Dam’s themselves have not created flood frequencies or intensities, but many flood control activities have shunted water a way from one area and subsequently increased both frequency and intensity down stream.
Anything that lowers the time water remains “on the land” can increase flooding. Railroads, roadways, and agriculture often disrupt natural stream flow that results in a down cutting of the stream channels. That channelization traps water preventing it from reaching its flood plains and re-watering the local aquifer, instead rushing down stream. Also as the channel cuts downward it also drains the water table instead of recharging it and thus add to the flooding.
MalcolmTsays
@193 Dams and flooding: Ross River Dam (1971) in Townsville North Queensland was designed as both water storage and flood mitigation and seems to be working well in both roles. Certainly, the city hasn’t flooded as badly since its construction as before – and we do get enough cyclones and post-cyclonic rain depressions to give us a fairly good idea.
Rod Bsays
raypierre (152): Simply (maybe too much so…), blackbody radiation and radiation from molecular vibration, rotation (and possible even electron) have a different genesis and significantly different characteristics. (I’m using “blackbody” as the generic planck function radiation, not as the ideal actual blackbody.) Blackbody is broadband (technically including the entire E-M spectrum); vibrotation radiation is single frequency, though maybe has a number of single frequencies. Blackbody radiation is continuous and quantized only in the vein that translation energy (of a molecule or an airplane) is quantized into almost infinitely small levels. Vibrotation is quantized only at the single frequency of vibration or rotation, and at most 3, 4, or so hf multiples about that single frequency. Blackbody radiation comes from vibrating charges that were created solely by heat/temperature, and it is temperature that is the sole cause of the radiation, though the physical characteristics of the body help determine how much radiation is generated. Vibrotation radiation is predominately caused or determined by the physical makeup of the molecule in a bath of any sort of E-M radiation. Blackbody radiation is continuous in time while vibrotational radiation is bursty, determined by such things as Einstein coefficients and molecular collision rates, both of which are only very loosely related to amBEant temperature.
The rub: the actual physics and mathematics of molecular radiation is very complex and difficult; for blackbody, not so much. Plus, stemming from the very basic fact that a photon is a photon and that at the basic level photon absorption and emission of any type have much in common, as you say, blackbody math and physics can be used for molecular radiation analysis with very good accuracy, though not exactness. Does the lack of exactness matter? I suspect that some of it might, though that is currently only an idea and of no worth to anyone else. In the meantime it seems to work quite well and so Planck (and Kirchoff and Beers and even Stefan) have given us tremendous insights into molecular radiation. We even use Stefan-Boltzmann, a strictly full spectrum blackbody construct, to build the basic models of greenhouse gas stuff with its multi-layered atmosphere from a flat surface stuff.
This is accomplished mostly by playing with emissivity, which of course is 1.0 for a black body. But with generic planck radiation the overall emissivity is less than 1.0 overall and moreover has a wavelength dependency. Even though it would never occur in reality there is no mathematical reason why we can’t construct a body that has an emissivity of 0.0 everywhere except say 15.00um where it has a 1.0 emissivity. There are a couple of things that fall off the wagon here, but probably of little import, so violà: Planck physics allows a super helpful analysis of greenhouse gas called molecular radiation. [Though your description of this is much better than mine here…]
But they are not the same thing.
Though the other Ray and others differ…
Rod Bsays
In her defense Curry did moderate out a blantant ad hominem toward Gavin in a comment. Though, to detract some, as I said in a comment to her, moderating with strike through is not near as good as a deletion.
A representative of the American Wind Power Assn. said, twice, he would provide the figures that indicated wind power provided significant power during the period of peak demand yet, in spite of six requests, he never did so.
As the crisis unfolded in Texas wind power dribbled down to nothing. Before you dispute that, keep in mind the peak demand was not Wednesday morning, it was Wednesday evening between 8 and 9pm Central time.
Has anybody noticed that Antartic Sea Ice is very low this year, though it the melting seems to have almost stopped now. This is interesting because it was supposed to be defying the trend.
[Response: Personal gripe: everyone loves to average Antarctic sea ice over the entire domain, but this is about as sensible as averaging sea surface temperatures on the Pacific coast of the U.S. with sea surface temperatures on the Atlantic side. Actually, it’s the same thing! It doesn’t make any sense, but it is done all the time, especially by people (including — ahem — many of my colleagues) who’ve never been to Antarctica and can’t appreciate the scale of the place.
Anyway, the trend has been negative (less ice) for the entire satellite record in the Amundsen, Bellinghausen, and even most of the Ross Sea. It is positive (more ice) over most of the coastline of East Antarctica. It is interesting if indeed the average trend is now flattening out, but the average trend was never statistically significant anyway. I wish NSIDC and others would start showing plots of both areas separately on their web site. Looking at the average is very close to meaningless.–eric]
“… Wind power was a bit player in Texas as recently as four years ago. Today, wind turbines produce a significant share of the state’s electricity.
But the growth of wind power has attracted powerful critics: the owners of natural-gas power plants…..”
…
“… On a recent day, a stiff 24-mile-an-hour wind was blowing …. The Papalote wind farm was turning that into 116 megawatts …. Its top output is 180 megawatts. Over one 24-hour period, said Mr. Collier, it ran at 88% of its maximum—nearly unheard of in the wind business.”
Ray Ladburysays
Rod B., True blackbody radiation is continuum, but there are no true blackbodies. Real materials–and this includes CO2–can only emit light corresponding to transitions between its energy states. This can, however, form a portion of a blackbody spectrum when the radiation fields is in equilibrium with the surrounding matter. There is no separate “blackbody” radiation. And you should know this, because you have not been able to produce a single reputable source that backs your assertion. I really seriously doubt that Landau did not understand blackbody radiation.
Ray Ladburysays
Edward Greisch, Having scientists write the nations laws is a recipe for disaster. Unfortunately, the skills needed to understand the laws of nature are quite different from the skills required to understand law an politics. WRT mitigating the threats due to climate change, the sole requirement the scientists can levy is that they be effective at addressng the problem. However, effectiveness is only one requirement of a good law. What we need to do is ensure that we elect politicians who have at least a nodding acquaintance with reality. If we are to insist on the expertise of the scientists, we must also respect the expertise of good policy makers
David B. Bensonsays
An earlier commenter asked about models. Here are some useful starting points.
RE: “whether ocean oscillations (…) could explain the global warming of the past 40 years
RE: Climate Cycles: What the Russians say.
The English translation of “Cyclic Climate Changes and Fish Productivity by L.B. Klyashtorin and A.A. Lyubushin can be downloaded for free thru this link:
NB: This mongraph is 223 pages. The Russian edition was published in 2005 and the English translation, in 2007. This book is not about climate science and they don’t discuss the origin of the ocean and atmospheric oscillations.
By analyzing a number of time series of data related to climate, they found that the earth has global climate cycles of 50-70 years with an average of about 60 years which have cool and warm phases of about 30 years each. They summerize most of the studies published upto early 2005 that show how this climate cycle influences fish catches in the major fisheries.
The last warm phase began in ca 1970-75 (aka the Great Shift) and ended in ca 2000. The global warming from ca 1975 is due in part to this warm phase. A cool phase has started and they predict it should last about 30 years. See Fig. 2.23.
In Fig. 2.22 and Table 2 they show that increasing world fuel consumption does not correlate with or affect the cool and warm phase of the 60 year cycle.
Several others studies have found this 60 year cycle. During the cool phase La Nina years usually out number El Nino years as was the case from ca 1940-70. This can be seen in the plot of the MEI at Klaus W’s website.
I haven’t checked to determine if the book was referenced AR4.
There seems to be a “consensus” on two things that don’t seem right to me.
First is cooling during winter at the south pole. I looked at the data from Amundsen/Scott station (from the GISS website), and it doesn’t look statistically significant to me.
Second is Eric’s statement that regarding Antarctic ice, “the average trend was never statistically significant anyway.” But I compute it as being a small but statistically significant increase (at about 15000 km^2/yr).
Am I missing something?
[Response: Nope, you are probably right on both counts. Last time I checked, both of the statements I made were accurate, but it was probably more than a year ago. That’s what happens with barely-significant trends. I do hope that you appreciate the main point I was trying to make though, right? –eric]
Take a large variety of bouncy balls. Each bounces in its own characteristic way. Now tie them all together in a web with short pieces of elastic. How do they bounce?
I’m sure I’ve said that before, or something much like it, so I won’t go on.
Dave Werthsays
This is totally off from anything that’s been discussed so far but it’s an open thread.
I’ve been arguing with a guy over on another blog (SmartPlanet.com). He has a web page up at:
He’s saying of course that it’s all natural. I’ve been telling him that it’s a simple numerical chart without any insight into the underlying causes and that he should take into account at least solar forcing which was significant in the first half of the 20th century but not since then.
Maybe someone more knowledgeable than I can take a look at it and give me some more solid understanding about how to counter his arguments if you care to.
Klyashtorin and Lyubushin actually have attempted to model climate change with their 60-year cycle. It turned out to be a miserable failure at anticipating the continued global warming since 2000:
In fact the warming is statistically significant even since 2000, in spite of the end of the putative “last warm phase.”
The whole “global warming is due to ocean cycles” nonsense is nothing but the latest attempt to muddy the waters by those who simply don’t want to accept the truth — that it continues, and it’s caused by human activity. The “it’s the sun” nonsense didn’t work, nor did the “galactic cosmic rays” nonsense, so they’re trying the next excuse. Can you smell the desperation?
