Originally posted by JohhnyBGood
Of course if the Sun reduces its output then it will be cooler than it would be otherwise, but yet that still does nothing about the greenhouse
effect. All laws of physics stay working all the time.
reply to post by mbkennel
Ooh - that sounds very definitive doesn't it!, except the AGW case doesn't rest on the 'laws of physics' does it!.
Yes it does.
Instead it rests on the very small warming effect caused by man made CO2, being amplified by presumed and unverified, totally positive feedback
mechanisms to create a runaway effect.
A couple of the 'unverified' mechanisms are pretty damn simple and verified:
a) water is a greenhouse gas too with a few week timescale in atmosphere instead of thousands of years. Hotter air takes in more water. This is plain
old weather knowledge 100 years old. Why is it warmer at night when its humid or cloudy instead of dry and clear like a desert? (everybody knows
desert nights are chilly).
b) icy tundra melts, stuff inside which used to be permanently frozen now decays and emits methane and CO2. Also methane hydrates on the sea floor.
There is of course the famous paleoclimate data which shows yes lagging CO2 (a few hundred years) after temperature---which is evidence for
feedforwards (planet warms from orbital solar forcing which gives a small warming, greenhouse gases come out from ground/oceans and it gets warmer and
warmer).
By the way, CO2 is responsible for only about half of human contribution to global warming. There are other gases which are more potent (per
molecule) emitted, and in fact these are easier economically to control, though no one is as big a contribution as CO2.
It is further assumed that climate sensitivity is a linear function of temperature - when it is far more likely that it actually decreases
with temp in a self governing system.
Have you been to Venus recently?
When is it far more likely that it decreases with temperature? And at what temperature difference does that start to happen? What are the physical
mechanisms? How to they compare quantitatively to the feedforward mechanisms? What's the experimental evidence for them?
You need answers for these if you want scientists to agree---because that's what's there on mainstream climate modeling.
I agree that there is "some" eventual feedback mechanism that might happen, for instance climate like that 100 million years ago when the coal and oil
we're burning (there were alligators in the arctic then) grow plants and algae in a huge green soup for millions of years and have the carbon fall to
the bottom of the ocean and not be decayed by bacteria and continue for a long time. Of course humans are extinct in this scenario.
I've heard though that this might not even happen, that now, compared to then, the aerobic bacteria are more effective and would probably eat the
plants better and release the CO2 back into the atmosphere, maybe fossil fuels were a one time shot. If we take all the fossil fuels and put them back
in the atmosphere we get a climate like that when the fossil fuels were made. Very very very hot.
The real danger is that we are in fact headed for another ice-age!
What's the evidence for this, and on what timescale?
edit on 18-12-2011 by mbkennel because: (no reason given)
