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Tuesday, November 6, 2012

The New Stephens Cartoon

Graeme Stephens and company have a new paper in Nature Geoscience, that contains the above new and improved Earth Energy Budget cartoon.  All both of you that follow my ramblings know that I have had quite a few issues with past Earth Energy Budget cartoons that were not only wrong, but deceptively wrong.  Propaganda comes to mind.

Graeme a crew have a clue.  This cartoon is even better than the Bjorn Stevens and Steven Schwartz Cartoon I have mentioned on occasion  First let me highlight a major point in the above, -187.9 +/- 12.5 Wm-2 All-Sky Longwave Absorption.   With the average energy of the surface of the Earth being ~ 398 Wm-2, the -187.9 Wm-2 would have an equivalent energy of about 210 Wm-2 or an equivalent "surface" temperature of 246.7 degrees Kelvin which is -26.4 C degrees.  The effective radiant temperature of the atmosphere is -26.4 C  with a range from -30 to -23 C degrees approximately.  A doubling of CO2 is supposed to change that average temperature by about 1.5 C degrees.

If you were to imagine a band of constant temperature between -23 and -30 C degrees in the atmosphere, you would noticed that at certain times of the year, that band would disappear below the surface of the Earth.  Adding CO2 would move where that band penetrated the surface closer to the poles or higher in the mountains by whatever distance it would be 1.5 C degrees cold than it is now.  As you get closer to the poles, the percentage of surface there is, that would be impacted by the 1.5 C degree reduction gets smaller until at 90 degrees South or North there is no longer any surface to be impacted.

If you consider energy, the 1.5 C degrees is roughly 3.7 Wm-2.  That increase in energy has a decreased impact on temperature as the surface to be impacted warms.  At the equator, 3.7 Wm-2 added to a surface at 500 Wm-2 would have 3.7/503.7=0.069 or a 0.7 percent impact on temperature.   Instead of the surface temperature at that spot on the equator being 33.3 C it would be about 33.8 C or about one half of a degree warmer.  The average warming in the inhabited regions of the Earth would be about 0.67 C degrees or less.  UNLESS, there is significant positive feedback.

Since that amount of no feedback warming at the "true" surface of the Earth is less than the uncertainty in the "average" "surface" temperature of the Earth associated with an energy of 398 Wm-2 +/- 5 Wm-2, discussing short term initial impacts of a doubling is like arguing over the number of angels that can do the Polka on a pin head.  Basically, only pinheads would even attempt to discuss initial impacts of small changes in CO2 forcing in face of the over whelming uncertainty.  For a pinhead to confidently state that warming due to CO2 doubling will be between 1.5 and 4.5 C degrees at a 95% confidence level is ludicrousness squared.

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