How could it happen that more than a dozen of the most prestigious scientific associations signed and submitted this letter on ‘climate change’ without having ensured that the used terminology is sufficiently defined. Read the rest of the entry
The UNFCCC does not define ‘climate’ at all, while
WMO says: 'climate' is average weather.
This website will provide information and ask, does science know what climate is?

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W.J. Gibbs expected WMO’s initiative to define weather and climate in 1987


Dr. Gibbs seems to have been a conventional trained scientist, still aware that good research work needs good definitions. Back in 1987 he discussed “Defining Climate” in a six page long paper[1], on the notion that it is useful in any field of study to re-examine the meanings attached to apparently simple words frequently. Before continuing, it is to stress, that WMO did not follow his recommendation, instead ‘permitted’[2] the conclusion of the UN Framework Convention on Climate Change (FCCC) without a definition of weather and climate at all. Did WMO did it with intention, or can WMO explain why such definitions are not needed?

Dr. Gibbs, who was Permanent Representative of Australia with WMO from 1962 to 1978[3], saw it quite differently, assuming that if a significant ambiguity has developed in the use of the terms weather and climate, there is merit to exploring the definitions so as to avoid serious misunderstanding. Whatisclimate has no problems to agree with this, but despite Dr. Gibbs’ good intention not willing to accept the use of these terms as an appropriate means in scientific field.

NOTE: Question, Info, Comment etc are from ‘whatisclimate’,

Ditto if marked: WIC, or otherwise; Sept.09, 2007

Excerpts from: W.J. Gibbs, 1987, “Defining Climate”,

Question, Info, Comment etc are from ‘whatisclimate’

  • The term ‘weather’ will here be used

to indicate the state of the atmosphere (pressure, temperature, humidity, wind, etc.) over a given locality or region during a given period of time (minutes , hour, day, month, season, year, decades, etc.).

WIC-Question: What to do with a description, which states only four weather features, although one could possibly list a dozen or more, and is silent on who is determining, the locality and time period.

WIC-Comment: The ‘state of the atmosphere’ is not weather. The ‘state of the atmosphere’ may govern the weather together with the ‘global natural system’.

  • The term ‘climate’ is used to indicate the

statistical probability of the occurrence of various states of the atmosphere (pressure, temperature, humidity, wind, etc.) over a given locality or region during a given calendar period.

WIC-Comment: It seems Gibbs is trying a trick. Instead of speaking of average weather, he calls it “statistical probability”, which either is based on historical statistic, or assumed average weather conditions; assumed but whom?

  • The essential difference between these two

definitions is that weather relates to the state of the atmosphere during one, and only one, specific period, whereas climate relates to the statistical likelihood of occurrences of states of the atmosphere over a specific calendar period. The latter definition assumes no major change of climate such as those, which have occurred on the time-scale of millennia in the past.

WIC-Comment: Any ‘statistical likelihood’ can only be established to certain aspects of “the weather”, or “the state of the atmosphere”, e.g. temperature.


WIC-Question: Why is Gibbs not able to realize that it is impossible to construe an “essential difference”.

Gibbs thereon discusses - inter alias- following points:

  • A different WMO/ICSU concept of weather and climate in 1967.
  • Methods of statistical analysis to describe climate
  • Rainfall distributions, Rainfall time series, and

The following excerpts are from the: Conclusion


There are a number of different interpretations of the word ‘climate’ currently in use within the scientific community, within governmental and non-governmental institutions and among the public at large, and the following are proposed for general adoption:

WIC-Observation: Those questions have been getting worst since W.J. Gibbs published his paper in 1987. Any serious discussion of the two basic terms has practically stopped with issuing the UNFCCC. Where was Dr. Gibbs’ voice when this happened five years later?

  • CLIMATE is the statistical probability of the

occurrence of various states of the atmosphere over a given region during a given calendar period;

WIC-Question: What constitutes

  • a state of the atmosphere,
  • various states of the atmosphere, and

what are ‘statistical probabilities’, of what type, basis, combination, duration, and so on?

  • WEATHER is the state of the atmosphere

over one given region during one given period (minute, hour, day, month, season, year, decade, etc.).

WIC-Opinion: Gibbs definition is of little help and neither fits necessarily a layman’s expectation, nor is useful for academic research. The state of the atmosphere can and should be described in physical, dynamical & chemical terms.

It is important to reduce difficulties likely to arise from different notions as to the word ‘climate’.

WIC-Comment: WIC fully agrees.

The constituent bodies of WMO and of other governmental and non-governmental agencies would seem to be the appropriate bodies to take the initiative.

WIC-Comment: WIC fully agrees.

WIC-Conclusion: The paper demonstrates how a serious scholar could and should be concerned about any weather and climate term ambiguity.

WIC-Conclusion: Totally unacceptable are WMO, IPCC, and other institutions’ politics of silence regarding the terms ‘weather’ and ‘climate’: No definition; No discussion.

WIC-Question: Can science work without reasonable definitions?


[1] W.J. Gibbs, 1987, “Defining Climate”, WMO Bulletin, No. 36 , p. 290-296.

[2] The FCCC negotiations took place under the auspices of the UN General Assembly (Res. 25/212 of 21 Dec. 1990), with the support of WMO and UNEP.

[3] Director of the Bureau of Meteorology (Australia) from 1962 to1978 and first Vice-President of the World Meteorological Organization from 1967 to 1975, and chairman of the Executive Committee’s Panel of Experts on Climate Change and Variability from 1976 to 1978.


Essay 2010
Is the term ‚climate’ too unspecific?
Pages 10

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Essays from 1992 to 1997 on CLIMATE
by Dr. Arnd Bernaerts
“Legal Means for Understanding the Marine and climatic Change Issue”,
p.24 presented at the 28th Annual Conf. of the Law of the Sea Institute, Honolulu

“Conditions for the protection of the global climate”,
p.53 presented at GKSS Research Center Geesthacht


Black Sea-Model Case
--Paper, p.53
--Conf-Paper, p. 6


Four short texts
1994 Moscow

1994 LOS

1993 LOS

1992 Nature

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