Andy Dessler Smokes Richard Lindzen
As Andy says at the beginning,
it all fits together, its this coherence of data, and even if any one of these data set is wrong, it really would not affect your confidence because we have so much other data which suggests it's warming and because of this the IPCC calls this unequivocal, which means essentially beyond doubt. . . . The key thing to look at is look for coherence, look for lots of evidence supporting a point and you will clearly see why scientists are convinced that the mainstream view of climate science is rightThe bottom line being
The real question I want to address here is this question of how much does carbon dioxide warm the climate. This is really the key question. It's not a question of does carbon dioxide warm the climate. I think that Prof. Lindzen and I will agree it does. It's a question of magnitude, a question of how much it warms the climate. What we are going to talk about here is this question of climate sensitivity. That's often referred to as climate sensitivity. We are going to use a standard measure which is how much warming would occur if we doubled carbon dioxide, so we are going to go through the math and do a very simple calculation that indicates that we might be screwedEnjoy
Posts
52 comments:
So: the 'skeptics' crowd as a general rule sees no coherence or - if they be really evil - pretend not to see it. This reflects in their discussion methodology.
Is that Woody Allen reading large blocks of text from Lindzen's slides? Yawn. How not to do powerpoint.
Oh Henry.
Jeez ... Lindzen pulled the opposite of the old graphic scam: "Make the scale large and hide the fluctuations" ... he went from the larger to the appropriate scale, and claimed that the right scale did not have a trend ... which it seemed obviously to have.
I know he is an eminent man and all that ... but he may have been taking lessons from Monckton.
Toby
Wow, Monckton, I mean Lindzen, really did not fare well there. He looked and sounded worn out too.
I really liked Andy's use of "delta T_i" to indicate the things we know from the bare CO2 effect, rather than the more traditional (or is it? more familiar to me anyway) use of the W/m^2 of radiative forcing. We really do know that number, the 1.2 C raw sensitivity to doubling CO2, and even Lindzen seems to be able to agree on it, and it clarifies the whole feedback discussion rather than introducing yet another ratio.
However, this format did allow both of them to seem confusing about feedbacks and the runaway issue. Lindzen harped on it, but it's a valid point that Dessler really should have made first: if the feedbacks add up to 1 or more, we do indeed get a runaway - that's reason for anybody to be alarmed by the equation. And it's the fundamental reason why from almost all the data and models (James Annan may object, but...) we have much more uncertainty on the high side than the low side, in sensitivity.
Lindzen's first point on this was actually wrong. He made a stability analogy, claiming or implying that positive feedbacks are unstable. In this context they are not - unless they add up to more than one - and that's fundamentally because the actual system is inherently stabilized by the Planck feedback (the sigma T^4 bit Andy mentioned) - but Andy got that wrong too, claiming it was related to lapse rates. As far as I know, at least, the lapse rate feedback is a completely different concern and related to the moist adiabat and "hot spot" issue in itself.
The other thing I think Andy got wrong was the overall total cloud effect. Yes clouds reflect lots of light. They also absorb lots of thermal radiation. When you add both together I thought the total cloud effect was actually a slight warming, rather than cooling, of Earth. RealClimate had some numbers on this a while back, but maybe I'm misremembering.
Anyway, overall it was a really good talk, very well presented for a technically oriented audience.
My wife concludes that the color of Dessler's shirt does not cohere with with the color of what seems to be his khakis.
My wife recommends more funding for the study of the perception of matching colors among climate scientists.
A feedback that does not converge (an infinite feedback) is not needed to give us a result that would be catestrophic. Indeed (not that anyone thinks this is possible) even a result like that seen on Venus does not continue without let. Of course there is more than one definition of runaway that is being used.
Can the video be downloaded from somewhere and then watched offline?
"which means essentially beyond doubt", the Catholics have a term for this, called "infallibility".
And honestly, nothing screams that you are full of skeit more than saying that you are infallible. The Pope gets away with it because he is the Vicar of Christ and he can damn you to hell with his mighty staff. You, on the other hand, just sound like a tool.
