric heat content may help to quantify the differences between surface and tropospheric heating trends, and hence the impact of land cover types on the surface temperature changes.

Correlations of T and TE with NDVI reveal that TE shows a stronger relationship to vegetation cover than T, especially during the growing season, with values that are significantly different and of opposite signs (-0.31 for T vs. NDVI; 0.49 for TE vs. NDVI). Our results suggest that land cover types influence both moisture availability and temperature in the lower atmosphere and that TE is larger in areas with higher physical evaporation and transpiration rates. As a result, TE can be used as an additional metric for analyzing near-surface heating trends with respect to land cover types. Moreover, TE can be tested as a complementary variable for assessing the impact of land surface and boundary layer processes in reanalysis and weather/climate model studies.”

This paper is directly related to the Roderick et al 2009 paper which we posted on at

Pan Evaporation Trends And Its Relation To The Diagnosis of Global Warming – Comments On A New Article By Roderick Et Al 2009.