On Jun 19, 9:52 pm, "Coby Beck" <[EMAIL PROTECTED]> wrote:
> "William M Connolley" <[EMAIL PROTECTED]> wrote in message
> <news:[EMAIL PROTECTED]>...
>
>
>
> > Anyone read the latest Hansen in Proc Roy Soc:
>
> >http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_2.pdf
>
> > Anyone believe it?
>
> I believe it, at least the first few pages. Do you? And if not what
> specifically and why?
>
> Coby
I have to agree with William Connelly's words that it doesn't fully
demonstrate the inevitablility of SLR massively greater than IPCC
projections. But I've never read anything that totally rules it out,
so I don't agree with (what I perceive to be) his tone. That said I'm
an ex-sceptic enthusiast - not a modeller at the BAS. So whaddo-I-
know. ;)
We're not warming out of a glacial period, we're warming out of an
interglacial - the comparative lack of NH icecover seems to me to be a
significant enough factor to make direct analogy tricky (like some of
the MOC shutdown = new ice age stuff - zzzz). Albedo flip bothers me
more in cases like the Antarctic Peninsular, which seems to be a toe-
hold for this process onto the Antarctic continental periphery
(possibly removing the buttressing of the ice sheet in some limited
areas), rather than a major factor in global forcings to come.
The Hansen team's argument about spring forcing and it's implications
for rapid response to an increase of forcings seems reasonable, but I
don't see how it can then be extended to argumemts at resolutions of
less than a century.
I must admit that if I had to bet, I'd bet on the IPCC SLR results
underprojecting. But as the IPCC themselves state:
"Models used to date do not include uncertainties in climate-carbon
cycle feedback nor do they include the full effects of changes in ice
sheet flow, because a basis in published literature is lacking."(AR4
SPM).
So an acceptance of underprojection on this issue seems implicit in
what they say. There's not really much cause to suspect a negative
feedback from either ice-sheet or carbon cycle feedbacks.
In reality we're (globally) not going to do anything serious about
reducing emissions and other human impacts. And as Michael Tobis says
"years, 100 years, these are pretty close to each other dynamically
but pretty far apart in practical impact." So we'll find out in due
course.
If someone claims there's NO chance of a multi-metre SLR by 2100 I'd
be very interested in their reasoning. Because I doubt they could do
as well as Hansen's team has in reaching the opposite conclusion. I
just see doubt on both sides, and when facing a threat I have doubt
about, I take precautions assuming the worse.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
Global Change ("globalchange") newsgroup. Global Change is a public, moderated
venue for discussion of science, technology, economics and policy dimensions of
global environmental change.
Posts will be admitted to the list if and only if any moderator finds the
submission to be constructive and/or interesting, on topic, and not
gratuitously rude.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/globalchange
-~----------~----~----~----~------~----~------~--~---
