Re: [escepticos] Freeman Dyson y el cambio climático

[Pedro J. Hdez]

Borja Marcos escribió:
> Creo que esto que dice Freeman Dyson no tiene desperdicio
>
> http://www.edge.org/documents/archive/edge219.html#dysonf
>
> ¿Realmente un personaje de la relevancia de Dyson, por mucho que sea o 
> haya sido miembro del famoso comité "Jason" que asesora al gobierno de 
> EEUU desde los años 50, necesita dedicarse a la propaganda y la 
> demagogia? Desde luego lo que dice a mi me da qué pensar.
Siempre es un placer leer a Dyson, pero no es lo mismo ser una mente 
original y poco convencional cuando se es joven que después de mayor 
querer seguir siéndolo y no poder seguir el ritmo del conocimiento. A mí 
me ha llamado la atención el siguiente argumento de Dyson

Everyone agrees that the increasing abundance of carbon dioxide in the 
atmosphere has two important consequences, first a change in the physics 
of radiation transport in the atmosphere, and second a change in the 
biology of plants on the ground and in the ocean. Opinions differ on the 
relative importance of the physical and biological effects, and on 
whether the effects, either separately or together, are beneficial or 
harmful. The physical effects are seen in changes of rainfall, 
cloudiness, wind-strength and temperature, which are customarily lumped 
together in the misleading phrase “global warming”. In humid air, the 
effect of carbon dioxide on radiation transport is unimportant because 
the transport of thermal radiation is already blocked by the much larger 
greenhouse effect of water vapor. The effect of carbon dioxide is 
important where the air is dry, and air is usually dry only where it is 
cold. Hot desert air may feel dry but often contains a lot of water 
vapor. The warming effect of carbon dioxide is strongest where air is 
cold and dry, mainly in the arctic rather than in the tropics, mainly in 
mountainous regions rather than in lowlands, mainly in winter rather 
than in summer, and mainly at night rather than in daytime. The warming 
is real, but it is mostly making cold places warmer rather than making 
hot places hotter. To represent this local warming by a global average 
is misleading.

Y ahora yo haría la comparación con la explicación física detallada en 
http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/

que concluye

So, if a skeptical friend hits you with the "saturation argument" 
against global warming, here's all you need to say: (a) You'd still get 
an increase in greenhouse warming even if the atmosphere were saturated, 
because it's the absorption in the thin upper atmosphere (which is 
unsaturated) that counts (b) It's not even true that the atmosphere is 
actually saturated with respect to absorption by CO_2 , (c) Water vapor 
doesn't overwhelm the effects of CO_2 because there's little water vapor 
in the high, cold regions from which infrared escapes, and at the low 
pressures there water vapor absorption is like a leaky sieve, which 
would let a lot more radiation through were it not for CO_2 , and (d) 
These issues were satisfactorily addressed by physicists 50 years ago, 
and the necessary physics is included in all climate models.

saludos

Pedro J.


>
>
>
>
> Borja.
>
>
> ----------------
> "The thing he realised about the windows was this: because they had 
> been converted into openable windows after they had first been 
> designed to be impregnable, they were, in fact, much less secure than 
> if they had been designed as openable windows in the first place."
> Douglas Adams, "Mostly Harmless"
>
>
>
> _______________________________________________
> Escepticos mailing list
> Escepticos en dis.ulpgc.es
> http://correo.dis.ulpgc.es/mailman/listinfo/escepticos
>