“In an interview with the Texas Tribune, ERCOT CEO Trip Doggett put it this way: “I’m not aware of any nuclear plant problems, and I’m not aware of any specific issues with wind turbines having to shut down due to icing. I would highlight that we put out a special word of thanks to the wind power community because they did contribute significantly through this timeframe. Wind was blowing, and we had often 3,500 megawatts of wind farm generation during that morning peak, which certainly helped us in this situation.”
Peak demand may have been in the afternoon, but according to ERGOT the critical period was in the morning, when the coal plants were failing. And even in the afternoon, wind power continued to provide 7% of the power, according to the article.
Jim Steelesays
tamino says: “the globe has definitely continued to warm since 2000”
How do you separate the globe absorbing more energy versus recording higher temperatures?
For example with less ice on the Arctic Ocean to insulate the -2C Arctic Ocean from the -20C or more air temp, you could record higher temperatures but the globe would actually be cooling. Likewise an increase in the frequency of El Nino’s would create higher recorded temperatures but El Nino’ s are venting energy.
Seems like Argo data is the best metric to resolve this issue.
Brian Dodgesays
“they found that the earth has global climate cycles of 50-70 years with an average of about 60 years”
“The last warm phase began in ca 1970-75 (aka the Great Shift) and ended in ca 2000.” Harold Pierce Jr — 6 Feb 2011 @ 7:58 PM
If this were true, and you go back 50-70 years from 2000, one cycle, temperatures should be as warm as today. They aren’t
Brian Dodgesays
“Suppose the rain in Spain fell only on the plain. All the calcium ions were leached away and never replenished from erosion from the mountains.” Chris Dudley — 6 Feb 2011 @ 2:20 AM
The rain isn’t only falling on the plain in Spain, but also on the Andes mountains in South America. Because they are tall, and because the atmosphere gets cooler with height, even if it’s too hot in the lowlands -“very little rain falls down wind on the Sahara” – for precipitation to make it to the ground (virga), it will still be raining or snowing on the Andes peaks. At 5 km elevation, the temperature will be 25 to 40 degrees Centigrade cooler than at the surface.
Modelling the Andes as a pyramid 7000 km long, 200 km wide, and 4 km tall gives a volume of 2.33e5 km^3 for the top 2 km (This is likely a conservative underestimate, since the average height is 4 km, but there are ~ 50 peaks over 6 km). A large fraction of the rocks are of volcanic origin, and contain feldspar minerals.
This would contain ~1e17 moles CaO equivalent at 1% concentration(The anorthite fraction of plagioclase feldspars weathers, releasing Calcium ions – CaAl2Si2O8 + H2O + 2CO2 => Ca2+(aq) + 2HCO3-(aq) + [Al2O3 + SiO2](kaolin). The Ca2+(aq) + 2HCO3-(aq) => CaCO3(solid) + H20 + CO2(gas))
CO2 is 22727 moles per tonne, so the CaO equivalent in the top half of the Andes could fix ~4e12 tonnes of CO2 to CaCO3. The earth’s atmosphere contains about 3e12 tonnes of CO2.
You should do the same calculation for the Cascades, Aleutian, and other volcano chains. Uplift mountain ranges (Rockies, Himalayas) contain more sedimentary/metamorphic rock, in which the Calcium is already CaCO3. Some ranges (Sierras, Urals, Alps) have a mix of of rocks, and have eroded down to their igneous roots which contain feldspars, and have heavily metamorphosed rocks that contain Calcium in non-carbonate forms- see http://en.wikipedia.org/wiki/Category:Calcium_minerals. The calcium carbonate fraction of weatherable rocks can also sequester CO2 into the deep ocean – CaCO3(solid) + H20 + CO2(gas) => Ca2+(aq) + 2HCO3-(aq). See Enhanced Carbonate Dissolution as a Means of Capturing and Sequestering Carbon Dioxide, Greg H. Rau1,2, Ken Caldeira2, Kevin G. Knauss2, Bill Downs3, and Hamid Sarv3
Rod Bsays
JCH (182) plus much of the dam/flood control projects were scaled back because of the recent many-year droughts — per the experts.
Rod Bsays
R. Gates, I really don’t want in on this discussion, but feel compelled to offer a small comment. I think protagonist scientists, given their learned studies and passionate concerns, ought to be writing letters to Congress (in addition to testifying). But the shrillness and paranoia shown in the referenced letter (183) I’ll guarantee is no way to get their point accepted. For those who might correctly say that the shrillness and paranoia was small I would add that a tiny amount in a letter to Congress is enough to get it stuck directly in the bug letter bin.
> but the globe would actually be cooling
And the heat would be going — where?
Rod Bsays
raypierre, thanks for the response (185).
Septic Matthewsays
204, Mike Smith: As the crisis unfolded in Texas wind power dribbled down to nothing.
That appears not to have been the case. Read the links that Hank Roberts and I provided. I hope for a really good survey soon.
Septic Matthewsays
206, eric in comment: Personal gripe: everyone loves to average Antarctic sea ice over the entire domain, but this is about as sensible as averaging sea surface temperatures on the Pacific coast of the U.S. with sea surface temperatures on the Atlantic side
Gracious! Are you questioning the practice of averaging the temperatures over the whole earth?
Rod Bsays
Ray Ladbury (208), you keep hiding behind the semantics of ‘no such thing as a black body’ which I can’t argue with. I’m talking of the radiation stemming from Planck’s equation. Call it what you like. His equation has things like h, c, pi, wavelength, and T. Nothing about vibration and rotation levels anywhere for miles around.
[Response: Hey Rod! Get this. Clausius and Clapeyron walk into a bar. Great prediction of vapor pressure vs. temperature, sez Clausius to Clapeyron. But hey,sez bartender, no molecules in sight, in that formula. Must not have anything to do wit da molecules. Comes in Stefan and Boltzmann, carryin a big Plank, Is thermodynamics! Is wonderful! Is true whatever da stuff is made of! –raypierre]
Rod Bsays
Ray Ladbury, cogent helpful comment in 209, IMO.
Jim Steelesays
Hank Roberts #224 asked “And the heat would be going — where?”
Most likely the same place the day time heat goes at night. But it is not always a matter of where did the heat go? but where did it come from?
Regards Antarctica or any mountainous region on the globe you can have a foehn wind storm that raises temperatures by 30C within 24 hours. If we used surface temperature data only, we could easily misconstrue that warming as added energy. But it is really the result of asymmetrical temperature measurements that had not accounted for the upper layers of atmospheric heat, that have now been mixed and brought down to the surface. These foehn winds typically have unique names around the world like the Chinooks.
Simple changes in wind can lead to a warming event that is dynamical but in no way represents increased heat input. For example Hartman and Wendler 2005, ‘On the significance of the 1976 Pacific climate shift in the climatology of Alaska’, showed the warming in Alaska was dynamical ad associated with the observed wind changes. Both advection and disruption of the thermal inversion were suggested mechanisms.
Likewise other recorded warming in the Arctic is likely dynamical. I believe Rigor, Wallace and Colony, 2002, ‘Response of sea ice to the Arctic Oscillation”- or perhaps it was another Rigor paper- detailed how much of the Arctic ice loss was due to wind shifts more actively moving ice out through the Fram strait. The winds were coming from the coldest part of Siberia and at very cold temperatures that were not melting the ice but removing it. The heat from exposed warmer ocean waters then get advected and measured as a rise in temperature.
The major portion of the rise in global temperatures are recorded in the polar regions and during the winter and at the nightly minimums. All places and times where thermal inversions most present. The above dynamical responses seem better able to explain much of the warming compared to the notion of “polar amplification” which appears based on reduced albedo. Albedo has little impact during the dark polar winters, although undoubtedly albedo plays some smaller role in the summer.
That’s why OHC, via Argo, should be the main metric to separate temperature changes from heat changes. OHC will be better able to determine if heat is being added or subtracted, but even then there will be problems and OHC pre ARgo will have wide error bars. Surface temperatures by themselves can be very misleading.
So let me ask a question in return. During and after the 1998 El Nino global temperatures rose and fell by ~0.8 C. That change equaled the century warming trend. Where did all that heat come from? and where did go?
Rick Brownsays
RodB @223 – I’ll give you credit for generally being civil and clearly not being a numbskull, but you do contribute more than your share of nonsense here. Nonetheless, I think your suggestion that the letter from scientists referenced @183 displays “shrillness and paranoia” may take the cake. Care to point out the relevant passages? And remember, if someone’s actually out to get you it isn’t paranoia.
200, Jim Steele: Dam’s themselves have not created flood frequencies or intensities, but many flood control activities have shunted water a way from one area and subsequently increased both frequency and intensity down stream.
And others, no one has written that dams are a panacea or problem-free. But does anybody agree with eric’s statement that I quoted?
In CA there is a movement to remove the Hetch Hetchy dam and reservoir that supplies drinking water to San Francisco. To the most extreme environmentalists, the drinking water to San Francisco is not worth the damage to the natural Sierra Nevada ecology. It’s a claim I suppose you can make.
[Response:I do research in the area between there and Yosemite Valley, estimating forest change types and amounts. That movement started long ago, with John Muir in fact. It’s not so much an issue of ecological damage–that’s long done and it’s a relatively small area anyway. It’s always been more an issue of National Park management policies, and aesthetics. If you’ve seen pictures of the pre-dam H-H valley, you know why. And it’s still spectacular, even flooded.–Jim]
No one is talking about removing Hoover Dam and undoing the damage done to Imperial, Los Angeles and San Diego Counties, and the Colorado River Delta. Whatever else you might claim about Hetch Hetchy and the dams on the Colorado, they have not increased the damage from downstream flooding.
john byattsays
The only way that Wivenhoe could have prevented any flooding in Brisbane would have been with hindsight, The claims of incompetence are coming from the climate change skeptics, trying to project their own feelings of guilt?
