BBC’s quotes include a bit more:
–excerpt follows—-
“The one big caveat is whether SIM’s data is accurate.
Scientists in the field appear to believe it is – but as the UV changes it sees are so large compared with previous methods, they would prefer confirmation.
Commenting in Nature Geoscience, Katja Matthes from the Helmholtz Centre in Potsdam, Germany, describes the results as “intriguing, albeit somewhat provisional”.
“The trends seen in the SIM observations are still under discussion and remain to be confirmed,” she writes.
She also points out that SIM measures only a proportion of the ultraviolet region of the spectrum….”|
wilisays
But hasn’t sunspot activity been rapidly increasing this year? So shouldn’t that mean a warmer winter in Europe and parts of the US?
Paul Tremblaysays
Has anyone followed the debate between skeptical science and Pielke Sr here:
Perhaps as a non scientist, I am missing something, but to me it strikes that Pielke has to be one of the most dishonest debaters ever. He makes a claim that CO2 forcings are only 20%. Other posters point out specifically why he is wrong. He evades, throws out irrelevant information, and finally concludes with the statement that no one really knows for sure, the question is not important, so lets move on. When cornered, he won’t answer directly, but raises questions mostly irrelevant.
Wili, the story above is reporting a brand new result, a surprising one, that has not been confirmed yet from other data and instruments.
So there’s no good way to make a prediction about the weather based on it.
What if adding more ultraviolet changes aerosols to make the sky hazier and more reflective? Could that happen? Googling speculatively, turns up:
“It is hypothesized that many substances in the atmosphere, including volatile organic compounds (VOCs) and their oxidation products, very fine particles and others absorb and/or utilize UV energy. The long-term UVI trends and its main controlling factors in four seasons during the previous 2 decades are discussed, UV energy consumption by atmospheric chemical and photochemical processes, is especially important during summer….” http://www.sciencedirect.com/science/article/pii/S1352231011009939
Analysis of ultraviolet radiation in clear skies in Beijing and its affecting factors
Jianhui Bai, LAGEO, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
24 September 2011
Joan Baez once said something like: “if you are faced with a choice between a hypothetical situation and a real one, choose the real one.”
Any who choose to participate in the discussion threads with Dr. Pielke at SkS, please show restraint and exercise decorum. He is a guest and respect is to be given.
Thank you.
David B. Bensonsays
wili @203 — There is a lag between the sunspot cycle and warmth/coolth just as there is a lag between solar insolation and the warmest/coolest parts of the annual cycle.
ldavidcookesays
RE: 205
Hey Hank,
I believe that the greatest influence of the added 11 yr cycle UV may be isolated to the N. Jet Stream pattern. Not that I have a source other then 8yrs of NOAA, NCDC, SRRS observations, the interesting thing I have seen emerge over the last 11 years are the changes in the Walker Circulation and the N. Jet Stream’s seasonal elipitical pattern change. I believe this may have been also suggested by some of the present researchers associated with the Hadley Center UV/SIM story.
The problem is trying to associate which is which. Is the extra volume contained in the current N. Jet driven by UV heating or by cross zonal equatorial heat flow. Which I believe returns the discussion to what also drives the equatorial heat increases, is it a reduction in cloud cover caused by CO2 warming, aerosol population changes or added Tropopause UV energy reducing high altitude wv condensation?
VOCs not withstanding, have you any insights you can share?
Cheers!
Dave Cooke
wilisays
Thanks, David. That makes sense.
Sun spots do seem to be increasing rather rapidly, though, so maybe we can expect a somewhat milder MN winter in 2012-2013? (I know, I know, the study is only preliminary and other factors play large roles.)
It has already been visited by the sorts of idiots that think you can even lie to physicists about how science works.
Former Skepticsays
Daniel @206:
I agree with your call for civility, and would like to thank you and the other folks over at SkS for being so persistent and patient in the RPSr. threads.
Having said that, RPSr.’s answers – or the lack of them, rather – is very revealing. While I would not go as far to call him “dishonest”, as Paul (@204) opines, his evident evasiveness to the very direct, cogent and polite answers by dana, Albatross, Tom Curtis et al. is both disappointing and expected (given past evidence both here and elsewhere on the intertubes).
Good luck in continuing the discussion, though I have a sneaky suspicion that RPSr. will soon leave in a huff again upon another self-perceived slight on his person.
Pumping CO2 into hot rock, deep enough it acts as a supercritical fluid — then drawing some back out to run turbines, then reinjecting the cooled gas. Still takes energy overall to sequester the CO2, and transfers some geothermal heat to the surface — but uses the heat in the reservoir. New idea.
caerbannogsays
Folks attending the GSA meeting in Minneapolis might be treated to a freak show tomorrow outside the main entrance of the conference center.
wili,
Of course sunspots are increasing–we’re moving into solar max. To my knowledge, though, the Sun is still below normal activity for this portion of the cycle. However, given the much prolonged solar min of the last cycle, it’s hard to say what normal should be for this one.
Why would you expect a correlation between solar cycles and winters in Minnesota? Nobody seems to have published the idea anywhere. Do look, maybe I missed something.
I did find a contrary suggestion (from Lockwood, Harrison, Woollings and Solanki, speculating about cooling):
Environ. Res. Lett. 5 (April-June 2010) 024001
doi:10.1088/1748-9326/5/2/024001
Are cold winters in Europe associated with low solar activity?
I’d like to make a request for a post, if you don’t mind. I frequently run into people with gross misconceptions about how the models work. They are insistent about all of their misconceptions. I do point them (with glee) to the excellent two part post here at RC on climate model FAQs.
But it would be nice (both fun to read, and useful for those people who don’t understand) if you could provide an English language synopsis of the actual structure of the specific models (and model components) that you work with. In business computing this would be termed a “Functional Design,” a document that describes (for the layman) how the programs work without getting into the nitty-gritty and getting bogged down in the actual computing details.
It would be a great read, and it would also be a great resource for refuting those people who think that climate models work by tweaking parameters and forcing temperatures to rise with CO2 levels through presumed correlations, rather than through the cumulative effects of individually modeled physical relationships.
Please consider doing so, if you have the time.
Hunt Janinsays
I second the point made in 216 above.
Richard Birdsays
Sphaerica: that would be an excellent idea and really helpful.
I have a specific problem in accepting this version of modelling as stated by the Skeptical Science site:
Amplification: ” How does this work? The amount of water vapor in the atmosphere exists in direct relation to the temperature. If you increase the temperature, more water evaporates and becomes vapor, and vice versa. So when something else causes a temperature increase (such as extra CO2 from fossil fuels), more water evaporates. Then, since water vapor is a greenhouse gas, this additional water vapor causes the temperature to go up even further—a positive feedback.
How much does water vapor amplify CO2 warming? Studies show that water vapor feedback roughly doubles the amount of warming caused by CO2. So if there is a 1°C change caused by CO2, the water vapor will cause the temperature to go up another 1°C. When other feedback loops are included, the total warming from a potential 1°C change caused by CO2 is, in reality, as much as 3°C ”
My problem is with the statement: “If you increase the temperature, more water evaporates and becomes vapor”.
