Nuclear Power at TED Conference

[hanelyp]

One thing I'll note about climate change: Over hundreds of millions of years Earth's climate has kept returning towards an average despite wide variations in CO2 levels, continental drift, and even massive disturbances like large asteroid impacts and super volcanoes. SOMETHING must be working pretty well damping the disastrous excursions the fear mongers keep trying to tell us man made CO2 emissions will cause.

[chrismb]

Hold it right there. The things I don't know about climatology would fill libraries, but I think I do understand the basic greenhouse mechanism. CO2 is transparent in the visible so it doesn't absorb much "impinging solar energy" at all. It's by absorbing the energy re-radiated by the Earth at thermal wavelengths that CO2 contributes to warming.

Just for info, CO2 absorbs at wavelengths of EM which peak for black body radiators at below -60C and above 420C. It doesn't absorb much at the peak wavelengths of a black body radiator in the 0 to 30 C range. What CO2 does is it keeps the polar regions around the -60C range, rather than the -120C range they'd get to otherwise (and if they did, then they'd act as a big thermal sink for the rest of the planet). This is how CO2 keeps the planet warm.

The other thing to note is that CO2's IR absorption is presumed linear with concentration. This comes down to an empirical law called Beer's law, and this isn't theoretically based and isn't necessarily true either. The correlation is known to completely reverse itself with even small concentrations of other, particular, gas types.

I have asked a very simple question of some climate scientists - why hasn't anyone shot a laser up to that 3 way mirror on the moon, and back, (or send some dedicated bit of kit into low earth orbit for the purpose) to measure the *actual* EM absorption of the atmosphere in the IR. This will tell us a whole lot more that presuming Beer's empirical law holds true.

...just for info...

[MSimon]

I think you got Beer's law wrong:

http://en.wikipedia.org/wiki/Beer%E2%80%93Lambert_law

It is a log relationship with concentration.

Otherwise I agree totally.

[chrismb]

I'm happy to stand corrected on any specifics I forget. Though, I think it boils down to a generally approximate linear relationship for very small (viz 400ppm) concentrations, which is what I was thinking of, wrt CO2. In any case, it is empirical and this is the issue I raise, and a source of inaccuracy, for CO2 climate models.