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?

Reference links :
How Spitsbergen Heats the World
NEW 2009

Roger A. Pielke Sr. and the meaning of "climate"

  In his recent paper "A broader view of the role of humans in the climate system"(11/2008)1, Prof. Pielke addressed also the "Definition of climate". Actually he belong to the few scientists that care about this matter. In November 2008 he presented once again a comment on his invaluable weblog:, with which he had started it in 2005, under the same title "What is Climate? Why Does it Matter How We Define Climate?"2 , and an unchanged text. Our comment in autumn 2007 is available at section: B-211, and had some reservations. Can we agree more today?

1)R. Pielke Sr. says: For many, the term "climate" refers to long-term weather statistics. However, more broadly and more accurately, the definition of the climate is a system consisting of the atmosphere, hydrosphere, lithosphere, and biosphere.


The definition of Climate for "many" as long-term weather statistics is the official definition of WMO for almost a century until today.

On this globe a "system consisting of the atmosphere, hydrosphere, lithosphere, and biosphere" is NATURE and explains nothing about CLIMATE

Further more UNFCCC (Climate Change Convention), says: "Climate system" means the totality of the atmosphere, hydrosphere, biosphere and geosphere and their interactions. (Art.1).

What would have been necessary to recognize that the UNFCCC does not provides a definition on climate at all.

2)R. Pielke Sr. says: Human actions that influence the climate system include the radioactive forcing from added atmospheric CO2, but also include the biogeochemical influence of CO2, and a variety of atmospheric aerosol forcing, nitrogen deposition onto land and the oceans, and land-cover changes.


A arbitrary collection of a half-dozen components of the global nature (system) does hardly makes the 'climate-system' more understandable. There are maybe many hundreds more;

and what means - for example- 'land-cover-changes'?

3)R. Pielke Sr. says: Each of these factors influence long-term weather statistics as well as other aspects of the climate.


Suddenly he is back to the common definition on climate

4)R. Pielke Sr. says: The IPCC assessment process focused mainly on the effect of CO2 and devoted less attention to the effect of the other human climate forcing in altering the global climate system.


Here he referring to the 'climate system', although he earlier explained that: "the definition of the climate is a system consisting of...".

The inconsistency is highlighted by referring to "human climate forcing". Speaking accurately in the sense of Prof. Pielke would mean: other human activities that are forcing a system which consist of the atmosphere, hydrosphere, lithosphere, and biosphere.

R. Pielke Sr. says in section "Climate system heat changes":

    -Global warming (or global cooling) can be more accurately quantified in terms of accumulation (or loss) of heat in the Earth system as measured in joules.

    -Moreover, because the surface temperature is a massless two-dimensional global field while heat content involves mass, the use of surface temperature as a monitor of climate change is not accurate for evaluating heat storage changes.

    -Note: The paper thereon refers to a figure on "Ocean Heat Content", with the 'latest estimate of change in global average heat storage in the upper 700 meters of the ocean'.


R. Pielke explained it in the same way as in 2005. What is obvious that the explanation given on 'climate' (respectively 'climate system'), is without any reference to the used terms, as e.g. 'heat changes' , surface-temperature changes', global warming or cooling.

Could it be that R. Pielke wants to say: If we know the heat content, we can tell the range of human influence on climate? If so, why is this aspect in no way reflected in the definition on climate?

    Remark: We have great doubt that anyone can correctly assess the heat content and changes of the oceans with any reasonable accuracy. But we believe that the short and long-term status of the atmosphere, usually described as weather and/or climate is determined by the oceans and seas, due to its constant supply of heat and water in the atmosphere.

6) R. Pielke Sr. says: (..forcing), no time lags are associated with heat changes, since the actual amount of heat presents at any time is accounted for. Moreover, because the surface temperature is a massless two-dimensional global field while heat content involves mass,. the)


The extract actually symbolizes the crux of insufficient and inconsequent terminology.

    - Weather statistics are not "weather-statistics" but statistics about a parameter of weather, e.g. temperature-statistics.

    - Even if one is adding statistics on wind, rain, snow and cloud-cover, that are only few existing parameters, but is not the weather at one location at a give time. For this very reason meteorology has never come up with a definition about weather.

    - Although the heat content of the ocean is a very decisive factor, it is not what makes the climate tick, but it is the heat and the water the ocean surface is releasing over time and space.

7) R. Pielke Sr. says in section "Regional forcing and feedbacks": The concept of a global average radiative forcing is generally a poor metric for assessing the impact of diverse climate forcings and feedbacks.


'Radiative forcing' is not reflected in Pielke's definition on climate.

While the term 'radiative forcing' is explanatory, 'climate forcing' would in the interpretation of climate by Pielke mean: "forcing a system consisting of the atmosphere, hydrosphere, lithosphere, and biosphere", which explains nothing.

Not the poor metric of radiative forcing is necessarily a problem, but the fact that the 'diverse climate forcings' mean anything, respectively nothing.

Could it be that many, if not countless forcings and feedbacks in the global natural system would be poor metric for assessing what makes weather and climate changing?

8) R. Pielke Sr. says: Weather events such as drought, flood, and hurricanes are regional events and are essentially independent of a global average radiative imbalance.


This sentence surprises as it ignores that definition of the climate shall mean a system consisting of the atmosphere ...etc.

9) R. Pielke Sr. says: Such regional climate forcing due to human activities represent a major but underrecognized climate forcing on long-term global weather pattern. Indeed, heterogeneous climate forcing may be more important with respect to our weather than changes in weather patterns associated with the more spatially homogeneous radiative forcing of the well-mixed greenhouse gases.


It is a wonderful piece of all in a tumble, or does Pielke wants to say that long-term global weather pattern is climate? Respectively that climate is long term weather-statistics?

What are weather patterns? How can 'weather pattern' scientifically be analyzed? Only by the means of statistics, or else? What is weather? What is change in weather pattern? To be clear: Every aspect can be explained and analyzed, but is it reasonably reflected in the term climate as used by R. Pielke?


Our previous comment to Prof. Pielke Sr handling of climatic terms from September 2007 (B-211), reasoned : "At least it illustrates hat there had been little interest to search and demand a reasonable climate definition." Little has changed.

April 2009

1"Physics Today", 2008, American Institute of Physics, p, 54-55.
2, July 11, 2005
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


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1994 LOS

1993 LOS

1992 Nature

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