Good article about scientific consensus

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Scientific consensus is *not* emperical verification. That is precisely what my examples were illustrating.

Too technical? Perhaps not, but dealing with a field that physicists don't really know. Biology is certainly not "too technical" for the average physicist, but that doesn't change the fact that the average physicist doesn't know nearly enough about biology to reasonably approach the major questions in it. In science, people are specialized into very narrow disciplines, and once they go outside their area of expertise they aren't much better than any other layman.


You base your rejection of the scientific consensus on the perceived failings of non-experts who happen to promote the scientific consensus?

Yeah... that's not at all convincing.


A PhD in physics is irrelevant to climate change. It might make him an expert on some area of physics, but it doesn't make him any more reliable about climatology, or biology, or any other field.

Yes, it is, actually, because scientists are the ones best equipped to understand the data. The things you mentioned were later disproved when new evidence came to light. New evidence means old ideas can be wrong. But, based on the evidence they had, those wrong ideas were the best conclusions that could be made. Now, you could hypothesize that at some point we might find new data that will change our conclusions, but in the present we can only act on what evidence we have available to us.

I think of harping on scientific consensus while insisting that the audience is incapably of evaluating the evidence for themselves as a new spin on argument from authority. Aside from the logical fallacies involved with an argument from authority, I just get plain riled by the very nature of them, being told that I have to accept a conclusion because of who it comes from just doesn't sit well with me. In the case of climate change, the way in which skeptics and questioners have been ostracized and marginalized just leaves a bad taste in my mouth, to my way of thinking if the science was that solid it could stand on it's own merits without being shielded from criticism.

You're wrong on that, Dox. It is not an argument from authority fallacy because I am not claiming the scientific consensus as absolute proof of anything. An argument from authority is acceptable in an inductive argument, provided that it is a legitimate authority.


I don't say you have to accept the conclusion. I only say that it is irrational to assume that someone who knows more about a subject than you do is wrong. It is far more likely that you are the one who is mistaken. This applies to all of us when we leave our particular field.


I think climate skeptics have exaggerated the extent of their "persecution" a great deal.

A PhD physicist would know the difference between a well supported theory and an ad hoc model that has been fiddled to fit the data.

It turns out the particle physicists have the best scientific theory ever formulated -- the Standard Model of Particles and Fields which, despite the name, is a scientific theory which predicts accurately to twelve decimal places.

ruveyn

Last edited by ruveyn on 02 Sep 2010, 7:57 am, edited 1 time in total.

So had Isaac Asimov, as related in his novel Caves Of Steel in regard to the annoying Malthusian Prophets Of Doom.

That's not even remotely true.

Here is a another good text at a site hosted by the American Institute of Physics:



"Here's what all scientists agreed they knew by 1988

To stay at a constant temperature, the Earth must radiate as much energy as it receives from the Sun. We receive this energy mostly as visible light which warms the surface. Being much cooler than the Sun, the Earth radiates most of its energy as infrared rays. A calculation using basic laws of physics shows that a planet at our distance from the Sun, emitting the same total amount of energy as it receives, will have a temperature well below freezing. Then why is the actual average surface temperature higher, about 14°C? Infrared radiation beaming up from the surface is intercepted by "greenouse" gas molecules in the lower atmosphere, and that keeps the lower atmosphere and the surface warm. The radiation that finally escapes is mostly emitted from higher levels of the atmosphere, levels that are indeed well below freezing (-18°C, for details see the essay on simple models).

The nitrogen and oxygen gases that make up most of the atmosphere don't intercept infrared radiation. The most important greenhouse gases are water vapor and carbon dioxide (CO2). The level of carbon dioxide in the atmosphere was observed to be rising rapidly, and the only reasonable explanation was that this was due to the enormous emissions from human activities."

from: http://www.aip.org/history/climate/summary.htm




And a simple physical model that I found at the website of a scientist who studies the dynamics and evolution of planetary atmospheres :


"Tutorial on the Greenhouse Effect

This page presents a simple physical model of the greenhouse effect that demonstrates how the blanketing effect of greenhouse gases in the atmosphere can elevate the surface temperature of a planet. The model is an instructional "toy model," meaning it strips the process down to its essential elements so that the basic ideas are easy to convey. Models that are used to make predictions by climate experts are substantially more sophisticated, but at root the physics are similar to what is described below.

The first key idea is that hot objects lose heat faster than cold objects. This is obvious from everyday experience (you can feel the heat coming from a fire). Detailed observations show that the rate of heat loss is very sensitive to temperature -- specifically, if the temperature is doubled (on an absolute scale), the rate of heat loss is not twice as high -- it is sixteen times as high.