The author is not implying a direct causal link from CO2 to WV content. He is saying that temperature increase causes an increase in WV content. But that would imply that for ANY global temperature increase, even a natural increase. That would imply:
A natural rise in temperature produces more water vapour – which increases temperature – which produces more water vapour – which increases temperature – and so on…. a runaway feedback effect which must lead eventually to either atmospheric saturation or heat catastrophe. I assume this doesn’t happen in reality. (!)
My understanding of the physics involved is that warmer air has the CAPACITY to hold more water vapour. That is all. Can someone clarify how the principle of Amplification is supposed to work, and why there is not a runaway chain?
Pursuant to Sphaerica (Bob)’s request for a post on the structure of models…
Kate (of ClimateSight) did such a study as a summer project (she’s studying to be a climate scientist). I believe she will even have a poster presentation on the topic at the upcoming AGU meeting. Perhaps she would be happy (perhaps even delighted) to contribute a guest post to RC,or perhaps do one in collaboration with RC regulars (Gavin?).
Just a thought…
dhogazasays
Richard Bird:
A natural rise in temperature produces more water vapour – which increases temperature – which produces more water vapour – which increases temperature – and so on…. a runaway feedback effect which must lead eventually to either atmospheric saturation or heat catastrophe. I assume this doesn’t happen in reality. (!)
You’re making the common improper assumption that a positive feedback must inevitably lead to a runaway feedback. Do some googling for stuff like “convergent series positive terms” …
For Richard Bird
You’re asking a frequently answered question (might even be found if you look at the “Start Here” link at the top of the page for the FAQs; try there.
Richard, the amplification is limited because the atmosphere does not have an infinite capacity to hold water, and you aren’t applying an unlimited forcing. Think of it in terms of a pot of water with a candle under it – it gets warm to a certain point, but no more, even if you just leave the candle there. Putting the lid on the pot will keep some of the heat trapped, but you still reach a point where the water isn’t going to get any hotter.
Of course, the planet is a lot more complex than a pot of water. :)
Just to clarify what others have already said, you said:
[The author] is saying that temperature increase causes an increase in WV content. But that would imply that for ANY global temperature increase, even a natural increase.
This is absolutely true. Feedbacks are a result of temperature change, regardless of the forcings behind that change.
The water vapor feedback is, in fact, an important element that greatly increases climate sensitivity.
You go on to say:
A natural rise in temperature produces more water vapour – which increases temperature – which produces more water vapour – which increases temperature – and so on…. a runaway feedback effect which must lead eventually to either atmospheric saturation or heat catastrophe.
This is incorrect, as dhogaza and Hank both point out.
There are multiple factors, but in a nutshell consider a diminishing series. Using made up numbers, what if the increase in water vapor results in half as much warming as a previous increase in water vapor? You have:
1 + 1/2 + 1/4 + 1/8 + … + 1/∞ → 2
The point is that if the increase in temperature ∆T1 from an increase in water vapor ∆V0 from an initial increase in temperature ∆T0 is not as great as the initial increase (i.e. ∆T1 < ∆T0) then you do not have a runaway and so do not have a problem.
And, as Hank points out, there are other factors (such as increased condensation, creating increased clouds, creating increased albedo).
Meowsays
@220: Or, to state it simply right here, doubling CO2 directly causes a temperature jump dT1. That jump makes the atmosphere take up water vapor sufficient to raise the temperature an additional dT2. That jump, in turn, causes the uptake of more water vapor sufficient to raise the temperature an additional dT3 and so on infinitely. But dT3 < dT2, and dT4 < dT3, etc. Since each term is smaller than the last, the series of temperature increases dTx converges to a finite value, much as the series
1 + 0.5 + 0.25 + 0.125 + ...
converges to 2.
CMsays
Bob #216 — excellent suggestion.
Meanwhile, I think this lovely paragraph from an otherwise dry review article deserves wider readership:
For a balanced view, it is useful to watch an animation of the output of such a model, starting from an isothermal state of rest with no water vapor in the atmosphere and then “turning on the sun,” seeing the jet stream develop and spin off cyclones and anticyclones with statistics that closely resemble those observed, watching the Southeast Asian monsoon form in the summer, and in more recent models, seeing El Niño events develop spontaneously in the Pacific Ocean. (Held and Soden, “Water Vapor Feedback and Global Warming”, Annu. Rev. Energy Environ. 2000. 25:441–75)
(Question: Where can one watch an animation like that? Preferably with blow-by-blow commentary pointing out the interesting features to an untrained eye?)
Meowsays
@223:
The point is that if the increase in temperature ∆T1 from an increase in water vapor ∆V0 from an initial increase in temperature ∆T0 is not as great as the initial increase (i.e. ∆T1 < ∆T0) then you do not have a runaway and so do not have a problem.
Not quite. What matters is not the relationship between ∆T0 (caused by CO2 in this example) and ∆T1 (caused by the “first round” of WV increase), but that between ∆T1 and ∆T2, ∆T2 and ∆T3, etc.: as long as ∆T2 < ∆T1, ∆T3 < ∆T2, etc., the feedback converges to a finite value. This is true even if ∆T1 > ∆T0. So, purely hypothetically, if doubling CO2 causes ∆T0 = 1K, and that causes ∆T1 = 1.5K, and that causes ∆T2 = 0.75K, etc., the total resulting ∆T is 4K.
CAPTCHA: evils oatfol
David B. Bensonsays
For those who find that the sclimate model FAQs are not enough, try “A Climate Modelling Primer” by Henderson-Sellers.
pmp5says
I know it isn’t your guys job to address what happens on other blogs, but I was wondering if somebody here would comment on this.
On her blog, Judith Curry stated:
“The deep uncertainty is associated with our reliance on projections from climate models, which are loaded with uncertainties and do not adequately treat natural climate variability.”
I was wondering if there was any work really addressing the last point. Do models adequately treat natural climate variability? Is the natural climate have significantly more or less variation (variance?) than the models?
I asked on her site, and I got a response related to mean values, but I know you can models means without doing a good job of modelling variation in other fields.
thanks
[Response: It’s not really clear what she is referring to. Climate models obviously do have internal variability and also respond to natural forcings. Whether that is ‘adequate’ depends entirely on what the purpose is. If you are looking to find the climate change signal in the noise, the models have a range of noise levels (which encompass the variability seen in the real world) and you can test how sensitive your attribution is to the different amounts of internal variability (see santer et al, 2009: 2010 for instance). If you are interested in the sensitivity of internal modes to different forcings, I’d say the models were adequate for somethings – the NAO, the Southern Annular mode, – and not yet adequate for something like ENSO. Without a little context or specifics it’s hard to say more. – gavin]
Bob Loblawsays
Another way of visualizing feedback – think of a microphone and speaker in a large hall. A person talks into the microphone, the voice comes out over the speaker, and gets picked up again by the microphone. Total amount of noise is more than just the single event of the first broadcast of the person’s voice.
