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Politics : The Environmentalist Thread -- Ignore unavailable to you. Want to Upgrade?

To: Alastair McIntosh who wrote (26809)	12/11/2009 4:38:46 PM
From: Win Smith	Respond to of 36917

I don't think the "forcing" means that the earth is absorbing that much more energy; my general understanding is that there's very little net energy absorbed and that radiation in = radiation out, energy wise, just at different frequencies and relative intensities. A wikipedia blurb, less clear than usual: The radiative forcing of the surface-troposphere system due to the perturbation in or the introduction of an agent (say, a change in greenhouse gas concentrations) is the change in net (down minus up) irradiance (solar plus long-wave; in Wm-2) at the tropopause AFTER allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values. [2] In a subsequent report[3], the IPCC defines it as: "Radiative forcing is a measure of the influence a factor has in altering the balance of incoming and outgoing energy in the Earth-atmosphere system and is an index of the importance of the factor as a potential climate change mechanism. In this report radiative forcing values are for changes relative to preindustrial conditions defined at 1750 and are expressed in watts per square metre (W/m2).":36 en.wikipedia.org I think the "surface and tropospheric temperature and state held fixed" is the issue here; what actually happens under forcing is that they heat up and radiate more energy out to restore the balance. I think it's pretty clear at this point that there a lot of complications in measuring the radiation balance precisely, and things are a lot more complicated than "forcing raises temperature", though. If the DSCOVR satellite would provide a good measurement of the net radiation absorbed or lost by the earth I can't imagine why it wouldn't be launched. The expense seems to be trivial as it would pretty well settle the question of global warming. There's a story there, somewhat polemically told in nytimes.com .