I am going to be out enjoying some snow skiing this week, but I will leave you with a thought that was a prominent part of this video:
The catastrophe that Al Gore and others prophesy as a result of greenhouse gasses is actually not, even by their admission, a direct result of greenhouse gas emissions. Even the IPCC believes that warming directly resulting from manmade CO2 emissions is on the order of 1 degree C for a doubling of CO2 levels in the atmosphere (and many think it to be less).
The catastrophe comes, not from a mere 1 degree of warming, but from the multiplication for this warming 3,4,5 times or more by hypothesized positive feedback effects in the climate. Greenhouse gas theory gives us warming numbers we might not even be able to find amidst the natural variations of our climate; it is the theory of strong positive climate feedback that gives us the apocalypse.
So, In a large sense, the proposition that we face environmental Armageddon due to CO2 rests not on greenhouse gas theory, which is pretty well understood, but on the theory that our climate system is dominated by strong positive feedbacks. This theory of positive feedback is almost never discussed publicly, in part because it is far shakier and less understood than greenhouse gas theory. In fact, it is very probable that we have the sign, much less the magnitude, of major feedback effects wrong. But if we are considering legislation to gut our economies in order to avoid a hypothesized climate catastrophe, we should be spending a lot more time putting scrutiny on this theory of positive feedback, rather than just greenhouse gas theory.
Tom Nelson quotes an email from S. Fred Singer that states my position well:
I believe a fair statement is that the GH [greenhouse] effect of CO2 etc must exist (after all, CO2 is a GH gas and is increasing) but we cannot detect it in the record of temp patterns.
So we must conclude that its contribution to climate change is swamped by natural changes.
Why do models suggest a much larger effect? Because they all incorporate a positive feedback from WV [water vapor], which in actuality is more likely to be negative. Empirical evidence is beginning to support this explanation.
Empirical evidence is beginning to support this explanation. Strange that he doesn’t say what the evidence actually is. Sounds like denialist mythology again. Or can you tell us what evidence shows this?
I posted the following on the Coyote Blog, but it makes sense to post it here, too…
Positive feedback in the climate? Hello? Positive feedback means you’re going to hit the rails. If any positive feedback existed in the climate, we would have hit the rails millions years ago, and stayed there. We simply wouldn’t exist to ponder the question. By the very nature of positive feedback, rest assured that it doesn’t exist in the climate. There is absolutely no reason to give credence to such a ludicrous notion. It’s a notion generated by complete idiots who are lucky to get the correct shoe on the correct foot on any given day. Anybody who even contemplates that these idiots might have a point is guaranteed to have not the slightest iota of grounding in the hard sciences, and should report to the nearest soylent green processing center.
Positive feedback is destructive. Negative feeback isn’t. It’s that simple.
Two interesting pieces of evidence are (1) the temperature increase since the turn of the last century; and (2) the increase in temperature over that time period. If we assume for the sake of argument that the entire increase in temperature was due to CO2, one can generate a simple estimate of climate sensitivity, which is pretty darn low.
In other words, if the climate is super-sensitive to CO2, temperatures should have risen a lot more by now than they actually have.
Apparently pro-AGW folks get around this problem by hypothesizing that there is many-year lag due to oceans. However, as far as I know, this entity has never been shown to exist. Moreover, the lag due to aeresol forcings from volcanoes is clearly only a few years at most. How many years is the lag from CO2? And why should it be very different from that for volcanoes? And how would one measure it?
Hank – just like the author of this blog, you don’t understand what positive feedback actually means. If anyone’s a complete idiot in their understanding of this, it’s you.
dreamin – your simple estimate would be wrong because that’s not how you calculate climate sensitivity. And you don’t believe that water has a high heat capacity? Oh dear. Tell me, generally speaking, which places have more extreme climates? Those near oceans, or those far from oceans?
Typo: the plural of gas is gases.
“And you don’t believe that water has a high heat capacity?”
Why do you feel the need to set up strawmen? It only makes you less credible.
How many years is the lag from CO2? Why is it very different from that of volcanoes? And how would one measure it?
“Tell me, generally speaking, which places have more extreme climates? Those near oceans, or those far from oceans?”
Those far from oceans. And here’s a question for you: How long did it affect the Pinatubo eruption to have most of its cooling effect on Boston? Same question for Fargo.
