Comments By Mike Smith of My Weblog “Debate Question For Professor Steve Schneider and Colleagues”

In response to my weblog Debate Question For Professor Steve Schneider and Colleagues Mike Smith and I have exhanged e-mails on these three hypotheses. With Mike’s permission, I have extracted the text from our e-mails and reproduced with minor edits below. 

Mike Smith is CEO of WeatherData Services, Inc., An AccuWeather Company.  Smith is a Fellow of the American Meteorological Society and a Certified Consulting Meteorologist.   He is a recipient of the American Meteorological Society’s Award for Outstanding Contributions to Applied Meteorology and WeatherData has received the Society’s Award for Outstanding Services to Meteorology by a Corporation.

Mike’s comments are in regular text, and mine are italicized.

Mike Smith’s first e-mail

Hi Roger,

I have been reading the exchange regarding the SF articles.  There is something I would like to circle back on.  You say, “only one of these is true” if I am reading you correctly,

1. The human influence is minimal and natural variations dominate
climate variations on all time scale;

2. While natural variations are important, the human influence is significant and involves a diverse range of first-order climate forcings (including, but not limited to the human input of CO2);

3. The human influence is dominated by the emissions into the atmosphere
of greenhouse gases, particularly carbon dioxide.

I do agree with you that, 30 years from now, when we know much more, likely only one of the three contentions will be the “most correct” answer.  But, I don’t believe we are at that point.

Given our current knowledge, why can’t the most likely answer be, “Somewhere between 1 and 2”?  I believe the current state-of-the- science is telling us #3 is not correct.  I agree with you that there are many human forcings that influence climate, but it is not clear to me that the Wichita heat island (which I have informally documented) or the Reno heat island (see Anthony Watts’ website) have much influence on world climate (i.e., would the climate in Rome or Honolulu be different if the RNO and ICT heat islands did not exist?).  Does the deforestation in Brazil influence the climate in South Africa? IF the answer is “no”, then on a planetary scale #1 is the correct answer.

My best educated guess is the most correct answer is about 70%  #1 and 30%  #2.  I realize you believe this answer would be incorrect. Please tell me where you think I am off base.    If you wish to publish this question and your answer, it would be fine.  I believe we gain with open debate.

Thanks and best wishes,


Roger A. Pielke Sr. Reply and Mike Smith’s further response

Hi Mike

 Thank you for your feedback. I agree that the three hypotheses need to be addressed with respect to scale. Our research (and that of others) indicates that there are well defined effects of land use/land cover change, the human input of aerosols including both changes in atmospheric concentrations and deposition, and biogeochemical effects due to added trace gases including CO2 on local and regional scales. From your e mail, it seems we both agree on this. If true, the first hypothesis is rejected for these spatial scales (as is the third hypothesis).

Mike Smith Response – I agree with this.

Roger A. Pielke Sr’s Comment

With respect to the global scale, the proper metrics include changes in atmospheric concentrations, alterations in circulation patterns, etc. There is no question that added CO2 is from human activities….

Mike Smith Response – I agree

Roger A. Pielke Sr’s Comment

……and this has altered the global average concentration of this gas.

Mike Smith Response

I agree, but I’m not sure we fully know the extent.  There is some evidence for natural variation in CO2 concentrations (i.e., do changes in ocean heat content significantly vary their contribution to atmospheric CO2 concentration?).

Roger A. Pielke Sr’s Comment

In terms of effects on circulations, there are now a number of papers that illustrate with models that there are changes due to several of the human climate forcings listed above.

Mike Smith Response

Yes, but are the models sufficiently robust to make this determination at this time?

Roger A. Pielke Sr’s Comment

I have concluded the first hypothesis is also rejected on the global scale, but agree this needs further investigation (models by themselves, of course, cannot be used to test hypotheses).

Mike Smith Response

I see your point and you may well be proven correct.  However, we seem to be in the early stages of testing the ‘natural variations’ hypothesis.  I am referring to the ‘blank sun.’  The very low levels of sunspot activity the last two years — which seems to be continuing — and which I would call a “natural” variation, may give us a chance to sort out natural from manmade forcings.  The IPCC has (I’m paraphrasing) rejected the hypothesis that variations in the sun’s output have a significant effect on earth’s climate.
The falling temperature trend since 1998 (and, at best, lack of warming in the oceans about which you have written extensively) that seems to parallel the fall in solar output will give us a chance to test several of these hypothesis, especially in view of the record (for modern times) levels of CO2 concentration.  We seem to be getting close to the point where the IPPC’s hypothesis (CO2 is the dominant forcing) is rejected if temperatures and ocean heat content continue to fall while CO2 levels continue to rise.

Other credentialed climate scientists are invited to e-mail me their comments also, and, if appropriate, they can also be posted as a guest weblog.

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