The second key idea is that planets are near an equilibrium where heat lost to space almost exactly equals sunlight gained. Because hot objects lose heat rapidly, they tend to cool off if they have no energy source to maintain their temperature. On the other hand, because cold objects only lose heat slowly, they tend to warm up in the presence of energy sources. In both cases, the objects converge toward a condition where they lose heat at exactly the same rate that it is supplied by energy sources. In the case of planets, the energy source is sunlight.

Let's see how this works for a planet with no atmosphere. At the position of Earth, the absorbed sunlight is 240 Watts/meter2. In equilibrium, this means that the planet would lose heat to space -- as infrared radiation -- also at a rate 240 Watts/meter2. How can we calculate the temperature from this? Detailed measurements show that, mathematically, the relationship between heat loss and temperature can be described by the equation F = σ T4, where F is the rate of heat loss (the "heat flux") and σ is a fundamental physical constant (called the Stephan-Boltzmann constant) with a value of 5.67 x 10-8 Watts/meter2 Kelvin4. We can rearrange this equation to state that, for a planet with no atmosphere,

T = (F/σ)1/4.

Plugging in F=240 Watts/meter2 and σ=5.67 x 10-8 Watts/meter2 Kelvin4, we find that T=255 K, which corresponds to a temperature of -18oC or 0oF.

Thus, if Earth had no greenhouse effect, the average surface temperature would be 0oF -- far below the freezing temperature! The oceans would be totally frozen and life would not exist on Earth.

How does having an atmosphere with greenhouse gases affect this situation? The greenhouse effect only works if the atmosphere is transparent to sunlight but opaque to infrared (heat) wavelengths. Many gases -- CO2, water vapor, methane -- behave just this way. These are the greenhouse gases.

In this case, the Earth still gains 240 Watts/meter2 from the sun. It still loses 240 Watts/meter2 to space. However, because the atmosphere is opaque to infrared light, the surface cannot radiate directly to space as it can on a planet without greenhouse gases. Instead, this radiation to space comes from the atmosphere.

However, atmospheres radiate both up and down (just like a fire radiates heat in all directions). So although the atmosphere radiates 240 Watts/meter2 to space, it also radiates 240 Watts/meter2 toward the ground! Therefore, the surface receives more energy than it would without an atmosphere: it gets 240 Watts/meter2 from sunlight and it gets another 240 Watts/meter2 from the atmosphere -- for a total of 480 Watts/meter2 in this simple model.

Now like the atmosphere, the Earth's surface is near an equilibrium where it gains and loses energy at almost the same rate. Because the surface gains 480 Watts/meter2 (half from sunlight and half from the atmosphere), it also must radiate 480 Watts/meter2. Unlike the atmosphere, however, the ground can only radiate in one direction -- upward. Thus, the surface radiates 480 Watts/meter2 upward, and because the atmosphere is opaque to this infrared light, it is absorbed by the atmosphere rather than escaping to space. Notice that the atmosphere, the surface, and the planet as a whole each gain energy at exactly the same rate it is lost.

We can again use the simple expression T = (F/σ)1/4 to calculate the temperature of the surface. Using F = 480 Watts/meter2 and σ=5.67 x 10-8 Watts/meter2 Kelvin4, we find that T=303 K, which corresponds to 30oC or 86oF.

Key points:

♦ Without greenhouse gases, we calculated that the surface temperature would be 255 K (0oF), whereas with greenhouse gases we calculated the surface temperature would be 303 K (86oF). Therefore, the blanketing effect of atmospheric greenhouse gases has caused an elevation of the surface temperature. This is the greenhouse effect!

♦ The greenhouse effect is NOT a situation where "heat is trapped and can't escape." The above calculation makes clear that the opposite is true: the greenhouse effect is how the atmosphere adjusts so that it CAN lose heat when greenhouse gases are present in the atmosphere. About the same amount of heat escapes to space regardless of whether a greenhouse effect exists.

♦ In our simple model, we predicted an elevation in surface temperature of 48oC (86oF). This is an overestimate. On the real Earth, the current average surface temperature is 288 K (59oF), not 303 K, so the actual greenhouse effect causes a warming of only 33oC (59oF) relative to an atmosphere without a greenhouse effect. Thus, the crude model presented here overestimates the strength of the greenhouse effect by 50%. This discrepancy is caused by several factors that we neglected. For example, some sunlight is absorbed in the atmosphere rather than at the surface, and some infrared radiation from Earth's surface can escape to space rather than being absorbed in the atmosphere. These effects are all included in real climate models. Properly taking these effects into account would lead to a predicted temperature much closer to the actual temperature.