Wivenhoe is operated strictly to a Manual, the operators are bound by law to follow the manual. they did, Holding back more water would have placed the dam in danger of catastrophic collapse. was only 60cm from that
john byattsays
Re my. Catastrophic collapse re Wivenhoe, should have read automatic catastrophic
release,
Dynamical processes (as you characterize them) can raise or lower temperature, in fact they do both. They are responsible for fluctuations, especially on small geographical and short time scales. But over the long haul, over the entire globe, they tend to average out to zero. They’re part of the “noise” in global temperature, not the signal (or if you prefer, part of the weather not the climate). Your portrayal gives the opposite impression, and you’re mistaken.
Your statement that “The major portion of the rise in global temperatures are recorded in the polar regions and during the winter and at the nightly minimums” is likewise, just plain wrong. The arctic (but not the antarctic) is warming faster than any other region (except perhaps the antarctic peninsula), but it’s also a small fraction of the entire globe. Your conflating the most rapidly warming region with the “major portion of the rise” indicates that you simply don’t understand what the major portion of the rise is. The same is true of the more rapid nighttime and winter warming — you need to think it through more carefully.
I agree that ocean heat content is an excellent metric. As soon as the data problems with Argo are solved, it may be a worthwhile substitute for global average temperature. Until different research groups can agree on what the ocean heat content actually is, it seems to me that global average temperature is the best we’ve got — and one for which the different data records are in excellent agreement. Your comments which suggest its inappropriateness are just smoke and mirrors.
Edward Greischsays
I second 231 Rick Brown.
Edward Greischsays
209 RayLadbury: “Having scientists write the nations laws is a recipe for disaster.”
It couldn’t get any worse. Disaster is where we are headed. The scientists at least have the IQ required to figure it out. Where do you get the idea that “Having scientists write the nations laws is a recipe for disaster.”? That is just an ad homonym attack on scientists. Scientists do not fit your stereotype. Ethics and morality are now in the jurisdiction of the new science called sociobiology. Reference: Sam Harris’ latest book “The Moral Landscape: How Science Can Determine Human Values”; “The Science of Good & Evil” by Michael Shermer and The Brights project on ethics and morality without god. http://the-brights.net/
That means that ethics and morality are no longer in the jurisdictions of religion and philosophy.
“politicians who have at least a nodding acquaintance with reality” can be counted on the fingers of one hand. There is one physicist in congress.
I don’t have a quote for you of corporations directly writing laws on hand, but I have seen them. You get to congress by getting votes, not by passing an exam on policy writing.
dhogazasays
Rod B:
JCH (182) plus much of the dam/flood control projects were scaled back because of the recent many-year droughts — per the experts.
Given your track record of falling for a vast number of denialist claims due to your political leanings, I don’t think that I’m out of line in suggesting that if you want people to pay attention to this claim, that you should link to *credible* sources that support it.
Paul Krugman op-ed piece on climate change and food production. It is probably time to start talking about the social science related to climate change.
[Response: Bold highighting mine. I agree, we should all be learning more about this. –eric]
In regard to dams for flood mitigation, this has been a practice in Australia for some time. Many areas (most productive areas?) of the country go from drought to flood with a few ‘normal’ years in between. It’s the ‘normal’ years when farmers make their money. These ‘normal years’ have been non-existent this decade across large parts of the nation (not just Queensland).
The difficulties now facing Australia are that most areas suitable for dams are already dammed and global warming is making droughts and flooding more extreme.
The recent floods show that although floods can be mitigated, they cannot be prevented. I understand that Wivenhoe has prevented flooding in recent years. It would appear that the floods would have come sooner and maybe have been more severe on Brisbane city if not for Wivenhoe. The flood inquiry should tell us more about that and if that, in fact, was the case.
To drain the water storage component of the dual purpose dam in preparation for a flood not yet forecast is fraught with the danger that drought may come first and the water will run out (as it has in some large centres during recent droughts). With the recent huge improvements to weather forecasts on a medium term scale as well as the short term scale, flood mitigation and water storage can be and has been fine-tuned (AFAIK).
There is a Murray-Darling plan being developed this year (another attempt following forty plus years of attempts) and that should address some of the issues surrounding water management for floods and droughts of Australia’s largest river catchment, in the context of climate change.
Re my post on flood mitigation in Australia, a disclaimer – I have no expertise in hydrology or dam design/management. (In this context, my background is in agricultural policy.)
Oh, SM, you don’t get one fact straight without twisting another, do you?
Please, that’s too hysterically funny — you’re talking about Schwarzenegger, the Sierra Club, a bunch of water agencies, and a huge civil engineering improvement program. And you’re agin’ it??
“The Schwarzenegger Administration’s report confirms earlier conclusions by our organization and others that restoration of Hetch Hetchy Valley in Yosemite National Park is feasible and practical, and can be achieved with no harm to San Francisco Bay Area water and power users and Central Valley irrigation districts…. ”
//”…notion of “polar amplification” which appears based on reduced albedo. Albedo has little impact during the dark polar winters, although undoubtedly albedo plays some smaller role in the summer.”//
I don’t agree with this. Summer temperature changes over the Arctic ocean are small, since the melting sea-ice keeps air temperatures near the freezing point. In fact, the first signs of Arctic amplification are in the cool months. Mark Serreze has some recent articles explicitly pointing out that the feedback involves extra heat that is absorbed being carried through winter. That’s another thing I talked about in my feedback posts here at RC (Part 1). I also want to note that models still produce polar amplification without an ice-albedo feedback, so there’s other (probably bigger) things at play. Jianhua Lu has some work on polar amplification, and once again, I refer to Pierrehumbert (2002) on the issue of the Pole-Equator temperature gradient in climate shifts.
On your interpretation of changes in Arctic and dynamics, is way too simplistic and you’re ignoring several articles on the subject. First “Arctic ice loss” and its causes vary from region to region. Rigor shows wind-driven anomalies important near the coast (though this enhances thermodynamic anomalies) but Francis et al (2005) looked at different regions, including Barents, Kara, Laptev, E. Siberian, Chukchi, and Beaufort and found various relative roles in causal factors for sea ice responses. Rothrock and Zhang (2005) decomposed into thermal and wind components, and found that the downward rise is largely in response to Arctic temperatures. Even further, there’s work showing the AO patterns may not be independent ofgreenhouse-forced climate change.
This is a somewhat esoteric discussion of a moist “runaway” model where the atmosphere is unsaturated up to about 25 km and all the rain that happens originates from above that altitude. Not sure that mountains would be all that important. You can look at the model here: http://www.geosc.psu.edu/~jfk4/Meteo_466/Readings/Kasting_Icarus_88.pdf
Raypierre is arguing that rain must reach the ground owing to the need to balance evaporation and so silicate weathering must occur. I am now wondering if a large fraction of silicates might be protected from weathering owing to precipitation being geographically restricted.
To back track, I asked raypierre to shoot down Hansen’s assertion that burning all fossil fuels would lead to the Venus Syndrome since raypierre’s book has reappeared out of the publishing process. He has a nice clean argument based on the idea that the temperature at the top of the atmosphere is limited if there is a condensable greenhouse gas in equilibrium with a non-gas reservoir and so there is a maximum rate at which the atmosphere can shed energy. This maximum means that other greenhouse gases are not all that important once the maximum is approached because the condensable gas comes to dominate the opacity. If we accept that Venus must have had a true water runaway first then Hansen is wrong modulo some worries that raypierre has about cloud albedo. But the argument is especially clean because it says only the Sun can trigger a true runaway, not other greenhouse gases.
But, possibly, Venus had a ‘moist runaway’ where the stratosphere became wet enough to lose the original oceans but the solar input was never high enough to drive a true water runaway before the oceans were lost. Other noncondensable greenhouse gases can play a somewhat more decisive role in this borderline region so maybe Hansen is not shot down. But to get to a wet enough stratosphere, other greenhouse gases are still diluted in importance and, very importantly, the timescale for losing the oceans is quite long compared with the timescale for removing carbon dioxide from the atmosphere by forming carbonate rocks from the metal ions released from weathering of silicate rocks. So, Hansen is down again because even if we can moisten the stratosphere enough using carbon dioxide to prime things, it won’t stick around long enough to lose even 10 meters of ocean before the stratosphere dries up again.
So, is there then any way to reduce weathering of silicates to put Hansen back in the running? Probably not, but now a one dimensional model may not be adequate to answer the question. Suppose rain only falls at the poles where the clouds are lower? Another question is could the equatorial stratosphere get wet sooner and stay wet longer and make a difference that way? If we lost 500 m of ocean, the salinity would be quite different and maybe that counts as total catastrophe even if the process does not go to completion and there is a billion year reprieve before the loss process starts up again?
