AJH wrote:
On Thu, 18 Sep 2008 12:30:14 +0100, "dennis@home"
wrote:

Anyway the best thing to do is to reduce the water vapour as it is water
that carries the energy to create storms, etc. The only way to do that is to
stop them burning the rain forests and let them re-grow. You may have to
fight a war to do this.

How much water is transpired from rainforests (or any vegetation)
compared with that from the oceans?

Cutting CO2 is not going to fix the main problem.

There seems to be some disagreement as to what the "main problem" is!

I've only just dipped into this thread but I gather:

1) the greenhouse effect is real, well known for 2 centuries and
necessary to keep the earth's surface warm enough to sustain life as
we know it. Many gases in the atmosphere will trap long wavelength re
radiation from the surface, having passed the higher energy solar
input, but absorption bands differ. Those wavelengths that atmospheric
water absorbs on a clear day already get intercepted to a large
degree. Those that CO2 absorbs don't all get caught whilst CO2 is a
small portion of the atmosphere. Catching re radiation should warm the
atmosphere but measurements are uncertain??

2) Whilst CO2 has formed a much larger proportion of the atmosphere
and in the last 400, 000 years has cyclically tracked ice ages between
levels of about 185 and 285 parts per million (according to ice core
data which may be disputed) in the whole time hominids are known to
have existed these limits have not been exceeded till iron age man
started clearing forests.

3)Since the beginning of the industrial age CO2 atmospheric levels
have risen from 300 parts per million (the level I was taught at
school) to ~385 parts per million. This level is proportional to
estimates of fossil carbon burned but is less than a direct
relationship, indicating that the biosphere buffers some and I'm not
sure where cement making fits in to this as a CO2 source.

4) rain falls as carbonic acid and the sea is measurably more acid,
this inhibits the beasties that store CO2 as calcium carbonate.

5) Of the three major organs of the biosphere (land, oceans and
atmosphere) we dump most CO2 into the smallest by mass, the
atmosphere, such that its stock of CO2 has grown from 550,000 million
tonnes to 700,000 million tonnes in 200 years and is rising by 6,000
million tonnes/annum increasing, this is 10% of the annual (natural)
CO2 flux between land an atmosphere. Indicating the atmospheric CO2 is
recycled every 3.5 years.

6) apart from trapping exhaust gases and storing them the only
mechanisms for getting CO2 from the atmosphere are biological
processes like photosynthesis and bugs directly creating carbonates.

So the question I would like answered is does it matter if CO2 levels
reach 500 parts per million?

The pundits seem to say yes but not necessarily because of warming,
more because of changing patterns of rainfall which agricultural
systems cannot adapt to. The causal link still needs to be explained
to me a bit better. I can understand that, from life experience, that
such a drastic change in CO2 isn't likely to have no effect and
probably is likely to have a bad effect. We've seen a previous
atmospheric pollution problem, loss of parts of the ozone layer,
solved quite quickly (or is it??) by global agreement, I think the
same is true of acid rain.

Having changed from a nation producing 75% of our own food in a benign
temperate climate to one importing 50% of it's food and an
agricultural system that cannot adapt...

Now I appreciate I have limited intellect, the very fact that I'm
wasting my unwelcome additional free time looking at this box when I'm
still capable of work proves that, so has anyone an actual solution or
is it just an argument?

I attended a conference recently where a solution was put forward but
it depends on global co operation, which I frankly do not believe will
happen, it suits me because it relates to my trade. It also panders to
rich nations as it seems to offer a buy out option.

AJH

I'll take your exact figures on trust, but I think that is a fairly
accurate summary.

There area few other items to add.

Things like pollution, water vapour and certain other chemicals that are
greenhouse contributors wash out of the air pretty quickly: Co2 does not.

The issue as to whether it matters is that even if the risk of it
mattering is relatively small, the chances are that if it matters, it
really really matters, are rather large. I.e. the risk of a very
significant effect is pretty large. Its not like oh well, theres a 30%
chance it will be a bit warmer for a few years, its more like well there
is a 5% chance that human life will become impossible on 90% of the
inhabited land surface. That's the worrying thing.


Ultimately we (in te west anyway) can create live and grow food in
artificial ecospheres if we have to, but boy we will need a lot of
energy to build and run them.

And if that energy produces more Co2, and that is implicated in the
problem its no solution at all.