This weekly roundup thread is intended for all culture war posts. 'Culture war' is vaguely defined, but it basically means controversial issues that fall along set tribal lines. Arguments over culture war issues generate a lot of heat and little light, and few deeply entrenched people ever change their minds. This thread is for voicing opinions and analyzing the state of the discussion while trying to optimize for light over heat.
Optimistically, we think that engaging with people you disagree with is worth your time, and so is being nice! Pessimistically, there are many dynamics that can lead discussions on Culture War topics to become unproductive. There's a human tendency to divide along tribal lines, praising your ingroup and vilifying your outgroup - and if you think you find it easy to criticize your ingroup, then it may be that your outgroup is not who you think it is. Extremists with opposing positions can feed off each other, highlighting each other's worst points to justify their own angry rhetoric, which becomes in turn a new example of bad behavior for the other side to highlight.
We would like to avoid these negative dynamics. Accordingly, we ask that you do not use this thread for waging the Culture War. Examples of waging the Culture War:
-
Shaming.
-
Attempting to 'build consensus' or enforce ideological conformity.
-
Making sweeping generalizations to vilify a group you dislike.
-
Recruiting for a cause.
-
Posting links that could be summarized as 'Boo outgroup!' Basically, if your content is 'Can you believe what Those People did this week?' then you should either refrain from posting, or do some very patient work to contextualize and/or steel-man the relevant viewpoint.
In general, you should argue to understand, not to win. This thread is not territory to be claimed by one group or another; indeed, the aim is to have many different viewpoints represented here. Thus, we also ask that you follow some guidelines:
-
Speak plainly. Avoid sarcasm and mockery. When disagreeing with someone, state your objections explicitly.
-
Be as precise and charitable as you can. Don't paraphrase unflatteringly.
-
Don't imply that someone said something they did not say, even if you think it follows from what they said.
-
Write like everyone is reading and you want them to be included in the discussion.
On an ad hoc basis, the mods will try to compile a list of the best posts/comments from the previous week, posted in Quality Contribution threads and archived at /r/TheThread. You may nominate a comment for this list by clicking on 'report' at the bottom of the post and typing 'Actually a quality contribution' as the report reason.
Jump in the discussion.
No email address required.
Notes -
The Anthropogenic Global Warming hypothesis is based upon flat earth mathematics.
It would appear the guys-n-gals at Quantumville recalled the high-school formula for determining the surface area of a disc consists of its radius squared times pi (i.e., r² × π) and how the greater surface area of a sphere consists of its radius squared times pi times four (i.e., r²π × 4).
Thus a disc with a radius of 1 will have a surface area of pi (i.e., 3.14) and the same disc converted to a sphere will therefore have a surface area four times more than the original disc (i.e., 12.57). Applying this mathematical thinking to the terraqueous planet we all live on their abstractive minds effectively reduced it to a flat disc which has been expanded four times.
Then they mentally painted this flat earth black.
Thereupon they reduced the (measured) insolation of the oblate spheroid known as Planet Earth to a quarter of its real-world strength – and directed it to impinge upon every square millimetre of their phantom planet twenty-four-seven forever and a day – thereafter applying a radiance versus temperature constant and thus they had their flat earth temperature of -18° Celsius.
As this is at odds with the +15° Celsius real-world temperature they confected the “greenhouse effect” to account for the missing 33° Celsius.
This is where the weirdity of a blackbody flat earth bathed twenty-four-seven with quadruply-weakened sunbeams turns into utter bizarrerie as they deemed some trace gases in the frigid upper troposphere, busily absorbing infrared light radiating from the blackbody surface and emitting it in all directions, to be thus radiating some of it back to the heat-source and thereby raising its temperature via this ‘back-radiation’ thaumaturgy the requisite thirty-three degrees (from -18°C to +15°C).
Moreover, this sci-fi scenario conveniently ignores how the other atmospheric gasses constituting some 99% of the air we all breathe – which are heated at ground-level by conduction and thence by convection as hot air rises and cold air sinks to such an extent as to dominate in determining the thermal structure of the lower atmosphere (troposphere) – are also emitting infrared light in all directions.
Furthermore, no externally heated substance – be it heated by conduction (direct transference from the heat source), by convection (heated gases rising and mingling and mixing with sinking cooler gases), or by radiation (via the heat source emitting infrared light) – can actually raise the temperature of its heat-source (let alone to such a precise degree as 33° Celsius, no more and no less, provided some specified trace gases remain at pre-industrial parts-per-million levels).
(This real-world matter-of-factness does not apply to all the phantom planets in the noncausative quantum solar system, of course, which are busily raising the surface temperature of its central star – the heat-source for all those blackbody flat planets – above 5778° K via a massive-scale variant version of this phantasmagorical ‘back-radiation’).
To summarise:
The physical earth is not flat.
The physical earth is not black.
The physical earth is not static (it is constantly rotating).
