The results to last fortnight's poll were as follows:
The French want to allow 'refugees' seeking asylum in the UK to lodge their claim while still in France.
Good idea (we can reject them out of hand and they remain France's problem) - 73%
Bad idea - 27%
That is of course on the assumption that their claims are processed by British officials, and not simply rubber stamped by French officials keen to get rid of them.
-------------------------------
So China and the USA signed up to this Paris Agreement on restricting CO2 emissions last week.
Which made me think, unless they are just doing this for presentational reasons, maybe I'm wrong and there is something in this global warming stuff.
So I re-read a standard explanation, all just about plausible until this bit:
Without this natural greenhouse effect, primarily owing to water vapor and carbon dioxide, Earth’s mean surface temperature would be a freezing -1°F, instead of the habitable 59°F we currently enjoy. Despite their small amounts, then, the greenhouse gases strongly affect Earth’s temperature. Increasing their concentration augments the natural greenhouse effect.
That is, I am afraid, complete bollocks and if that's all they've got as evidence then I am still not buying it.
The real reason why the surface is approx. 30C warmer than it 'should' be, bearing in mind distance from the sun and albedo is because of Boyle's Law.
UPDATE: I conferred with VFTS, the more appropriate gas law is one of Gay-Lussac's Laws:
The pressure of a gas of fixed mass and fixed volume is directly proportional to the gas's absolute temperature… This law holds true because temperature is a measure of the average kinetic energy of a substance; as the kinetic energy of a gas increases, its particles collide with the container walls more rapidly, thereby exerting increased pressure.
So higher pressure = higher temperature and higher temperature = higher pressure and vice versa. The top half of the atmosphere pushes the bottom half down (compresses it) ; and the bottom half pulls the top half down (expands it). The bottom half is warmer than it 'should' be and the top half is colder than it 'should' be. On average, it is the right temperature, the -1F referred to in the first excerpt.
The atmosphere works like a giant heat pump - the upper atmosphere is colder than it should be and the lower atmosphere is warmer than it should be. The actual temperature half way up by volume i.e. 5.6 km is approx. 30C cooler than the surface and is in fact exactly what you would predict, bearing in mind distance from the sun.
So that's this week's Fun Online Poll.
Vote here or use the widget in the sidebar.
Put On Your Big Boy Pants, Maybe?
3 hours ago
36 comments:
"That is, I am afraid, complete bollocks and if that's all they've got as evidence then I am still not buying it."
I fear you have misread Boyle's Law. Boyle's Law states that as a gas is compressed, so it heats up, but it only heats up because work is being done compressing the gas. In the atmosphere, no work is being done because nothing is actively being compressed. Sure there is pressure, but it is not changing in a given position.
So their explanation is only half bollocks: the water vapour is doing all the work of keeping us warm. They have to say what they say about CO2, though, or else they will be classed as heretics (deniers) and put to the Extraordinary Question.
B, you walked right into that one.
Boyle observed that you compress a gas and it heats up. Then the heat dissipates away over time into the surrounding container as you would expect. If the gas were in a perfectly insulated container, it would retain the extra temperature for ever, obvs.
Ignoring the bit of the heat that dissipates away to the earth (which reflects it back anyway), where is the extra temperature going to go? It will just heat up the nearest bit of the atmosphere - to the extent it was cooler in the first place.
Seeing as all air at the same level is going to be a similar temperature, not much happens and the temperature remains the same and never dissipates.
For sure, warm air rises and cool air falls, but as it rises it expands and cools, and as it falls it is compressed and heats up. By going up and down, air is doing work on itself and maintaining the original position.
See here.
Excellent. This also explains why the atmosphere of Venus at altitudes where it is Earth-equivalent pressure is exactly what the present Earth atmosphere would be, should the Earth be as close to the Sun as Venus. The Venusian atmosphere is about 97% CO2; for the "CO2 is a greenhouse gas" meme to be right, this temperature should be a little more than 11 "doublings" higher - i.e. at least 11K higher, depending upon the accepted "environment climate sensitivity" (presently accepted to be ~1K per doubling, though some argue it could be 8K).
