Re: [asa] WG1 IPCC Chapter 1 - More Scientifically Erroneous Statements

From: PvM <>
Date: Sun May 20 2007 - 19:11:55 EDT

"Projecting changes in climate due to changes in greenhouse gases 50
years from now is a very different and much more easily solved problem
than forecasting weather patterns just weeks from now. To put it
another way, long-term variations brought about by changes in the
composition of the atmosphere are much more predictable than
individual weather events." [from page 105]

In fact, while this may sound contradictory, it is self evidently
true. As I have explained before, climate and weather are two very
distinct concepts. Predicting when a particular storm will hit a
particular place and drop rain or excessive winds, is not trivial due
to the complex interactions and the chaotic nature. Due to the latter,
weather predictions beyond a few days in the future quickly become
unreliable. On the other hand we have climate which is an averaged
concept both in time and space, which avoids the complications of
individual weather events in favor of a more balanced statistical

Realclimate has some excellent resources on this topic such as

<quote>Although ultimately chaos will kill a weather forecast, this
does not necessarily prevent long-term prediction of the climate. By
climate, we mean the statistics of weather, averaged over suitable
time and perhaps space scales (more on this below). We cannot hope to
accurately predict the temperature in Swindon at 9am on the 23rd July
2050, but we can be highly confident that the average temperature in
the UK in that year will be substantially higher in July than in
January. Of course, we don't need a model to work that out -
historical observations already give strong evidence for this
prediction. But models based on physical principles also reproduce the
response to seasonal and spatial changes in radiative forcing fairly
well, which is one of the many lines of evidence that supports their
use in their prediction of the response to anthropogenic forcing.

Of course from actual model simulations we do know that these are
indeed reliable assumptions.

despite this some 'skeptics' still seem to get this wrong as evidenced

Pielke's success rate in debunking IPCC seems to be quite low as
people such as Tim Lambert has shown.

<quote>Roger Pielke Sr is still blogging, and William Connolley
details Pielke Sr's third failed attempt to knock holes in the IPCC

Three attempts so far. And all failed... Good thing this is not a game
of baseball.

The butterfly arguments (sic) by Pielke were described already in an
earlier post (
and totally debunked, seems he did not learn much since then.

Hope this clarifies.
In Christ

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Received on Sun May 20 19:12:08 2007

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