Actually, I do think that the net effect of clouds is to cool the planet. The number that I remember being estimated is about 20 W/m^2. (Unfortunately, though, I can't track down where I read this.) As I recall, this comes from significantly larger (by 5 or 10X) warming and cooling effects individually, so there is a large cancellation of the effect.
Dessler did beautifully. Lindzen was his usual effervescent self.
Honestly, I have to wonder whether there is some sort of strategy on Lindzen's part: put the audience to sleep before Dessler gets the chance for a rebuttal. More likely try and convince the audience that there is nothing to get excited about -- or that if the other individual seems more excitable than his own flat-line this is evidence of their alarmism.
Except of course when thin-skinned Lindzen actually does get "excited" because Dessler criticizes Lindzen's examples from climate literature -- which happen to be well-debunked Lindzen papers so that the criticism can be made out to be some sort of personal attack. If I didn't know any better I would say that it was a deliberate ploy on Lindzen's part to win the sympathy of the audience.
*
Regardless, the simple fact that Dessler is responding to Lindzen by pointing out flaws in Lindzen's arguments could -- by the same token -- be construed as a personal attack. After all, whatever positions Lindzen takes they are his personal positions and he can construe the expression of disagreement as a personal attack.
Except of course during a debate one is expected to express disagreement. The only difference in this case being that Lindzen is appealing to the literature as a means of externally supporting the points he is making in the debate rather than supporting those points by means of arguments internal to the debate itself. And the literature that he is using for this support consists of his well-debunked studies.
A personal (ad hominem) attack would be more along the lines of, "Don't believe Lindzen because he was mean to his mother." Pointing out the flaws in his arguments? Perfectly legitimate. And if he doesn't want his papers criticized he shouldn't cite them -- particularly as something authoritative in order to support points that he is trying to make in the debate. Cite something by somebody else that Dessler can criticize without your taking it as a personal affront.
Reminds me of the child who commits patricide then throws himself on the mercy of the court as an orphan.
@Joel, if Clouds cool the Planet as a negative feedback, why has there been thirty years of atmospheric warming and increased Ocean heat content?
JCrabb said...
"@Joel, if Clouds cool the Planet as a negative feedback, why has there been thirty years of atmospheric warming and increased Ocean heat content?"
Because clouds aren't the only feedback and some feedbacks are positive?
Heck, with carbon dioxide alone you would have warming, just not as much of it. And net feedback could be negative without preventing carbon dioxide from warming the climate system -- only it would dampen the warming effects from what they would be in the absence of any feedback.
However, from the literature I have seen clouds may actually be a positive feedback.
See for example:
"The current study uses recent CERES TRMM satellite observations to test the iris hypothesis of Lindzen et al. (2001). We find that their study is too low in albedo by 0.161 and moderately low in the top-of-atmosphere longwave flux by 17 W m^-2 for tropical cloudy-moist area (Tb , 260 K). When combined, these two effects change the strong negative feedback in Lindzen et al. to a weaker positive feedback in this study. Thus, if there were an IR iris, the earth would also have an anti-IR iris or shortwave iris that would counterbalance the IR iris for the earth’s radiation. Future studies should examine the use of infrared sounder cloud heights as opposed to a simple brightness temperature threshold to improve the analysis."
pg. 7, Bing Lin et al (1 Jan 2002) The Iris Hypothesis: A Negative or Positive Cloud Feedback, Journal of Climate, Vol. 15, pp. 3-7
... as well as the more recent:
"Several independent cloud and ERB datasets suggest that there might have been a decrease in high-level cloud cover during the past several decades that has reduced LWCRF over time. ERBS, ISCCP fl ux dataset, and ocean heat content measurements indicate that this slight cooling effect has recently been Trends in Observed Cloudiness and Earth's Radiation Budget opposed by a stronger warming effect caused by a weakening of SWCRF."
pp. 32-3, Joel R. Norris and Anthony Slingo, Trends in Observed Cloudiness and Earth's Radiation Budget, from Strungmann Forum Report: Cluuds in the Perturbed Climate System: Their Relationship to Energy Balance, Atmospheric Dynamics, and Precipitation, Edited by Jost Heintzenberg and Rober J. Charlson (2009) MIT Press ISBN 978-0-262-01287-4
Dessler talks "coherence" and Lindzen talks "incoherence" and never the twain shall meet.