How much noise? It depends. Each time the microphone picks up speaker’s output, the sound gets fed through the amplifiers and sent back out the speakers. If each pass through the amplifier is smaller than the previous one, we get a nice echo effect and a finite amount of sound. If each pass is bigger than the previous one, we get that horrible ear-shattering squealing sound we’ve heard at so many weddings. That’s the run-away feedback.
Joe Cushleysays
Interesting, almost throwaway comment about a change in climate in the 14th century exacerbating the course of the Black Death Plague in Europe.
Last month i posted my first Tshirts i designed here, with related climate themes. I tweaked the designs now and just released “Climate”.
It features the following text: “The oceans are warmer Today than they were, 30 years ago,means there’s about, on average, 4 percent more water vapor lurking around” – Kevin Trenberth, Scientist
Feedback is welcome, especially what you think would make other great “text additions” in this regards to climate science, with educational aspect.
Currently only available in Europe but soon in the USA as well.
OK, pet peeve here. It drives me absolutely nuts when “dissenting” scientists like Roger, Judy and Roy make vague, unverifiable, unfalsifiable statements about the skill of climate models or other supposed shortcomings in the case for anthropogenic causation. It is utterly unscientific. It falls into the category of what Pauli decried as “so bad it’s not even wrong!” It sounds more like a theological debate than a scientific discussion.
I realize that they have no model and can therefore make no predictions, but is this really the best they can do?
Vague is worse than wrong. Vague is bu****it
SecularAnimistsays
Gavin wrote re: Judith Curry: “Without a little context or specifics it’s hard to say more.”
Denigrating “climate models” without context or specifics is a common denier tactic. Judith Curry’s sweeping, context-free, unspecific generality will no doubt be copied-and-pasted all over the web within hours by people who don’t have the slightest idea what she’s talking about.
Richard Birdsays
Hank and others: Thanks for the responses on amplification. All clear, the essential factor is the initial ∆T1. Whether the series will converge or diverge depends that value. (As pointed out elsewhere, if other factors such as albedo, ocean circulation etc are involved, sufficient to a produce ∆T1=1 then the ‘runaway’ scenario becomes real. Well, fingers crossed on that for now I suppose…)
My next question was to have been: Is an amplification factor also applied in models to natural forcings such as solar irradiance, and if so is that well estimated? The obvious point being, if net solar forcing post 1900 is under-estimated, then the CO2 forcing may be over-estimated. However I see there has been a lot of discussion around that in 2005: https://www.realclimate.org/index.php/archives/2005/12/natural-variability-and-climate-sensitivity/#comments
So I will change my question to: has anything new developed around that subject since 2005? eg on cloud feedbacks?
A purely empirical observation here: London. Oct 2 2011 (near the fall equinox so giving a median picture) Blue sky, little wind; 29 deg C. Oct 4 2011, overcast with low cloud, little wind: 19 deg C. 10 deg change presumably due to cloud cover. I observed similar variations while driving from London to South of France on Oct 5 & 6, passing from blue sky to thin cloud, heavy cloud and blue sky again all day. In the space of 10-20 miles each time: Thin cloud = 2 deg drop, heavy cloud = 4-5 deg drop. Those were local variations over very short timescale. So over 24 hours, 10 deg drop seems right. Not very scientific but interesting.
Empirically, if thick cloud cause 10 deg drop. 2.5% reduction in low cloud cover -> 0.25 deg C ∆T.
IPCC Energy balance diagram: Reflection of solar energy + aerosols etc = 77 W/sm. Rough guess,70 W/sm reflection by clouds alone? Assumed AGW effect is 1.7 W/sm. Empirically, Reduction of cloud cover by 2.5% -> 1.7 W/sm increase in energy at earth surface. My all means shoot me down here, but a simplistic ‘back of envelope’ estimate of 2.5% variation in area of cloud cover would account for most of the ‘gaps’ of 1.7 W/sm and 0.25 deg C between estimated natural warming and recorded warming as set out in Hansen’s 1988 paper. (I think the figure was lower than 1.7 W/sm in 1988 but I don’t have the exact figure)
I would be interested to know if there is any reliable data on global area of cloud cover over last 40-50 years, and whether any correlation with either solar activity or temperature is apparent.
Seriously, it seems you’re retracing the steps many others have already followed, starting with ideas that either you’re coming up with on your own, or that come from somewhere people are publishing stuff that’s not reliable.
It’s no surprise logic and deduction fail; nobody knows all the basics needed to figure out what’s going on just by thinking without looking stuff up.
But, really, reading the Start Here and FAQs will avoid a lot of the most commonly encountered misapprehensions.
The traditional Usenet method — “post what you know and await correction” — invites a lot of recreational typing, but isn’t all that efficient.
Ray Ladburysays
Richard Bird,
But clouds also warm–it depends on which clouds when and where.
Septic Matthewsays
228, gavin in line: Without a little context or specifics it’s hard to say more. – gavin]
It was the quote that was removed from its context. For the context, click on the link. I reproduce it here:
“The short ISCCP time record, covering only about 22 years, shows some signs of a slower variation. Cloud amount increased by about 2% during the first three years of ISCCP and then decreased by about 4% over the next decade. ISCCP began right after one of the largest El Ninos this century (in 1982-83) and the eruption of the El Chichon volcano, both of which may have caused some changes in clouds. There were other, weaker El Ninos in 1986-87, 1990-91 and 1992-94 and another volcanic eruption (Mt. Pinatubo) in 1991. Note however, that there appear to be no related changes in cloud top pressure/temperature or optical thickness (the small change in 1991 is caused by including the extra sunlight reflected by volcanic aerosol with clouds which affects the cloud top pressure/temperature determined for very thin cirrus clouds). The surface temperature shows a decrease of about 1 K from 1983 to about 1991. Since there a number of events occurring during this time period, the cause of these cloud variations is not yet understood.
Such variations are referred to as “natural” variability, that is the climate varies naturally for reasons that are not fully understood. The problem for understanding climate changes that might be produced by human activities is that the predicted changes are similar in magnitude to those shown here. The difference between natural and human-induced climate change will only appear clearly in much longer ( >= 50 years) data records….”
—
As to why you need more than 50 years, with that particular data set, see generally the method explained at:
But I thought that was during the Mediaeval Warm Period?! ;-)
Yes, but the end of it.
Don’t know about the much-touted English wine industry, but those Greenland Norse felt an increasing climatic pinch during the 14th century. (For example, the more northerly “Western settlement”–around present-day Nuuk (formerly Godthab)–was abandoned during this time.) Last known contact with Scandinavia (before the modern era, of course) was 1410.
All of the answers so far on why positive feedbacks can converge are presented in a linear framework of feedback analysis, and are actually incapable of yielding useful information on whether a “runaway” effect occurs as the traditional feedback factor goes to one, where the linear analysis becomes invalid.
