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Need to talk about  -July 2010

B 206

IPCC says that there are important differences
between weather and climate.

Is the claim serious science?
Posted by ArndB/1 July 2010

The last IPCC-Report 2007 claims that there are important differences between weather and climate , by saying that:
A common confusion between weather and climate arises when scientists are asked how they can predict climate 50 years from now when they cannot predict the weather a few weeks from now. The chaotic nature of weather makes it unpredictable beyond a few days.

• Projecting changes in climate (i.e., long-term average weather) due to changes in atmospheric composition or other factors is a very different and much more manageable issue.
• As an analogy, while it is impossible to predict the age at which any particular man will die, we can say with high confidence that the average age of death for men in industrialised countries is about 75.

The text is from the section FAQ 1.2 : “What is the Relationship between Climate Change and Weather?”, and obviously intended to create the impression that ‘climate science’ is more reliable than weather forecasting. That is utterly nonsense, and can only pass undetected as long as it is presented in a terminology which is meaningless. The terms and explanation given do not meet the lowest academic standards, which shall be discussed to show the superficiality of the text (cited above).

According FAQ 1.2, as throughout the scientific literature, “Climate is generally defined as average weather”.  The problem starts with the search for a sufficient definition on “weather”. All scientific glossaries are very constraint on offering one.  The IPCC Glossary does not offer any explanation, while other glossaries usually provide only very general description, like this three: 

• ___ Weather is a short-term phenomenon, describing atmosphere,
  ocean and land conditions hourly or daily.
• ___ Weather is not constant. It is dynamic and always changing.
• ___ Weather is the day-to-day state of the atmosphere, and its
  short-term (minutes to weeks) variation.

One of the rare exception is the very comprehensive Glossary of the American Meteorological Society  (AMS). After a brief explanation of weather as: “The state of the atmosphere, mainly with respect to its effects upon life and human activities”, (full text in box below), the weather issue is broken down to: 

• The “present weather” table consists of 100 possible conditions,
• with 10 possibilities for “past weather”, while
• Popularly, weather is thought of in terms of temperature, humidity, precipitation, cloudiness, visibility, and wind. 

Even if the AMS-Glossary is silent on “future weather”, the nonsense get a face. If the “weather” consists of 100 possible conditions, how can “past weather” consist only of 10 conditions? Who is making the selection? Who decides over the period of time, whether data are used over a period of time ranging from months to thousands or millions of years? What are the “10 possibilities for past weather”? Which mix of data represents the past weather or the future weather? The extreme shortcoming of the explanation is revealed by the reference to “popularly weather”, which may reflect the layman’s version reasonably, but not necessarily. If AMS Glossary actually says that popular weather exist –presumably- of five conditions, past weather consists of 10 conditions and present weather consists of 100 conditions it seems that this is nonsense talking. There is no such thing as small, medium, and big weather, with few, several, or many dynamo-physical atmospheric elements. Weather is either weather, or it is statistics on weather components. This lack of reasoning should by now be clear if the FAQ-1.2 states: “it is the statis­tics of changes in weather over time that identify climate change.” The sentence is faulty in many respect, and it is silly to speak about “statistics of change in weather”. This intervention might become clearer by discussing the two IPCC examples (above) about the difference between weather and climate.

EXAMPLE 1: IPCC is saying that projecting changes in long-term average weather (e.g. climate) is a much more manageable issue than to predict weather for longer than a few days.
COMMENT: Yes, if it is not said what ‘weather’ is, it is much easier to speak about future climate (average weather), by ignoring 90% or 99% of the ‘100 possible conditions of the present weather’. As only few conditions and components of the weather, are not WEATHER, the way the scientific community is using the words: weather, climate, average weather, statistical weather, climate change, etc, undermines a fruitful discussion, and as these terms are highly emotional in the layman’s sphere, it is reckless and irresponsible as well.

EXAMPLE 2: As statistic is a useful tool to predict the probable life span of a human being, in analogy, statistical weather (e.g. average weather, or climate), can be predicted either, at least much better than a weather forecast for a couple of days.
COMMENT: This is a piece of stunning naivety. It is already astonishing that the usually indicated time difference between weather and climate, which is – according definition-  ranging from months to millions of years (the classical period is 30 years), is ignored. While the life time for every human being is short and finite, an unlimited time span from few months to millions of years, is something for fairy tales, but hardly serious in science. An ‘average weather’ from 200’000 to 100’000 BC, or likewise, between the year 2100 and 3000, is little more than an image, and has little to do with science.  Beside from the point that ‘weather’ is not reasonably defined, who is defining the time period involved, and selects the weather components? With regard to the IPCC’s analogy only one thing can be said with certainty: Climate can not die.

The reasoning of the authors of the FAQ 1.2 on a difference between weather and climate, is an annoyance. It is a reckless attempt to misguide the general public and politics to believe that science is better and more reliable in climatology than in weather forecasting. At best it is wishful thinking, as the author’s reasoning produced empty terms  and inconsequent  explanations. It is particularly unfortunate that the discussed material is not the remote opinion of a few scientist, but obviously have the backing of vast majority of the scientific community, as none of the 500 Lead Authors and 2000 Expert Reviewers of the IPCC Report seem to have cared about the text. Atmospheric science should ensure that it defines and works with sufficient terms and definitions.    

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