If you agree with the no-feedback response of 1 K, is one conclusion inescapable?

Question

That conclusion being that the climate sensitivity for 2xCO2 is between 2 and 4.5 K? Or at the very least that feedbacks will provide a net amplifying effect?

Lindzen and Spencer's hypothesis sounds great, but an insensitive climate system is *not* compatible with past climatic fluctuations -- the transitions to and from glacial periods, for instance.

Answer 1

That's my sense. I really don't understand how you can justify the low climate sensitivity argument without being inconsistent with past climate changes. If climate sensitivity is low, how does the planet transition from interglacial to glacial period? We know the orbital forcing isn't powerful enough to cause the transition alone. How do you explain the PETM? I think the only way to justify a low climate sensitivity value is to ignore paleoclimate data.



"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."

http://julesandjames.blogspot.com/2006/03/climate-sensitivity-is-3c.html



Several studies have shown that for climate sensitivity values less than 2°C for a doubling of CO2, the probability drops to near zero very quickly. On the other hand, the distribution of possible sensitivity values has a long tail, and values significantly higher than 4.5°C can't be ruled out. Especially over long timescales.

http://www.greenoptions.com/wiki/climate-sensitivity



*edit* Lindzen and Choi, aside from containing several errors, only considered very short-term feedbacks and is irrelevant to longer-term climate sensitivity.

https://answersrip.com/question/index?qid=20091031101439AANmz0b

http://www.realclimate.org/index.php/archives/2010/01/lindzen-and-choi-unraveled/



Even Roy Spencer admits as much: "it has not yet been demonstrated that short-term feedbacks in the real climate system (or in the models) are substantially the same as the long-term feedbacks....It is not clear to me just what the Lindzen and Choi results mean in the context of long-term feedbacks (and thus climate sensitivity)"

http://www.drroyspencer.com/2009/11/some-comments-on-the-lindzen-and-choi-2009-feedback-study/



And I really don't understand why Portland references Stern et al., which certainly doesn't seem to support his "the planet is cooling when CO2 is high" claim. Probably because the claim is false and makes no physical sense.

http://scholar.google.com/scholar?cluster=9083653138147746934&hl=en&as_sdt=2000



Portland: "I see no reason to accept a theory that is at odds with all the evidence."



Then you shouldn't accept Lindzen or any other of the few studies proposing a low climate sensitivity, now should you?

Answer 2

Definition of a negative feedback:



"Negative feedback mechanisms are self-regulating responses to changes experienced by a system or organism, usually due to external influences. These mechanisms feed some of the output of these changes back into the system to trigger counter-responses which result in restoring the system to its previous undisturbed state, or mitigating the effects of the initial change."



http://wiki.answers.com/Q/What_is_a_negative_feedback_mechanism



You are assuming that a negative feedback in climate has to restore the system to its "previous undisturbed state", but it can also "mitigat(e) the effects of the initial change". In other words you are assuming two steps forward two steps back is the only type of negative feedback that can exist. Whereas a two steps forward one step back system can also exist.



Lindson and Choi have said that they have redone their work and the initial conclusion stands. But we should wait until they publish their results before it can be quoted.



Trevor: In the ice core sample a 100 ppm rise in co2 is associated with a six degree rise in temperatures world wide. It does not correlate nicely. These same ice core shows higher interglacial peaks of temperature with lower co2 levels. Again bad correlation.



Edit: Trevor. From my understanding of the co2 lagging temperature explanation, the 100 ppm rise in co2 is what is responsible for the interglacial warming.



Bob: Are you saying that the Iris Effect relies on a positive and then a negative feedback? That is the first I heard of it.

Answer 3

I see you’ve gone into more detail with this question so I shall do likewise.



In your earlier question I stated that I believed a value of 1.2K for a doubling of atmospheric concentrations of CO2 was realistic provided there were no feedbacks. When feedbacks are brought into play the situation becomes infinitely more complicated and effectively it becomes a case of establishing the proportion of warming that can be attributed to anthropogenic causes.



Sticking with the 1750 starting point of 280ppmv then a doubling would see that rise to 560ppmv. Today the concentration is as good as 400ppmv.



The relationship between CO2 and temp is one of a diminishing curve – it’s not quite logarithmic but logs will suffice.



The rise from 280 to 400 is a factor of 1.429 and the rise from 280 to 560 is a factor of 2.000.



log 1.429 = 0.155, log 2 = 0.301, 0.155 ÷ 0.301 = 0.515 Thus, logarithmically speaking we’re half way to a doubling of CO2 (relative to temp).



Mathematical and computer modelling tells us that a doubling CO2 should produce a temp rise of between 1.5 and 4K.