Typically, we define some reference system, such as the Planck restoring feedback (i.e., the increased radiant emission to space in a warmer world, or less emission on a cooling planet) and then define feedbacks relative to that. In a linear world view, if we call the temperature anomaly ∆T0 for a planet where only the Planck radiative restoring response were active (usually ~1.2 C per doubling of CO2), then the real temperature anomaly is ∆T = ∆T0/(1-f), where f is a feedback factor that depends on how much a particular variable (such as water vapor) changes with temperature, and on how much that change actually impacts Earth’s radiation balance. If f ~ 0.5 then climate sensitivity is doubled, but OLR still increases with temperature and you converge to a stable solution.
Physically, you can think of 1-f as being related to the slope of a line in G vs. T space, where G is the net TOA energy balance (outgoing thermal emission – incoming absorbed sunlight) and T is the surface temperature; note that G increases with T. See Figure 3.1 here to see this visually. The less steep the slope, the higher the climate sensitivity, since the surface temperature must rise more in order for the planet to re-establish radiative equilibrium. Water vapor feedback makes the outgoing radiation more linear than T^4, so the Planck restoring feedback still wins out in the end (allowing for stability), but it isn’t as effective.
More generally, when f reaches one, you reach a bifurcation point but you have to know something about the global structure of the energy surface in G-T space, rather than the local departure from a stable equilibrium point. When f goes to one, it doesn’t need to be a “runaway” effect (but it could be). This would happen if the absorbed solar radiation were high enough, and you reached a point where the water vapor feedback were strong enough so that OLR did not increase with temperature.
Septic Matthewsays
234, Richard Bird: I would be interested to know if there is any reliable data on global area of cloud cover over last 40-50 years, and whether any correlation with either solar activity or temperature is apparent.
Here is a start, though it isn’t cloud cover per se , but the change in forcing effected by the cloud cover. At least I think it’s a start.
http//wattsupwiththat.com/2011/10/11/wrong-again/
dhogazasays
Richard Bird:
A purely empirical observation here: London. Oct 2 2011 (near the fall equinox so giving a median picture) Blue sky, little wind; 29 deg C. Oct 4 2011, overcast with low cloud, little wind: 19 deg C. 10 deg change presumably due to cloud cover.
Why presumably due to cloud cover? Why not an influx of cool marine air leading to the switch from clear skies to clouds?
While thinking about this, please re-read Hank’s post 235 above …
I hope you don’t consider this too far off topic, but I am having an exchange with a very persistent blogger who claims that CO2 and temperature changes during transitions between glacial and interglacial periods are inconsistent with established theory. Please can you confirm whether my argument is correct:
CO2 can only exert a forcing if its atmospheric concentration changes. The larger the change, the larger the forcing.
If the rate of change in CO2 concentration is very slow, global temperatures can almost keep up with the effects of the changing CO2, so the net forcing at any point in time is CLOSE TO ZERO.
The difference in CO2 levels between glacial and interglacial periods was at most 100ppm (and at least 100ppm lower than today) and the change took place over thousands of years in response to the gradual changes in ocean temperature. Consequently, the very gradual increase in CO2 levels could never have exerted sufficient warming effect (it’s strictly a feedback in this case) to overcome the effects of other changes due to albedo and Milankovitch cycles. Instead, its concentration simply rose and fell in response to the ocean temperature changes caused by other things.
So in that particular scenario, CO2 could only ever have amplified the effects of other things (indeed, the large changes in temperature cannot be explained without it).
I think the point you’re missing is that CO2 cannot “protect” the Earth against cooling due to other processes unless its own concentration is rising quite fast…… whereas going into a glacial period it would actually be falling due to falling ocean temperature, hence amplifying the cooling.
#244–Ed, you remember the 2009 Copenhagen Conference! What’s confusing you is that Revkin doesn’t make clear that he’s only talking about a sub-event dealing with the Amazon; the larger conference dealt comprehensively with climate change issues, from sea level rise to–well, just about any related issue you choose:
#245–I’m an amateur, Paul, but I’m sorry to say that I think you’re wrong. “Forcing” usually denotes a term in the energy budget during a particular time, and need not be changing–for instance, insolation is a forcing, and varies only within relatively tight limits. (Indeed, they used to call it the “solar constant.”)
You are right, of course, that CO2 changes during glacial cycles are feedbacks, but that’s not because they are slow, it’s because they are driven by temperature changes initially.
And according to RC’s own Dr. David Archer, it’s quite possible that human-emitted CO2 could protect the planet from the next glacial:
Of course, that would be a (very) long-term benefit, which we would first have to suffer the much nearer-term disasters in order to enjoy.
Ray Ladburysays
Paul Briscoe,
Your correspondent is full of fetid dingo kidneys. The forcing is proportional to the CO2 concentration, not to its change. The predominant negative feedback is radiation of IR photons from the top of the atmosphere into space–which depends on the temperature at TOA. If CO2 increases, it will take a while for the atmosphere to heat up sufficiently that the radiation out again equals radiation in.
In any case, for glacial/interglacial cycles CO2 is a feedback, not a forcing. The main driver is small changes in insolation due to changes in Earth’s orientation, orbit, etc.–Milankovitch cycles. I wish these idjits would just learn some science.
Pete Dunkelbergsays
Risk is the right term – the human term. How much damage are we risking and how soon? Uncertainty in model projections given a fixed emissions scenario is is in timing. A projection of a certain result plus or minus Delta X by year 2100 =
it might happen already in 2090 or not until 2110. Curry issue answered QED
In some ways, it does exactly what I was asking of Gavin, except that it is a general answer. I was (and still would like to see) a discussion of one, specific, actual climate model, how it is designed and how it operates.
This link also looks to be of interest in a more scatter-shot way, although I haven’t even perused it much yet.
[Feedback on the quality/accuracy/value of either of these links is appreciated.]
The radiative forcing from CO2 is defined as the net change in the top of atmosphere energy budget between the initial and final state, and has nothing to do with how fast it got there. If you had two identical planets in every way (same sunlight, orbital configuration, same albedo, etc) except that one had 100 ppm of CO2 and another had 1000 ppm of CO2, the latter would be warmer, and one could predict this without knowledge of the history of CO2 concentration. So even if CO2 were rising in small increments, so would the temperature.
Also keep in mind that since the radiative forcing is proportional to the logarithm of concentration, even 100 ppm rise can mean a lot when you start from a low background state.
I talked more about CO2 in its glacial-interglacial role in this RC post. The CO2 role is probably small in the 41 kyr obliquity band but is large, and comparable to the modern CO2 forcing, in the 100 kyr band and helps provide for the full magnitude (and global character) of the Antarctic ice core record (see e.g., Jouzel et al., 2007, Science)
Re 200:
good coverage at:
http://www.bbc.co.uk/news/science-environment-15199065
“…The researchers emphasise there is no impact on global warming.”
BBC’s quotes include a bit more:
–excerpt follows—-
“The one big caveat is whether SIM’s data is accurate.
Scientists in the field appear to believe it is – but as the UV changes it sees are so large compared with previous methods, they would prefer confirmation.
Commenting in Nature Geoscience, Katja Matthes from the Helmholtz Centre in Potsdam, Germany, describes the results as “intriguing, albeit somewhat provisional”.