[Response: Chris, if you think you are still trying to save Hansen’s argument, you are way of the mark here. The silicate weathering issue is very relevant to what happens in the atmosphere of a rocky planet during a moist runaway, but the time scales of silicate weathering are so long that this issue plays no significant role whatsoever in the question of whether the Earth does something like a moist runaway in response to anthropogenic CO2 emissions. Your invoking of the Kasting moist runaway calculation is also irrelevant to the issue of Hansen’s argument, because he can only get those conditions because the solar absorption is substantially higher than Earth. Alternately (though implausibly( you could get those conditions with Earth’s solar absorption, but only for CO2 concentrations way, way in excess of any conceivable fossil fuel inventories. There is, in principle, a question of whether clouds could bump up the climate sensitivity so much that you could get conditions similar to Kasting’s calculation with only 5000 Gt or so of carbon emissions, but the climate fluctuations of the cenozoic really make that extremely, extremely implausible. It is always entertaining to think about extreme climates, and working through the way the hydrological cycle works on a very hot planet is stimulating. But if you still think you are on the track of rescuing Hansen’s irreperably broken argument about runaway conditions on Earth, you are just wasting everybody’s time. –raypierre]
[Response: And another thing. If you’re going to discuss silicate weathering during a wet runaway, (keeping in mind we’re not talking about AGW here), you also need to keep in mind that even if rain somehow conspired to miss all the continents, you would still have weathering of ocean floor silicates, and that becomes increasingly important as the oceans get hot. That alone would tend to give you low CO2 during a wet runaway, as I argued in an AGU talk some years back. But if you want to beat silicate weathering and generate a very hot climate, there’s an easy way to do that. Just trigger a Snowball. Then (depending somewhat on dust) the CO2 builds up to huge concentrations before deglaciating, and you’re left with a hot super-greenhouse world. Because of the strong silicate weathering during the snowball aftermath, though, it’s not going to stay hot for long enough to lose much of the ocean. Again, we’re not talking about anything relevant to AGW here, but it’s bound to be happening out there somewhere in the galaxy, right as we speak. –raypierre]
Jim Steelesays
Tamino suggests; “Your portrayal gives the opposite impression, and you’re mistaken.” and “Your conflating the most rapidly warming region with the “major portion of the rise” indicates that you simply don’t understand what the major portion of the rise is”
I agree that much of what I mentioned is “noise” that often equals out on an annual average. In part I was simply trying to highlight that an increase in surface temperature can not be simply taken as an input of energy to the global system. But indeed I am also arguing that oscillations can create asymmetries in heat distribution that last for 30 or more years. I also understand that over centennial scales that such oscillation should average out. But they are superimposed on two trends that were increasing this century solar and CO2. Using sunspots as a proxy spots have doubled since 1900, and the past 50 years solar energy is higher than the past 150. And granted solar may account for around 25% of the century trend, but it also means trends generated by oscillations superimposed on that solar trend will not just revert back to “zero”.
The warming in Alaska is associated with the Pacific Decadal Oscillation wind changes. A 30 year Alaskan warming trend due to dynamical changes is more than noise. The Arctic warmed even more rapidly in the 30’s and 40’s than what has been recently observed. What does that mean? Read Bengtsson 2004 he states “The largest warming occurred in the Arctic (Johannessen et al. 2004) averaged for the 1940s with some 1.78C (2.28C for the winter half of the year) relative to the 1910s” and “It seems unlikely that anthropogenic forcing on its own could have caused the warming, since the change in greenhouse gas forcing in the early decades of the twentieth century was only some 20% of the present”. Like Rigor with ice and Hartman and Wendler with Alaska’s climate these changes are much morer than noise. Am I arguing that they account for all the warming? Maybe mostly, maybe just a little. But no matter what it must be part of the equation. And your insistence on characterizing those effects as simply noise so you can more easily dismiss it is often contradicted in the literature. There are many climate scientists trying to understand ocean oscillations because only then can they separate the factors affecting climate change. To simply say “You are wrong”, adds precious little to a scientific discussion. It adds about as much as deleting alternative viewpoint posts, so only your interpretation can hold sway.
I will check my files to give your references, but I am sure you are aware that there are several papers that show approximately 2/3 of the observed warming is reflected in the minimum temperature. I have witnessed that when using USHCN temperature for biological studies. In the Sierra most places had decreasing maximums. Combine that with the “most rapidly warming areas” at the poles and I see no reason to quibble with my statement unless it is simply for the purpose of character denigration. If your purpose is to delineate areas of warming that contribute more to the global average than what I have mentioned and to better clarify our discussion, then you should simply do so. Otherwise your dismissive approach can only disintegrate into a “I am right and you are wrong shouting match”
JCHsays
One of the early dam tussles was over over turning this Tasmanian beauty into a lake. They may have been experts, but they weren’t too smart. That was a great way to begin a prolonged losing streak.
Jim Steelesays
Tamino, The question I asked before and will ask again is
“How do you separate the globe absorbing more energy versus recording higher temperatures?”
It doesn’t require “debunking me” but by answering that question directly it could put anything I might argue into its proper perspective.
[Response: Let’s get clear here. Anybody who says that ocean heat content is the right metric but global mean temperature is the wrong metric of global warming is just engaging in pseudoscientific obfuscation. Global mean temperature is clearly a valid and important summary of the state of the system, and the one that is easiest for us to measure. Ocean heat content is another characterization of the state of the system, but one that is harder to get accurately. It is an important thing to measure, because ocean heat uptake is one of the terms in the energy budget that goes into figuring out how the Earth’s temperature is changing while it is approaching a new, hotter equilibrium in response to increased CO2. Ocean heat content fluctuations can cause transient fluctuations in the Earth’s temperature, but because the heat is just shuttling from one place to another on Earth, cannot lead to a sustained warming. In any event, we know the oceans are taking up heat (over long enough averaging periods) so we know that what they are doing is delaying the approach to equilibrium. The tricky thing is understanding how much they are delaying it. –raypierre]
Jim Steelesays
Chris Colose says:
“Summer temperature changes over the Arctic ocean are small, since the melting sea-ice keeps air temperatures near the freezing point. In fact, the first signs of Arctic amplification are in the cool months. Mark Serreze has some recent articles explicitly pointing out that the feedback involves extra heat that is absorbed being carried through winter. ”
I agree mostly with what you said above and that’s what I meant by “albedo effects in the summer”. I suspect as Serreze suggests that it will mostly have an impact on how quickly the ocean refreezes. However I read several paper regarding that and it was never clear how that was quantified. I suspect most of the heat is quickly lost as winter approaches but that depends on summer vertical mixing.
And granted what I wrote was to simple regards Arctic ice, however I was not trying to characterize the whole Arctic ice situation. My Arctic examples were illustrating how a rise in temperature could happen without additional energy input through dynamical processes. The northward intrusion of warm water from the Atlantic also plays a substantial role on ice extent. But then again that could be due to changing currents not added energy.
Again the main question I was asking is- how do you separate rises in temperature due to dynamical processes versus increased energy inputs such as CO2 forcing.
Chris Dudley– Look, I respect Jim Hansen and if you are going to bet on him being wrong it’s usually a loss, but his status might be giving much more attention to the runaway stuff than it deserves. If he’s going to argue for a plausible runaway scenario then it’s up to him to demonstrate this, and a few qualitative passing-by remarks in his book is not how you advance such a case. Like I said, I haven’t looked at his book (and I probably won’t in the close future) but I think raypierre has made his case clear in his textbook where he goes through quantiative efforts, and has mentioned the peer-reviewed work of many others (e.g., Kasting) which arrive at these conclusions. Right now, we can’t work with perfect models of hothouse climates, cloud feedbacks, their chemical and hydrololgic interactions, but you haven’t made a convincing case that they are so far off the mark as for the current literature to essentially be useless.
I also think that this is a very good academic discussion (and a topic I’d like to learn more about), but it would be better if all the uncertanties could be throught through and discussed communally rather than slanted to why Hansen might be right and raypierre might be wrong. Humans would be gone well before a “runaway greenhouse” if we added a couple atmospheres worth of CO2 to the air anyway, so while it’s great to talk about Venus or the Gliese planets, boiling everything down to humans needing to worry about a runaway right now is almost as silly as the Super Bowl halftime show.
Back to your post, another thing that’s important to note here is that the precipitation (which dominates weathering rates) is ultimately constrained by the absorbed shortwave radiation, so at some point you can increase the longwave opacity from CO2 and still asymptote to a cap on the global precip-evaporation amounts, and this is especially the case if you’re thinking about a situation where the solar flux is relatively low and the CO2 is very high. My guess is you’d need a model with good boundary layer physics in an alien atmosphere to really get a feel for what is going on, aside from the geologic issues you mention which can vary planet-to-planet.
Jim Steele says
Dam’s themselves have not created flood frequencies or intensities, but many flood control activities have shunted water a way from one area and subsequently increased both frequency and intensity down stream.
Anything that lowers the time water remains “on the land” can increase flooding. Railroads, roadways, and agriculture often disrupt natural stream flow that results in a down cutting of the stream channels. That channelization traps water preventing it from reaching its flood plains and re-watering the local aquifer, instead rushing down stream. Also as the channel cuts downward it also drains the water table instead of recharging it and thus add to the flooding.
MalcolmT says
@193 Dams and flooding: Ross River Dam (1971) in Townsville North Queensland was designed as both water storage and flood mitigation and seems to be working well in both roles. Certainly, the city hasn’t flooded as badly since its construction as before – and we do get enough cyclones and post-cyclonic rain depressions to give us a fairly good idea.
Rod B says
raypierre (152): Simply (maybe too much so…), blackbody radiation and radiation from molecular vibration, rotation (and possible even electron) have a different genesis and significantly different characteristics. (I’m using “blackbody” as the generic planck function radiation, not as the ideal actual blackbody.) Blackbody is broadband (technically including the entire E-M spectrum); vibrotation radiation is single frequency, though maybe has a number of single frequencies. Blackbody radiation is continuous and quantized only in the vein that translation energy (of a molecule or an airplane) is quantized into almost infinitely small levels. Vibrotation is quantized only at the single frequency of vibration or rotation, and at most 3, 4, or so hf multiples about that single frequency. Blackbody radiation comes from vibrating charges that were created solely by heat/temperature, and it is temperature that is the sole cause of the radiation, though the physical characteristics of the body help determine how much radiation is generated. Vibrotation radiation is predominately caused or determined by the physical makeup of the molecule in a bath of any sort of E-M radiation. Blackbody radiation is continuous in time while vibrotational radiation is bursty, determined by such things as Einstein coefficients and molecular collision rates, both of which are only very loosely related to amBEant temperature.
