On Wed, 21 Aug 2002, Uri Sabadosh wrote:

>Even if there is global warming, how do we know how much is caused by
>natural causes?

If you do some calculations you will quickly arrive to the conclusion that
the warming is not caused directly by heat generated by human activity.
The only other way is by catalytical effect. Increasing CO2 is one of
those. But CO2 increase can be monitored easier than temperature (the gas
diffuses everywhere relatively quickly). The whole question is, how much
are humans guilty of this and how much of a natural cycle are we in. Afaik
the knowledge on long term cycles and their variation is zilch. I am not
an expert but I can theorize that 2-3 meteorites hitting earth in the not
so distant past may have caused weather upheaval that makes our present
problems look like a pleasant summer shower in comparison. Same for more
serious volcanic activity in the past and other things. Nobody knows for
sure what caused the last ice age for example. Or what caused it to cease.
Or what it was like before it started (dinos liked it hot afaik - and it
WAS hot then. *Much* hotter than now. Natural too, no pesky arrogant
know-all mammals around then afaik.). From the spread of dino remains and
other vegetation fossils it seems that the hot areas of the planet
stretched much farther north and south than today. So maybe we are just
riding on the 'tail' of the ice age and the planet is getting back to
being its usual self now, warming up *again*. After all the dino age was
fairly long and it had to be hot as dinos were cold-blooded, and the
respective vegetation was hot weather type. Our 'temperate' age is very
short in comparison, but we already 'know' everything, and are sure to
have done it all by ourselves too. Yeah, right.

Peter

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