“The trends seen in the SIM observations are still under discussion and remain to be confirmed,” she writes.
She also points out that SIM measures only a proportion of the ultraviolet region of the spectrum….”|
But hasn’t sunspot activity been rapidly increasing this year? So shouldn’t that mean a warmer winter in Europe and parts of the US?
Has anyone followed the debate between skeptical science and Pielke Sr here:
http://www.skepticalscience.com/pielke-sr-and-sks-warming-estimates.html#comments
Perhaps as a non scientist, I am missing something, but to me it strikes that Pielke has to be one of the most dishonest debaters ever. He makes a claim that CO2 forcings are only 20%. Other posters point out specifically why he is wrong. He evades, throws out irrelevant information, and finally concludes with the statement that no one really knows for sure, the question is not important, so lets move on. When cornered, he won’t answer directly, but raises questions mostly irrelevant.
Am I missing something, [edit]?
Wili, the story above is reporting a brand new result, a surprising one, that has not been confirmed yet from other data and instruments.
So there’s no good way to make a prediction about the weather based on it.
What if adding more ultraviolet changes aerosols to make the sky hazier and more reflective? Could that happen? Googling speculatively, turns up:
“It is hypothesized that many substances in the atmosphere, including volatile organic compounds (VOCs) and their oxidation products, very fine particles and others absorb and/or utilize UV energy. The long-term UVI trends and its main controlling factors in four seasons during the previous 2 decades are discussed, UV energy consumption by atmospheric chemical and photochemical processes, is especially important during summer….”
http://www.sciencedirect.com/science/article/pii/S1352231011009939
Analysis of ultraviolet radiation in clear skies in Beijing and its affecting factors
Jianhui Bai, LAGEO, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
24 September 2011
Joan Baez once said something like: “if you are faced with a choice between a hypothetical situation and a real one, choose the real one.”
We don’t know yet.
Any who choose to participate in the discussion threads with Dr. Pielke at SkS, please show restraint and exercise decorum. He is a guest and respect is to be given.
Thank you.
wili @203 — There is a lag between the sunspot cycle and warmth/coolth just as there is a lag between solar insolation and the warmest/coolest parts of the annual cycle.
RE: 205
Hey Hank,
I believe that the greatest influence of the added 11 yr cycle UV may be isolated to the N. Jet Stream pattern. Not that I have a source other then 8yrs of NOAA, NCDC, SRRS observations, the interesting thing I have seen emerge over the last 11 years are the changes in the Walker Circulation and the N. Jet Stream’s seasonal elipitical pattern change. I believe this may have been also suggested by some of the present researchers associated with the Hadley Center UV/SIM story.
The problem is trying to associate which is which. Is the extra volume contained in the current N. Jet driven by UV heating or by cross zonal equatorial heat flow. Which I believe returns the discussion to what also drives the equatorial heat increases, is it a reduction in cloud cover caused by CO2 warming, aerosol population changes or added Tropopause UV energy reducing high altitude wv condensation?
VOCs not withstanding, have you any insights you can share?
Cheers!
Dave Cooke
Thanks, David. That makes sense.
Sun spots do seem to be increasing rather rapidly, though, so maybe we can expect a somewhat milder MN winter in 2012-2013? (I know, I know, the study is only preliminary and other factors play large roles.)
http://www.climate4you.com/Sun.htm
http://www.arrl.org/news/the-k7ra-solar-update-185
http://prop.hfradio.org/
I would note that there is a piece on climate denialism over at the American Institute of Physics website:
http://www.physicstoday.org/resource/1/phtoad/v64/i10/p39_s1
It has already been visited by the sorts of idiots that think you can even lie to physicists about how science works.
Daniel @206:
I agree with your call for civility, and would like to thank you and the other folks over at SkS for being so persistent and patient in the RPSr. threads.
Having said that, RPSr.’s answers – or the lack of them, rather – is very revealing. While I would not go as far to call him “dishonest”, as Paul (@204) opines, his evident evasiveness to the very direct, cogent and polite answers by dana, Albatross, Tom Curtis et al. is both disappointing and expected (given past evidence both here and elsewhere on the intertubes).
Good luck in continuing the discussion, though I have a sneaky suspicion that RPSr. will soon leave in a huff again upon another self-perceived slight on his person.
http://www.power-eng.com/news/2011/10/1512370892/cunning-way-of-generating-power-and-capturing-carbon.html
Pumping CO2 into hot rock, deep enough it acts as a supercritical fluid — then drawing some back out to run turbines, then reinjecting the cooled gas. Still takes energy overall to sequester the CO2, and transfers some geothermal heat to the surface — but uses the heat in the reservoir. New idea.
Folks attending the GSA meeting in Minneapolis might be treated to a freak show tomorrow outside the main entrance of the conference center.
Check out http://www.minnesotansforglobalwarming.com/m4gw/2011/10/michael-mann-is-coming-to-town.html for details (if you can stomach it).
wili,
Of course sunspots are increasing–we’re moving into solar max. To my knowledge, though, the Sun is still below normal activity for this portion of the cycle. However, given the much prolonged solar min of the last cycle, it’s hard to say what normal should be for this one.
> wili
> maybe we can expect … Minnesota
Why would you expect a correlation between solar cycles and winters in Minnesota? Nobody seems to have published the idea anywhere. Do look, maybe I missed something.
I did find a contrary suggestion (from Lockwood, Harrison, Woollings and Solanki, speculating about cooling):
Environ. Res. Lett. 5 (April-June 2010) 024001
doi:10.1088/1748-9326/5/2/024001
Are cold winters in Europe associated with low solar activity?
http://iopscience.iop.org/1748-9326/5/2/024001/fulltext
“… this is a regional and seasonal effect relating to European winters and not a global effect.”
Gavin et al…
I’d like to make a request for a post, if you don’t mind. I frequently run into people with gross misconceptions about how the models work. They are insistent about all of their misconceptions. I do point them (with glee) to the excellent two part post here at RC on climate model FAQs.
But it would be nice (both fun to read, and useful for those people who don’t understand) if you could provide an English language synopsis of the actual structure of the specific models (and model components) that you work with. In business computing this would be termed a “Functional Design,” a document that describes (for the layman) how the programs work without getting into the nitty-gritty and getting bogged down in the actual computing details.
It would be a great read, and it would also be a great resource for refuting those people who think that climate models work by tweaking parameters and forcing temperatures to rise with CO2 levels through presumed correlations, rather than through the cumulative effects of individually modeled physical relationships.
Please consider doing so, if you have the time.
I second the point made in 216 above.
Sphaerica: that would be an excellent idea and really helpful.
I have a specific problem in accepting this version of modelling as stated by the Skeptical Science site:
Amplification: ” How does this work? The amount of water vapor in the atmosphere exists in direct relation to the temperature. If you increase the temperature, more water evaporates and becomes vapor, and vice versa. So when something else causes a temperature increase (such as extra CO2 from fossil fuels), more water evaporates. Then, since water vapor is a greenhouse gas, this additional water vapor causes the temperature to go up even further—a positive feedback.
