Dear friends of Astronomy and geology Science,

Also read this
BBC - Science & Nature - Horizon - Snowball Earth

The controversial theory that for millions of years the Earth was
plunged into catastrophe - entirely smothered in ice up to one kilometre thick.
www.bbc.co.uk/science/horizon/.../snowballearth.shtml



BBC - Science & Nature - Horizon - Snowball Earth

Programme transcript. The controversial theory that for millions of
years the Earth was plunged into catastrophe - entirely smothered in ice up to
one kilometre thick.
www.bbc.co.uk/scien.../snowballearth_transcript.shtml



BBC - Science & Nature - Horizon - Snowball Earth

Links. The controversial theory that for millions of years the Earth was
plunged into catastrophe - entirely smothered in ice up to one kilometre thick.
www.bbc.co.uk/science/hor.../snowballearth_info.shtml



BBC - Science - Horizon - Archive 2000

BBC Horizon archive 2000-2001. Pure science, sheer drama - stories from
the whole range of scientific endeavours.
www.bbc.co.uk/science/horizon/2000.shtml


http://www.bbc.co.uk/science/horizon/2000/snowballearth.shtml

Snowball Earth
BBC2 9.00pm Thursday 22nd February 2001

There is a controversial theory that for millions of years the Earth was
entirely smothered in ice, up to one kilometre thick. The temperature hovers
around -40ºC everywhere, even in the tropics and the equator. If it did, then
virtually nothing could survive this ferocious climate. There are some
tantalising geological clues that show this theory may be true but the problem
is, the clues and the Snowball Earth theory defy the laws of nature.

For over fifty years a group of scientists has been trying to prove this
incredible period of Earth history. Struggling against scepticism and disbelief,
now finally the many mysteries have been solved and the scientific community is
slowly coming around to the extraordinary idea not just of the dramatic freeze,
but of an equally dramatic thaw. Scientists across the world are starting to
believe that in the past the Earth froze over completely for ten million
years... then warmed up rapidly about 600 million years ago. Almost all life was
wiped out. But out of the freeze emerged the first complex creatures on Earth.
Scientists now believe that the so-called Snowball Earth theory could hold the
key to the evolution of complex life on this planet.

The discovery of this theory is a classic scientific detective story. For
decades there had been a growing 'X-File' of geological anomalies haunting the
scientific community. Telltale signs of past glaciation have been found in
places that should have been much too hot - very near the equator. Even during
the most severe ice age, scientists believed that the ice only reached as far
down as Northern Europe and the middle of the USA. So what could these tropical
deposits mean?

Back in the 1960s one of the first climate modellers, Mikhail Budyko, stumbled
on an ingenious answer. Through some simple mathematical formulae, he calculated
that if the polar ice caps had spread past a crucial point, a runaway freezing
process would have followed, eventually freezing over the whole of the planet.
The idea fascinated scientists, but no one thought his runaway glaciation was
anything more than a theoretical result. Surely it had never actually happened
on planet Earth?

The idea foundered because according to the model, once the Earth was frozen
there was no way out - the Earth would remain frozen forever. The big freeze
would wipe out all life; we would not exist today. It seemed patently absurd.
But then came a series of insights and inspirations from a geologist in
California, Joe Kirschvink, who came up with a brilliant solution - that
volcanoes, protruding above the frozen landscape, would have carried on pumping
out carbon dioxide, the greenhouse gas, even though the world had entered the
deep freeze. On Snowball Earth there was no rain to wash this carbon dioxide out
of the atmosphere. Instead it would have built up to higher and higher
concentrations - until eventually it sparked off not just global warming but
global meltdown.

From the baking landscape of Africa to ice-covered Antarctica, Horizon follows
the tale of a theory which, if true, would have huge implications. Because
scientists now believe this cycle of freezing and frying may have created the
unique conditions needed for the evolution of complex life, including our own.

Further information


With Compliments from: Dr. BHUDIA : Science Group Of INDIA.
http://uk.groups.yahoo.com/group/venustransit_2004/
President:"Kutch Science Foundation".
Founder :"Kutch Amateurs Astronomers Club - Bhuj - Kutch".
Life Member:"kutch Itihaas Parishad".
kutchscience@..., kutchscience@...,
http://uk.geocities.com/wildlifeofkutch/
http://www.geocities.com/kutchscience
http://profiles.yahoo.com/kutchscience2000
http://in.groups.yahoo.com/group/scienceclubofindia
http://in.groups.yahoo.com/group/kutchscience
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