[ExI] Global Temperatures to Decrease

[spike]

> [mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of Samantha
Atkins
>  ....
> 
> > ...whether you want to reduce the global average temperature...Bryan
> 
> ...Nope, not when we may be headed for another little ice age... -
samantha

Am I the only one here that is unnerved by this ice age notion?  

In my misspent youth, we heard of the threat of another little ice age.  At
the same time a few sources spoke of global warming, a notion which made it
into the popular arts.

See Soylent Green, http://www.imdb.com/title/tt0070723/   

The warming people eventually won out, and ruled the debate during the 90s
and much of this decade, much to my relief.  But I have noticed in about the
past three-ish years, the Goracle and others have tended to use the term
"global climate change" as opposed to global warming.  This appears to
acknowledge the threat of another ice age.  

In my mind the negative impact to humanity of planetary warming is small and
carries plenty of benefits (increased food production, more wardrobe choices
in more places, fewer cold-related deaths and greater overall comfort for
exo-African species such as humans, etc.)  But the negative impact of an ice
age is great, and carries no benefits that I can think of.  (Anyone?  More
choices for locating the winter olympics?  Increased business for coffin
makers?  Greater opportunity for snowball fights?)

It is easier for me to imagine human-caused cooling than warming:
particulates in the upper atmosphere may increase the earth's albedo more
quickly than the addition of CO2 can trap more heat.  The affect of
particulates is proven and seen very soon after a particulate event, such as
the eruptions of Mount St Helens in 1980 and Mount Pinatubo in 1991.
Furthermore it is far easier for me to imagine a runaway effect toward
cooling: greater snowfall and longer periods of snow on the ground, further
increasing albedo, etc.  

With warming, it appears to me there is a rock solid feedback mechanism that
prevents the planet from ever getting too warm: Stefan Boltzmann's law (
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html ) which causes
the earth to radiate heat into space as a function of the fourth power of
the temperature (and yes I know the earth isn't exactly a blackbody, but the
P = 5.67E-8eA(T^4-Tc) equation still works.)  That would further explain
why, in the long past, the earth has apparently never gotten so warm that
nearly everything perished, whereas the ice ages must have been hell.

In the modern age, there is a further threat to weather related forced
migrations: if the planet cools sufficiently, ice caps expand, humanity (and
every other wretched beast) is squeezed towards the equator, we nuke each
other.  With warming, the ice melts, we pull back from the newly submerged
coastline, we divert rivers inland, build water control projects, life goes
on.  (Yes I have heard the theory about the shutting down of the Gulf
Stream, but it doesn't seem a damn bit convincing to me.  I am open to
counter-suggestion if someone knows a good link, that has actual equations
and solid science.)

Note that this post is primarily about *asymmetric threats* of cooling vs
warming.

spike