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Is it really this easy to refute Lindzen?
This is actually a QUESTION, ie a request for information.
As I understand it, the past record shows that solar forcing during Milankovich cycles was doubled by positive feedback loops. (Am I correct in this? References appreciated)
But Lindzen argues that cloud cover provides a negative feedback that will largely cancel out current forcing by anthropogenic CO2.
(Denialists, please note: Lindzen accepts both the reality of the current temperature rise and the existence of this forcing effect)
Is there any reason why Lindzen’s argument should not have applied equally to the past record? If so, please explain, with references to the literature if possible
If there is no such a reason, can we say that Lindzen’s theoretical model just doesn’t fit the facts, and must be wrong? If not, why not?
AteWaffles: In response to your question, I wrote: "Is there any reason why Lindzen’s argument should not have applied equally to the past record?"
In other words, I am looking for facts that *support* Lindzen and *refute* my position. That's what scientists do. Can you help?
Edit: amancall... asks me to face tha fact that warming stopped in 1995. So I checked the figures. Every year since 1995, except 1999 and 2000, has been warmer than 1995.
amancall... will you accept the evidence you yourself called for?
Rusty: your link is just to a Lindzen lecture. We all *know* what he asserts; i've stated my problem with it, and just repeating his assertions doesn't answer my question
Rich: WSJ isn't science. Lindzen and Farrell, 1977, which you proudly cite, predicted no ice age cooling at latitudes < 25o, contrary to fact; my point exactly.
- MTRstudentLv 61 decade agoFavourite answer
Knutti & Hegerl summarise some stuff from the last glacial maximum:
Which suggests that sensitivity to Milankovitch changes in heat flow is of the order suggested by the IPCC.
Now I respect Lindzen's approach and Spencer's different (but similar outcome) approach that suggest there could be flaws in estimates of climate sensitivity from models and recent short term observations, and that this might mean that climate sensitivity is lower than generally estimated.
However, I'm pretty sure that the existence of ice ages either means we missed something massive (seems unlikely), or Lindzen/Spencer's theories aren't that important.
Of course, climate sensitivity is a function of dozens of variables (at least) and it may well be nonlinear. Perhaps estimates of climate sensitivity from the past are not what we would experience now (after all, melting ice is a positive feedback - losing a square km of ice in the tropics is a big change in heat flow, losing polar ice not so much - therefore positive ice feedback might be stronger at lower temperatures). But clouds are such a big feedback and I'm not aware they've been demonstrated to suddenly act differently now to the way they've acted throughout geological history.
We have so many past estimates that I'm currently persuaded that Lindzen will ultimately be shown to be wrong. Spencer's hypothesis may be right (about internal variability making short term sensitivity estimates difficult), but I personally doubt that the lower climate sensitivity he seems to assume will fall out of it in the end.
The palaeoclimate estimates were the things that convinced me that our other estimates were likely accurate.
- BaccheusLv 71 decade ago
I believe Lindzen does indeed believe that clouds have always been a feedback. We just discussed the Faint Sun Paradox last week, and as much as I can understand, Lindzen believes that the earth was about as warm then despite a less active sun because clouds were thinner. He believes that increased cloud cover has been a negative feed back as the sun became more active, and is the reason that we are not much warmer now -- and that clouds will continue to be a negative feedback as the environment warms.
If he is right, then warming will be slower than predicted by the IPCC and others. I have not seen the rate of warming and sea-level rise that he predicts, nor unfortunately have I seen studies other than his that indicate that clouds will be a net negative feedback. Other researchers have found that clouds are reacting in both positive and negative ways. Personally, I don't believe he has the understanding of cloud behavior that he claims, but I personally don't have the qualifications to debate with him.
- d/dx+d/dy+d/dzLv 61 decade ago
I think that Lindzen needs an indirect anthropogenic aerosol effect to construct clouds that produce a different negative feedback in recent years as compared with prior centuries. The direct aerosol effect (global dimming) has been well studied and is accounted for in the IPCC projections. It is at least plausible that altering the nucleation seed concentration and chemistry will give a different droplet size distribution in clouds with different Mei scattering. Born and Wolf in Principles of Optics give the fundamentals of Mei scattering. Mei scattering is quite complex. There are both size and refractive index considerations. While back scattering generally increases when q/a ~ 1, there is a also a sweet spot where forward scattering becomes strong. Lindzen needs an effect that shifts the size distribution "a" closer to the maximum wave vector "q" of incoming solar radiation. All of this can be tested by analyzing spatial and temporal changes in the spectral distribution of outgoing radiation from satellite measurements. This information is available and I think Lindzen is competent enough to check. If the evidence supported his hypothesis, he would use it. His silence is telling.Source(s): I have done Mei scattering experiments with biological samples. One of my patents includes the use of Ag/SiO2 colloids to facilitate spectral measurements of biological samples.
- bob326Lv 51 decade ago
"Lindzen's research experience on the subject dates back to before most Global Warming believers were born."