More than 10 years? or less than 10 years?
Good. Next: when the sun rises, which place gets hot more quickly, a place far from the sea, or a place near the sea?
Don’t quite know what you’re getting at with Pinatubo. The stratospheric aerosols due to the eruption dissipated within a few years, so their effect on temperature was short lived. What of it?
Ummm, please answer my questions first:
How many years is the lag from CO2? Why is it very different from that of volcanoes? And how would one measure it?
“The stratospheric aerosols due to the eruption dissipated within a few years, so their effect on temperature was short lived.”
If the “thermal inertia” theory is correct, the effects should linger for quite a while. Just like Boston stays warmer in the winter than Fargo. Even though the summer sun is long gone.
Scientist, If you have a better definition for positive feedback, I would appreciate if you would post it or a link to it. Also, rather than simply claiming that people do not understand something, please try to raise the level of discourse by clarifying for everyone.
dreamin – you’re giving me a good laugh here. It would take me way too long to explain to you all the things you don’t understand. Get yourself a textbook or something.
Tony K – I’m not posting here to teach people basic science. Anyone who thinks ‘positive feedback’ means ‘temperature rises to infinity’ is beyond any help I am prepared to give them.
Hey “scientist”, you have me convinced — not!
The fact is that if the climate were very sensitive to CO2, it would have warmed up a lot more by now than it has.
Alarmists like “scientist” try to explain this problem away by positing some thermal heat bank where all this extra warming is hidden away, kinda like the monster that you used to worry was in your closet.
Trouble is, when your parents come and shine a light in the closet, there’s no monster there. And when you start asking challing questions about this thermal heat bank, it too proves illusory.
err, that should be “challenging” not “challing”
Scientist,
If you choose not to explain, people will assume that you don’t really know. And in any case, will not be persuaded. The concepts are not at all hard to understand. Why not simply help people out and explain them?
When people talk about positive feedbacks, what they’re actually talking about are positive perturbations on an overall negative feedback. The hotter things get, the faster heat is convected or radiated away, which is a massive negative feedback. Water vapour may make that slightly less negative, and as such is a positive feedback contribution, but the overall feedback is still negative. When you’re talking about the effect of changes in temperature and changes in water vapour, the bulk of the feedback drops out, and the feedback on the changes could indeed then be considered positive, but its a rather specialised usage of the term. It’s because of the dreadful way they’re explained by climatologists that people get confused.
It is true that positive feedback with a feedback coefficient below unity doesn’t give a runaway effect. It magnifies changes by a factor of 1/(1-f). But given the wide range of changes of forcings over the past few billion years, the climate would have been a lot more unstable than it has been if f were above 0.6 as proposed. And if there were any “tipping points” as some supposedly reputable scientists have claimed, we would have hit them. That’s a valid argument against a slightly different argument to the one you made.
Your examples regarding the thermal capacity of the oceans are a bit misleading. Oceans warm and cool more slowly than the land because they are transparent, not because water has a greater thermal capacity. Nevertheless, ocean surface waters can change temperature by many degrees in a matter of weeks. Adjusting a fraction of a degree, such as that proposed as being caused by AGW, would be far faster.
Where it gets complicated is when you get to the role of the deep ocean, and overturn. In fact the ocean has many different thermal capacities, when considered on many different timescales. The surface waters mix only slowly with the deeper water, on a timescale of hundreds to thousands of years. It is extremely nonlinear that way. Temperatures that when averaged over long periods are above or below normal can give net transfers of heat to or from deeper layers, and in return cool or warm the surface slightly, that could in principle give such an effect. The longer the delay involved, the slower the process and the less heat will be transferred in any given time, so it can only explain so much.
However, such effects ought to show up as long-term average temperature changes in the sub-surface ocean. Measurements are highly uncertain and subject to large errors – we don’t really know much about conditions below the surface except for a few samples at isolated spots – but observations by Levitus et al. have gone looking for these changes and failed to find them. I don’t regard the science here as conclusive yet.
There is also, as alluded to above, the impulse response function measured from volcanic eruptions that suggest the time constant is very short. And the calculation by Schwartz of the time constant from the autocorrelation function of temperatures suggests the global climate has about a five year delay on the decadal timescale at which AGW should show up.
