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  • From: Joe and Ellen Hecksel <jhecksel@voyager.net>
  • To: nafex@yahoogroups.com
  • Subject: [nafex] Global warming/climate change Off topic
  • Date: Sat, 23 Mar 2002 18:39:08 -0500

Hello all:

Thomas Olenio wrote:

>
> For all the greenhouse theories I am not convinced that man plays a
> significant roll in the cycling of the earth's climate.


First a confession: I am an engineer at my day job.

The concern is that climate systems are positive feedback systems.
Positive feedback, in the engineering sense, is a system where the
system output is also a system input. Picture a pile of dry kindling
wood. Fire produces heat. Heat is a necessary component for the spread
of fire. The pile of dry kindling is stable until a fire is started.
Then look out. The system will grow until a necessary input is depleted.

Dry regions are positive feedback systems much like the fire in the
woodpile. Deserts beget more desert. Dry air causes high pressure
regions. High pressure regions cause outward bound *dry* winds at low
elevations. Air from surrounding moist regions flow in at very high
elevations to make up for the dry air that flowed out at low elevation.
High elevation air, even though it may have originated over an ocean,
is intrinsically dry. Deserts export hot, dry wind which causes desert
to spread to surrounding regions.

Climatic pressures "wobble". My concern is that unthinking human
activity may be enough to tip a marginal climate into a fully blown
desert. Or human stupidity and greed may hasten a system going
over-center (visualize the common wall mounted light switch) by 10,000
years.

A couple of less commonly discussed positive feedback "loops" regarding
global warming.

-Much CO2 is dissolved in water. Warming the water releases much of the
CO2. You can replicate the phenomena by putting a pop bottle (no cans,
please) into the microwave and warming it up. Then open. Use diet pop,
it is easier to clean up.

-Another potential source of greenhouse gasses is the methane hydrate
that underlies much of the Arctic regions and the Continental shelves
north and south of the 45 parallels.
http://marine.usgs.gov/fact-sheets/gas-hydrates/title.html
Methane hydrate is a solid alloy of common water and of methane.
Methane hydrate separates back into water and methane *gas* at temps
above 50F (12C) regardless of pressure. Methane hydrate becomes
unstable at even cooler temperatures at lower pressures. Global warming
or lowering of the oceans due to water being trapped in glaciers could
release methane from either/or both sources of methane hydrate.


--
-Joe Hecksel
My personal website: http://my.voyager.net/~jhecksel
March's featured website: http://www.ranchovilasa-spurs.com/oak2.html



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