1.500 x 0.515 = 0.772K, 4.000 x 0.515 = 2.060K and this is the range into which the observed temperature rise should fall. And indeed it does. The average global temp in 1750 being 286.592K and for 2010 it’s 287.693, a difference of some 1.101K.



The observed value falls pretty much at the first quartile within the range and this is what we would expect to see due to the inability to reach a state of equilibrium due to the rapid rate of change.



The ‘missing’ component in the above being the feedbacks associated with ocean thermodynamics, atmospheric residency periods and variable potentials and the usual suspects – the Sun and volcanoes.



The Swedish chemist Svante Arhenius was the first to put forward the proposal linking temperature changes to a doubling of CO2. In his work titled (something like) The Effects of Carbonic Acid on the Atmosphere, Arhenius proposed that a 4K increase would result from a doubling of CO2, in doing so he wasn’t far off the mark but overlooked some of the compensatory factors.



In conclusion therefore, and bearing in mind the starting values, we find that CO2 forcing ties in nicely with the observed temperature change and that climate sensitivities / feedbacks do indeed appear to have a net amplifying effect.



- - - - - - - - - -



EDIT: TO ERIC. You’re referring to something that is in no way comparable to what I’m talking about.



The 6°C and 100ppmv variation in the ice core record is something that happens at intervals of 100,000 years and is the result of changes in Earth’s eccentricity (it’s orbit around the Sun). Increasing or decreasing insolation consequent to the orbital changes are the primary cause of temperature fluctuations, not changing CO2 levels, this is consequential not causal.

Answer 4

It is silly to assume that the climate is not sensitive to fluctuations. Deniers like to point out that climate has changed in the past is somehow proof that man cannot be effecting it. On the contrary, it only shows that the climate is very sensitive to small fluctuations.



Funny how Portland Joe's answer looks just like all of NW Jack's answers....hmmmm

Answer 5

Agreed. I believe that historical analysis of climate sensitivity to solar and orbital forcing, once the computational tools for this became available, were very influential in persuading climate scientists that feedbacks did amplify to about this extent.



I have grandchildren and would really like to think that Lindzen is right, but the facts won't let me.

Answer 6

Portand said it well. Your ignorance of the cause does not make a very sound theory. It seems to me you are going out of your way to assume it is extremley sensitive. Clearly transitions in glacial periods do not require the sensitivity unless you already assume that CO2 is a driving force in climate change. As Portland mentioned, it is inconveniently a lagging indicator.

Answer 7

Lindzen did some work with Earth Radiation Budget Experiment (ERBE) nonscanner data.

http://wattsupwiththat.com/2009/07/23/new-paper-from-lindzen/

It tended to show that the feedback was negative, and more related to short wave radiation than long wave radiation. This is exactly opposite the assumptions included in the IPCC models.



Your question points out the first bad assumption that lead to the other bad assumptions:



That high atmospheric CO2 concentrations were associated with global warming in the ice record, and low atmospheric CO2 concentrations were associated with global cooling.



Actually, rising atmospheric CO2 concentrations are associated with global warming, and decreasing atmospheric CO2 concentrations are associated with global cooling. The warming starts when the concentrations are low, then gets high. Most of the cooling occurs while the atmospheric CO2 concentrations are still high, but decreasing. Most of the time that the atmospheric CO2 concentrations are high, the earth is cooling.

http://wattsupwiththat.com/2009/01/30/co2-temperatures-and-ice-ages/



***Edit as per Dana's suggestion ***

The following paper is only a discussion of the CO2 record in comparison with the temperature record. It does not address the CO2 time lag issue.



What the paper states:



"We, therefore, use multivariate structural time series techniques to decompose Morthern and Southern Hemisphere Temperatures into stochastic trends and autoregressive noise processes. These results show that there are two independent stochastic trends in the data."



Meaning that the temperature changes in the Southern Hemisphere have nothing to do with those in the Northern Hemisphere other than the coming and goings of ice ages. Therefore, it is possible (albeit unlikely) that temperature anomalies for the early 20th century were off a couple of degrees, and the earth is now colder than it was then.



Saying that this paper disproves that the earth has warmed some since 1900 despite the fact that our best data shows otherwise, is no more ridiculous than saying that Trenberth's paper disproves Lindzen's finding that there is no net short term positive feedback, and there is little CO2 sensitivity despite our best data.