Enjoyed that, though Lindzen could use a course in Powerpoint!
Dessler was indeed coherent and made his points clearly. As to his rebuttal of Lindzen, the latter ought to know that being told "you are wrong" does not comprise a personal attack.
Cheers - John
tl;dw but I'll take your word for it!
Maybe the blogosphere can magically answer my questions...
'if the feedbacks add up to 1 or more, we do indeed get a runaway - that's reason for anybody to be alarmed by the equation. And it's the fundamental reason why from almost all the data and models (James Annan may object, but...) we have much more uncertainty on the high side than the low side, in sensitivity.'
But doesn't the linear approximation break down? (Zaliapin and Ghil, Another look at climate sensitivity, Nonlin. Processes Geophys., 17, 113-122, 2010)
I'm actually not clear what the methodological distinction is that leads to the statement that low values can be ruled out while high ones cannot. (Again in a new Early Online Release from the Journal of Climate, Constraints on climate sensitivity from radiation patterns in climate models Markus Huber, Irina Mahlstein, Martin Wild, John Fasullo, Reto Knutti)
I thought the weak constraint on the upper limit to climate sensitivity from twentieth century warming came from uncertainty in the aerosols. Can anyone tell me if Gunnar Myre's recent work has reduced this uncertainty? (Science 10 July 2009:
Vol. 325. no. 5937, pp. 187 - 190)
And about V. Masson-Delmotte and others, EPICA Dome C record of glacial and interglacial intensities, Quaternary Science Reviews
Volume 29, Issues 1-2, January 2010, Pages 113-128 ... this overlaps with other evidence (consilience again) but can it count as independent from warming from the last glacial maximum. They seem to give awfully small error bars (I make it from 3.15 to 3.23 deg C)?
While I'm at it with the questions, Sanderson, A multi-model study of parametric uncertainty in predictions of climate response to rising greenhouse gas concentrations, Journal of Climate 2010 ; e-View doi: 10.1175/2010JCLI3498.1 seems to say we should read anything into the fact that the new ‘CAMcube’ ensemble shows a range of sensitivity from 2.2 to 3.2K compared to 1.7K to 9.9K in the older climateprediction.net ensemble. Is that really true, that the reduction in range has no fundamental significance, were there decisions that resulted in that?
It seems to me that we are constraining sensitivity near three degrees pretty well.
Dessler Shoots the AGW argument in the foot...
POINT #1
At about 8:05 in the video Dessler says: "...The water vapor feedback even lags temperature by a few weeks. Which shows water vapor is reacting to surface temperature. Surface temperature changes then water vapor. You see, water vapor FOLLOWS the surface temperature exactly. The next time a skeptic tells you that the water vapor feedback, you know, doesn’t exist, or it’s purely hypothetical, you have a decision whether you can believe them or your own eyes. It’s quite clear that water vapor follows temperature.”
By that same logic, AGW can not exist because that it’s been shown that CO2 rise FOLLOWS temperature as well (by a few hundred years). Can you have it both ways?
POINT #2
On the topic of cloud feedback I believe Dessler makes several mistakes:
a: He says that clouds COULD cool less then they do today in the future. No evidence mind you, but they could. He says: “Don’t get confused with the elementary grad school mistake of confusing the magnitude of a function with its derivative. Just because they cool now, doesn’t mean that the derivative of the function is also cooling.”
Can not the same thing be said about CO2 and warming? Just because CO2 is warming now (according to AGW proponents) doesn’t mean that the derivative is also warming.
Especially since we know that CO2’s effects are logarithmic, not linear, so the “warming effect”
Also, Clouds are made of dust, ICE & WATER. When they absorb more heat the water falls out of them as rain, which in turn, cools things off. Which enhances the negative feedback.
RObb the denialist - your point 1 is completely wrong in every way, are you sure you aren't a poe?
I think its the same with your point 2 as well. Have you actually read anything about climate before?
