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A Bizarre Albedo Anecdote

by Andre
Tags: albedo, anecdote, bizarre
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Andre
#1
Jan26-06, 01:52 PM
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Suppose I was to publish this study.

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Andre et al, 2006, Earth Albedo variations dwarf greenhouse effect EOS, Vol. 87, No. 4, 24 January 2006

Abstract
We compute Earth albedo (reflectivity) in the period 1984-2004, using cloud data and coverage, confirmed by measuring reflectivity of the shadow side of the moon. We observe a remarkable decrease in reflectivity in the period 1984- 1997 followed by a gradual increase after that. Correlation of the data with global temperatures (GISStemp Hansen et al) reveals a statistical relevance of R2=0.575 apparently confirming the obvious relationship between reflectivity and temperatures.

The associated variation of energy flux in the Stefan Boltzman law with 10% albedo change, results in a black body temperature change of 2,7 K. However, since the actual temperature variation is a mere 0.6K we must conclude that Earth generates a robust negative feedback that effectively reduces the effects of large albedo changes. This result dwarfs the greenhouse gas forcing theory that considers only flux changes of an order of magnitude less.

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Is this true? No, unfortunately I did not write that study, however if you look at the data, the logic seems nevertheless to be very true, justifying to write it anyway.

http://home.wanadoo.nl/bijkerk/albedo-temp.GIF
http://home.wanadoo.nl/bijkerk/albedo2.GIF

But with exactly the same albedo data, we see this study instead:

E. PallÚ, P R. Goode, P. Monta˝Ús rodriguez, SE. Koonin (2006) Can Earth’s Albedo and Surface Temperatures Increase Together? EOS, Vol. 87, No. 4, 24 January 2006

Generating
this incredibly bizarre narration
based on a completely wrong -not confirmed- assumption about the recent temperatures (still rising - NOT!). The contrary as can be seen at the GISS temp graph.
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Andre
#2
Jan29-06, 12:57 AM
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Okay in common language this means that the study shows that clouds have a much stronger cooling effect than a warming effect. More clouds, more reflection, less sunlight on the ground, lower temperature. Less clouds, more sun, warmer.

Instead of all kind of scary assumptions about self sustained global warming - perhaps almost out of control - is out of the question. This is what the graphs show. Consequently, if less cloud cover is the bigger reason of causing global warming, why would CO2.

But the effect could have been much stronger, considering the back of the envelope calculations of black body temperature. Hence there is a mechanism that moderates the effect.

Conclusion, This is the strongest evidence ever that CO2 has little if any influence on climate and moreover that the climate is generally stable.
WarrenPlatts
#3
Jan29-06, 08:27 AM
P: 237
Quote Quote by Andre
Okay in common language this means that the study shows that clouds have a much stronger cooling effect than a warming effect. More clouds, more reflection, less sunlight on the ground, lower temperature. Less clouds, more sun, warmer.
Tell that to Venus!

If it weren't for global warming, we'd be in the middle of an ice age right now, based on the fact that Earth's perihelion now occurs during the northern summer.

Andre
#4
Jan29-06, 08:55 AM
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A Bizarre Albedo Anecdote

Quote Quote by WP
Venus
But why not Mars? with much more absolute CO2 content in it's atmosphere than Earth but with hardly any greenhouse effect

Anyway about Venus, Let's predict for Venus that it the Venus Express, arriving in April will confirm again the never really solved mystery of the 15% radiation imbalance reported here:

The mystery of Venus' internal heat", New Scientist, Vol. 88, 13 November 1980, p. 437.

Two years surveillance by the Pioneer Venus orbiter seems to show that Venus is radiating away more energy than it receives from the sun. If this surprising result is confirmed, it means that the planet itself is producing far more heat than the earth does.

F.W. Taylor of the Clarendon Laboratory at Oxford presented these measurements at a Royal Society meeting last week. Venus surface temperature is higher than any other in the solar system, at 480 C. The generally accepted theory is that sunlight is absorbed at Venus' surface, and re-radiated as infrared. The later is absorbed in the atmosphere, which thus acts as a blanket, keeping the planet hot. It is similar to the way a greenhouse keeps warm.

Pioneer has shown that there is enough carbon dioxide and the tiny proportion of water vapor needed to make the greenhouse effect work -- just. If this is the whole story, the total amount of radiation emitted back into space, after its journey up through the atmospheric blanket must be exactly equal to that absorbed from sunlight (otherwise the surface temperature would be continuously changing).

But Taylor found that Venus radiates 15 percent more energy than it receives. To keep the surface temperature constant, Venus must be producing this extra heat from within."
Then we could explain that right away with another article, which abstract would read:

Abstract

The main puzzling features of planet Venus have been attributed to several isolated, sometimes conflicting hypotheses. Here we show that a single mechanism can explain the basics of all of them.

Spinning terrestrial planets can be subject to considerable chaotic orbital and spinning perturbations. The gyroscopic response differences of the solid inner core, fluid outer core and mantle to these forcings may result in drifting away of the inner core spin axis from alignment to the main spin axis of the planet resulting in complicated secondary mechanical reactions and ultimately, in loss of spin, due to excessive drag and consequently heat. We propose that this past behavior of Venus has contributed significantly to the current slow retrograde spinning. We contend that this could also explains in principle, the lack of magnetic field, the high temperatures, the dense carbon dioxide atmosphere, the homogenous gravity and the specific geologic history of Venus.
Incidentely, there is a very old thread about that here somewhere.

Quote Quote by WP
If it weren't for global warming, we'd be in the middle of an ice age right now, based on the fact that Earth's perihelion now occurs during the northern summer.
Now about those Milankovitch cycles. The number of believers is declining fast. Richard Muller can explain why.

http://muller.lbl.gov/papers/Causality.pdf

Figure 1 should say it all. It's that weird 100,000 years cycle that kicked in 850,000 years ago that spoils it. Before that in the 41,000 years cycle world it would have been a neat solution.

Check Spencer Weart:

http://www.aip.org/history/climate/cycles.htm

As one reviewer said, "The sheer number of explanations for the 100,000-year cycle... seems to have dulled the scientific community into a semipermanent state of wariness about accepting any particular explanation."(57) The grand puzzle of the ice ages stood unsolved — except insofar as scientists now understood that nobody would ever jump up with a neat single solution.
But we're working on that. The Ice ages are not what they used to be.
WarrenPlatts
#5
Jan29-06, 12:00 PM
P: 237
Are you sure about the total amount of Martian CO2? According to the Handbook of Chemistry and Physics, Mars' atmosphere is 95% CO2, but the total pressure is only .007 bars, whereas on Earth it's only 0.03%. So on Earth there's .03 bars worth of CO2, whereas Mars only has .00665 bars worth of CO2. The Handbook doesn't list the total masses though.

That is weird about Venus radiating energy still. Do you think if a large moon collided with Venus, that would heat it up? Also forming in the inner solar system, it might have a higher concentration of heavy radioactive elements than Earth.

Regarding global warming, I was thinking of a March 2005 article by William Ruddiman in Scientific American that argued that humans have been adding CO2 to the atmosphere for 10,000 years now due to deforestation and agriculture, and that this has prevented the onset of a new ice age.
Andre
#6
Jan29-06, 03:36 PM
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ABout Mars, have been rambling a bit with the numbers here.

http://www.physicsforums.com/showthread.php?t=106854

Actually due to the lower gravity = force = pressure, it's even much more for Mars.

The story for Venus is much more complicated. Not collisions, but inner core and mantly gyroscopic precession properties, fighting each other in special circumstances, like chaotic resonance when precession and obliquity cycles are in resonance.

It's a long story.


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