The rub: the actual physics and mathematics of molecular radiation is very complex and difficult; for blackbody, not so much. Plus, stemming from the very basic fact that a photon is a photon and that at the basic level photon absorption and emission of any type have much in common, as you say, blackbody math and physics can be used for molecular radiation analysis with very good accuracy, though not exactness. Does the lack of exactness matter? I suspect that some of it might, though that is currently only an idea and of no worth to anyone else. In the meantime it seems to work quite well and so Planck (and Kirchoff and Beers and even Stefan) have given us tremendous insights into molecular radiation. We even use Stefan-Boltzmann, a strictly full spectrum blackbody construct, to build the basic models of greenhouse gas stuff with its multi-layered atmosphere from a flat surface stuff.
This is accomplished mostly by playing with emissivity, which of course is 1.0 for a black body. But with generic planck radiation the overall emissivity is less than 1.0 overall and moreover has a wavelength dependency. Even though it would never occur in reality there is no mathematical reason why we can’t construct a body that has an emissivity of 0.0 everywhere except say 15.00um where it has a 1.0 emissivity. There are a couple of things that fall off the wagon here, but probably of little import, so violà: Planck physics allows a super helpful analysis of greenhouse gas called molecular radiation. [Though your description of this is much better than mine here…]
But they are not the same thing.
Though the other Ray and others differ…
Rod B says
In her defense Curry did moderate out a blantant ad hominem toward Gavin in a comment. Though, to detract some, as I said in a comment to her, moderating with strike through is not near as good as a deletion.
Mike Smith says
@101
“Wind power didn’t run at nameplate power the whole time”?! They NEVER ran anywhere close to close to nameplate power. Here is a summary: http://meteorologicalmusings.blogspot.com/2011/02/separating-facts-from-spin.html
A representative of the American Wind Power Assn. said, twice, he would provide the figures that indicated wind power provided significant power during the period of peak demand yet, in spite of six requests, he never did so.
As the crisis unfolded in Texas wind power dribbled down to nothing. Before you dispute that, keep in mind the peak demand was not Wednesday morning, it was Wednesday evening between 8 and 9pm Central time.
adelady says
For those with an interest in dams and Brisbane floods, this is the best I’ve seen. Certainly a good counter to arguments that 2011 flooding was not as severe as earlier events.
http://bybrisbanewaters.blogspot.com/2011/02/2011-and-history-how-big-was-brisbanes.html
D. Price says
Has anybody noticed that Antartic Sea Ice is very low this year, though it the melting seems to have almost stopped now. This is interesting because it was supposed to be defying the trend.
[Response: Personal gripe: everyone loves to average Antarctic sea ice over the entire domain, but this is about as sensible as averaging sea surface temperatures on the Pacific coast of the U.S. with sea surface temperatures on the Atlantic side. Actually, it’s the same thing! It doesn’t make any sense, but it is done all the time, especially by people (including — ahem — many of my colleagues) who’ve never been to Antarctica and can’t appreciate the scale of the place.
Anyway, the trend has been negative (less ice) for the entire satellite record in the Amundsen, Bellinghausen, and even most of the Ross Sea. It is positive (more ice) over most of the coastline of East Antarctica. It is interesting if indeed the average trend is now flattening out, but the average trend was never statistically significant anyway. I wish NSIDC and others would start showing plots of both areas separately on their web site. Looking at the average is very close to meaningless.–eric]
Hank Roberts says
http://online.wsj.com/article/SB10001424052748704188104575083982637451248.html
“… Wind power was a bit player in Texas as recently as four years ago. Today, wind turbines produce a significant share of the state’s electricity.
But the growth of wind power has attracted powerful critics: the owners of natural-gas power plants…..”
…
“… On a recent day, a stiff 24-mile-an-hour wind was blowing …. The Papalote wind farm was turning that into 116 megawatts …. Its top output is 180 megawatts. Over one 24-hour period, said Mr. Collier, it ran at 88% of its maximum—nearly unheard of in the wind business.”
Ray Ladbury says
Rod B., True blackbody radiation is continuum, but there are no true blackbodies. Real materials–and this includes CO2–can only emit light corresponding to transitions between its energy states. This can, however, form a portion of a blackbody spectrum when the radiation fields is in equilibrium with the surrounding matter. There is no separate “blackbody” radiation. And you should know this, because you have not been able to produce a single reputable source that backs your assertion. I really seriously doubt that Landau did not understand blackbody radiation.
Ray Ladbury says
Edward Greisch, Having scientists write the nations laws is a recipe for disaster. Unfortunately, the skills needed to understand the laws of nature are quite different from the skills required to understand law an politics. WRT mitigating the threats due to climate change, the sole requirement the scientists can levy is that they be effective at addressng the problem. However, effectiveness is only one requirement of a good law. What we need to do is ensure that we elect politicians who have at least a nodding acquaintance with reality. If we are to insist on the expertise of the scientists, we must also respect the expertise of good policy makers
David B. Benson says
An earlier commenter asked about models. Here are some useful starting points.
“A Climate Modelling Primer” by Henderson-Sellers
Introduction to Three-Dimensional Climate Modeling 2nd Edition
Warren M. Washington and Claire Parkinson
http://www.palgrave.com/products/title.aspx?PID=270908
https://www.realclimate.org/index.php/archives/2008/11/faq-on-climate-models/
https://www.realclimate.org/index.php/archives/2009/01/faq-on-climate-models-part-ii/langswitch_lang/tk
http://www.climatescience.gov/Library/sap/sap3-1/final-report/sap3-1-final-all.pdf
Harold Pierce Jr says
Harold Pierce Jr says:
6 Feb 2011 at 7:21 PM
cm at 28
RE: “whether ocean oscillations (…) could explain the global warming of the past 40 years
RE: Climate Cycles: What the Russians say.
The English translation of “Cyclic Climate Changes and Fish Productivity by L.B. Klyashtorin and A.A. Lyubushin can be downloaded for free thru this link:
http://alexeylyubushin.narod.ru/Climate_Changes_and_Fish_Productivity.pdf?
NB: This mongraph is 223 pages. The Russian edition was published in 2005 and the English translation, in 2007. This book is not about climate science and they don’t discuss the origin of the ocean and atmospheric oscillations.
By analyzing a number of time series of data related to climate, they found that the earth has global climate cycles of 50-70 years with an average of about 60 years which have cool and warm phases of about 30 years each. They summerize most of the studies published upto early 2005 that show how this climate cycle influences fish catches in the major fisheries.
The last warm phase began in ca 1970-75 (aka the Great Shift) and ended in ca 2000. The global warming from ca 1975 is due in part to this warm phase. A cool phase has started and they predict it should last about 30 years. See Fig. 2.23.
In Fig. 2.22 and Table 2 they show that increasing world fuel consumption does not correlate with or affect the cool and warm phase of the 60 year cycle.
Several others studies have found this 60 year cycle. During the cool phase La Nina years usually out number El Nino years as was the case from ca 1940-70. This can be seen in the plot of the MEI at Klaus W’s website.
I haven’t checked to determine if the book was referenced AR4.
tamino says
There seems to be a “consensus” on two things that don’t seem right to me.
First is cooling during winter at the south pole. I looked at the data from Amundsen/Scott station (from the GISS website), and it doesn’t look statistically significant to me.
Second is Eric’s statement that regarding Antarctic ice, “the average trend was never statistically significant anyway.” But I compute it as being a small but statistically significant increase (at about 15000 km^2/yr).
Am I missing something?
[Response: Nope, you are probably right on both counts. Last time I checked, both of the statements I made were accurate, but it was probably more than a year ago. That’s what happens with barely-significant trends. I do hope that you appreciate the main point I was trying to make though, right? –eric]
john byatt says
#194 The major difference comparing Brisbane floods 1974/2011 was where the rain fell, see Australian BOM statement : http://www.bom.gov.au/climate/current/statements/scs24b.pdf
Hank Roberts says
Take a large variety of bouncy balls. Each bounces in its own characteristic way. Now tie them all together in a web with short pieces of elastic. How do they bounce?
I’m sure I’ve said that before, or something much like it, so I won’t go on.
Dave Werth says
This is totally off from anything that’s been discussed so far but it’s an open thread.
I’ve been arguing with a guy over on another blog (SmartPlanet.com). He has a web page up at:
http://www.thetruthaboutclimatechange.org/thetruth/
He’s saying of course that it’s all natural. I’ve been telling him that it’s a simple numerical chart without any insight into the underlying causes and that he should take into account at least solar forcing which was significant in the first half of the 20th century but not since then.
Maybe someone more knowledgeable than I can take a look at it and give me some more solid understanding about how to counter his arguments if you care to.
tamino says
Re: #211 (Harold Pierce)
Klyashtorin and Lyubushin actually have attempted to model climate change with their 60-year cycle. It turned out to be a miserable failure at anticipating the continued global warming since 2000:
http://replay.waybackmachine.org/20100104072004/http://tamino.wordpress.com/2009/12/22/cyclical-not/
The globe has definitely continued to warm since 2000:
http://tamino.wordpress.com/2011/01/20/how-fast-is-earth-warming/
In fact the warming is statistically significant even since 2000, in spite of the end of the putative “last warm phase.”