How much does water vapor amplify CO2 warming? Studies show that water vapor feedback roughly doubles the amount of warming caused by CO2. So if there is a 1°C change caused by CO2, the water vapor will cause the temperature to go up another 1°C. When other feedback loops are included, the total warming from a potential 1°C change caused by CO2 is, in reality, as much as 3°C ”
My problem is with the statement: “If you increase the temperature, more water evaporates and becomes vapor”.
The author is not implying a direct causal link from CO2 to WV content. He is saying that temperature increase causes an increase in WV content. But that would imply that for ANY global temperature increase, even a natural increase. That would imply:
A natural rise in temperature produces more water vapour – which increases temperature – which produces more water vapour – which increases temperature – and so on…. a runaway feedback effect which must lead eventually to either atmospheric saturation or heat catastrophe. I assume this doesn’t happen in reality. (!)
My understanding of the physics involved is that warmer air has the CAPACITY to hold more water vapour. That is all. Can someone clarify how the principle of Amplification is supposed to work, and why there is not a runaway chain?
Pursuant to Sphaerica (Bob)’s request for a post on the structure of models…
Kate (of ClimateSight) did such a study as a summer project (she’s studying to be a climate scientist). I believe she will even have a poster presentation on the topic at the upcoming AGU meeting. Perhaps she would be happy (perhaps even delighted) to contribute a guest post to RC,or perhaps do one in collaboration with RC regulars (Gavin?).
Just a thought…
Richard Bird:
You’re making the common improper assumption that a positive feedback must inevitably lead to a runaway feedback. Do some googling for stuff like “convergent series positive terms” …
For Richard Bird
You’re asking a frequently answered question (might even be found if you look at the “Start Here” link at the top of the page for the FAQs; try there.
Briefly: water vapor condenses making clouds.
Clouds (some kinds at some altitudes) increase albedo, reflecting incoming sunlight away.
http://www.skepticalscience.com/positive-feedback-runaway-warming.htm
http://www.google.com/search?q=site%3Arealclimate.org+runaway
Richard, the amplification is limited because the atmosphere does not have an infinite capacity to hold water, and you aren’t applying an unlimited forcing. Think of it in terms of a pot of water with a candle under it – it gets warm to a certain point, but no more, even if you just leave the candle there. Putting the lid on the pot will keep some of the heat trapped, but you still reach a point where the water isn’t going to get any hotter.
Of course, the planet is a lot more complex than a pot of water. :)
218, Richard Bird,
Just to clarify what others have already said, you said:
This is absolutely true. Feedbacks are a result of temperature change, regardless of the forcings behind that change.
The water vapor feedback is, in fact, an important element that greatly increases climate sensitivity.
You go on to say:
This is incorrect, as dhogaza and Hank both point out.
There are multiple factors, but in a nutshell consider a diminishing series. Using made up numbers, what if the increase in water vapor results in half as much warming as a previous increase in water vapor? You have:
1 + 1/2 + 1/4 + 1/8 + … + 1/∞ → 2
The point is that if the increase in temperature ∆T1 from an increase in water vapor ∆V0 from an initial increase in temperature ∆T0 is not as great as the initial increase (i.e. ∆T1 < ∆T0) then you do not have a runaway and so do not have a problem.
And, as Hank points out, there are other factors (such as increased condensation, creating increased clouds, creating increased albedo).
@220: Or, to state it simply right here, doubling CO2 directly causes a temperature jump dT1. That jump makes the atmosphere take up water vapor sufficient to raise the temperature an additional dT2. That jump, in turn, causes the uptake of more water vapor sufficient to raise the temperature an additional dT3 and so on infinitely. But dT3 < dT2, and dT4 < dT3, etc. Since each term is smaller than the last, the series of temperature increases dTx converges to a finite value, much as the series
1 + 0.5 + 0.25 + 0.125 + ...converges to 2.
Bob #216 — excellent suggestion.
Meanwhile, I think this lovely paragraph from an otherwise dry review article deserves wider readership:
(Question: Where can one watch an animation like that? Preferably with blow-by-blow commentary pointing out the interesting features to an untrained eye?)
@223:
Not quite. What matters is not the relationship between ∆T0 (caused by CO2 in this example) and ∆T1 (caused by the “first round” of WV increase), but that between ∆T1 and ∆T2, ∆T2 and ∆T3, etc.: as long as ∆T2 < ∆T1, ∆T3 < ∆T2, etc., the feedback converges to a finite value. This is true even if ∆T1 > ∆T0. So, purely hypothetically, if doubling CO2 causes ∆T0 = 1K, and that causes ∆T1 = 1.5K, and that causes ∆T2 = 0.75K, etc., the total resulting ∆T is 4K.
CAPTCHA: evils oatfol
For those who find that the sclimate model FAQs are not enough, try “A Climate Modelling Primer” by Henderson-Sellers.
I know it isn’t your guys job to address what happens on other blogs, but I was wondering if somebody here would comment on this.
On her blog, Judith Curry stated:
“The deep uncertainty is associated with our reliance on projections from climate models, which are loaded with uncertainties and do not adequately treat natural climate variability.”
http://judithcurry.com/2011/10/08/usgcrp-draft-strategic-plan/
I was wondering if there was any work really addressing the last point. Do models adequately treat natural climate variability? Is the natural climate have significantly more or less variation (variance?) than the models?
I asked on her site, and I got a response related to mean values, but I know you can models means without doing a good job of modelling variation in other fields.
thanks
[Response: It’s not really clear what she is referring to. Climate models obviously do have internal variability and also respond to natural forcings. Whether that is ‘adequate’ depends entirely on what the purpose is. If you are looking to find the climate change signal in the noise, the models have a range of noise levels (which encompass the variability seen in the real world) and you can test how sensitive your attribution is to the different amounts of internal variability (see santer et al, 2009: 2010 for instance). If you are interested in the sensitivity of internal modes to different forcings, I’d say the models were adequate for somethings – the NAO, the Southern Annular mode, – and not yet adequate for something like ENSO. Without a little context or specifics it’s hard to say more. – gavin]
Another way of visualizing feedback – think of a microphone and speaker in a large hall. A person talks into the microphone, the voice comes out over the speaker, and gets picked up again by the microphone. Total amount of noise is more than just the single event of the first broadcast of the person’s voice.
How much noise? It depends. Each time the microphone picks up speaker’s output, the sound gets fed through the amplifiers and sent back out the speakers. If each pass through the amplifier is smaller than the previous one, we get a nice echo effect and a finite amount of sound. If each pass is bigger than the previous one, we get that horrible ear-shattering squealing sound we’ve heard at so many weddings. That’s the run-away feedback.
Interesting, almost throwaway comment about a change in climate in the 14th century exacerbating the course of the Black Death Plague in Europe.
http://www.bbc.co.uk/news/health-15278366
But I thought that was during the Mediaeval Warm Period?! ;-)
Last month i posted my first Tshirts i designed here, with related climate themes. I tweaked the designs now and just released “Climate”.