Mr Wadsworth puts down Bayard's argument very effectively.
RR thanks. That's another good comparison, Venus with thick atmosphere, Mars with thin one and Moon with none.
... but to be fair, I've never been to any of those, much less walked up a mountain on one, not like on Earth where I and billions of others have experiencd this stuff first hand.
"Boyle observed that you compress a gas and it heats up."
Yes, but only while it is being compressed. The earth's atmosphere is compressed, it is not being compressed. No work is being done. Your explanation defies the first law of thermodynamics. A gas being compressed heats up, because the work to compress it puts energy into the gas and that energy has to go somewhere. If an already compressed gas gave off heat, then we wouldn't need central heating boilers, we'd just have compressed air cylinders sitting in our houses.
And no, the earth's atmosphere is not still warm from that far-off time when it formed and the compression happened.
I only have A level physics. However not all gas have the same chemical properties (I do have a Phd in Chemistry although not relevant to this). And therefore changing the composition from gas x to y must have an effect.
B, you missed the bit about compressing a gas contained in a perfect heat insulating container.
LF, quite probably. But even if we stripped out every last molecule of GHG, the surface would be 30C warmer than from sunlight alone.
Mark, no I didn't. The Earth's atmosphere is not "a perfect heat insulating container." If it was, it would have long since reached the melting point of rock, what with all the megajoules of heat pouring in from the sun every day.
"Boyle's Law states that as a gas is compressed, so it heats up"
Sorry, I was wrong there, that's the Combined Gas Law. Boyle's law gives the relationship between volume and pressure at a fixed temperature. We are talking about a mechanism where pressure, temperature and volume are varying.
"For sure, warm air rises and cool air falls, but as it rises it expands and cools, and as it falls it is compressed and heats up. By going up and down, air is doing work on itself and maintaining the original position."
In order for the hot air to rise in the first place, it must be heated from an outside source of energy. As it rises, it expands, because the pressure falls and the temperature falls. This is because the same amount of heat energy has to be spread over a greater volume of gas, therefore each given volume of gas contains less energy, therefore the temperature is lower. However, the air still contains the same amount of energy. Higher in the atmosphere it is cooler, so our rising air is cooled by conduction as it mixes with the cooler air until it is indistinguishable from the air about it. There is no internal mechanism by which the cooler air now becomes more dense than the air about it, causing it to fall.
Similarly, if a body of air is cooled by an outside agency (e.g. a rain shower) then it will fall and to the extent it is being compressed, so its temperature will rise, but again, only to the temperature of the air around it. If it rose above the air about it, the air would then start to rise again. It is not "doing work on itself" and contributes no heat to the surrounding air. If it was "doing work on itself", it would have to be acting as a source of energy and there is nowhere for that energy to come from (1st Law of Thermodynamics).
As Scotty said "Ye canna argue with the laws of physics".
B, you are deliberately misquoting me. This effect was onserved, measured and explained centuries ago. Instead of asking me to explain it yet again, why don't you just google what the standard scientific explanation is?They all say much the same thing. High pressure = higher temperature etc.
BTW Boyle's law only works for an ideal gas or at moderate temperatures/pressures.
Have you taken this into account?
LF, don't get picky. Simple question, if the atmosphere were purely N and O without any H2O, CO2 or CH4, how much colder would the surface temp be? 1C or 2C, or as much as 30C? All the explanations suggest 1C or 2C.
https://tallbloke.wordpress.com/2012/12/10/why-earths-surface-is-so-much-warmer-than-the-moons-part-1/
@MarkWadsworth"LF, don't get picky. Simple question, if the atmosphere were purely N and O without any H2O, CO2 or CH4, how much colder would the surface temp be? 1C or 2C, or as much as 30C? All the explanations suggest 1C or 2C.