There are many ways to estimate climate sensitivity, and dreamin gave a simplified version of one of them. I assume it was based on Idso’s paper on natural climate experiments – if so, I suggest you comment on Idso’s arguments in detail rather than dismissing it with a vague “that’s not how you calculate it.”
So you can see from that that the explanations aren’t quite as simple as you made out, and that patronising comments about people being “beyond help” are somewhat uncalled for.
If you know this, then the best thing you can do is to take the time to explain it, without being snide about it. It helps, even if only to the extent that we don’t use that particular argument again. If you didn’t know it, and yet are still pretending that one would have to be a fool not to, then consider yourself ‘caught out’. I assure you, seeing that sort of thing helps the sceptic case enormously. 🙂
Of COURSE the oceans have a much higher specific heat than land- That’s part of the negative feedback. It takes a lot more heat to warm the oceans than to warm the land. Part of that feedback goes into water vapor- you’ll get more convection, and more clouds from that- another negative feedback.
http://www.agu.org/pubs/crossref/2007/2007GL029698.shtml
– A. McIntire
demonstrations of apparent negative feedback to co2 forcing can be found in a couple of ways:
first, the lack of a distinct AGW fingerprint in the atmosphere. if the current warming is greenhouse driven, the area in the atmosphere around 9000m altitude (300 pascals pressure) ought to be warming more than the surface, as that is where the greenhouse effect takes place.
from the international journal of climatology:
http://www.uah.edu/News/pdf/climatemodel.pdf
nice chart of data here:
http://icecap.us/images/uploads/LINDZENTABLE.jpg
further, research done at NASA but published elsewhere after hansen is alleged to have attempted to censor it has shown that the basic forcing models used for atmospheric temperature are incorrect and leave out important terms that produce large negative feedbacks. the original equations were set using the assumption of an infinite atmosphere, a common approximation that sometimes works in such situations and allows equations to be more easily solved. but it is no longer 80 years ago, and we have plenty of computing power to do the job. a finite atmosphere appears to switch feedbacks from positive to negative.
http://met.hu/doc/idojaras/vol111001_01.pdf
finally, it offends common sense that a system that has been as stable as earth’s climate for a billion years could be dominated by positive feedback, particularly co2 feedback as co2 has been at levels 25 times as high as currently prevail at periods in the last 500 million years.
happy reading “scientist”. your point about evidence to back up a statement is reasonable. so here’s the data. let’s see if you can comment intelligently on it you enormous charlatan. i have never yet seen you do it. go ahead, prove me wrong…
Hank is quite right. If there was the positive water vapor feedback that the alarmists claim, it would have happened already. Temperature increase leads to water vapor increase leads to further temperature increase, which grows exponentially.
Mathematically, if the small change in temperature is T and the small change in water vapor is W, then dW/dt = a T and dT/dt = b w. If a and b are both positive we get exponential growth of the fluctuations with growth rate equal to root(ab).
This exponential growth would happen regardless of any CO2 input to the atmosphere. It would eventually be stopped due to nonlinear terms but not until the perturbations get large. As Hank says, if there was positive feedback we just wouldn’t be here.
It is “scientist” who is giving everyone else the laughs, with his inability to understand simple physics (like feedback, instability and even Newton’s 1st law) or answer simple questions, and as Stevo says, he is a great help to the skeptic cause. Keep up the good work, “scientist”!
Stevo – if there was any evidence of anyone here being willing to learn, I’d keep on trying to explain. But people are obviously very happy to be ignorant. They’ve decided beforehand what they want to believe, and they’re not going to listen to any real science. Anyone who talks of ‘sides’ and ‘the skeptic cause’ is clearly someone talking from a position of faith, not science. Any explanation of science, no matter how kindly worded, only garners abuse from them.
It helps, even if only to the extent that we don’t use that particular argument again – yeah, I wish! The same arguments are coming out time and time again. The author of this blog has twice, that I can find, said that the name of Greenland implies that mediaeval times were warmer than now. Both times, someone has corrected him. Did he take that in? And time and time again people are coming up with the nonsensical idea that there can’t be positive feedbacks because if there were, “we just wouldn’t be here”. I think you probably understand that that’s ridiculous, so why don’t you try telling them?