***End Dana inspired edit ***

If you prefer peer reviewed literature:

http://resources.metapress.com/pdf-preview.axd?code=q4050354235k32l6&size=largest

(full text) https://commerce.metapress.com/content/q4050354235k32l6/resource-secured/?target=fulltext.pdf&sid=tegocw450hlkbi55srbsuw45&sh=www.springerlink.com



That is why it is called a lagging indicator. The positive feedback theory is used to attempt to explain away this evidence that atmospheric CO2 never actually caused nor ended an ice age, but now, the positive feedback theory appears to be wrong also. If it were true, the earth should have heated up long ago, and stayed there.

http://en.wikipedia.org/wiki/Le_Chatelier%27s_principle



Consider the effects of increased vertical convection with rising temperatures.

http://resources.metapress.com/pdf-preview.axd?code=vl7536426072q7j7&size=largest

(full text) http://www.springerlink.com/content/vl7536426072q7j7/fulltext.html



IPCC Climate Models failed to predict no warming for the first decade of this century.



Edit @Dana:

I do not know exactly what caused and ended the ice ages, but I see no reason to accept a theory that is at odds with all the evidence.

http://www.uoguelph.ca/~rmckitri/research/McKitrick-hockeystick.pdf



Edit2 @Dana:

A theory is only as good as its ability to predict phenomena. The sensitive CO2 theory runs counter to the observed data of the ice ages (see above link), periods of warming and cooling in the past (see above links), and the recent disconnect between the run up of atmospheric CO2 and the lack of recent observed significant warming (first 2 links under sources). CO2 insensitive explains all this very well. Simply put, whatever it was, the atmospheric CO2 sensitivity theory has failed the usefulness test.



Edit @Bob326:

Neither of your links refute that the data is against CO2 sensitivity as stated in the links you attempted to refute. Looking at the extremes of 2 sigma to say there is a small chance that your CO2 sensitivity theory might be true despite that the data is not very convincing.



Chilingar et al: Even "bad" papers have good points. The point that I wanted you to notice is the increased role that vertical convection may have as a negative feedback mechanism as the earth warms. I would enjoy your critique of the paper, but you seem to prefer an Ad Hominem attack against the author rather than a valid critique.



Models: I appreciate that the scientific process involving models involves evaluating the model's failures and correcting for them. That does not however, mean that once the model is corrected (after the fact), it is validated.



Edit2 @Bob326:

"Short term 'pauses' in rising temperatures do not invalidate "CO2 sensitivity theory' anyway, BUT we can't even say that the temperatures have paused with any confidence."

Our best our best data (first link under sources) indicate they have. To the extent that there is room for error in those measurements, we also cannot say with any confidence that there has been any global warming since 1900. Only our best data says so, but there is almost no data for the Southern Hemisphere in the early 20th century.

http://www.aip.org/history/climate/20ctrend.htm

There is no statistical (or any other) reason to believe that the increases that we have seen lately are anything more than normal temperature variance.

http://news.bbc.co.uk/2/hi/science/nature/8511670.stm



"Trenberth et al. (linked above) show that Lindzen09's calculations were completely wrong."



No, they do not. What they do is say:



"To assess climate sensitivity from Earth radiation observations of limited duration and observed sea surface

temperatures (SSTs) requires a closed and therefore global domain, equilibrium between the fields, and robust methods of dealing with noise. Noise arises from natural variability in the atmosphere and observational noise in precessing satellite observations."



and also:



"Particular challenges are how to handle the large radiative and latitude, anomalies in ASR are simply opposite to those in perturbations from the Mount Pinatubo volcanic eruption in 1991, and possible spurious changes over time."



There is no dispute in this paper that the data indicates against a net positive feedback. It simply points out that there is enough noise that it is possible that the conclusion could be wrong despite the evidence.



Finally: "the *worst* paper on the GHE I've ever seen. They make error that freshman atmos students could pick up."



Is an attack on the author. You provided no evidence of any error in the paper. Indeed, I have provided much more detailed critiques of that paper in my previous answers. Again, I welcome you to critique the paper.



Models: "Your discussion of models in nonsense."

Based on that quote, I suspect that you actually believe that the models actually provided a useful theory in that they managed to make predictions that were correct more often than they were wrong (better than random). Allow me to relieve you of that myth:

http://www.co2science.org/articles/V13/N9/C1.php



Edit @beren:

Very observant. I know Jack, and we have discussed the format we use at length. We often trade links and answers, and usually do not answer the same questions. However, we do not always agree.

https://answersrip.com/question/index?qid=20100220132927AAAEbEl&show=7#profile-info-Yk1asOK4aa

Or - maybe it depends on who took them.



Edit4 @Bob326:

Better. When challenged, you improve.

Adiabatic calculations for vertical winds are normal. That is how orographic precipitation is explained. Doing the math in absence of assumptions about radiative forcing is how one gets a handle on the likely magnitude of the effect.



That said, I appreciate your skepticism in this instance.