"Old Man" <nomail@nomail.net> wrote in message news:3f1ed2cc_2@newsfeed...

'' <brewhaha@ecn.ab.ca> wrote in message
news:QWNTa.3981$Fy1.177114@localhost...

Old Man (nomail@nomail.net), in article nntp:/<3f1df6f4_1@newsfeed> ,

That water vapour is itself a greenhouse gas seems to be a bit of
a complication, and certainly not a part of mainstream press. But what
would cause an ice age besides nuclear winter or a volcanic eruption?
What makes us so close to an ice age?

We are in an ice age. We have been in it for the past 100,000 years.
We are now experiencing a 10,000 year interlude. Ice ages , even
the European "little ice age", aren't caused by a few volcanoes or
asteroid impacts. They are probably caused by variations in Earth's
orbit about the Sun, wherein one hemisphere (north/south) or the
other receives less radiation for an extended period of time. It
depends upon the location of the continents (continental drift) and
upon how much land area is above see level. It depends upon the
ocean currents. During Earth's long history, these factors have
changed, but not in a cyclic manner. While the Sun heated-up, the
Earth's atmosphere thinned and cooled. There is no long term mean.
Instead, there is a long term trend that may end in one big ice ball.
[O;d Man]

Interesting. Hasn't there also been some research suggesting that these

000 year interludes as you call them are sensitive to variations in deep
ocean currents as well? IIRC, slight warming can cause some polar ice
melting, which in turn changes the salinity of deep ocean waters and could
effectively shut-down such currents as the Gulf Stream. This could reduce
the mean temperature of Europe immediately and affect global weather
patterns. The scary thing about this scenario is the estimates that such

'shutdown' could happen in as little as 10 years (yes, just ten).

Your water vapor issue is also interesting, since an increase in global
ocean temperatures would (naturally) increase the average water vapor in

atmosphere. This increase in greenhouse gas could/might cascade and make
the planet uninhabitable. (I think this is one theory about Venus).

Similarly, a reduction in temperature could have the reverse effect. And
the increase in albedo from snow might accelerate the cooling. Makes one
wonder what phenomena (if any) are stabilizing the effects of water vapor

the atmosphere.

daestrom

Gregory L. Hansen (glhansen@steel.ucs.indiana.edu),

Who cares what the satellites say, we live on the ground.

On the one hand, they hav a perspective that really is global. On
the other, I don't think they're as accurate, because they rely on
infra-red transmission, AFAIK.

That would be surface temperatures,
primarily, with interference from clouds and from composition of the Earth
(which can conduct heat to permafrost or other water tables instead of
reflecting it as infra-red). It's a bit like having a magnet for the
needle in the haystack when you're a cow.

Old Man (nomail@nomail.net), in article nntp:/<3f1ed2cc_2@newsfeed> ,

(...)

We are in an ice age. We have been in it for the past 100,000 years.

That is absurd. Polar ice does not melt during an ice age.

They [ice ages] are probably caused by variations in Earth's
orbit about the Sun, wherein one hemisphere (north/south) or the
other receives less radiation for an extended period of time.

And what could possibly cause such an aberration? I'm not sure
that such an aberration WOULD cause an ice age, but I don't see it
happening under conditions short of asteroid impact.

It depends upon the location of the continents (continental drift) and
upon how much land area is above see level.

These things haven't changed significantly in the last century,
although global warming itself is likely to cause _more_ rising of sea
levels.

It depends upon the ocean currents.

Those are rather chaotic, and in my estimation they are
insignificant as causes of global warming. They are more of an effect,
because once the heat has been absorbed by the sea, it is just a matter of
time before it is released.

During Earth's long history, these factors have
changed, but not in a cyclic manner.

Much like the weather...but there _is_ a seasonal cycle, and
some would say that there was predictability in el-Nino.

While the Sun heated-up, the
Earth's atmosphere thinned and cooled. There is no long term mean.
Instead, there is a long term trend that may end in one big ice ball.
[O;d Man]

You keep repeating your point, but I don't think there's enough
weight on it. You talk about ancient history, then extend it to today's
trend, which IS an increase -- arctic dragonflies to name one. And I don't
think that there's anything preventing the Earth from approaching the Sun
before the end of the Sun's life.

