Re: [asa] Lesson in science: Soot and global warming

From: Rich Blinne <rich.blinne@gmail.com>
Date: Tue May 22 2007 - 17:54:23 EDT

On 5/22/07, Rich Blinne <rich.blinne@gmail.com> wrote:
>
>
>
> How does the IPCC handle Hansen et al 2005?
>
> Hansen et al. (2005) allowed the albedo change to be proportional to local
> > BC deposition according to Koch (2001) and presented a further revised
> > estimate [from Hansen et al 2004] of 0.08 W m2. They also suggested
> > that this RF mechanism produces a greater temperature response by a factor
> > of 1.7 than an equivalent CO2 RF, that is, the 'efficacy' may be higher
> > for this RF mechanism (see Section 2.8.5.7). This report adopts a best
> > estimate for the BC on snow RF of +0.10 0.10 W m2, with a low level
> > of scientific understanding (Section 2.9, Table 2.11).
>
>
> This means that the IPCC actually gives a higher estimate of BC in snow
> forcing than Hansen et al 2005.
>

Correction: I misread the IPCC paragraph. The "equivalent" RF (.08 x 1.7) is
within the error bars of the IPCC best estimate.

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Received on Tue May 22 17:55:04 2007

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