It features the following text: “The oceans are warmer Today than they were, 30 years ago,means there’s about, on average, 4 percent more water vapor lurking around” – Kevin Trenberth, Scientist
Feedback is welcome, especially what you think would make other great “text additions” in this regards to climate science, with educational aspect.
Currently only available in Europe but soon in the USA as well.
Have a look
http://galaxymachine.de/en/galaxy-machine-blog/27-climate-change-science.html
OK, pet peeve here. It drives me absolutely nuts when “dissenting” scientists like Roger, Judy and Roy make vague, unverifiable, unfalsifiable statements about the skill of climate models or other supposed shortcomings in the case for anthropogenic causation. It is utterly unscientific. It falls into the category of what Pauli decried as “so bad it’s not even wrong!” It sounds more like a theological debate than a scientific discussion.
I realize that they have no model and can therefore make no predictions, but is this really the best they can do?
Vague is worse than wrong. Vague is bu****it
Gavin wrote re: Judith Curry: “Without a little context or specifics it’s hard to say more.”
Denigrating “climate models” without context or specifics is a common denier tactic. Judith Curry’s sweeping, context-free, unspecific generality will no doubt be copied-and-pasted all over the web within hours by people who don’t have the slightest idea what she’s talking about.
Hank and others: Thanks for the responses on amplification. All clear, the essential factor is the initial ∆T1. Whether the series will converge or diverge depends that value. (As pointed out elsewhere, if other factors such as albedo, ocean circulation etc are involved, sufficient to a produce ∆T1=1 then the ‘runaway’ scenario becomes real. Well, fingers crossed on that for now I suppose…)
My next question was to have been: Is an amplification factor also applied in models to natural forcings such as solar irradiance, and if so is that well estimated? The obvious point being, if net solar forcing post 1900 is under-estimated, then the CO2 forcing may be over-estimated. However I see there has been a lot of discussion around that in 2005: https://www.realclimate.org/index.php/archives/2005/12/natural-variability-and-climate-sensitivity/#comments
So I will change my question to: has anything new developed around that subject since 2005? eg on cloud feedbacks?
A purely empirical observation here: London. Oct 2 2011 (near the fall equinox so giving a median picture) Blue sky, little wind; 29 deg C. Oct 4 2011, overcast with low cloud, little wind: 19 deg C. 10 deg change presumably due to cloud cover. I observed similar variations while driving from London to South of France on Oct 5 & 6, passing from blue sky to thin cloud, heavy cloud and blue sky again all day. In the space of 10-20 miles each time: Thin cloud = 2 deg drop, heavy cloud = 4-5 deg drop. Those were local variations over very short timescale. So over 24 hours, 10 deg drop seems right. Not very scientific but interesting.
Empirically, if thick cloud cause 10 deg drop. 2.5% reduction in low cloud cover -> 0.25 deg C ∆T.
IPCC Energy balance diagram: Reflection of solar energy + aerosols etc = 77 W/sm. Rough guess,70 W/sm reflection by clouds alone? Assumed AGW effect is 1.7 W/sm. Empirically, Reduction of cloud cover by 2.5% -> 1.7 W/sm increase in energy at earth surface. My all means shoot me down here, but a simplistic ‘back of envelope’ estimate of 2.5% variation in area of cloud cover would account for most of the ‘gaps’ of 1.7 W/sm and 0.25 deg C between estimated natural warming and recorded warming as set out in Hansen’s 1988 paper. (I think the figure was lower than 1.7 W/sm in 1988 but I don’t have the exact figure)
I would be interested to know if there is any reliable data on global area of cloud cover over last 40-50 years, and whether any correlation with either solar activity or temperature is apparent.
> the ‘runaway’ scenario becomes real. Well, fingers crossed
Nope. Try one of these for more help:
http://www.google.com/search?q=site%3Arealclimate.org+FAQ+runaway
Seriously, it seems you’re retracing the steps many others have already followed, starting with ideas that either you’re coming up with on your own, or that come from somewhere people are publishing stuff that’s not reliable.
It’s no surprise logic and deduction fail; nobody knows all the basics needed to figure out what’s going on just by thinking without looking stuff up.
But, really, reading the Start Here and FAQs will avoid a lot of the most commonly encountered misapprehensions.
The traditional Usenet method — “post what you know and await correction” — invites a lot of recreational typing, but isn’t all that efficient.
Richard Bird,
But clouds also warm–it depends on which clouds when and where.
228, gavin in line: Without a little context or specifics it’s hard to say more. – gavin]
It was the quote that was removed from its context. For the context, click on the link. I reproduce it here:
http://judithcurry.com/2011/10/08/usgcrp-draft-strategic-plan/
For Richard Bird:
Tried this search (you can improve on it; look for key words, narrow the range, try Scholar): http://www.google.com/search?q=data+on+global+area+of+cloud+cover
From the first few hits, this:
http://isccp.giss.nasa.gov/climanal1.html
which says:
“The short ISCCP time record, covering only about 22 years, shows some signs of a slower variation. Cloud amount increased by about 2% during the first three years of ISCCP and then decreased by about 4% over the next decade. ISCCP began right after one of the largest El Ninos this century (in 1982-83) and the eruption of the El Chichon volcano, both of which may have caused some changes in clouds. There were other, weaker El Ninos in 1986-87, 1990-91 and 1992-94 and another volcanic eruption (Mt. Pinatubo) in 1991. Note however, that there appear to be no related changes in cloud top pressure/temperature or optical thickness (the small change in 1991 is caused by including the extra sunlight reflected by volcanic aerosol with clouds which affects the cloud top pressure/temperature determined for very thin cirrus clouds). The surface temperature shows a decrease of about 1 K from 1983 to about 1991. Since there a number of events occurring during this time period, the cause of these cloud variations is not yet understood.
Such variations are referred to as “natural” variability, that is the climate varies naturally for reasons that are not fully understood. The problem for understanding climate changes that might be produced by human activities is that the predicted changes are similar in magnitude to those shown here. The difference between natural and human-induced climate change will only appear clearly in much longer ( >= 50 years) data records….”
—
As to why you need more than 50 years, with that particular data set, see generally the method explained at:
http://moregrumbinescience.blogspot.com/2009/01/results-on-deciding-trends.html
#230–To respond more or less seriously to a jocular comment:
Yes, but the end of it.
Don’t know about the much-touted English wine industry, but those Greenland Norse felt an increasing climatic pinch during the 14th century. (For example, the more northerly “Western settlement”–around present-day Nuuk (formerly Godthab)–was abandoned during this time.) Last known contact with Scandinavia (before the modern era, of course) was 1410.
Richard Bird,
All of the answers so far on why positive feedbacks can converge are presented in a linear framework of feedback analysis, and are actually incapable of yielding useful information on whether a “runaway” effect occurs as the traditional feedback factor goes to one, where the linear analysis becomes invalid.
