Text 11818, 97 rader
Skriven 2007-02-08 10:42:11 av Shabaz (15258.babylon5)
  Kommentar till text 11814 av rec.arts.sf.tv.babylon5.moderated (15254.babylon5)
Ärende: Re: Global warming, among other things
==============================================
On Feb 8, 5:50 pm, Christophe Bachmann <Chris_...@Compuserve.com>
wrote:
> Josh Hill a =E9crit :
>
> > On Tue, 06 Feb 2007 03:23:48 +0000, Andrew Swallow
> > <am.swal...@btopenworld.com> wrote:
>
> >> Josh Hill wrote:
> >> [snip]
>
> >>> There's really both a good and bad point here -- the good is that if
> >>> we act now we have the tools to deal with the problem without serious
> >>> disruptions, the bad is that despite this our government is so
> >>> dysfunctional that we haven't.
>
> >> Global Warming is something to be solved over a 100 years, a President
> >> that will be gone in 2 years is not important.
>
> >> At the level of individual states develop and debug policies that
> >> work.  Then and only then apply the policies at Federal Government and
> >> the UN levels.
>
> > Unfortunately, there's no time for that. We have to act now, because
> > if we don't, we'll see a 20 foot sea level rise and as many as half
> > the earth's animal species gone in much less than your 100 years, and
> > because the gases being released /now/ will cause warming for hundreds
> > of years.
>
> > As to solutions, I respectfully disagree. We know what the solutions
> > are. The Bush Administration simply refuses to implement them.
>
> Please, let's not be over-alarmist. I agree absolutely that something
> big must be done very soon if we want to avoid very bad things, but the
> IPCC :
>
> http://www.ipcc.ch/
>
> has stated that the increase in sea levels would most likely (>90%
> confidence) be less than 58 cm (less than two feet) in the next 100 years.
> The problem with "global warming" is that it is a very complex thing
> that can have a lot of quite unintended consequences. If you want the
> word straight from the horse's mouth please download :
>
> http://www.ipcc.ch/SPM2feb07.pdf
>
> the Summary for Policymakers of the first volume of "Climate Change
> 2007" of the Working Group I of the Intergovernmental Panel on Climate
> Change (IPCC), also known as the Fourth Assessment Report (AR4).
>
> --
> Greetings, Salutations,
> Guiraud Belissen, Ch=E2teau du Ciel, Drachenwald,
> Chris CII, Rennes, France

20 foot sounds wrong to me too. I think that number is from the
potential sea level rise if one of the big ice reserves, like
greenland or the arctic, would melt entirely. And while there are
studies that show increasing vulnerability to warming in these areas,
it's not really part of any projections at this point, and certainly
not projected to happen completely with any certainty within a hundred
years, far as I know.

But the IPCC AR4 SPM didn't quite say "most likely (>90% confidence)
be less than 58 cm" either. The IPCC runs several scenarios to predict
temperature rise and sea level rise, and 59 cm is the top level range
of the "high scenario" A1FI, which basically has the world developing
towards globalisation and with a technological focus that is fossil
intensive (entire range for that scenario is 26 - 59 cm). However, the
model predictions for this assessment report did not include one very
important factor this time: ice sheet flow dynamics. Basically, our
understanding has gone up about them a bit which actually has led to
two realizations: the impact of ice sheet flow dynamics could be
higher than we thought, and we now can actually say things with less
certainty than we previously could. So, in contrast with the TAR, the
models do not "include the full effects of changes in ice sheet flow,
because a basis in published literature is lacking". Which has
actually lead to lower sea level estimates compared to the TAR sea
level rise estimates (88 cm for the top end range for the highest
scenario), which lead to some confusion, since not everyone realized
that one included these dynamics and one didn't, making it impossible
to compare the estimates directly, since it is apples and oranges.

The AR4 SPM does mention that recent observation suggest that these
dynamics could lead to extra sea level rise, even though they can't
say how much at this point: "Dynamical processes related to ice flow
not included in current models but suggested by recent observations
could increase the vulnerability of the ice sheets to warming,
increasing future sea level rise. Understanding of these processes is
limited and there is no consensus on their magnitude." .

RealClimate also mentions this at the end of their initial analysis of
the AR4 SPM here: http://tinyurl.com/2w6vqf which explains it probably
a bit more clearly than me. ;)

-Shabaz
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