The whole “global warming is due to ocean cycles” nonsense is nothing but the latest attempt to muddy the waters by those who simply don’t want to accept the truth — that it continues, and it’s caused by human activity. The “it’s the sun” nonsense didn’t work, nor did the “galactic cosmic rays” nonsense, so they’re trying the next excuse. Can you smell the desperation?
Hank Roberts says
For Dave Werth:
http://www.google.com/search?q=site%3Arealclimate.org+%22recovering+from+the+little+ice+age%22&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
Mark C says
@Mike S.#204
As the crisis unfolded in Texas wind power dribbled down to nothing.
The following article appears to refute your contention…
http://www.evwind.es/noticias.php?id_not=10068
“In an interview with the Texas Tribune, ERCOT CEO Trip Doggett put it this way: “I’m not aware of any nuclear plant problems, and I’m not aware of any specific issues with wind turbines having to shut down due to icing. I would highlight that we put out a special word of thanks to the wind power community because they did contribute significantly through this timeframe. Wind was blowing, and we had often 3,500 megawatts of wind farm generation during that morning peak, which certainly helped us in this situation.”
Peak demand may have been in the afternoon, but according to ERGOT the critical period was in the morning, when the coal plants were failing. And even in the afternoon, wind power continued to provide 7% of the power, according to the article.
Jim Steele says
tamino says: “the globe has definitely continued to warm since 2000”
How do you separate the globe absorbing more energy versus recording higher temperatures?
For example with less ice on the Arctic Ocean to insulate the -2C Arctic Ocean from the -20C or more air temp, you could record higher temperatures but the globe would actually be cooling. Likewise an increase in the frequency of El Nino’s would create higher recorded temperatures but El Nino’ s are venting energy.
Seems like Argo data is the best metric to resolve this issue.
Brian Dodge says
“they found that the earth has global climate cycles of 50-70 years with an average of about 60 years”
“The last warm phase began in ca 1970-75 (aka the Great Shift) and ended in ca 2000.” Harold Pierce Jr — 6 Feb 2011 @ 7:58 PM
If this were true, and you go back 50-70 years from 2000, one cycle, temperatures should be as warm as today. They aren’t
Brian Dodge says
“Suppose the rain in Spain fell only on the plain. All the calcium ions were leached away and never replenished from erosion from the mountains.” Chris Dudley — 6 Feb 2011 @ 2:20 AM
The rain isn’t only falling on the plain in Spain, but also on the Andes mountains in South America. Because they are tall, and because the atmosphere gets cooler with height, even if it’s too hot in the lowlands -“very little rain falls down wind on the Sahara” – for precipitation to make it to the ground (virga), it will still be raining or snowing on the Andes peaks. At 5 km elevation, the temperature will be 25 to 40 degrees Centigrade cooler than at the surface.
Modelling the Andes as a pyramid 7000 km long, 200 km wide, and 4 km tall gives a volume of 2.33e5 km^3 for the top 2 km (This is likely a conservative underestimate, since the average height is 4 km, but there are ~ 50 peaks over 6 km). A large fraction of the rocks are of volcanic origin, and contain feldspar minerals.
This would contain ~1e17 moles CaO equivalent at 1% concentration(The anorthite fraction of plagioclase feldspars weathers, releasing Calcium ions – CaAl2Si2O8 + H2O + 2CO2 => Ca2+(aq) + 2HCO3-(aq) + [Al2O3 + SiO2](kaolin). The Ca2+(aq) + 2HCO3-(aq) => CaCO3(solid) + H20 + CO2(gas))
CO2 is 22727 moles per tonne, so the CaO equivalent in the top half of the Andes could fix ~4e12 tonnes of CO2 to CaCO3. The earth’s atmosphere contains about 3e12 tonnes of CO2.
You should do the same calculation for the Cascades, Aleutian, and other volcano chains. Uplift mountain ranges (Rockies, Himalayas) contain more sedimentary/metamorphic rock, in which the Calcium is already CaCO3. Some ranges (Sierras, Urals, Alps) have a mix of of rocks, and have eroded down to their igneous roots which contain feldspars, and have heavily metamorphosed rocks that contain Calcium in non-carbonate forms- see http://en.wikipedia.org/wiki/Category:Calcium_minerals. The calcium carbonate fraction of weatherable rocks can also sequester CO2 into the deep ocean – CaCO3(solid) + H20 + CO2(gas) => Ca2+(aq) + 2HCO3-(aq). See Enhanced Carbonate Dissolution as a Means of Capturing and Sequestering Carbon Dioxide, Greg H. Rau1,2, Ken Caldeira2, Kevin G. Knauss2, Bill Downs3, and Hamid Sarv3
Rod B says
JCH (182) plus much of the dam/flood control projects were scaled back because of the recent many-year droughts — per the experts.
Rod B says
R. Gates, I really don’t want in on this discussion, but feel compelled to offer a small comment. I think protagonist scientists, given their learned studies and passionate concerns, ought to be writing letters to Congress (in addition to testifying). But the shrillness and paranoia shown in the referenced letter (183) I’ll guarantee is no way to get their point accepted. For those who might correctly say that the shrillness and paranoia was small I would add that a tiny amount in a letter to Congress is enough to get it stuck directly in the bug letter bin.
Hank Roberts says
> but the globe would actually be cooling
And the heat would be going — where?
Rod B says
raypierre, thanks for the response (185).
Septic Matthew says
204, Mike Smith: As the crisis unfolded in Texas wind power dribbled down to nothing.
That appears not to have been the case. Read the links that Hank Roberts and I provided. I hope for a really good survey soon.
Septic Matthew says
206, eric in comment: Personal gripe: everyone loves to average Antarctic sea ice over the entire domain, but this is about as sensible as averaging sea surface temperatures on the Pacific coast of the U.S. with sea surface temperatures on the Atlantic side
Gracious! Are you questioning the practice of averaging the temperatures over the whole earth?
Rod B says
Ray Ladbury (208), you keep hiding behind the semantics of ‘no such thing as a black body’ which I can’t argue with. I’m talking of the radiation stemming from Planck’s equation. Call it what you like. His equation has things like h, c, pi, wavelength, and T. Nothing about vibration and rotation levels anywhere for miles around.
[Response: Hey Rod! Get this. Clausius and Clapeyron walk into a bar. Great prediction of vapor pressure vs. temperature, sez Clausius to Clapeyron. But hey,sez bartender, no molecules in sight, in that formula. Must not have anything to do wit da molecules. Comes in Stefan and Boltzmann, carryin a big Plank, Is thermodynamics! Is wonderful! Is true whatever da stuff is made of! –raypierre]
Rod B says
Ray Ladbury, cogent helpful comment in 209, IMO.
Jim Steele says
Hank Roberts #224 asked “And the heat would be going — where?”
Most likely the same place the day time heat goes at night. But it is not always a matter of where did the heat go? but where did it come from?
Regards Antarctica or any mountainous region on the globe you can have a foehn wind storm that raises temperatures by 30C within 24 hours. If we used surface temperature data only, we could easily misconstrue that warming as added energy. But it is really the result of asymmetrical temperature measurements that had not accounted for the upper layers of atmospheric heat, that have now been mixed and brought down to the surface. These foehn winds typically have unique names around the world like the Chinooks.
Simple changes in wind can lead to a warming event that is dynamical but in no way represents increased heat input. For example Hartman and Wendler 2005, ‘On the significance of the 1976 Pacific climate shift in the climatology of Alaska’, showed the warming in Alaska was dynamical ad associated with the observed wind changes. Both advection and disruption of the thermal inversion were suggested mechanisms.
Likewise other recorded warming in the Arctic is likely dynamical. I believe Rigor, Wallace and Colony, 2002, ‘Response of sea ice to the Arctic Oscillation”- or perhaps it was another Rigor paper- detailed how much of the Arctic ice loss was due to wind shifts more actively moving ice out through the Fram strait. The winds were coming from the coldest part of Siberia and at very cold temperatures that were not melting the ice but removing it. The heat from exposed warmer ocean waters then get advected and measured as a rise in temperature.
The major portion of the rise in global temperatures are recorded in the polar regions and during the winter and at the nightly minimums. All places and times where thermal inversions most present. The above dynamical responses seem better able to explain much of the warming compared to the notion of “polar amplification” which appears based on reduced albedo. Albedo has little impact during the dark polar winters, although undoubtedly albedo plays some smaller role in the summer.
That’s why OHC, via Argo, should be the main metric to separate temperature changes from heat changes. OHC will be better able to determine if heat is being added or subtracted, but even then there will be problems and OHC pre ARgo will have wide error bars. Surface temperatures by themselves can be very misleading.
So let me ask a question in return. During and after the 1998 El Nino global temperatures rose and fell by ~0.8 C. That change equaled the century warming trend. Where did all that heat come from? and where did go?
Rick Brown says
RodB @223 – I’ll give you credit for generally being civil and clearly not being a numbskull, but you do contribute more than your share of nonsense here. Nonetheless, I think your suggestion that the letter from scientists referenced @183 displays “shrillness and paranoia” may take the cake. Care to point out the relevant passages? And remember, if someone’s actually out to get you it isn’t paranoia.
http://www.dallasnews.com/business/headlines/20101213-ralph-hall-gearing-up-for-new-role-as-chairman-of-house-science-and-technology-committee.ece
http://www.newyorker.com/talk/comment/2010/11/22/101122taco_talk_kolbert
Septic Matthew says
200, Jim Steele: Dam’s themselves have not created flood frequencies or intensities, but many flood control activities have shunted water a way from one area and subsequently increased both frequency and intensity down stream.
