Wednesday, 26 February 2020

Yes, but that's the same thing, they're doing double counting.

Another failed debunking-the-debunkers attempt by Skeptical Science:
Myth: Each unit of CO2 you put into the atmosphere has less and less of a warming impact. Once the atmosphere reaches a saturation point, additional input of CO2 will not really have any major impact.

It's like putting insulation in your attic. They give a recommended amount and after that you can stack the insulation up to the roof and it's going to have no impact." (Marc Morano, as quoted by Steve Eliot)
The mistaken idea that the Greenhouse Effect is 'saturated', that adding more CO2 will have virtually noeffect, is based on a simple misunderstanding of how the Greenhouse Effect works.

The myth goes something like this:
* CO2 absorbs nearly all the Infrared (heat) radiation leaving the Earth's surface that it can absorb. True!
* Therefore adding more CO2 won't absorb much more IR radiation at the surface. True!
* Therefore adding more CO2 can't cause more warming. FALSE!!!

Here's why; it ignores the very simplest arithmetic...

The air doesn't just absorb heat, it also loses it as well! The atmosphere isn't just absorbing IR Radiation (heat) from the surface.

It is also radiating IR Radiation (heat) to Space. If these two heat flows are in balance, the atmosphere doesn't warm or cool - it stays the same.

Similarly we can change how much heat there is in the atmosphere by restricting how much heat leaves the atmosphere rather than by increasing how much is being absorbed by the atmosphere.

That's the same thing! If more warmth is absorbed then, by definition, less is radiated. You can't add the two together. It's like saying "I earn £2,000 a month and spend £2,000 a month, so each month I earn £4,000."


Bayard said...

Quite apart from the fact that there is no "Greenhouse Effect", the warming effect of CO2 (and, mainly, H2O) is in scattering the IR radiation, reflecting some down back to the surface. There used to be a handy little infographic from the IPCC explaining this, but it no longer exists, possibly because they realised it was giving out the wrong message or possibly because it mentioned that H2O is a "greenhouse gas", something the IPCC are quite keen to hide.

Physiocrat said...

All the carbon dioxide would form a layer less than 4 metres deep at surface temperature and pressure. It absorbs just three narrow wavelengths in the infra red, corresponding to the vibrations of the carbon dioxide molecule. How much of this radiation is even captured is unknown. I have yet to find a quantum-molecular explanation for the so-called greenhouse effect.

The title "greenhouse effect" is misleading. Glass greenhouses have next to no effect on radiant heat passing in and out.

The most probable causes of heat retention are reflection from water particles in clouds, and latent heat effects from rising clouds. We all know that clear nights are cold but cloudy nights are warmer. If human action is the cause, I would suspect changes in land use, in particular, agricultural practices.

Mark Wadsworth said...

B, yes, I part-read one of those IPCC reports in 2007 or 2008, and that's what made me realise that the whole thing is a massive exaggeration at best.

Ph, the land use one is an interesting thought. How would you go about finding out?

Physiocrat said...

Identify the biggest scale changes in land use in the past 100 years and try to work out the consequences. Conversion of tropical rain forest to arable/grazing use, and irrigation are probably the main ones.

Graeme said...

The greening of the Sahel is a good place to start. As is the fact that the area around Kilimanjaro used to be denuded of vegetation (allegedly caused by global warming) but is now green is another place to look

Graeme said...

A sample paper of just how little is known

James Higham said...

How little is known is the issue.