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Re: Under a Green Sky
"Looking at the ancient evidence, Ward notes that ice caps began to shrink."
I am curious how one can know ice caps were shrinking from ancient
evidence. How do they know what the atmosphere was composed of by
looking at earth? Is it the types of animals? Is it the current level
of CO2 in the fossils or in the dirt/rock? A larger amount of plants?
Are the methods of ancient climate deduction included in the book for
non-experts like me?
On Nov 18, 2007 5:06 PM, Tommy Tyrberg
> >>Looking at the ancient evidence, Ward notes that ice caps began to
> >>shrink. "Melting all the ice caps causes a 75-meter increase in sea
> >>level. [That] will remove every coastal city on our planet."
> >Not going to happen. But if things continue, Greenland will be
> >ice-free in a few hundred years. That means "only" 7 m of sea level
> >increase. Half that, and Bangladesh is practically gone. Even just 1
> >m would make half of the country disappear in the dry season and the
> >rest during the monsoon. How will we evacuate 150 million people
> >(present estimate)?
> The Greenland Icecap is not going to melt in a few hundred years. It
> takes much longer. At the end of the last glaciation 11600 years ago
> climate in northern Europa became as warm or warmer than today and
> much drier, but even so it took 2000 years for the residual
> Scandinavian icecap to melt, even though it could calve into the
> Bothnian Gulf for much of the time. The only way an icecap can melt
> fast is if it can calve out into the sea. The Greenland icecap can't
> since its bed is above sealevel. Note that not even the southern dome
> of the Greenland icecap melted during the previous (Eemian)
> interglacial when arctic temperatures were about 6 degrees centigrade
> warmer than now.
> As for MIS 11 (Holstein) when the Greenland ice and at least part of
> the West Antarctic ice melted, the worrying thing about is that it
> was apparently NOT an extremely warm interglacial. Both fauna and
> flora seem to indicate lower temperatures than during the Eemian and
> in loess profiles the previous (MIS 13) interglacial has a much
> stronger weathering horizon. Where MIS 11 was unusual is that it was
> an exceptionally long interglacial, so duration may be more important
> then temperature.
> Concerning Bangladesh, that country will be gone in a few centuries,
> climate warming or not. The Ganges and Brahmaputra are dammed now,
> little sediment therefore comes into the delta and the sea is going
> to erode it away pretty quickly. The same thing is happening to the
> Nile Delta since the Assuan dam was built.
> Tommy Tyrberg