"
I didn't think I was being picky.
If H20, C02, methane etc are responsible for the temperature being 1C then surely increasing them could cause climate change?
FWIW I think changing the atmosphere's composition could be a bad thing, I am not sure if all the computer models are correct.
Very warm in Northampton for the time of year.
L Fairfax. N and O aren't infrared absorbents so without GHGs we should expect lower temps. Putting more GHG's into the atmosphere over time would be likely to accelerate global warming or possibly counter global cooling if that were evident. As it is the Milankovitch [spelling?] cycles currently should be enabling cooling and the Milankovitch cycles are thought to have been responsible for ushering in global ice ages and inter-glacials for about the last million years. That we are not experiencing cooling but warming and that we have spent the last couple of hundred years pushing CO2 into the atmosphere via fossil fuels etc would be the obvious explanation for such 20th/21C warming.
That the models we are being guided by actually manage to model variations in GHG concentrations and global temperature changes that have been recorded over the last hundred years or so rather well would suggest current mainstream science is on the right side of the anthropomorphic GW debate. Those pushing cod physics in order to cast doubt on these arguments really should remain focused on LVT and CI. Or else their advocacy for those things will just be tarnished by repeated efforts to align themselves with conspiracy theorists and the global warming deniers confederacy of cranks. It's almost as if some have cottoned onto the fact that denying AGW is at least popular with the masses whereas LVT is not so gaining a following for AGW denial might spill over into some increased support for LVT?
LF and PC, I note that neither of you wishes to answer my earlier simple question.
PC, I am not "denying AGW", I am asking how much of the apparent extra 30C is due to GHG. I'm happy with any answer between 0C and 30C
Mark, how can I be misquoting you when I cut and pasted your very words?
OK, you are postulating a mechanism whereby heat is transferred from the outer the atmosphere to the inner atmosphere by air being cooled at the outside atmosphere and so, becoming less bouyant, sinking down towards the surface of the Earth. As it approached the surface, it is compressed and so becomes warmer, according, you say, to Boyle's Law (which actually doesn't say anything of the kind). Because it is now warmer, it then warms the air close to the surface, making that air warmer than it would otherwise be.
"That is, I am afraid, complete bollocks"
The air cannot carry heat energy from the outer to the inner atmosphere because the amount of energy in the air as it falls has to remain the same unless it is heated by conduction or radiation, which we are discounting for the purposes of this discussion. In the example you link to it says that the gas heats up, but there are two reasons for this. Firstly there is the work done to compress the gas puts extra energy into the gas and so makes it hotter and secondly the amount of heat in the gas is being concentrated in a smaller volume and so the temperature, although not the total energy, increases accordingly. (This is why there is the same amount of energy in a kettle full of boiling water as there is in a bath full of tepid water, although the temperature of one is obviously greater than the that of the other). We can disregard the first source of energy in the atmosphere because we have neither cylinder nor piston and so no work is being done. If you don't have a cylinder then even though the volume of the gas is decreasing and the temperature is rising, the amount of energy in it remains the same and so the temperature cannot rise above that of the surrounding air, which means that no energy can be transferred to the surrounding air.
If energy was transferred to the surrounding air, as in you postulated model, then the parcel of air in question must be hotter than the surrounding air, therefore for at the volume and pressure of the surface it must contain more heat, therefore at any given volume and pressure it must contain more heat, since heat cannot be either created or destroyed, therefore wherever it is in the atmosphere, it will be lighter than the surrounding air therefore it can never have sunk in the first place.
With no atmosphere, Venus would have a surface temperature of 130oC
2. With global clouds (which are present) but no greenhouse effect, Venus would have a surface temperature of minus 50oC
3. With global clouds and the actual greenhouse effect, Venus's real surface temperature averages at 470oC
That's from the open University website.