And others, no one has written that dams are a panacea or problem-free. But does anybody agree with eric’s statement that I quoted?
In CA there is a movement to remove the Hetch Hetchy dam and reservoir that supplies drinking water to San Francisco. To the most extreme environmentalists, the drinking water to San Francisco is not worth the damage to the natural Sierra Nevada ecology. It’s a claim I suppose you can make.
[Response:I do research in the area between there and Yosemite Valley, estimating forest change types and amounts. That movement started long ago, with John Muir in fact. It’s not so much an issue of ecological damage–that’s long done and it’s a relatively small area anyway. It’s always been more an issue of National Park management policies, and aesthetics. If you’ve seen pictures of the pre-dam H-H valley, you know why. And it’s still spectacular, even flooded.–Jim]
No one is talking about removing Hoover Dam and undoing the damage done to Imperial, Los Angeles and San Diego Counties, and the Colorado River Delta. Whatever else you might claim about Hetch Hetchy and the dams on the Colorado, they have not increased the damage from downstream flooding.
john byatt says
The only way that Wivenhoe could have prevented any flooding in Brisbane would have been with hindsight, The claims of incompetence are coming from the climate change skeptics, trying to project their own feelings of guilt?
Wivenhoe is operated strictly to a Manual, the operators are bound by law to follow the manual. they did, Holding back more water would have placed the dam in danger of catastrophic collapse. was only 60cm from that
john byatt says
Re my. Catastrophic collapse re Wivenhoe, should have read automatic catastrophic
release,
tamino says
Re: #230 (Jim Steele)
Dynamical processes (as you characterize them) can raise or lower temperature, in fact they do both. They are responsible for fluctuations, especially on small geographical and short time scales. But over the long haul, over the entire globe, they tend to average out to zero. They’re part of the “noise” in global temperature, not the signal (or if you prefer, part of the weather not the climate). Your portrayal gives the opposite impression, and you’re mistaken.
Your statement that “The major portion of the rise in global temperatures are recorded in the polar regions and during the winter and at the nightly minimums” is likewise, just plain wrong. The arctic (but not the antarctic) is warming faster than any other region (except perhaps the antarctic peninsula), but it’s also a small fraction of the entire globe. Your conflating the most rapidly warming region with the “major portion of the rise” indicates that you simply don’t understand what the major portion of the rise is. The same is true of the more rapid nighttime and winter warming — you need to think it through more carefully.
I agree that ocean heat content is an excellent metric. As soon as the data problems with Argo are solved, it may be a worthwhile substitute for global average temperature. Until different research groups can agree on what the ocean heat content actually is, it seems to me that global average temperature is the best we’ve got — and one for which the different data records are in excellent agreement. Your comments which suggest its inappropriateness are just smoke and mirrors.
Edward Greisch says
I second 231 Rick Brown.
Edward Greisch says
209 RayLadbury: “Having scientists write the nations laws is a recipe for disaster.”
It couldn’t get any worse. Disaster is where we are headed. The scientists at least have the IQ required to figure it out. Where do you get the idea that “Having scientists write the nations laws is a recipe for disaster.”? That is just an ad homonym attack on scientists. Scientists do not fit your stereotype. Ethics and morality are now in the jurisdiction of the new science called sociobiology. Reference: Sam Harris’ latest book “The Moral Landscape: How Science Can Determine Human Values”; “The Science of Good & Evil” by Michael Shermer and The Brights project on ethics and morality without god. http://the-brights.net/
That means that ethics and morality are no longer in the jurisdictions of religion and philosophy.
“politicians who have at least a nodding acquaintance with reality” can be counted on the fingers of one hand. There is one physicist in congress.
“the expertise of good policy makers” doesn’t happen. They just copy what the corporations write. See:
http://climateprogress.org/2010/10/14/video-proof-david-koch-the-polluting-billionaire-pulls-the-strings-of-the-tea-party-extremists
I don’t have a quote for you of corporations directly writing laws on hand, but I have seen them. You get to congress by getting votes, not by passing an exam on policy writing.
dhogaza says
Rod B:
Given your track record of falling for a vast number of denialist claims due to your political leanings, I don’t think that I’m out of line in suggesting that if you want people to pay attention to this claim, that you should link to *credible* sources that support it.
Emphasis again on the *credible* bit.
The Raven says
Paul Krugman op-ed piece on climate change and food production. It is probably time to start talking about the social science related to climate change.
[Response: Bold highighting mine. I agree, we should all be learning more about this. –eric]
Sou says
In regard to dams for flood mitigation, this has been a practice in Australia for some time. Many areas (most productive areas?) of the country go from drought to flood with a few ‘normal’ years in between. It’s the ‘normal’ years when farmers make their money. These ‘normal years’ have been non-existent this decade across large parts of the nation (not just Queensland).
The difficulties now facing Australia are that most areas suitable for dams are already dammed and global warming is making droughts and flooding more extreme.
The recent floods show that although floods can be mitigated, they cannot be prevented. I understand that Wivenhoe has prevented flooding in recent years. It would appear that the floods would have come sooner and maybe have been more severe on Brisbane city if not for Wivenhoe. The flood inquiry should tell us more about that and if that, in fact, was the case.
To drain the water storage component of the dual purpose dam in preparation for a flood not yet forecast is fraught with the danger that drought may come first and the water will run out (as it has in some large centres during recent droughts). With the recent huge improvements to weather forecasts on a medium term scale as well as the short term scale, flood mitigation and water storage can be and has been fine-tuned (AFAIK).
There is a Murray-Darling plan being developed this year (another attempt following forty plus years of attempts) and that should address some of the issues surrounding water management for floods and droughts of Australia’s largest river catchment, in the context of climate change.
Sou says
Re my post on flood mitigation in Australia, a disclaimer – I have no expertise in hydrology or dam design/management. (In this context, my background is in agricultural policy.)
Hank Roberts says
> extreme environmentalists
Oh, SM, you don’t get one fact straight without twisting another, do you?
Please, that’s too hysterically funny — you’re talking about Schwarzenegger, the Sierra Club, a bunch of water agencies, and a huge civil engineering improvement program. And you’re agin’ it??
http://www.sierraclub.org/ca/hetchhetchy/articles.asp
“The Schwarzenegger Administration’s report confirms earlier conclusions by our organization and others that restoration of Hetch Hetchy Valley in Yosemite National Park is feasible and practical, and can be achieved with no harm to San Francisco Bay Area water and power users and Central Valley irrigation districts…. ”
Read up on it before you attack something you’re only imagining, would ya?
http://www.sierraclub.org/ca/hetchhetchy/
Chris Colose says
Jim Steele,
//”…notion of “polar amplification” which appears based on reduced albedo. Albedo has little impact during the dark polar winters, although undoubtedly albedo plays some smaller role in the summer.”//
I don’t agree with this. Summer temperature changes over the Arctic ocean are small, since the melting sea-ice keeps air temperatures near the freezing point. In fact, the first signs of Arctic amplification are in the cool months. Mark Serreze has some recent articles explicitly pointing out that the feedback involves extra heat that is absorbed being carried through winter. That’s another thing I talked about in my feedback posts here at RC (Part 1). I also want to note that models still produce polar amplification without an ice-albedo feedback, so there’s other (probably bigger) things at play. Jianhua Lu has some work on polar amplification, and once again, I refer to Pierrehumbert (2002) on the issue of the Pole-Equator temperature gradient in climate shifts.
On your interpretation of changes in Arctic and dynamics, is way too simplistic and you’re ignoring several articles on the subject. First “Arctic ice loss” and its causes vary from region to region. Rigor shows wind-driven anomalies important near the coast (though this enhances thermodynamic anomalies) but Francis et al (2005) looked at different regions, including Barents, Kara, Laptev, E. Siberian, Chukchi, and Beaufort and found various relative roles in causal factors for sea ice responses. Rothrock and Zhang (2005) decomposed into thermal and wind components, and found that the downward rise is largely in response to Arctic temperatures. Even further, there’s work showing the AO patterns may not be independent ofgreenhouse-forced climate change.
Chris Dudley says
Brian (#221),
This is a somewhat esoteric discussion of a moist “runaway” model where the atmosphere is unsaturated up to about 25 km and all the rain that happens originates from above that altitude. Not sure that mountains would be all that important. You can look at the model here: http://www.geosc.psu.edu/~jfk4/Meteo_466/Readings/Kasting_Icarus_88.pdf
Raypierre is arguing that rain must reach the ground owing to the need to balance evaporation and so silicate weathering must occur. I am now wondering if a large fraction of silicates might be protected from weathering owing to precipitation being geographically restricted.
To back track, I asked raypierre to shoot down Hansen’s assertion that burning all fossil fuels would lead to the Venus Syndrome since raypierre’s book has reappeared out of the publishing process. He has a nice clean argument based on the idea that the temperature at the top of the atmosphere is limited if there is a condensable greenhouse gas in equilibrium with a non-gas reservoir and so there is a maximum rate at which the atmosphere can shed energy. This maximum means that other greenhouse gases are not all that important once the maximum is approached because the condensable gas comes to dominate the opacity. If we accept that Venus must have had a true water runaway first then Hansen is wrong modulo some worries that raypierre has about cloud albedo. But the argument is especially clean because it says only the Sun can trigger a true runaway, not other greenhouse gases.