Typically, we define some reference system, such as the Planck restoring feedback (i.e., the increased radiant emission to space in a warmer world, or less emission on a cooling planet) and then define feedbacks relative to that. In a linear world view, if we call the temperature anomaly ∆T0 for a planet where only the Planck radiative restoring response were active (usually ~1.2 C per doubling of CO2), then the real temperature anomaly is ∆T = ∆T0/(1-f), where f is a feedback factor that depends on how much a particular variable (such as water vapor) changes with temperature, and on how much that change actually impacts Earth’s radiation balance. If f ~ 0.5 then climate sensitivity is doubled, but OLR still increases with temperature and you converge to a stable solution.
Physically, you can think of 1-f as being related to the slope of a line in G vs. T space, where G is the net TOA energy balance (outgoing thermal emission – incoming absorbed sunlight) and T is the surface temperature; note that G increases with T. See Figure 3.1 here to see this visually. The less steep the slope, the higher the climate sensitivity, since the surface temperature must rise more in order for the planet to re-establish radiative equilibrium. Water vapor feedback makes the outgoing radiation more linear than T^4, so the Planck restoring feedback still wins out in the end (allowing for stability), but it isn’t as effective.
More generally, when f reaches one, you reach a bifurcation point but you have to know something about the global structure of the energy surface in G-T space, rather than the local departure from a stable equilibrium point. When f goes to one, it doesn’t need to be a “runaway” effect (but it could be). This would happen if the absorbed solar radiation were high enough, and you reached a point where the water vapor feedback were strong enough so that OLR did not increase with temperature.
234, Richard Bird: I would be interested to know if there is any reliable data on global area of cloud cover over last 40-50 years, and whether any correlation with either solar activity or temperature is apparent.
Here is a start, though it isn’t cloud cover per se , but the change in forcing effected by the cloud cover. At least I think it’s a start.
http//wattsupwiththat.com/2011/10/11/wrong-again/
Richard Bird:
Why presumably due to cloud cover? Why not an influx of cool marine air leading to the switch from clear skies to clouds?
While thinking about this, please re-read Hank’s post 235 above …
Bacterial Communication Could Affect Earth’s Climate, Researchers Discover
http://www.sciencedaily.com/releases/2011/10/111012151718.htm
Biogeochemistry is certainly complex.
Do you know anything about a botched meeting on the Amazon a la
http://dotearth.blogs.nytimes.com/2011/10/13/on-false-equivalence-and-false-inequivalence/
?
I don’t know anything about the alleged meeting, so I need some help.
I hope you don’t consider this too far off topic, but I am having an exchange with a very persistent blogger who claims that CO2 and temperature changes during transitions between glacial and interglacial periods are inconsistent with established theory. Please can you confirm whether my argument is correct:
CO2 can only exert a forcing if its atmospheric concentration changes. The larger the change, the larger the forcing.
If the rate of change in CO2 concentration is very slow, global temperatures can almost keep up with the effects of the changing CO2, so the net forcing at any point in time is CLOSE TO ZERO.
The difference in CO2 levels between glacial and interglacial periods was at most 100ppm (and at least 100ppm lower than today) and the change took place over thousands of years in response to the gradual changes in ocean temperature. Consequently, the very gradual increase in CO2 levels could never have exerted sufficient warming effect (it’s strictly a feedback in this case) to overcome the effects of other changes due to albedo and Milankovitch cycles. Instead, its concentration simply rose and fell in response to the ocean temperature changes caused by other things.
So in that particular scenario, CO2 could only ever have amplified the effects of other things (indeed, the large changes in temperature cannot be explained without it).
I think the point you’re missing is that CO2 cannot “protect” the Earth against cooling due to other processes unless its own concentration is rising quite fast…… whereas going into a glacial period it would actually be falling due to falling ocean temperature, hence amplifying the cooling.
#244–Ed, you remember the 2009 Copenhagen Conference! What’s confusing you is that Revkin doesn’t make clear that he’s only talking about a sub-event dealing with the Amazon; the larger conference dealt comprehensively with climate change issues, from sea level rise to–well, just about any related issue you choose:
http://en.wikipedia.org/wiki/Climate_Change:_Global_Risks,_Challenges_and_Decisions
#245–I’m an amateur, Paul, but I’m sorry to say that I think you’re wrong. “Forcing” usually denotes a term in the energy budget during a particular time, and need not be changing–for instance, insolation is a forcing, and varies only within relatively tight limits. (Indeed, they used to call it the “solar constant.”)
You are right, of course, that CO2 changes during glacial cycles are feedbacks, but that’s not because they are slow, it’s because they are driven by temperature changes initially.
And according to RC’s own Dr. David Archer, it’s quite possible that human-emitted CO2 could protect the planet from the next glacial:
http://doc-snow.hubpages.com/hub/The-Long-Thaw-A-Review
Of course, that would be a (very) long-term benefit, which we would first have to suffer the much nearer-term disasters in order to enjoy.
Paul Briscoe,
Your correspondent is full of fetid dingo kidneys. The forcing is proportional to the CO2 concentration, not to its change. The predominant negative feedback is radiation of IR photons from the top of the atmosphere into space–which depends on the temperature at TOA. If CO2 increases, it will take a while for the atmosphere to heat up sufficiently that the radiation out again equals radiation in.
In any case, for glacial/interglacial cycles CO2 is a feedback, not a forcing. The main driver is small changes in insolation due to changes in Earth’s orientation, orbit, etc.–Milankovitch cycles. I wish these idjits would just learn some science.
Risk is the right term – the human term. How much damage are we risking and how soon? Uncertainty in model projections given a fixed emissions scenario is is in timing. A projection of a certain result plus or minus Delta X by year 2100 =
it might happen already in 2090 or not until 2110. Curry issue answered QED
FYI, for anyone else interested in the models, this is a tremendous read:
Climate Models: An Assessment of Strengths and Weaknesses
(also available here).
In some ways, it does exactly what I was asking of Gavin, except that it is a general answer. I was (and still would like to see) a discussion of one, specific, actual climate model, how it is designed and how it operates.
This link also looks to be of interest in a more scatter-shot way, although I haven’t even perused it much yet.
[Feedback on the quality/accuracy/value of either of these links is appreciated.]
Paul (245)
The radiative forcing from CO2 is defined as the net change in the top of atmosphere energy budget between the initial and final state, and has nothing to do with how fast it got there. If you had two identical planets in every way (same sunlight, orbital configuration, same albedo, etc) except that one had 100 ppm of CO2 and another had 1000 ppm of CO2, the latter would be warmer, and one could predict this without knowledge of the history of CO2 concentration. So even if CO2 were rising in small increments, so would the temperature.
Also keep in mind that since the radiative forcing is proportional to the logarithm of concentration, even 100 ppm rise can mean a lot when you start from a low background state.
I talked more about CO2 in its glacial-interglacial role in this RC post. The CO2 role is probably small in the 41 kyr obliquity band but is large, and comparable to the modern CO2 forcing, in the 100 kyr band and helps provide for the full magnitude (and global character) of the Antarctic ice core record (see e.g., Jouzel et al., 2007, Science)