Methuselah Jones  wrote:
>
> I'd say we understand enough to say that we potentially have a serious
> problem. When we can't consistently predict whether it's going to rain
> tomorrow, I don't know how we can say anything with any certainty about
> the next decade or the next century. Yes, the climate is warming[1].

The climate has been warming since the end of the Little Ice Age in
the 1300s, and in a more general sense since the end of the previous
glacial maximun about 13,000 years ago.  In the last century it
appears
the rate of warming has increased.  The fact that glaciers are melting
across decades has very little to do with the weather day to day.

Does the amount of arable land in total across the planet change?
In a very rough sense as the ice recedes the deserts grow.  The
problem
isn't the total fertility but the fact that the good parts move
around.  That
has triggered migrations in the past.  But now that aircraft can take
people a half planet way in a couple of days migrations are already
happening that far exceed historical ones.  Social turbulance is
happening with or without global warming, but social turbulance is
what global warming is causing.  Interesting conundrum.

> Yes,
> curbing greenhouse gasses is a good idea. Alarmism, however, is not.

It's not quite certain that curbing greenhouse gasses is a good idea.
In the past scientists would take climate data from ice core samples,
estimate historical climate trends, draw the curve, and extrapolate
the curve based on ancient data.  The initial conclusion was that our
current state was just before the start of the next ice age.  If those
methods were correct, then adding greenhouse gasses might end up
a good idea.  It's a huge if, but the issue is about extrapolating the
curve into the future and that data can be viewed several ways.


> Whatever's going to happen is going to happen.

Unless the portion we can control is enough to effect the final
outcome, and once we figure that out for sure we take the correct
action.

> Humans do make an impact
> on the environment, obviously, but I think the overall impact on the
> macrocosm is less significant than many think it is. As Ray Bradbury
> said, "The human race likes to give itself airs. One good volcano can
> produce more greenhouse gases in a year than the human race has in its
> entire history."

This is a point utterly missing from the press accounts of global
warming.
Photos of glaciers decades old and in recent years show that global
warming is happening.  Ignore the contribuition of volcanoes and it is
easy to conclude that humanity is the sole cause of the changes.
Humanity *does* contribute but there is no discussion in the press of
the degree of natural contributions and less than I would like in the
lay
science magazines I read - Sci Am and Discover.

The idea that humanity has the entire impact is just as false as the
idea
that the natural effects are so overwhelming that human impact is
insignificant.  Where we are in that spectrum, I don't see enough
discussion
about that.  I remember a phase of denial and some still deny.  I
think right
now we're in a phase of overreaction going the other way that fails to
account for the natural impact.  it will take some time for a balance
to settle
out.

On volcanos - They also release gaseous chlorine.  That chlorine rises
into the stratosphere and consumes ozone.  The process ionized the
chlorine into chloride and eventually it settles into the ocean to be
a
part of salt.  When freon was banned it was assumed that human impact
was the only contributor to ozone depletion.  It turns out the
volcanic
impact of the chlorine is a couple of orders of magnitude larger than
the
human impact, even though chlorflourcarbons last much longer in the
stratosphere than volcanic chlorine.  Banning freon was definately an
overreaction IMO.  But how the numbers turn out with greenhouse
gases, all I know is the field is still too volatile to see where it
will settle.
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