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Re: Climate change & big rocks



I wrote-

>> With the amount of particulate matter that a bollide would
>> release-it is quite possible that their was no or little light for
>> years.  Plants would die rapidly - The more food you need, the more
>> likely you are to die in those circumstances.  This applies in the
>> sea (where the base of the food chain in photoplankton) just as much
>> as on land.
>
>"Little or no light for years?"
>
> When you say little or no light, do mean pitch dark, twilight or an
> overcast day in Cleveland?


The models all have a large amount of uncertainty- However for a simple 
example of what particulate matter can do.

 The volcano in the Phillipines in 1991 put a plume of particulate matter
around the world that lowered the world average by 1-2C for about two years.
 A bolide, the size of the one that crashed 60 odd million years ago
 would, at minimum, place 10000 times as much- Not just from
the vapourised meteorite and crust,  but the many fires started by flaming
fragments.   Then super earth-quakes,  heat and air shockwave, followed
by freezing cold. - Sometimes it seems suprising that anything
other than bacteria and insects survived it- IT doesn't seem suprising 
that 65% of species were wiped out-to me at least.

I think most of the species of plant and animal that became extinct-
would have done so within a couple of months, years at most, of the
impact.  With the amount of particulate matter- It seems probable that
their would have been a period of pitch black, world wide for days
-perhaps weeks (the models are imprecise) with attenuated light after
that for years, perhaps decades.  - Before normal weather patterns
bought the particles back to earth.

This would tie in neatly with the extinctions of those animals 
which needed the most food (those over 25 kg) or cold blooded
(unable to keep warm during the plunging temperatures)


                Tony Mills
                Roehampton Institute London
                Tel (work) ++44 181-392-3121
                tonym@roehampton.ac.uk