Runaway Global Warming

[Quantum Quack]

Albedo is, canonically, across all light frequencies, and most often used to express reflectivity of visible light. Long wave infrared is important in the greenhouse effect (i.e. our atmosphere is opaque to many long-IR frequencies) but something with an albedo of "essentially zero" will be black, and will absorb almost all the light energy it receives.

Isn't Billy T speculating on only a partial Albedo?

Now the question becomes what reduction in albedo does a small fraction (say 0.001) of the water drops or ice crystal with soot in them in the cloud make?

That is to say, that the clouds may appear darker from above and not necessarily black as in asphalt. ( ...as you may have suggested?)

 

[billvon]

Isn't Billy T speculating on only a partial Albedo?

He can answer that. I assume he is assuming the ordinary definition of albedo, since he posted a table that uses ordinary albedo.

That is to say, that the clouds may appear darker from above and not necessarily black as in asphalt. ( ...as you may have suggested?)

If they appear white they have a high albedo, and reflect most energy. (Most of the energy from the Sun is within the visible spectrum.) And of course we see via reflected light; we see things that reflect a lot of light as white, and things that reflect almost none as black.

 

[Billy T]

... (1) Dresden was burned in early 1945, and thus we should see a spike in temperature if we really saw such a massive increase in energy absorption. But 1945 was a historically cold year, and indeed 1940-1970 had a net negative temperature slope.
(2) So a tiny fraction of soot in a cloud would make clouds in the area black (akin to fresh asphalt) when observed from overhead? Since that has never been observed by aircraft or satellite, even though we've had plenty of sooty fires (both large and small) that's something that's probably not happening.

On (1) No the burning of all the wood in Dersden's buildings would be a tiny release of heat compared to the coal burnt in Germany during the same four days Desden smoldered. Also Dersden's smoke was not transport to high altitude by the Hadley cell circulation. I don't think it went even half as high as a thunder storm cloud does. They rise to much higher heights as a "Taylor instability" - water vapor in the rising column of air condenses and keeps it much warmer and less dense (buoyant) than the air it is rising thru. When this is no longer the case at the top, but still is lower down, the cloud spreads out laterally as more is still feeding up.

On (2) Again no. I didn't say that the soot would turn the clouds black; but a very small fractional content of soot would (due to the hundreds of small angle scatterings / random walk in "angle space" nature of cloud reflections). I said the albedo could be reduced from ~2/3 to ~1/3. Look at the chart in post 517 of the albedo of various substance: 1/3 is typical of ice and old snow - they don't look black from above, do they?

Here is link I made almost a decade ago on the Dresden air raid (its mathematical planning of the bomb mix mainly but an interesting story about the planners strike going all the way up to Churchill to resolve.): http://www.sciforums.com/threads/60th-anniversary-bombing-of-dresden.44891/page-2#post-770552

 

[billvon]

On (2) Again no. I didn't say that the soot would turn the clouds black; but a very small fractional content of soot would (due to the hundreds of small angle scatterings / random walk in "angle space" nature of cloud reflections). I said the albedo could be reduced from ~2/3 to ~1/3.

You said albedo would be effectively zero. That would be black. You cannot have an almost zero albedo and still have it look white.

On (1) No the burning of all the wood in Dersden's buildings would be a tiny release of heat compared to the coal burnt in Germany during the same four days Desden smoldered.

And that paled in comparison to all the coal burned in England in the 1950's. The black smog killed thousands. But even then there was no significant increase in temperature; indeed, temperatures did not start a rapid rise again until about 1978.

 

[Billy T]

You said albedo would be effectively zero. That would be black. You cannot have an almost zero albedo and still have it look white.

If I said that it should or must have been in the context of heavy (a few % soot fraction) I'm sure I said "reduced to 1/3 from 2/3" and that is how you said that makes a 400W/m^2 increase in solar heating (and I agree it would for the high clouds that were reflecting 2/3).

And that paled in comparison to all the coal burned in England in the 1950's. The black smog killed thousands. But even then there was no significant increase in temperature; indeed, temperatures did not start a rapid rise again until about 1978.

Of course not. London is a tiny fraction of the cross section intercepting sunlight compared to the Hadley circulation between -30degrees South to +30 degrees North latitude. That is half the total earth's cross section for sunlight!

 

[Billy T]

Humans are still reforming to uninhabitable the earth:

In the more than two decades since world leaders first got together to try to solve global warming, life on Earth has changed, not just the climate. It's gotten hotter, more polluted with heat-trapping gases, more crowded and just downright wilder.

The numbers are stark. Carbon dioxide emissions: up 60 percent. Global temperature: up six-tenths of a degree. Population: up 1.7 billion people. Sea level: up 3 inches. U.S. extreme weather: up 30 percent. Ice sheets in Greenland and Antarctica: down 4.9 trillion tons of ice. "Simply put, we are rapidly remaking the planet and beginning to suffer the consequences," says Michael Oppenheimer, professor of geosciences and international affairs at Princeton University.

Links to four related stories below at the link above:
1. NOAA: Globe sets 5th hottest-month record of 2014 Associated Press
2. UN weather agency: 2014 on track for hottest year Associated Press
3. GLOBAL ECONOMY-Creaking euro zone, China sound warnings for global growth Reuters
4. Climate change adaptation comes of age in U.N. talks: TRFN Reuters

No.3 sounds like some good news, but is not - will just relax some of the efforts at alternate energy system* as oil glut continues with ever lower prices - Already US demand for "big cars" is rapidly increasing with < $2 prices for gasoline appearing.

* Including a switch to sugar cane alcohol fuel. Perhaps somewhere in the universe there is intelligent live, but not here.

 

[zgmc]

In another forum that I frequent, someone just posted how they think CO2 is just a fad. Nothing to worry about. We should be more concerned with over-fishing. I wonder what the world would be like if Ted Danson had taken up global warming instead...