On Mon, 4 Aug 2008 15:04:59 -0700 (PDT), wrote:

On 4 Aug, 17:54, Paul Hyett wrote:
On Mon, 4 Aug 2008 at 04:52:05, Jellore wrote in
uk.sci.weather :

Great show on tonight's Australian ABC channel outlining the risk of
carbon and methane release from the melting of permafrost.

I thought the worst supposed threat was from the melting of 'methane
hydrates'?
--
Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me)

I studied the climate impacts of methane gas hydrates as part of my
PhD in the mid 90s - the methane from melting permafrost would be a
mixture of destabilised gas hydrates and free gas trapped below the
hydrate layer.

No-one really knows how much methane is present in hydrate form, and
how easy it would be to destabilise, so we don't know how big the bomb
is, or how long the fuse is.

We do know that in the past, in the Eocene some 55 million years ago,
large quantities of gas hydrates were outgassed in a (geologically)
short period of time, and the world warmed around 5 centigrade. And
further in the past, some 250 million years ago, massive outgassing of
hydrates seems to have played a part in the great mass extinction at
the end of the Permian period.

In both cases, a period of rapid warming just prior to the hydrate
release was the immediate trigger. Of course the world's very
different now....

has this been mentioned here yet?
http://news.bbc.co.uk/1/hi/world/americas/7538341.stm


--
Regards, Paul Herber, Sandrila Ltd.
http://www.sandrila.co.uk/ http://www.pherber.com/