Thursday, 17 November 2022

"Carl Sagan testifying before Congress in 1985 on climate change"

The video below popped on YouTube. Watch carefully from 3 mins 20 seconds or so, this is where he launched (or re-launched) the Big Climate Lie.

Note how Sagan constantly refers to "Earth's surface", not mentioning clouds. By implication, he is including clouds when considering solar radiation absorbed (or else his calculation wouldn't give the answer of about 30 degrees), so the obvious next question would be "Do clouds and cloud free ocean/land surface, in total, radiate upwards the same amount as they absorb in solar radiation?", as a reality check if nothing else, to which the answer is a resounding "Yes."

If the answer were "No", then this would raise a lot of questions - maybe there is a positive (or a negative) Greenhouse Effect? if so, what causes it?

Sagan neatly sidesteps this obvious question, and at 4 mins 20, launches into an alternative reality where clouds don't exist, and the solar radiation absorbed by clouds and oceans/land is all directly absorbed by the land/oceans. If it were, it would be a lot cooler - he is mathematically correct in saying that land/oceans would be about 30 degrees cooler than they are (the accepted figure nowadays is 33 degrees). James Hansen explained the calculation in more detail in 1988, three years later.

[Enjoy the cutaway shots of Al Gore with dollar signs rolling in front of his eyes.]

At 4 mins 30 Sagan concludes, "And why is it too low... it's too low because something was left out of the calculation. What was left out of the calculation..?"

An attentive listener would have screamed, "The clouds, you moron!", but nope.

Sagan of course trots out his preferred answer: "The Greenhouse Effect" and then waffles on about CO2 trapping heat and all that nonsense.

18 comments:

Lola said...

Ho. That same video popped up on my youtube as well. I tell you, They Know Who We Are Where We Live. oo errr

Mark Wadsworth said...

L, I keep telling them where I live. And that their calculation is irrelevant and misleading.

Bayard said...

The more money there is behind these lies, the more persistent they are. I see plenty of science denying in the historic building world, mainly around the behaviour of water in its various forms in historic buildings. The "damp-proofing" industry is as much based on fake science as Alarmism.

ontheotherhand said...

If the earth was completely covered in cloud all the time, would it be warmer at ground level?

Mark Wadsworth said...

OTOH, that depends on how high the clouds are.

Venus is covered in clouds all the time, but they are very high.

Venus cloud tops absorb enough sunshine to warm them to 200K-ish.

Cloud tops are 70 km high.

Gravity induced lapse rate (gravity divided by spec heat cap) = 8 K/km.

Hard surface temp = 200K + (70 x 8) = 760K (or something like that).

ontheotherhand said...

Thanks MW. I understand that the extent of added warmth at ground level depends on the height of the permanent clouds, but is it warmer on average at ground level with permanent clouds at any height? e.g. if Venus clouds were only 1k high, would ground temperature be 208K? Here on earth, if we had permanent cloud, even low cloud, would the average ground temperature of the planet become higher?

ontheotherhand said...

At least he says at 5.48 that the "greenhouse effect is a misnomer for more reasons than one."

Mark Wadsworth said...

OTOH

"is it warmer on average at ground level with permanent clouds at any height?"

Clearly no.

"if Venus clouds were only 1 km high, would ground temperature be 208K?"

Yes.

"Here on earth, if we had permanent cloud, even low cloud, would the average ground temperature of the planet become higher?"

No. If clouds were lower than they are (assuming still 2/3 coverage) it would be cooler at sea level.

That is why there is more or less no GHE on Mars, despite it having more CO2 than Earth. There are a few very sparse clouds (mainly dust, not water vapour) at only (say) 1 km height, rest of hard surface is exposed and can radiate directly to space.

Mark Wadsworth said...

OTOH, the other thing that winds me up is that they say sea level temps are higher because they absorb reflected radiation.

This is putting the cart before the horse. Radiation is just one kind of energy transfer, there is not a fixed constant amount.

Far more accurate to say that sea level radiates more than expected because it is warmer than expected. It is converting lapse-rate temperature/energy back to IR radiation.

A three-bar electric heater isn't radiating because it absorbs radiation, it is hot because we put electricity through it and that electrical energy gets converted to radiation, thermal and light energy.

ontheotherhand said...

He also says at around 5 minutes, "The air between us is transparent. But if our eyes were sensitive at 15 microns in the infra red, we could not see eachother. The air would be black between us, and that's because of carbon dioxide which is very absorbing at 15 microns"

Can that be true? CO2 is only 4 parts per 1,000,000, so those molecules would have to work pretty hard to block out all 15 micron light

Bayard said...

"Sounds like a load of crap to me"
"It is a load of crap, sir".

Catch 22

Mark Wadsworth said...

OTOH, it's 400 ppm, not 4.

The claim might or might not be true, but is irrelevant as it has no impact on
a) sunlight hitting clouds or sea level surface.
b) the lapse rate.
c) the height of clouds.

B, I thought that was Austin Powers?

Bayard said...

"The claim might or might not be true,"

It isn't, even if our eyes were only sensitive to IR radiation of that wavelength, because there are not enough CO2 molecules to stop all the IR. A particle of black dust is very absorbing of visible light. If the air has 400ppm of black dust particles in it, it wouldn't be black, it would be slightly smoky. You probably got more than 400ppm of smaoke particles in an average pub at closing time, back when smoking in pubs was allowed.

Bayard said...

"B, I thought that was Austin Powers?"

Probably quoting Catch-22.

Mark Wadsworth said...

B, don't let them drag you into irrelevant topics. Neither here nor there. The 33 degree GHE is based on a crass, pseudo-scientific and provably incorrect calculation. End of discussion.

Bayard said...

True, however little things like that prove that either CS doesn't know what he is talking about, or he is a liar.

Mark Wadsworth said...

B, well, you can see across a smoky pub, like you can see through a few yards or mist or fog. But you can't see through a hundred yards of mist or fog.

As ever, I wouldn't bother arguing the toss on this, seeing as it is irrelevant - it can't change the lapse rate.

Lapse rate on Venus is exactly what we would expect based on acceleration due to gravity on Venus and an atmosphere that is nearly 100 CO2. Those are the only two relevant variables (apart from Latent Heat on Earth).

Bayard said...

"But you can't see through a hundred yards of mist or fog"

Maybe not, but it isn't black, as CS was claiming. Even the thickest, densest smo, where you can hardly see you hand on the end of an outstretched arm doesn't cut out all light.