The physical earth is not bathed with quadruply-weakened sunbeams.
Sunlight does not impinge upon every square millimetre of the physical earth twenty-four-seven (only during daytime).
Sunlight does not impinge with equal intensity upon every square millimetre of the daytime hemisphere (most obliquely at polar latitudes and dawn-dusk regions).
All atmospheric gases are heatable (not just several trace gases).
All heated atmospheric gases radiate infrared light (not just several trace gases).
The physical atmosphere insulates the daytime hemisphere from heating-up to unliveable temperatures (unlike its nearest neighbour the airless moon).
The physical atmosphere insulates the nighttime hemisphere from freezing to unliveable temperatures (unlike its nearest neighbour the airless moon).
In the physical world no externally heated substance can raise the temperature of its heat-source.
In the physical world some specified trace gases can (as evidenced in notable past eras) exceed by several thousand parts-per-million those several hundred parts-per-million pre-industrial levels deemed sacrosanct by influential doomsayers and/or panicmongers.
tl;dr: there is no “greenhouse effect” in reality (nor “greenhouse gases” either).
This seems awfully vague for a post claiming that somebody did the math wrong. If you believe it's wrong, why don't you run through exactly what the wrong calculation is, why it's wrong, and how to do that calculation correctly? I suspect whatever you're alleging will fall apart when you do that.
As a simple issue, yes of course the actual Earth is not flat, and the entire surface is not bathed in sunlight 24/7. These seem likely to be simplifying assumptions to me. If you wanted to calculate the amount of energy that the Earth received from the Sun, then it would in fact be a very reasonable idea to model the Earth as a flat disc constantly facing the sun. The amount of energy that the Earth actually receives from the Sun should match this model pretty well, since it accounts for the actual effective area facing the sun on our roughly spherical and rotating Earth. Your objections aren't novel, you just haven't noticed or accounted for the fact that they're intended to cancel out.
More options
Context Copy link
Stop! Stop! I don't think the strawman can take much more!
More effort than this, please.
More options
Context Copy link
More options
Context Copy link
Thank you all for the replies. When I get access to the computer once again, I'll try to respond to your questions in detail.
More options
Context Copy link
This is quite an odd angle of attack if your goal is to discredit anthropogenic global warming. The greenhouse effect was demonstrated in the 19th century well before the "guys-n-gals at Quantumville" produced any proper climate models of the Earth, and can be observed in action just as well on other planets like Venus and Mercury.
More options
Context Copy link
This is... not even wrong.
The greenhouse effect exists; it's why Venus is hotter than Mercury, despite being further from the sun. You can model it using basic physics, treating the Earth as a sphere and having its atmosphere, and its average surface temperature is indeed hotter with an atmosphere than without.
Increasing the amount of CO2 in the atmosphere increases the greenhouse effect; when you do that simple model based on basic physics, the increased temperature due to anthropogenic CO2 is a meaningful fraction of a degree. None of this is even slightly controversial.
Where AGW skepticism has some legs is when it comes to modeling feedback mechanisms; without them, the temperature increase isn't anything to really worry about. We know positive and negative feedback mechanisms exist, and they interplay in a complicated way. How much total warming does a positive forcing result in? Most models suggest there's a significant multiplier involved (in large part due to increased water vapor), though there's more uncertainty involved than taking everything the models say at face value.
More options
Context Copy link
And Sun is hotter than Earth, so insulation effect does not break the second law of thermodynamics.
If I would teach physics I would print this comment and give students to find as many mistakes as they can in this reasoning.
More options
Context Copy link
...are you really complaining that they didn't write out and evaluate the surface integral over the daylit hemisphere ∫∫S Isuncos θincidencedS? I assure you that it simplifies to Isunπr²
I assume you are referring to the second law of thermodynamics? The greenhouse effect doesn't violate the second law. The net heat flow is still surface>atmosphere>space. The fact that infrared-absorbing gasses reflect some of this heat back to the surface would not cause the surface to "heat up" in the absence of external solar radiation. The net effect is to slow down the rate of energy emission from the surface out into space. Net heat flows from hot to cold in every step.
I appreciate putting someone in their place with the power of calculus, but a simpler demonstration would be a diagram of light hitting the earth. The portion of light captured by earth will be a circle, not the surface area of a half sphere, let alone the surface area of a full sphere.
The last (which is @Sky is assuming) would be attained if, with a paper earth, we cut earth open and lay it flat on the table to capture sunlight on all its surface.
Those are really fancy symbols there @popocatepetl
Are you sure you know what they mean?
I’ve got a strange hunch that you do not. The jig is up.
phrase of jig INFORMAL•NORTH AMERICAN
More options
Context Copy link
Oh sure, that's the simplifying assumption which is presumed to be understood. Unfortunately, OP did not understand it. He may be confused by how the locally-valid rule I = Isuncos θincidence can give rise to the much simpler rule PEarth = Isunπr² when summed over all localities. The way to resolve such confusion is to evaluate the integral yourself and see that it all cancels out.
