OFF: Re: Life On Mars..?

[J Strobridge]

Keith A Henderson writes:

> Interestingly though, land ice is a very rare occurrence when you look at the
> entire history of the Earth....all 4.5 billion years of it.  I don't know
> exactly what the percentage of time is that experienced ice sheet development,
> but it has to be less than, say, 5% of the time.  So, the issue of

yeah - I've heard something similar (as below)

> anthropogenic global warming seems pretty odd when you look at the really big
> picture.  Coal swamps in Antarctica in the Cretaceous period is a little hard
> to imagine (and Antarctica was only a *little* bit farther north then).  So
> this is *still* an ice age in reality, just not in Ohio anymore... :)
>

mmmm - As I recall, one of the current theories is that most of the
really cold periods were not necessarily represented by ice advance.
An increase in the expanse of glaciers could (I'm not sure that 'would'
is the correct word here) be caused by a considerable increase in
precipitation (read: snow) but during the periods of massively low global
temperatures large areas of continental landmass may have simply been very,
cold waterless tundra deserts, although where the water was actually locked
up I've no idea.   I think the theories go along the lines that glacial
advance occupied only a small part of a true "Ice Age".   In fact, if I
remember correctly, the global maximum temperature of this most recent
period (whatever its name happens to be - hanged if I can remember)
occurred around 10,000 years ago (c.8,000BC) right at the end of a
glacial advance while the last icesheets were still barely retreating
from the Scottish Highlands and temperatures have, apparently, been
falling ever since.

> P.S.  And no, if all the world's land ice melted, sea level would not rise so
> much as to flood most of the land...it would rise approximately 80 meters.  So
> Kevin Costner would not need to grow gills...

But the politicians would still have to move out of the Houses of
Parliament  8-)

Actually the New Scientist has good news here - apparently the people
that measure the rate of the rise of sea level have been getting their
figures wrong.   It's done by satellite and they made a compensation for
satellite drift the wrong way which doubled their figures.   So instead
of sea level currently rising at 4mm a year it's probably only 1-3mm

Doesn't that make you feel safer!

jill

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J.D.Strobridge at ed.ac.uk                         eset08 at tattoo.ed.ac.uk
                                                ELIJSA at srv0.arts.ed.ac.uk

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