RoboSkeptic,
I think the first point you make is just a tad wayward. In both cases they can be classed as a feedback. Thus...
orbital variations induces warming > increase CO2
Increasing CO2 induces warming > increase water vapour
And much like the argument that Dessler is making (water vapour enhances the effect of GHGs - positive feedback), the CO2 released during ice-age terminations enhances the warming from orbital variations (positive feedback).
Same ting, just a different forcing underlying the resultant feedback.
HeyNonnyNonnyMouse
JK - strictly speaking, you're right, the meaning of total feedbacks greater than 1 is indeed that the "linear approximation breaks down". The units of feedback are relative to the bare Planck response that stabilizes temperatures, so greater than 1 means that feedbacks are larger than that.
So feedbacks greater than 1 means the climate doesn't respond linearly to perturbations. Which means the standard measure of sensitivity (temperature change after doubling CO2), if that particular number is actually something that can even be determined, might tell you very little about the response to smaller or larger forcing changes. For small forcings, with feedbacks greater than 1, the effective sensitivity number is infinite. Which I take to mean runaway.
It might not runaway very far; feedbacks depend on temperature, so once temperature is high enough at some point the linearized feedback terms add up to less than 1 again and you get stability.
The fact that we've actually had ice ages in the past, with the planet seeming to flip between two steady state conditions (large ice sheets in the Northern hemisphere, or not) might be suggestive of inherent instability. That would mean the response to even a small perturbation could be very large.
There's also time-dependence to consider: the rate of temperature rise depends on how long the various feedback terms take to come into place. Ice-albedo is going to be slower than water vapor, for instance, so for short time-scales you might have a stable climate, with it unstable over longer times.
If anybody's going to be alarmist about climate change, why not point out the obvious - we can't constrain the feedback terms sufficiently to be certain that even a small perturbation of the climate system won't cause some massive game-changing response (over the long term)...
The sound quality during "Dick" Lindzen's opening presentation is poor - and coupled with the fact that he modulates the strength of his voice between great booms and whispers, I really couldn't hear what he was saying. It became really soporific, so I just had to stop trying to hear. Probably all for the best that I couldn't fathom his words, as it prevented me getting annoyed by anything he claimed. Oh yeah, and "Andy" Dessler "smokes", as you said he did. I read his book ("The Science and Politics of Global Climate Change") and it seemed dry as dust, but in this live presentation he "kicks ash".
"He says that clouds COULD cool less then they do today in the future. No evidence mind you, but they could."
Forgive me, but I see nothing strange or untoward in that comment.
could = may possibly = may or may not, depending on circumstances
It's simply stating the bleedin' obvious.
We know roughly what types of cloud give positive and negative feedbacks now. What we don't know with any sort of precision at present is how much and what type of cloud will form where in the atmospheric column in a warming world, and so whether clouds will lead to greater cooling, a slight cooling, no overall change, slight warming or greater warming is essentially not quantifiable with any sort of precision at present.
Cymraeg llygoden
JCrabb said...
"@Joel, if Clouds cool the Planet as a negative feedback, why has there been thirty years of atmospheric warming and increased Ocean heat content?"
I recommend reading more carefully and also understanding the arguments more carefully as you hopelessly confuse various things. Saying clouds in net cool the planet is not the same thing as saying that clouds are a negative feedback for climate change. The former is a statement about the NET effect of clouds while the latter is a statement that also incorporates the (complex and uncertain) issue of how clouds change as the climate changes.
For example, if low clouds (which definitely cause net cooling) tend to decrease with a warming climate, then this change in clouds would provide a positive feedback. On the other side of things, Richard Lindzen's (discredited) iris hypothesis suggested that clouds provide a negative feedback because high (cirrus) clouds in the tropics would actually decrease in a warming climate and this decrease would cause cooling because these HIGH clouds cause more warming than they do cooling.
I think that you and I are on the same side in the larger debate over AGW, but that doesn't mean I am any happier to see you confusing scientific issues than I am when I see the rabid deniers on Watts' blog doing the same.