Regards Earth temperatures and the contribution of greenhouse gases. Estimates from published scientific papers suggest far more than the 1 or 2 degrees Celsius you suggest.
Here's those citations and some informed discussion on the subject of a co2 free atmosphere.
http://www.skepticalscience.com/What-would-a-CO2-free-atmosphere-look-like.html
B, are you seriously denying the following:
1. At sea level, air is thicker, atmospheric pressure is higher and temperatures are higher, compared to
2. At high altitudes, air is thinner, atmospheric pressure is lower and temperatures are lower.
3. It has always been thus.
4. The amount by which sea level is warmer than it should be (-1F) is equal and opposite to the amount by which it is colder than it should be at high altitudes.
4. Even in the absence of any GHG, the temperature difference would exist?
PC, thanks, so the same website in a different place says that in the absence of CO2, surface temperatures would be 2.5C lower. That is quite different to saying that in the absence of GHG they would be 30C lower.
So the original explanation was at least 90% bollocks, even if not quite 100%, even by their own admission?
Have I missed something?
MW. Yeh sort of. How about like most of the article?
"There have been a number of studies which examine the evolution of the climate system with no CO2 in the atmosphere. Such experiments are described for example in Pierrehumbert et al (2007) , or by Voigt and Marotzke (2009). From these papers, one can trigger a full snowball Earth with a sufficient reduction in atmospheric CO2. A substantial reduction in water vapor (shown below, from Lacis et al (2010) as well as increase in the surface albedo are important feedbacks here, showing that removing the non-condensing greenhouse gases (mostly CO2) in the atmosphere can collapse nearly the entire terrestrial greenhouse effect. What’s more, since the albedo increases substantially, the total greenhouse effect can be thought of as providing even more than 33 K of warming relative to Earth’s blackbody emission temperature"
PC, I wish you would just give a straight answer to the bloody question.
If your genuinely held belief is "The earth's surface is 33C warmer than it would be without C02", then please say so.
But you are still getting off the actual topic.
Base line earth surface temperature in absence of atmosphere = -15C.
Can we please agree on this?
Even the purest atmosphere with just the N and O, the surface temperature would be 30C warmer = +15C.
Can we agree on this? Or do you seriously contend that Gay-Lussac's Law is a load of nonsense?
(I couldn't actually give a shit what the temperature would be in the absence of any atmosphere whatsoever "black body emissions temperature". That is not a relevant question. Or do the warmenists now want to get rid of N and O as well?)
"The top half of the atmosphere pushes the bottom half down (compresses it) ; and the bottom half pulls the top half down (expands it)."
No it doesn't, because nothing is moving. The top half is not moving down and neither is the bottom half. If they were both moving down, and the bottom half was moving down faster than the top half, which it would have to be doing if it was expanding it, very soon all the air would be a liquid on the surface of the earth.
MW. Oh sorry,didn't realise you'd dropped Boyles law.
As per article"In the Lacis et al experiments, removing the CO2 from the atmosphere generates a cooling of around 30 C..." There's no point in pretending you can zero in on one particular temp for a CO2 free atmosphere as a whole range if temps are consistent with a variety of albedo feedbacks. Including snowball Earth.
B and PC, I have been trying to engage in civilised debate with you, until you actually give answers to my questions above so that I can understand what your views actually are, it is impossible for me to continue with this. It is completely pointless. You appear to have absolutely no opinion apart from the firmly held belief that i am wrong.
I refer you to my post on civilised debate.
For any normal person who would ilke to know my response to Bayard's proposition that "nothing is moving" allow me to point out that in a gas full of molecules, all those molecules are moving incredibly quickly. That is what temperature is, the measure of the average kinetic energy (speed) of molecules in a substance. And as we have established, pressure and temperature of a gas are directly proportional.
"B, are you seriously denying the following:"
No, none of them. All I am pointing out is that your explanation of why those points are so is contrary to the laws of physics.
