[alancalverd (OP)]

There has been an ongoing debate in this forum (and a few other places, too) about the influence of carbon dioxide on global climate.

As I see it, the principal  CO2 absorption lines in the atmospheric infrared spectrum have been saturated for as long as we have any valid data - at least 70 years. But every so often someone claims "pressure broadening" means that the line width has increased so significantly in that time that the world is in peril.

But as I understand it, pressure broadening in a very dilute mixture is not a function of the partial pressure of the subject gas, which has admittedly increased from .0002 to .0003 bar in the last 10,000 years, but a function of the total pressure of the mixture (1 bar), which has if anything decreased as the temperature has risen.

Comments and elucidation welcome.

[Origin]

But every so often someone claims "pressure broadening" means that the line width has increased so significantly in that time that the world is in peril.

I think these 'someones' are not putting forth a very compelling argument.

[Bored chemist]

But every so often someone claims "pressure broadening" means that the line width has increased so significantly in that time that the world is in peril.

Where?