♦ An increase in the abundance of CO2, water vapor, methane, and other greenhouse gases causes a decrease in the fraction of infrared radiation from the surface that can escape to space. This forces the surface temperature to increase as the Earth strives to reach the new equilibrium. More greenhouse gases mean a stronger greenhouse effect and a hotter planet.

♦ When the greenhouse gas abundance is increased, it takes time for the system to warm to the new equilibrium temperature. During these times, the Earth absorbs slightly more sunlight than it loses heat, which is what allows the warming. Thus, during these times, the Earth is slightly out of equilibrium. What this means is that even if the abundances of greenhouse gases became constant right now, the Earth would continue to warm by another 0.5-1oC (1-2oF) over the next 50-100 years as it reached the new equilibrium temperature. This delayed warming has already been caused and is unavoidable. Of course, additional warming will occur if greenhouse gas abundances continue to increase. "

from: http://www.lpl.arizona.edu/~showman/greenhouse.html



Also the climate models as the Goddard Institute for Space Studies (GISS) model have predicted future temperature trends accurately despite its "chaotic" "non-linear dynamics".
link: http://pubs.giss.nasa.gov/docs/2006/200 ... etal_1.pdf


Good work Orwell you are 100% right.

The Greenhouse Effect is not what is questioned, that is actually quite able to be considered a design feature of the planet. However it is the environmentalist scare tactics involved acting as though the Greenhouse Effect is going to run out of control (90's era propaganda at least). As such, they leave out the aspect of negative feedback systems, i.e. dihydrogen monoxide..., actually, they do mention part of it in the bullet you quoted:

"An increase in the abundance of CO2, water vapor, methane, and other greenhouse gases causes a decrease in the fraction of infrared radiation from the surface that can escape to space. This forces the surface temperature to increase as the Earth strives to reach the new equilibrium. More greenhouse gases mean a stronger greenhouse effect and a hotter planet."

However, they neglect to mention that water vapour also increases the amount of infrared light absorbed during the day cycle. It is only during the night cycle that cloud cover allows for the retention of infrared light.

No. It. Isn't.

Empirical - research that derives its data by means of direct observation or experiment

Empirical verification means 'I have the data'. A consensus is 'I have people who agree with me'.

Generally speaking the scientific consensus follows the data -- however, scientific consensus is not data.


The aether was. Epicycles were a bad interpretation of the data that already existed. They were (for those who don't know) special extra cycles superimposed on the orbits of the planets, to make their orbits around the Earth make sense. Then someone looked at *the same data* and said, 'hey wait a minute, this would be much simpler if everything just orbited the Sun instead'.

Note that I said, "practically", which means that scientific consensus is based on empirical verification, I'm not saying that consensus is the data.

I know that consensus is not infallible as you sated but it is the best we can get, and the community of scientists know better than you.


Are you implying that when a theory is falsified it means it must not have been empirical verified? If that is so, it doesn't make sense, it contradicts scientific principles because it seems your assertion implies that empirical verfication must lead to unfalsifiability.


Which means that science has evolved and improved with time.


No, I don't claim that and I doubt anyone here would do that, and I don't see what is so wrong about that. I mean, how else can it be better, currently? Would you think of having a better proposal for a better adherence to reality? Note that this question is moot, but anyway.

Unlike string theory, the theory that humans are partially responsible for climate change actually does have empirical support.

I don't know how that "popular" is the string theory actually, it may probably be in the media though, but isn't the standard model the current accepted theory rather?[/quote]

String theory is actually quite popular. The standard model is the accepted theory of three of the four known forces, however the majority of scientists believe it is also incomplete and leaves some unresolved questions. String theory is appealing because it not only seems to be the best theory available to resolve a fundamental mystery in physics, e.i. that quantum field theory is in contradiction with general relativity but it is also incorporates the other forces besides gravity as well. Thus making it a theory of everything.

Let me preface this: I am not arguing against string theory. With that out of the way, it may be a nice "theory of everything" and be desirable in that aspect, but if it is not yet testable it is not yet a theory, rather it is a hypothesis. When people start giving the title "theory" or "fact" to things which still need to be empirically challenged, it kinda degenerates all of science.

Yes, some physicists criticize the string theory that it should not be classified as a theory for lack of empirical support, which makes sense, and I think some even suggest that it is pseudoscience.


That's great! You finally agree that the acceptance of Creationism as science, degenerates all of science.