Well sure there are positive feedbacks for the climate system. We use them all the time.
For example who hasn’t felt the blast of hot air after switching on their EVAPORATIVE HEATER?
That’s a firm scientific principle well understood and used in many household applications.
So let me list some of the modern marvels based on the science of positive climate feedback.
…
um…
Well there’s…
Shit.
I got nothing.
“if there was any evidence of anyone here being willing to learn, I’d keep on trying to explain.”
In that case, why do you continue to post here?
Looks to me like you are making excuses for being unable to back up your claims or respond to challenging questions.
You ever hear of someone getting a nasty cloud burn?
Scientist my ass. What you are is a koolaid guzzling moron.
“Scientist”…? “Social” or “Christian”?
Scientist,
It’s time for you to start doing something more useful with your time.
You certainly weren’t convincing any skeptics and, now that Stevo has chewed you up and spit you out, you aren’t going to convince any undecided lurkers either. In fact, you’re hurting your cause. Personally, as a skeptic, the more posters there are like you, the better we look.
You’ve been schooled on amplification before. You insist on repeating sound bites without addressing things with deeper understanding. Are you a hack? A moron?
So, if I understand the positive-feedback effect correctly, CO2 warms the atmosphere, which in turn makes it able to hold more water vapor which, being a potent greenhouse gas, gives rise to even more warming – until the saturation point is reached and it rains out, cooling things down (or words to that effect)
Two problems here:
1) Except in places where it’s too cold or dry, the water vapor already exists in the atmosphere, and the greenhouse effect of the water vapor alone warms the atmosphere, which in turn leads to more water vapor and so on. Why does this not happen? Why does this process have to wait for CO2 to come along to start the ‘snowball rolling’?
2) As the greenhouse effect of water vapor is much greater than that of CO2, the atmosphere will warm more from water vapor than it would from CO2. How then, given the fact of the second law of thermodynamics, can CO2 have any warming effect whatsoever?
Speaking of the second law of thermodynamics, if IR radiation from the surface warms the atmosphere by way of the greenhouse effect, how then does the atmosphere warm the surface – given that the atmosphere cannot be warmed to a higher temperature than the surface?
Scientist, can you please answer these questions
So, if I understand the positive-feedback effect correctly, CO2 warms the atmosphere, which in turn makes it able to hold more water vapor which, being a potent greenhouse gas, gives rise to even more warming – until the saturation point is reached and it rains out, cooling things down (or words to that effect)
Two problems here:
1) Except in places where it’s too cold or dry, the water vapor already exists in the atmosphere, and the greenhouse effect of the water vapor alone warms the atmosphere, which in turn leads to more water vapor and so on. Why does this not happen? Why does this process have to wait for CO2 to come along to start the ‘snowball rolling’?
2) As the greenhouse effect of water vapor is much greater than that of CO2, the atmosphere will warm more from water vapor than it would from CO2. How then, given the fact of the second law of thermodynamics, can CO2 have any warming effect whatsoever?
Speaking of the second law of thermodynamics, if IR radiation from the surface warms the atmosphere by way of the greenhouse effect, how then does the atmosphere warm the surface – given that the atmosphere cannot be warmed to a higher temperature than the surface?
Scientist, can you please answer these questions
So, if I understand the positive-feedback effect correctly, CO2 warms the atmosphere, which in turn makes it able to hold more water vapor which, being a potent greenhouse gas, gives rise to even more warming – until the saturation point is reached and it rains out, cooling things down (or words to that effect)
Two problems here:
1) Except in places where it’s too cold or dry, the water vapor already exists in the atmosphere, and the greenhouse effect of the water vapor alone warms the atmosphere, which in turn leads to more water vapor and so on. Why does this not happen? Why does this process have to wait for CO2 to come along to start the ‘snowball rolling’?
2) As the greenhouse effect of water vapor is much greater than that of CO2, the atmosphere will warm more from water vapor than it would from CO2. How then, given the fact of the second law of thermodynamics, can CO2 have any warming effect whatsoever?
Speaking of the second law of thermodynamics, if IR radiation from the surface warms the atmosphere by way of the greenhouse effect, how then does the atmosphere warm the surface – given that the atmosphere cannot be warmed to a higher temperature than the surface?
Scientist, can you please answer these questions