Sure, Cl, but we can know from paleoclimate studies, of both warmer interglacials and yet warmer times in the Pliocene and Miocene, that whatever clouds are present don't do what Lindzen hopes they do. This is why he avoids paleo like the plague.
Has anyone got info or a link to the temperature projection trend that Andy showed re. Lindzen saying a warming trend had twice the odds and as no warming?
Arthur,
feedback doesn't even have to be close to 1 to produce a nonlinear response. The relationship is
DT = DT0 / (1 - f)
which expands to
DT = DT0 + f * DT0 + f^2 * DT0 + ...
So for f^2 not a lot smaller than |f| it will be significantly nonlinear.
A better example of runaway on Earth would be the 'Snowball Earth' episodes. It appears total feedback exceeds unity when continental ice sheets extend down to 45 degrees latitude. And yes, the runaway stops when the ice reaches the equator :-)
The deglaciation out of the snowball is another example. Spectacular.
Yes Steve... but Lindzen is a side issue in regard to the reason for my reply (and beyond that for that matter ;-).
Cymraeg llygoden
Steve Bloom says of Lindzen, "This is why he avoids paleo like the plague."
It may also explain to some extent the level of effort that denialists have put into discrediting paleoclimate studies.
What is missing in all this argument over feed-backs is their non linearity and the multi variability(lags) of the time frames. Tipping points people, where a small change has a massive outcome, before and after changes do not have the same significance.
All the feed-backs have limits where they run out. The change in Arctic albedo will not be as significant when there is no summer sea ice. Water vapor will not increase after the oceans have evaporated.
We like nice little boxes, nature does not.
Little Mouse
PS I do not have the faintest idea how to put numbers to the above statement.
Martin, despite f^2 being "nonlinear" (in f), it is actually still applying a linear response to the real question of how temperature changes with forcing; the f^2 is just an additional term in the ratio between temperature and forcing, but the assertion is that there *is* a determinable ratio between temperature and forcing (at least for small forcings).
But for f > 1 that ratio becomes infinite, and the response of temperature to forcing is nonlinear (superlinear) even for small forcings. That's instability.
@guthrie (the alarmist)
you said "your point 1 is completely wrong in every way, are you sure you aren't a poe?"
How is that point wrong in any way. Dessler says water vapor follows tempreature exactly. So it must be a result of the rising temprature. His words, not mine. It's been well documented that CO2 lags temp, so according to Dessler's logic, more CO2 has to be a result of the rising temp. Ad hom @ me all you'd like. It doens't change the fact that you need an awful lot of circular reasoning to follow the AGW dogma.
I'm glad you gave me so much evidence as to why my point 2 is wrong as well. As long as you think it, it must be true.
@Anonymous
Thanks for pointing out the non-anthropogenic nature of GW. Didn't we just end a (little) ice age in the 1800's? Hmmm and CO2 has been going up since when again?
RobbSkeptic,
"By that same logic, AGW can not exist because that it’s been shown that CO2 rise FOLLOWS temperature as well (by a few hundred years). Can you have it both ways?"
Actually, the "CO2 lagged T in the past so can't possibly force temperature now" myth has been refuted ad nauseum, so I won't go into details here. It might be worth your while to do much more reading before pontificating and arguing with people.
MapleLeaf
Robb the Skeptic: Yes, you can have extra CO2 from carbon cycle feedback or from human activity. If you do not understand the difference between CO2 and water vapor then you need to do more research.
Am I correct in assuming the modellers' prediction of widespread droughts means more water vapour from evaporation and so more global warming?
http://www2.ucar.edu/news/climate-change-drought-may-threaten-much-globe-within-decades
HollyStick,
The contribution to tropospheric WV is dominated by evaporation form the oceans. That said, recent research has shown that ET (combined evaporation and transpiration over land), after increasing steadily until about 2000, has now started to decrease, and that the decrease is on account of reduced ET from terrestrial areas in the Southern Hemisphere on account of moisture stress. In fact, many of the same regions expected to dry out by the Dai study that you linked to (e.g., southern Africa, Australia, parts of S. America) have been shown to have already experienced reduced ET based on in-situ observations.