The Earth is warmed by the sun. Space is a vacuum and therefore not warmed by anything. Thus space is cold. Air is an insulator. Thus we would expect that the atmosphere was warmest near the (sun-warmed) surface and coldest at the outer edge. This is what we observe.
The atmosphere is held in position round the earth by gravity. Gravitational attraction is inversely proportion to the cube of the distance between two bodies. Thus we would expect that, as we go further from the Earth's surface the gravitational attraction of the earth on its atmosphere to decrease and hence the amount of gas held there by gravity also to decrease, hence the atmosphere to become thinner. This we also observe.
"Base line earth surface temperature in absence of atmosphere = -15C.
Can we please agree on this?"
We can.
"Even the purest atmosphere with just the N and O, the surface temperature would be 30C warmer = +15C."
Indeed. So how does that not fit with the "Earth's surface warmed by the sun and air acting as an insulator" model? Why do we need a "giant heat pump" or air "doing work on itself" or Gay-Lussac's Law to disprove the idea that "Without this natural greenhouse effect, primarily owing to water vapor and carbon dioxide, Earth’s mean surface temperature would be a freezing -1°F, instead of the habitable 59°F"?
B, you explain it differently to me is all. There is no real disagreement.
What is now not clear to me is wheher you agree or disagree with the statement that
"Without this natural greenhouse effect, primarily owing to water vapor and carbon dioxide, Earth’s mean surface temperature would be a freezing -1°F, instead of the habitable 59°F"?
Can you clarify whether you agree or disagree with this statement.
Which brings me back to the other question which nobody wants to answer.
"How much colder do you think the earth's surface would be without any C02 in the atmosphere?"
Whereby I am happy with any answer between 0C and 30C. I just want your best guess.
"B, you explain it differently to me is all. There is no real disagreement."
Only that your explanation seems to want to breaks some fundamental laws of physics.
"What is now not clear to me is whether you agree or disagree with the statement that: "Without this natural greenhouse effect, primarily owing to water vapor and carbon dioxide, Earth’s mean surface temperature would be a freezing -1°F, instead of the habitable 59°F"?
Well, to the extent that it appears to be the case that that statement should read "Without an atmosphere, Earth’s mean surface temperature would be a freezing -1°F, instead of the habitable 59°F"?, I disagree with it. However in addition, you and I both know that the vast majority of the work of reflecting heat radiation back to the earth's surface is done by clouds, so I have another disagreement, which is the inclusion of CO2 in the list of GHGs. Clouds have a noticeable effect, but they are is not responsible for the entire 60°F difference. (When I made my first comment, I hadn't read the post carefully enough and didn't notice the actual temperature they were quoting).
"How much colder do you think the earth's surface would be without any C02 in the atmosphere?"
At a guess, not measurably colder. But all the plants would die.
@Mark Wadsworth said...
" LF and PC, I note that neither of you wishes to answer my earlier simple question."
Sorry I should said done. I don't know to be honest. I know that greenhouse gases must increase the warmth (my scientific knowledge shows that they do absorb IR) but I am not qualified enough to calculate how much.
The article Mark links to does not refer to Gay Lussac's law
What Its states is this -
"Down at sea level, where the pressure is high, and the molecules are more densely packed together, more of the energy from the incoming sunlight is absorbed by each litre or pint of air ..."
from the paragraph -
"Down at sea level, where the pressure is high, and the molecules are more densely packed together, more of the energy from the incoming sunlight is absorbed by each litre or pint of air. This is because empty gaps between molecules don’t absorb any energy, the sunlight just goes straight through. But if the sunlight hits a molecule of a type which can absorb energy, the molecule gets hotter. About 16% of the incoming energy from the Sun is absorbed in the atmosphere and most of that absorption will take place nearer the surface. That’s where the energy is more likely to be absorbed by molecules in the air, because that’s where they are packed more closely together. Gravity acting on the mass of the atmosphere to create a pressure gradient leading to higher density and heat capacity near the surface is another reason Earth’s near surface temperature is warmer than the Moon’s. Gravity acting on the mass of the atmosphere to create a pressure gradient leading to higher density and heat capacity near the surface near the surface is another reason Earth’s near surface temperature is warmer than the Moon’s. Air also spreads heat around from hotter places to cooler places, warming them up, reducing the differential in temperature between equator and poles and damping down temperature swings by helping to keep the night side warmer, along with the ocean."
