Re: [asa] Subglacial Water System Moving Faster Than Previously Thought

From: PvM <>
Date: Sun Feb 18 2007 - 13:43:49 EST

From SPM AR4

In general, uncertainty ranges for results given in this Summary for
Policymakers are 90% uncertainty intervals unless stated otherwise,
i.e., there is an estimated 5% likelihood that the value could be
above the range given in square brackets and 5% likelihood that the
value could be below that range. Best estimates are given where
available. Assessed uncertainty intervals are not always symmetric
about the corresponding best estimate. Note that a number of
uncertainty ranges in the Working Group I TAR corresponded to 2-sigma
(95%), often using expert judgement. </quote>

So no, these are not 1-sigma error bands but 90% error bands. Hope
this clarifies.

On 2/16/07, Janice Matchett <> wrote:

> I can't wait until the full IPCC report comes out because I am trying to
> figure out what they are talking about with the 1.6 W/mē radiative forcing
> (with 1-sigma ranges apparently from 0.6 W/mē to 2.4 W/mē). It appears to me
> that their 2-sigma values would overlap 0 W/mē which is probably from where
> the 90% probability that they listed comes from (with 10% less than 0 W/mē).
> If this is the case then they are dramatically overstating the importance of
> the calculated radiative forcing in the same way that stating that the
> gravitational acceleration was 9.8 m/sē (with 1 sigma values from 4.0 m/sē
> to 16.0 m/sē) would be too imprecise a measurement of g to be of great use."
> ~ 4 posted on 02/15/2007 8:21:39 PM EST by burzum

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Received on Sun, 18 Feb 2007 10:43:49 -0800

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