More options
Context Copy link
More options
Context Copy link
More options
Context Copy link
The greenhouse effect is so trivially shown experimentally that it's a fairly standard activity for 6th grade kids to do.
I'm wondering where you got this rather interesting sequence of thoughts from. There are a whole bunch of various obvious errors that jump out - for example you seem to be confused as to what is actually warming, as you seem to think the Earth itself is a single system (like when you say no substance can raise the temperature of its heat source).
Actually that does not demonstrate the greenhouse effect!
From the PDF at the link: "This activity mirrors how a greenhouse works, but it’s not exactly the same as the greenhouse effect that is taking place in the Earth’s atmosphere."
The effect of the actual greenhouses is due to the glass preventing the air dissipating its heat due to convection.
The poorly-named “greenhouse effect” doesn’t actually explain how greenhouses work, it has to do with the so-called “back-radiation”.
Do you have a link to an experiment that demonstrates the actual effect in action? It should be easy to find one if the effect is real.
Whoops, I linked the wrong one. The normal idea is to mix baking powder and vinegar in a jar to create CO2 and then compare it to various controls, like here.
That experiment seems to demonstrate that a jar with a higher concentration of CO2 in it will be hotter than a jar with regular air in it, after a period of being heated by an external source (eg a heat lamp) for 5 to 10 minutes.
The “greenhouse effect” however isn’t quite this. It is rather that the surface of the Earth is said to supposed to be -18C, but then the surface of the Earth heats the atmosphere which in turn heats the surface of the Earth to a higher temperature, raising it by +33C to reach +15C. i.e. the atmosphere is externally heated (by the Earth) and it then heats its heat source (the Earth) to a greater than original temperature.
As such the experiment you cited doesn’t demonstrate this. It would need to, for example, show that the gas in the jar ends up raising the heat source (e.g. the heat lamp)'s temperature.
Specifically what's warming is not "the Earth" but the oceans and troposphere. The other layers of the atmosphere are actually cooling because of the enhanced greenhouse effect within the troposphere. So it's not the "heat source" that is being heated (most of the infrared radiation being captured by GHGs comes from radioactive decay of elements within the Earth's crust).
Earth's internal power = 44 TW. Sunlight striking the Earth = 170 PW = 170,000 TW.
(from Atomic Rockets' Boom Table)
Even accounting for albedo reflecting like 30% of that number straight back into space, Earth's internal heating is a tiny contributor to its energy balance. It's not like the giant planets, where internal heat is much more significant to overall energy balance (because radioactive heat scales with mass i.e. radius^3 and leftover heat from their formation scales with radius^5 while solar heat scales with radius^2, and also because they're further from the Sun); Neptune actually does radiate over twice as much energy as it receives from the Sun, though I don't think this is true of the others.
More options
Context Copy link
More options
Context Copy link
More options
Context Copy link
More options
Context Copy link
More options
Context Copy link
More options
Context Copy link
Sorry. Is it some troll? And you wasted such username on it?
Really? That is on level "Australia does not exists, it is all lies"
Are you also claiming that glass/plastic greenhouses are a Jewish plot?
More options
Context Copy link
...right, that's not what the "black-body spectrum" refers to. All macroscopic objects at finite temperature emit radiation with a temperature-dependent spectrum that we call "black body radiation". The human body, coffee mugs, hot steel rods, etc. are all very far from black in color, yet the radiation they emit is all extremely well predicted by the black body spectrum.
In fact, the greenhouse effect is basically just saying that a blacker earth would be hotter, and a more reflective earth would be cooler. If the earth is very reflective, only a small portion of the sun's rays will be absorbed, so the earth's surface will radiate heat until it gets to a temperature where the absorbed energy is equal to the black-body emitted energy. Same thing in reverse if the earth starts absorbing a greater fraction of the sun's energy.
Please study more high school physics before proclaiming you've found a glaring error in a century-old physics phenomenon.
Climate change might not be happening, and even if it is happening it might very well basically be a nothingburger for human civilisation... but these have nothing to do with the rock-solid fundamental physics of the greenhouse effect.
More options
Context Copy link
I don't know who is putting this out (you linked nothing, therefore, we don't know if they disclaimed that this is an abstracted model), but if we're gonna be really pedantic, we could also point out that the Earth technically isn't even a sphere of any level of perfection (at least, when you take away the water).
More options
Context Copy link
Can you link to a source for the supposedly-erroneous models?
I know enough about heat transfer to run some hand calculations (and write them out in a hopefully-comprehensible way), but I don't want to start from scratch.
More options
Context Copy link
Spot on.
Thanks
More options
Context Copy link
Avoid low effort comments like this, please.
More options
Context Copy link
More options
Context Copy link
More options
Context Copy link