Errata:

"CO2 contributed 50% of the total (+/- a bit) millions & millions & millions of years ago."

Should be:

CO2 contributed 30% of the total (+/- a bit) millions & millions & millions of years ago.

CO2 + CH4 + N2O contributed 50% of the total ...

qanda,

Let me get this straight, you AND the IPCC say that today only 50% of the total greenhouse effect comes from H2O, and the other 50% comes from the LLGHGs?

Is that your position?

Regards,

Geoffrey Kelley, Mount Eliza

Geoffrey, this will be my last post to this thread.

“Let me get this straight, you AND the IPCC say that today only 50% of the total greenhouse effect comes from H2O, and the other 50% comes from the LLGHGs?

Is that your position?”

No.

In today’s climate:
Water Vapor ~ 50%
Clouds ~ 25%
LLGHG’s ~ 25%

Perhaps this might help;
Science 15 October 2010: Vol. 330 no. 6002 pp. 356-359, DOI: 10.1126/science.1190653

Abstract

Ample physical evidence shows that carbon dioxide (CO2) is the single most important climate-relevant greenhouse gas in Earth’s atmosphere. This is because CO2, like ozone, N2O, CH4, and chlorofluorocarbons, does not condense and precipitate from the atmosphere at current climate temperatures, whereas water vapor can and does. Noncondensing greenhouse gases, which account for 25% of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75% of the greenhouse effect. Without the radiative forcing supplied by CO2 and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state.

If you can’t read the full paper, it’s concludes with:

“From the foregoing, it is clear that CO2 is the key atmospheric gas that exerts principal control over the strength of the terrestrial greenhouse effect. Water vapor and clouds are fast-acting feedback effects, and as such are controlled by the radiative forcings supplied by the noncondensing GHGs. There is telling evidence that atmospheric CO2 also governs the temperature of Earth on geological time scales, suggesting the related question of what the geological processes that control atmospheric CO2 are. The geological evidence of glaciation at tropical latitudes from 650 to 750 million years ago supports the snowball Earth hypothesis (9), and by inference, that escape from the snowball Earth condition is also achievable. On million-year time scales, volcanoes are the principal source of atmospheric CO2, and rock weathering is the principal sink, with the biosphere acting as both source and sink (10)

cont'd

cont'd

Besides CO2, methane is another potent greenhouse control knob, being implicated in the Paleocene-Eocene thermal maximummass extinction 55 million years ago, when global warming by up to 5°C (12) occurred because of a massive release of methane from the disintegration of seafloor clathrates (13, 14). Methane is the second most important noncondensing GHG after CO2. Of the 2.9 W/m2 of GHG radiative forcing from 1750 to 2000, CO2 contributed 1.5 W/m2, methane 0.55 W/m2, and CFCs 0.3 W/m2, with the rest coming from N2O and ozone (15). All of these increases in noncondensing GHG forcing are attributable to human activity (16)…

The anthropogenic radiative forcings that fuel the growing terrestrial greenhouse effect continue unabated. The continuing high rate of atmospheric CO2 increase is particularly worrisome, because the present CO2 level of 390 ppm is far in excess of the 280 ppm that is more typical for the interglacial maximum, and still the atmospheric CO2 control knob is now being turned faster than at any time in the geological record (20)…

9 J. L. Kirschvink, in The Proterozoic Biosphere: A Multidisciplinary Study, J. W. Schopf, C. Klein, D. Des Maris, Eds. (Cambridge Univ. Press, Cambridge, 1992), pp. 51–52.

10 R. A. Berner, The Phanerozoic Carbon Cycle: CO2 and O2 (Oxford Univ. Press, New York, 2004) - The same RA Berner, Geffrey.

12 J. C. Zachos, G. R. Dickens, R. E. Zeebe, An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics. Nature 451, 279 (2008).

13 G. R. Dickens, J. R. O’Neil, D. K. Rea, R. M. Owen, Dissociation of oceanic methane hydrate as a cause of the carbon isotope excursion at the end of the Paleocene. Paleoceanography 10, 965 (1995)

14 G. A. Schmidt, D. T. Shindell, Atmospheric composition, radiative forcing, and climate change as a consequence of a massive methane release from gas hydrates. Paleoceanography 18, 1004 (2003)

15 J. Hansen et al., Efficacy of climate forcings. J. Geophys. Res. 110, D18104 (2005).

cont'd

cont'd

16 K. L. Denman et al., in Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, S. Solomon et al., Eds. (Cambridge Univ. Press, Cambridge, 2007), pp. 499–587.

20 D. Archer et al., Atmospheric lifetime of fossil fuel carbon dioxide. Annu. Rev. Earth Planet. Sci. 37, 117 (2009)."

Bye Geoffrey

Scientists playing "whack-a-mole" with the "no warming for 15 years" myth:

http://skepticalscience.com/dueling-scientists-oregonian.html

qanda,

I'm sure, like myself, Geoffrey appreciates you going to the trouble to explain things - and references too!

: )