If a mathematician with years of experience says 2+2=5, does that make him right? Lindzen has added greatly to our understanding of atmospheric dynamics and has an impressive list of publications, but if your theory contradicts observations (e.g. ice ages), then it doesn't work. Perhaps there does exist an 'infrared iris' acting on some scale, but as of yet, evidence for it is pretty thin.
It's the other way around - Lindzen argues that the tropical [cirrus] cloud fraction was greater in the Archaean, that this provided a net positive forcing, and along with GHGs and a greater ocean extent, was enough to keep temperatures above freezing. In terms of the current warming, he thinks that SSTs are inversely correlated with tropical cirrus coverage, and warmer temperatures will allow more infrared 'leakage', thus providing a "large negative feedback".
No statistically significant warming ≠ no warming.
- Dana1981Lv 71 decade ago
That's always been my reaction to the Lindzen/Spencer low climate sensitivity argument. If clouds are indeed a significant negative feedback which create a low climate sensitivity, how does the planet transition between interglacial and glacial periods? The orbital forcing (from Milankovitch cycles) isn't that strong.
There was one recent study of the Palaeocene–Eocene Thermal Maximum about 55 million years ago, during which the planet warmed 5-9°C. It was a similar global temperature to today's, and they key feature of the maximum was a large release of carbon from an unknown source. The study found that the rise in CO2 at the time can explain only between 1 and 3.5°C of the warming. So again the question is if there's this negative cloud feedback which prevents significant warming, as Lindzen and Spencer propose, how did the planet warm 5–9°C during this period?
There's a good description of climate sensitivity estimates from the last ice age transition from climate scientist James Annan here:
"We can also look to the paleoclimate record for evidence from our planet's past climate. During the last ice age, the total radiative forcing was roughly 8Wm-2 lower than today (mostly due to lower CO2 and large ice sheets, with dust and vegetation changes also contributing). 8Wm-2 is roughly twice the forcing of doubled CO2 (although in the opposite direction), so with the global temperature at that time being about 6C cooler than at present, a climate sensitivity of about 3C looks pretty good again. However, again there are significant uncertainties in all of these values I've quoted, and it's also not clear that one value of climate sensitivity will necessarily apply both to doubled CO2 and to this rather different forcing. In fact model results (such as our own) show a fair amount of uncertainty in the response to these different scenarios."
So it's not quite so simple that we can say these transitions disprove Lindzen's hypothesis, but they're pretty strong evidence that there isn't some big negative feedback that prevents significant warming.
*edit* Vampire MM - you're mistaken. Only deniers with zero scientific education are smart enough to refute climate scientists!
- rusty_1491Lv 51 decade ago
Richard Lindzen has lectured that The IPCC models don't fit the facts. He's explained that not only cloud cover and aerosols as a negative feedback has not accurately been taken into account, but also the feedback mechanism of water-vapors has been overstated. Even the IPCC has continually lowered it's radiative-forcing coefficient which still may be too high. Temperature observations do not confirm what the algorithms predict. Two-Thirds of the alarmists predicted temperature increases come from this Radiative Forcing theory, if the theory is exaggerated then their is no climate crisis.
- Eric cLv 41 decade ago
So what you are saying is that a person can become a professor at one of the most prestigious universities, but is so stupid that even amateurs can refute him.
If you think that Milankovich cycles are 100% proven to be the causes of the ice ages, I suggest you start reading what people outside the climate science community have to say.
Dana: Negative feedbacks does not necessarily mean two steps forward, two steps back. It can also mean two steps forward, one step back.
- amancalledchudaLv 41 decade ago
Well, if it were that simple, Paul, exactly the same argument could be used to utterly refute Catastrophic Anthropogenic Global Warming.
It is, after all based on the same kind of theoretical models that are equally not fitting the facts (how many of them correctly predicted that the warming would stop in 1995? None, right?)
Now, you’re perfectly happy to be sceptical of Lindzen’s argument, on the ground that his model doesn’t accurately reproduce reality.
However, if I do exactly the same thing with Catastrophic Anthropogenic Global Warming, you Global Warming Liars label me a “Denialist”.
Is it simply a case of “One rule for you... different rule for everyone else”?
As ever with Global Warming - Don't believe the hype.
- RichLv 61 decade ago
Lindzen's research experience on the subject dates back to before most Global Warming believers were born. And, no, it is not easy to refute. However, it is simple to refute (in your own mind) something about which you know nothing.Source(s): http://online.wsj.com/article_email/SB100014240527... http://mirabeli.meteo.furg.br/aulas/MC/Lidzen_Farr...
- Anonymous1 decade ago
"So what you are saying is that a person can become a professor at one of the most prestigious universities, but is so stupid that even amateurs can refute him."
Deniers are *CONSTANTLY* telling us just that exact same thing, only on a much larger scale.
So I guess the answer is a resounding, 'yes!'