Dai, Trenberth and Qian (2004) have shown that large areas are already showing robust drying trends, while other (smaller) areas are becoming more moist.
Some regions will receive more precipitation as the planet warms, while others will receive less precipitation. Things are not looking good for the Mediterranean, portions of Australia, southern Africa and parts of S. America in terms of future water supply.
MapleLeaf
@Anonymous
Enlighten me...how about showing me some "ad nauseum" links to your refutation. Don't give me anything from Real Climate & I won't give you anything from Watts
@Rocco
I never said there wasn't a difference between WV & CO2. I also never said we weren't adding extra CO2 to the atmosphere. What I said was Dessler's logic is flawed. The entire AGW argument revolves around circular logic that when added up, just doesn't equate.
A fact for both of you to chew on is: The planet has been warming since the end of the LIA. CO2 has been on the rise since around the same time.
It's no wonder AGW proponents like to talk about the last 30 years so much.
And you're both so much more educated than I am. Maybe you can answer a few questions.
What is the ideal temperature for the planet?
If there is increased cloud cover + more water vapor as a result of AGW, would you expect more or less precipitation across the globe? Would more precipitation act as a positive or negative feedback?
Please, oh mighty gods of knowledge, educate this poor ignorant denialist.
Thanks, MapleLeaf.
The southwest US may also be in trouble.
Eli is a wise bunny, yes the US SW is very likely also going to suffer...
ML
According to my link:
"...While regional climate projections are less certain than those for the globe as a whole, Dai’s study indicates that most of the western two-thirds of the United States will be significantly drier by the 2030s. Large parts of the nation may face an increasing risk of extreme drought during the century..."
http://www2.ucar.edu/news/climate-change-drought-may-threaten-much-globe-within-decades
I suspect that at some point they will find they need water pipelines from the north more than oil pipelines.
Robb,
Especially over timescales on the order of decades, the most ideal climate is the current one because it...and the associated sea level...is the one that we and the flora and fauna are adapted to.
I don't see how precipitation is, in and of itself, either a positive or negative feedback...unless one confuses the surface energy budget with the climate system's total budget. Since you want to be educated, I would suggest reading a book like "Global Warming: The Hard Science" by L.D. Danny Harvey. It will help to explain why the surface temperature is relatively insensitive to an imposed change in upward and downward heat fluxes at the surface but much more sensitive to a net radiative change applied to the whole system.
As for asking to be educated, it is hard to educate people who don't want to be educated but would instead prefer to believe what their ideological predispositions make them want to believe. Perhaps you don't fall into that category but I see little evidence so far to support that notion.
Oh, and by the way, just in case you still think your point #1 about the water vapor following temperature and the analogy to CO2 makes any sense whatsoever, here is why it doesn't: "Skeptics" citing the fact that CO2 lags temperature are using it to argue that therefore CO2 doesn't affect temperature. Dessler is not using the fact that water vapor lags temperature to argue that water vapor doesn't affect temperature...In fact, we know that it does. He is just using it to point out that the effect goes the other way too. Scientists agree that the effect between CO2 and temperature also goes both ways.
Rob the Skeptic,
In distinguishing causality between correlated variables, you need to keep in mind the physics. Indeed, CO2 is NOT the cause of the initial temperature rise during the end of an ice age. The initial warming is caused by changes in insolation due to changes in Earth's position and orientation relative to the Sun. Eventually CO2 is given off by thawing permafrost, the oceans and other reservoirs. This CO2 then intensifies the warming and causes it to last longer than could be explained by Milankovitch cycles alone. This is well known.
In the case of H2O vapor and insolation, Dessler's point--which is correct--is that since it takes time to come into equilibrium, water vapor cannot be the initial cause of the warming, although it is a feedback.
You really need to at least understand the science enough to know what you are skeptical of. This is pretty basic stuff.
Maybe it's useful to explain that the change in insolation causes initial warming and the CO2 that is then naturally produced adds to the warming; but this time we are also artifically producing a lot more CO2 which will increase the warming a lot more.