In short, we are talking about a relatively short-term, but
pronounced, trend. I regard much of environmentalism as a game of balance.
In that respect, I'm not sure that phasing out coal-fired electric power
(in Alberta) was a permanent (or sensible) decision, seeing as we've
recently cut natural gas production in the interests of bitumen.

Josh Halpern wrote:

Tendacious, tendacious, and further tendacious.

Tendentious is not good enough for Josh, so he's come up with a
portmanteau that takes sides: tending to the mendacious.

The points below are very important, but not quite all that can and should
be said. We do not really have a high confidence model for the global
weather changes over the past few tens of thousands of years. We have an
exceedingly oversimplified model that suggests increases in water vapor,
methane, CO2, and some other greenhouse gasses should produce a slight
increase in average temperature. Some much more questionable predictions
have been made for the impact this would have on local weather, which is
what we really get to measure. Given the uncertainty in the models I think
we cannot avoid the question of just what large scale effects a sudden

in the CO2 concentration might have, coupled with massive deforestation

destabilization of a number of environmental factors by overgrazing, water
born contamination, etc. There are a number of positive feedback effects
which may suggest some unstable cusps, like those indicated by some data
which show a very rapid decent into ancient ice ages. It is not impossible
that we are flipping a switch in the weather patterns that we will not be
able to unswitch, and the price could be substantial. Or as others have
pointed out, we might just clumsily be slowing down the plunge into the

ice age, to our benefit. It would be nice to know what we are really

don't you think?

"Old Man" <nomail@nomail.net> wrote in message news:3f1ed2cc_2@newsfeed...

'' <brewhaha@ecn.ab.ca> wrote in message
news:QWNTa.3981$Fy1.177114@localhost...

Old Man (nomail@nomail.net), in article nntp:/<3f1df6f4_1@newsfeed> ,

wrote:

A little global warming, if true, whatever the
cause, would be very good news for life on Earth. [Old Man]

The "if true" part makes me wonder how accurate the rest of the
analysis is, because I don't see much reason to doubt global warming.

Look at the satellite data. It doesn't agree with ground based
(biased) observations. The European middle ages were warmer
than present. The "little ice age" that followed was devastating
to European civilization and ended only 150 years ago. So, yes,
it's warmer now than 300 years ago, but not warmer than a
thousand years ago. Ice cores from Greenland show that past
temperatures have been highly variable with abrupt changes.
During the last 100,000 years it has been much colder than now.
The last 10,000 years (inner glacial warm period) have been much
warmer, but that could, and probably will, end soon. In order
to accept the current concept of "global warming", one has to
assume that, until very recently, the Earth's biosphere was in long
term equilibrium, but this is not the case, and never has been.

That
water is the overwhelming greenhouse gas is something new to me. I've
written about how ignoring water temperatures in judging whether we

global warming is folly, because the heat capacity of water (not to
mention the heat of vaporization) is so much more than that of air.

That water vapour is itself a greenhouse gas seems to be a bit of
a complication, and certainly not a part of mainstream press. But what
would cause an ice age besides nuclear winter or a volcanic eruption?
What makes us so close to an ice age?

We are in an ice age. We have been in it for the past 100,000 years.
We are now experiencing a 10,000 year interlude. Ice ages , even
the European "little ice age", aren't caused by a few volcanoes or
asteroid impacts. They are probably caused by variations in Earth's
orbit about the Sun, wherein one hemisphere (north/south) or the
other receives less radiation for an extended period of time. It
depends upon the location of the continents (continental drift) and
upon how much land area is above see level. It depends upon the
ocean currents. During Earth's long history, these factors have
changed, but not in a cyclic manner. While the Sun heated-up, the
Earth's atmosphere thinned and cooled. There is no long term mean.
Instead, there is a long term trend that may end in one big ice ball.
[O;d Man]

Maybe you could put this process to work in the places in the rain
forests where they cut all the trees, then we'll see which is
better...

What, and shade all those coffee plants? You'd hav half of the
internet on your case if you even started making coffee more expensive
in that manner (I guess the Britons and Aussies would say it's okay as
long as you don't do it with Tea) :-)