MW. Seriously you can't bemoan the lack of civilised debate whilst simultaneously coming out with."give a straight answer to the bloody question" or "I couldn't actually give a shit what the temperature would be in the absence of any atmosphere whatsoever".
I wouldn't mind but you actually go on to state and then ask:
M.W "Base line earth surface temperature in absence of atmosphere = -15C.
Can we please agree on this?".MW.
Can you spot your own contradiction! I mean can you give a shit, or did you want an answer?
As to your 'question': "How much colder do you think the earth's surface would be without any C02 in the atmosphere?
Whereby I am happy with any answer between 0C and 30C. I just want your best guess."
I have offered my best 'guess' already. Again:
"In the Lacis et al experiments, removing the CO2 from the atmosphere generates a cooling of around 30 C..." [So that might be well below the 0-30 degree C limit you offered as a range].There's no point in pretending you can zero in on one particular temp though for a CO2 free atmosphere as a whole range of temps are consistent with a variety of albedo feedbacks. Including snowball Earth."
So this was an answer even if you didn't like it!
Assuming a lower albedo implies a higher temperature and vice versa.
If we get a snowball earth as a result of removing all the greenhouse gases [as most climatologists would predict] we get extremely high albedo and even lower temperatures. Your question seems to ignore all possibility of feedback effects and so seems not only impossible to realise but impossible to understand. Which does rather confirm my earlier inclination expressed above that such posts [as DBCR has also now pointed out] which seem to align one with weird and wacky maverick views on science [esp GW] are at best misplaced on such a forum and at worst detrimental to the cause of LVT and CI that the site purports to be focused on.
B. Gravitational attraction is inversely proportion to the square [not the cube] of the distance between two bodies. Hence often referred to as the inverse square law.
"In the Lacis et al experiments, removing the CO2 from the atmosphere generates a cooling of around 30 C..."
Yes, but they weren't experiments, if I read the paper correctly. They just got some figures and did some computer modelling. You can prove just about anything like that. I also notice that the website you link to has the strapline "Getting skeptical about global warming skepticism", so no bias there then.
"Gravitational attraction is inversely proportion to the square [not the cube] of the distance between two bodies. Hence often referred to as the inverse square law."
Yer dead right there. Not that it makes any difference to my explanation.
B. Well cubing and squaring are broadly similar I guess. Lacis didn't do experiments? Nope, rather tricky to simulate planet earth minus co2 in a laboratory.
And there are numerous such studies finding rather large reductions in temp' as a result of a co2 free atmosphere.
From theoretical papers come all manner of insights in science. Computer modelling does rather well at weather forecasting too so no need to be quite so down on it.
As for the blog bias, that's pretty irrelevant and logically fallacious. The papers cited are not dependant on the blog author of the blog. As I said previously, it's fairly uncontroversial among climate scientists to assume large reductions in surface temps from big reductions in GHGs. Including snowball Earth.
"Nope, rather tricky to simulate planet earth minus co2 in a laboratory."
Not at all, all you need is a very long airtight tube that you can fire infra red rays down and see how they are scattered, then compare the scattering with no CO2 with that for a normal earth atmosphere mix. Not cheap to do, admittedly, but perfectly doable.
As scientists say about data, if you torture it long enough, it will tell you anything you want it to.
"The papers cited are not dependant on the blog author of the blog."
Well, presumably the author chooses which papers to show, even if he has no control over the content.
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