Terra has been in the current ice age since the beginning of the Pleistocene and despite calling more recent times the Holocene and even the Anthropocene, is still in it.
For the first almost two-thirds, the climate cycled between stades and interstades, following the (approxcimately) 43 ky changing in tilt . More recently the cycling has been through three stages, interglacial, stade and interstade. Currently we are in an interglacial (the Holocene/Antropocene) and because of the slug of CO2 added, going to stay in one for about 100,000 years.
See David Archer's "The Long Thaw".
@Joel
First off, thanks. Your's was the first reasoned response to me. But I have to respectfully say that your first point is a non-answer.
"Especially over timescales on the order of decades, the most ideal climate is the current one because it...and the associated sea level...is the one that we and the flora and fauna are adapted to."
The planet doesn't deal in "timescales on the order of decades". Nor does it care what "we and the flora and fauna are adapted to." The fact is we just don't know what the ideal global mean temprature is. To attempt to set an arbitrary number based on our beliefs is ego-maniacal and pointless.
Second, I have actually had Harvey's book since about 2000. It's one of the first I read (out of about 20 now). Looking back (and at Harvey's other works), it was clearly written with a pro-AGW (a church I used to belong to) agenda. Have you read anything else he's done? The book , to its credit, is one of the things that sparked my interest in GW.
IMO the data points to the conclusion that we don't know 1/10 of what we need to about the way the climate system works.
Your third point about educating those who "prefer to believe what their ideological predispositions make them want to believe" Is exactly how I feel about most AGW proponents (hence the "church" reference above). And sadly, between the censoring of dissenting opinions on AGW leaning blogs (I'm looking at you Real Climate) and the ad-homs I read most skeptics receiving, I see little evidence that most AGW-ers want to hear anything that contradicts their beliefs.
I'll leave you with a response to you and the poster a_ray_in_dilbert_space.
You make the usual "leap of faith" that because skeptics like me don't think that man made CO2 is affecting temp that we don't believe CO2 plays any role in warming the planet. Of course it does, and the lag + add theory of how CO2 and temperature are linked does hold merit.
Here is what I see in the data...please try to process this before applying any models/physics/forcings/feedbacks.
CO2 levels were around 280ppm circa 1850? I think we can agree on that. Today's levels are around 390pmm. I think we can agree on that. I also think we can agree that the temperature has been rising since the end of the LIA (1880 or so).
How much of that 110ppm increase has man put into the atmosphere and how much has been released through the natural recovery from the LIA? If you listen to most AGW'ers the answer is all. I can't tell you how many times I've heard that man is responsible for 30% of the CO2 in the atmosphere. When in reality they mean there's been a 30% rise in atmospheric CO2.
From everything I've read, we're responsible for between 3-5% of atmospheric CO2 or about 20ppm of 390ppm. You do the math and tell me whether mother earth would have reached the magical "tipping point" of 350ppm all by herself.
Here's another way to look at it. Mankind puts roughly 27 billion tons of CO2 into the atmosphere from fossil fuel consumption (that's pretty widely accepted) The weight of the earth's atmosphere weighs 4.41 million billion tons. So the burning of fossil fules = 6ppm/yr.
Forget forcings, and physics equations and complex (though not complex enough) models. They may all be valid (except Trenberth's energy budget). We should be concentrating on the real problems that damage the planet.
But again, thanks for your civility in your response.
Robb:
Well, if I criterion is whether or not the "planet cares" (whatever that means) then I don't think that will give us any guidance on just about any policy issue. Does the planet care whether or not terrorists fly planes into buildings? I think not. Does that mean that we shouldn't care? Does the planet care whether our economies grow or stagnate, whether unemployment is low or high, ...?
As for your math on CO2...It's all wrong. If you look at how much CO2 levels rose with temperature during the ice age - interglacial cycles, you come out with something like 15-20 ppm per degree C. And, the fact that there seems to be a measurable several hundred year lag between temperature and CO2 (as skeptics love to point out) suggests that we wouldn't have been likely to yet see that much from the temperature rise alone. So, even if you blame the entire temperature rise since ~1850 on natural causes (problematic though such a claim is), you still get humans responsible for most of the CO2 rise.