But, possibly, Venus had a ‘moist runaway’ where the stratosphere became wet enough to lose the original oceans but the solar input was never high enough to drive a true water runaway before the oceans were lost. Other noncondensable greenhouse gases can play a somewhat more decisive role in this borderline region so maybe Hansen is not shot down. But to get to a wet enough stratosphere, other greenhouse gases are still diluted in importance and, very importantly, the timescale for losing the oceans is quite long compared with the timescale for removing carbon dioxide from the atmosphere by forming carbonate rocks from the metal ions released from weathering of silicate rocks. So, Hansen is down again because even if we can moisten the stratosphere enough using carbon dioxide to prime things, it won’t stick around long enough to lose even 10 meters of ocean before the stratosphere dries up again.
So, is there then any way to reduce weathering of silicates to put Hansen back in the running? Probably not, but now a one dimensional model may not be adequate to answer the question. Suppose rain only falls at the poles where the clouds are lower? Another question is could the equatorial stratosphere get wet sooner and stay wet longer and make a difference that way? If we lost 500 m of ocean, the salinity would be quite different and maybe that counts as total catastrophe even if the process does not go to completion and there is a billion year reprieve before the loss process starts up again?
[Response: Chris, if you think you are still trying to save Hansen’s argument, you are way of the mark here. The silicate weathering issue is very relevant to what happens in the atmosphere of a rocky planet during a moist runaway, but the time scales of silicate weathering are so long that this issue plays no significant role whatsoever in the question of whether the Earth does something like a moist runaway in response to anthropogenic CO2 emissions. Your invoking of the Kasting moist runaway calculation is also irrelevant to the issue of Hansen’s argument, because he can only get those conditions because the solar absorption is substantially higher than Earth. Alternately (though implausibly( you could get those conditions with Earth’s solar absorption, but only for CO2 concentrations way, way in excess of any conceivable fossil fuel inventories. There is, in principle, a question of whether clouds could bump up the climate sensitivity so much that you could get conditions similar to Kasting’s calculation with only 5000 Gt or so of carbon emissions, but the climate fluctuations of the cenozoic really make that extremely, extremely implausible. It is always entertaining to think about extreme climates, and working through the way the hydrological cycle works on a very hot planet is stimulating. But if you still think you are on the track of rescuing Hansen’s irreperably broken argument about runaway conditions on Earth, you are just wasting everybody’s time. –raypierre]
[Response: And another thing. If you’re going to discuss silicate weathering during a wet runaway, (keeping in mind we’re not talking about AGW here), you also need to keep in mind that even if rain somehow conspired to miss all the continents, you would still have weathering of ocean floor silicates, and that becomes increasingly important as the oceans get hot. That alone would tend to give you low CO2 during a wet runaway, as I argued in an AGU talk some years back. But if you want to beat silicate weathering and generate a very hot climate, there’s an easy way to do that. Just trigger a Snowball. Then (depending somewhat on dust) the CO2 builds up to huge concentrations before deglaciating, and you’re left with a hot super-greenhouse world. Because of the strong silicate weathering during the snowball aftermath, though, it’s not going to stay hot for long enough to lose much of the ocean. Again, we’re not talking about anything relevant to AGW here, but it’s bound to be happening out there somewhere in the galaxy, right as we speak. –raypierre]
Jim Steele says
Tamino suggests; “Your portrayal gives the opposite impression, and you’re mistaken.” and “Your conflating the most rapidly warming region with the “major portion of the rise” indicates that you simply don’t understand what the major portion of the rise is”
I agree that much of what I mentioned is “noise” that often equals out on an annual average. In part I was simply trying to highlight that an increase in surface temperature can not be simply taken as an input of energy to the global system. But indeed I am also arguing that oscillations can create asymmetries in heat distribution that last for 30 or more years. I also understand that over centennial scales that such oscillation should average out. But they are superimposed on two trends that were increasing this century solar and CO2. Using sunspots as a proxy spots have doubled since 1900, and the past 50 years solar energy is higher than the past 150. And granted solar may account for around 25% of the century trend, but it also means trends generated by oscillations superimposed on that solar trend will not just revert back to “zero”.
The warming in Alaska is associated with the Pacific Decadal Oscillation wind changes. A 30 year Alaskan warming trend due to dynamical changes is more than noise. The Arctic warmed even more rapidly in the 30’s and 40’s than what has been recently observed. What does that mean? Read Bengtsson 2004 he states “The largest warming occurred in the Arctic (Johannessen et al. 2004) averaged for the 1940s with some 1.78C (2.28C for the winter half of the year) relative to the 1910s” and “It seems unlikely that anthropogenic forcing on its own could have caused the warming, since the change in greenhouse gas forcing in the early decades of the twentieth century was only some 20% of the present”. Like Rigor with ice and Hartman and Wendler with Alaska’s climate these changes are much morer than noise. Am I arguing that they account for all the warming? Maybe mostly, maybe just a little. But no matter what it must be part of the equation. And your insistence on characterizing those effects as simply noise so you can more easily dismiss it is often contradicted in the literature. There are many climate scientists trying to understand ocean oscillations because only then can they separate the factors affecting climate change. To simply say “You are wrong”, adds precious little to a scientific discussion. It adds about as much as deleting alternative viewpoint posts, so only your interpretation can hold sway.
I will check my files to give your references, but I am sure you are aware that there are several papers that show approximately 2/3 of the observed warming is reflected in the minimum temperature. I have witnessed that when using USHCN temperature for biological studies. In the Sierra most places had decreasing maximums. Combine that with the “most rapidly warming areas” at the poles and I see no reason to quibble with my statement unless it is simply for the purpose of character denigration. If your purpose is to delineate areas of warming that contribute more to the global average than what I have mentioned and to better clarify our discussion, then you should simply do so. Otherwise your dismissive approach can only disintegrate into a “I am right and you are wrong shouting match”
JCH says
One of the early dam tussles was over over turning this Tasmanian beauty into a lake. They may have been experts, but they weren’t too smart. That was a great way to begin a prolonged losing streak.
Jim Steele says
Tamino, The question I asked before and will ask again is
“How do you separate the globe absorbing more energy versus recording higher temperatures?”
It doesn’t require “debunking me” but by answering that question directly it could put anything I might argue into its proper perspective.
[Response: Let’s get clear here. Anybody who says that ocean heat content is the right metric but global mean temperature is the wrong metric of global warming is just engaging in pseudoscientific obfuscation. Global mean temperature is clearly a valid and important summary of the state of the system, and the one that is easiest for us to measure. Ocean heat content is another characterization of the state of the system, but one that is harder to get accurately. It is an important thing to measure, because ocean heat uptake is one of the terms in the energy budget that goes into figuring out how the Earth’s temperature is changing while it is approaching a new, hotter equilibrium in response to increased CO2. Ocean heat content fluctuations can cause transient fluctuations in the Earth’s temperature, but because the heat is just shuttling from one place to another on Earth, cannot lead to a sustained warming. In any event, we know the oceans are taking up heat (over long enough averaging periods) so we know that what they are doing is delaying the approach to equilibrium. The tricky thing is understanding how much they are delaying it. –raypierre]
Jim Steele says
Chris Colose says:
“Summer temperature changes over the Arctic ocean are small, since the melting sea-ice keeps air temperatures near the freezing point. In fact, the first signs of Arctic amplification are in the cool months. Mark Serreze has some recent articles explicitly pointing out that the feedback involves extra heat that is absorbed being carried through winter. ”
I agree mostly with what you said above and that’s what I meant by “albedo effects in the summer”. I suspect as Serreze suggests that it will mostly have an impact on how quickly the ocean refreezes. However I read several paper regarding that and it was never clear how that was quantified. I suspect most of the heat is quickly lost as winter approaches but that depends on summer vertical mixing.
And granted what I wrote was to simple regards Arctic ice, however I was not trying to characterize the whole Arctic ice situation. My Arctic examples were illustrating how a rise in temperature could happen without additional energy input through dynamical processes. The northward intrusion of warm water from the Atlantic also plays a substantial role on ice extent. But then again that could be due to changing currents not added energy.
Again the main question I was asking is- how do you separate rises in temperature due to dynamical processes versus increased energy inputs such as CO2 forcing.
Chris Colose says
Chris Dudley– Look, I respect Jim Hansen and if you are going to bet on him being wrong it’s usually a loss, but his status might be giving much more attention to the runaway stuff than it deserves. If he’s going to argue for a plausible runaway scenario then it’s up to him to demonstrate this, and a few qualitative passing-by remarks in his book is not how you advance such a case. Like I said, I haven’t looked at his book (and I probably won’t in the close future) but I think raypierre has made his case clear in his textbook where he goes through quantiative efforts, and has mentioned the peer-reviewed work of many others (e.g., Kasting) which arrive at these conclusions. Right now, we can’t work with perfect models of hothouse climates, cloud feedbacks, their chemical and hydrololgic interactions, but you haven’t made a convincing case that they are so far off the mark as for the current literature to essentially be useless.
I also think that this is a very good academic discussion (and a topic I’d like to learn more about), but it would be better if all the uncertanties could be throught through and discussed communally rather than slanted to why Hansen might be right and raypierre might be wrong. Humans would be gone well before a “runaway greenhouse” if we added a couple atmospheres worth of CO2 to the air anyway, so while it’s great to talk about Venus or the Gliese planets, boiling everything down to humans needing to worry about a runaway right now is almost as silly as the Super Bowl halftime show.
Back to your post, another thing that’s important to note here is that the precipitation (which dominates weathering rates) is ultimately constrained by the absorbed shortwave radiation, so at some point you can increase the longwave opacity from CO2 and still asymptote to a cap on the global precip-evaporation amounts, and this is especially the case if you’re thinking about a situation where the solar flux is relatively low and the CO2 is very high. My guess is you’d need a model with good boundary layer physics in an alien atmosphere to really get a feel for what is going on, aside from the geologic issues you mention which can vary planet-to-planet.