Comments on: Reducing Arctic Ice Field(ing)

By: Lotharsson

Lotharsson — Fri, 17 Jul 2009 02:17:42 +0000

johnd, I don’t know. I had assumed that the negative feedback meant that rising temperatures rising led clouds in that model to act against rising temperatures…but as you suggest, maybe that’s not what was meant.

By: johnd

johnd — Fri, 17 Jul 2009 01:38:07 +0000

Lotharsson, on July 17th, 2009 at 10:19 am

I’m getting a bit lost, when they refer to producing a strong negative feedback, what is it that reacts negatively.
This defined the empirical correlation referred to-

“Klein and Hartmann (1993) showed an empirical correlation between mean boundary layer cloud cover and lower-tropospheric stability (defined in their study as the difference of 700-hPa and near-surface potential temperature).”

so does producing negative feedback mean that the difference of 700-hPa and near surface temperature falls as clouds increase?

By: Lotharsson

Lotharsson — Fri, 17 Jul 2009 01:24:07 +0000

I meant it is something so basic that any ordinary person who has ever stood under clear skies and cloudy skies day and night should be aware of.

If you include the emphasis in my version, then it’s not so obvious.

Or don’t people notice such differences or wonder why it is so?

A lot of people don’t these days, I suspect. Is this an “I’m getting old” moment?

By: johnd

johnd — Fri, 17 Jul 2009 01:18:03 +0000

Lotharsson, on July 17th, 2009 at 9:37 am Said:
“It’s basic to climate scientists, but McIntyre is not one.”

I meant it is something so basic that any ordinary person who has ever stood under clear skies and cloudy skies day and night should be aware of. Or don’t people notice such differences or wonder why it is so?
Is it that these days too many people rarely live outside an artificially controlled environment?

By: Human Dividend

Human Dividend — Fri, 17 Jul 2009 01:15:45 +0000

Have I missed something?

Damn shiftwork!

By: joni

joni — Fri, 17 Jul 2009 01:13:41 +0000

scaper – it is dying because of the actions of a few people – I am assessing the next move.

By: Dave55

Dave55 — Fri, 17 Jul 2009 01:05:56 +0000

scaper…

It’s still happening at both places … I post all over the place (except Piers’ and Bolt’s blogs)

By: scaper...

scaper... — Fri, 17 Jul 2009 01:03:24 +0000

For the readers…it looks like this place is slowly dying so the action is at Reb’s Gutter Trash.

By: Lotharsson

Lotharsson — Fri, 17 Jul 2009 00:19:22 +0000

BTW, note one other thing from that paper referenced by McIntyre. It suggests the oft-made allegation that “AGW proponents” have somehow rigged their models by “presuming positive feedback” from clouds may not be true:

When imposed in simple two-box models of the tropical climate … or into some GCMs’ parameterizations of boundary layer cloud amount … this empirical correlation leads to a substantial increase in low cloud cover in a warmer climate driven by the larger stratification of warmer moist adiabats across the Tropics, and produces a strong negative feedback.

By: Lotharsson

Lotharsson — Fri, 17 Jul 2009 00:11:54 +0000

The general public doesn't understand IPCC terms used to communicate levels of (un)certainty. As a consequence, they think the science is far more uncertain than it is.