Of course, this is also in line with the overwhelming circumstantial evidence: Why do you believe that the CO2 levels chose this particular century out of all in the past 3/4 million years to suddenly rise to levels well in excess of 300 ppm? The odds of that are just not very good. You also have to believe that some sink magically decided to take up most of the CO2 that we emit at the same time as the ocean or whatever decided to magically release "natural" CO2 to rise levels well above the range seen for the last 3/4 million years. That's a lot of magic!
I am also surprised to see you claim that we are responsible for only "3-5% of atmospheric CO2". I am not sure where this comes from but if it comes from comparing our annual input of fossil fuel CO2 into the atmosphere to the input from the biosphere and hydrosphere (and ignoring the transfers in the other direction), then I am surprised you would make this mistake if you have really read Harvey's book well. His book has the clearest explanation that I have seen of why it is wrong to confuse the rapid transfers between the different parts of the subsystem comprised of the atmosphere, land biosphere + soils, and ocean mixed layer with the transfers in and out of this entire subsystem. The point being that any slug of CO2 added to this subsystem rapidly partitions itself between the different parts but that the transfer out of this subsystem into the deep oceans is much slower...and, in fact, incomplete until other things can happen (like the leaching of calcium carbonate to offset the acidification of the oceans).
Robb the Skeptic,
OK, I really am not trying to be insulting, but I'm wondering why you think you are the first one to wonder how much of the CO2 in the atmosphere came from humans and how much was natural. Others have thought of it and even figured out how to determine the fraction--and it turns out that fossil CO2 has a different proportion of isotopes of Carbon than that found ambiently. It is enriched in Carbon-12 at the expense of Carbon-13. And we can show from old samples that the Carbon-14 content is effectively 0 (new samples are contaminated with nuclear fallout). Measurements show that we are responsible for essentially all of the increase. Not only that, only about half the carbon we've burned goes into the atmosphere. The rest has gone into the oceans where it has lowered the pH measurably.
So, given that you hadn't bothered to learn that, do you maybe wonder what else you don't know about climate?
Robb,
This may help clarify the role of CO2 as both a feedback and forcing in the paleoclimate: http://www.yaleclimatemediaforum.org/2007/10/common-climate-misconceptions-co2-as-a-feedback-and-forcing-in-the-climate-system/
WV is generally not a forcing for the simple reason that the absolute humidity is strongly constrained by the temperature, and WV fluxes settle out quite quickly.
"The contribution to tropospheric WV is dominated by evaporation form the oceans"
Evaporation is a slow process in still air. The wind is the force that transports most all of the water vapor from the oceans into the atmosphere and eventually onto the land.
Even if the surface water is cold, a stong wind will still transport water into the air. For example, the water of Pacific along North America are fairly cold but the temperature rain forests from Oregon to Alaska receives rain fall measured in meters.
At Vancouver Int. Airport, the average rainfall is about 1,200 mm but the amount is quite variable from year to tear and strongly influenced by the ENSO.
Air pressure also influences humidity. High pressure cell usually have hot,warm or cold dry air whereas low pressure cells have moist air (i.e., higher humidity) and usually bring rain or snow.
The heat of vaporization of water depends mostly on pressure and to slight extent on temperature since it is an associated liquid. As a hurricane moves from the Atlantic ocean into the warm water of the Gulf of Mexico, the decreasing air pressure in the interior results in "flash evaparation" of enormous amounts of water which is eventually dumped on the land and in cases far inland.
Harold Pierce Jr
I feel bad that I never learned about converging power series in 9th grade!! :-(
Good talk. Look for Part 2 on Climate Feedbacks at RealClimate any day now for some more :-)
Anyone able to help with the denier lunatic fringe here:
http://www.city-data.com/forum/16449289-post437.html
We've had an entire global warming conversation completely monopolized by a cherry-picking graphic-dropper. It's important, thousands and thousands of people are reading this site.
FWIW, the clown is posting three years of data. Post this or this
(You can find equivalents in the arctic report or on cryosphere)
Post a Comment