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Comments 93301 to 93350:
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Paul D at 19:53 PM on 7 March 2011Interactive animation of the climate change impact on agriculture
Maybe my eye sight is worse than I thought. But the variable is temperature, in fact the text says: Mean Local Temperature Change. Which suggests to me that the interactive educational tool is designed to show what would happen with a temperature change. Indeed, I can reduce the temperature to zero. Possibly the only fault is that it doesn't go into negative temperatures. Given that the vast majority of scientists understand the physics of temperature change and the effects. I would think the results are obvious. After all is it not skeptics that attach great meaning to the ability of growing grapes in different climates? Or are comments 1, 2 and 3 suggesting skeptics are using a poor metric for judging climate? -
Gilles at 19:44 PM on 7 March 2011Icing the Medieval Warm Period
"No subtraction is being done. " By "subtraction", I mean switching off the anthropic forcings in the runs. Is it what is done, or no? If yes, I repeat : the fact that you worsen a fit by switching off a component AFTER you have adjusted your fit to data is not surprising : it is always true. And it is hence not very useful to "prove" anything on the validity of your model. "GCMs are not statistical model fits, they are models of the physics, that allow you to find out the consequences of a set of assumptions regarding climate physics." DM : we saw in the post about sensitivities that there was still a fairly large range of different sensitivities compatible with the data (or they would be dismissed by them). Do the "different curves" used to generate this interval include all these values of sensitivities, yes, or no ? and if yes, how can they all be "equally true" ? If you can explain the same data with different physical models, you're pretty sure that they are almost all (but one) wrong. And you cannot exclude they are all wrong. This is not a situation usually associated with a "well understood" theory.Moderator Response: [Dikran Marsupial] You are assuming that the model with only non-anthropogenic forcings was not independently "tuned" (as far as tuning is possible). I doubt that is the case. As I said, the GISS Model E code is freely available, so you can always go and check for yourself. Secondly, the diagram shown was not meant to "prove" anything on the validity of the model. If there is a large range of sensitivities that are compatible with the data, that suggests that the models would be relatively insensitive to their adjustment. Lastly, no, all models are wrong (GEP Box); nobody expects any of them to be exactly right. The question is, are they sufficiently right to be useful. YOu have yet to provide any evidence that they are not useful, we all know they are "wrong", that is entirely uncontraverisal. -
RSVP at 19:38 PM on 7 March 2011A Real-World Example of Carbon Pricing Benefits Outweighing Costs
If winters are tending to be milder, it means the planet's energy efficiency has increased and thereby lowering average fuel consumption. Why is this fact always overlooked...or is this a sorely "inconvenient truth"? -
Dikran Marsupial at 19:38 PM on 7 March 2011Interactive animation of the climate change impact on agriculture
As we have no data for future climate (as it hasn't happened yet), please explain how we can forecast the effects of climate change on agriculture without a model? Nobody thinks that model output is data. Models exist to demonstrate the consequences of a set of assumptions regarding climate physics; they also allow our understanding of climate physics to be falsified, by making testable predictions. Disregarding any argument just because it involves the use of models is deeply unscientific. -
logicman at 19:35 PM on 7 March 2011Icing the Medieval Warm Period
Daniel: with reference to your moderator replies to comments #15 and #24 - here is the url for the original temperature anomaly graphics: earthobservatory.nasa.gov Of relevance to modern temps vs MWP is the recent paper Recovery mechanisms of Arctic summer sea ice. S. Tietsche,1 D. Notz,1 J. H. Jungclaus,1 and J. Marotzke1 The paper states clearly that temperatures in the Fram Strait are higher than at any time in the last 2ky - including the MWP. Tietsche_GRL_2011.pdfModerator Response: Hey, Welcome to Skeptical Science! Thanks for the link to the graphic (I haven't yet had the time to search for it, so many thanks)! Far be it for me to correct you, but I think you may have meant Spielhagen et al, 2011 wherein they present a 2,000 year marine sediment proxy record showing the unprecedented warming of which you speak. BTW, if you want to link to your website, please do so as many of the regulars here would find it invaluable. Thanks again! -
Camburn at 19:30 PM on 7 March 2011Interactive animation of the climate change impact on agriculture
The supposed underlying data ref IPCC is based on models which is based on more models. That is what I meant by underlying data. Models are not data but only assumptions. -
Camburn at 19:28 PM on 7 March 2011Interactive animation of the climate change impact on agriculture
Without knowing the underlying data used to make this little program, the results are pretty much worthless.Moderator Response: [Daniel Bailey] Do you have something constructive to offer besides the obligatory drive-by handwaving? As it stands, your comment contributes nothing to the dialogue on this thread. -
ms2et at 19:26 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
This is a most interesting topic and one which I think addresses a critical point about the climate system's response to certain forcings. It's very refreshing to see such an informative discussion which is purely objective and devoid of any personal attacks or sarcastic remarks, unlike some other sites. I'm a skeptic of AGW but always enjoy reading here because the debate is civil and friendly. This site's comments section is arguably the best for a balanced and thorough examination of the science. -
Bern at 17:42 PM on 7 March 2011The Climate Show Episode 8: Kevin Trenberth
I forgot to add - I'm not talking about plants to capture CO2 from fossil fuel burning - I'm talking about plants to capture CO2 from the atmosphere to reduce concentrations to a "safe" level. Perhaps enormous factory ships, sitting in the relatively calm & sunny equatorial waters? Capture the CO2, crack it in solar furnaces, compress to briquettes of carbon, and dump overboard to the deep ocean... How long would it stay there, though? Would, say, briquettes of graphite be gobbled up by some bottom-dwelling bacterium, and turned back into methane or CO2? And if it was, how long would it take that gas to make it back to the surface from the abyssal waters? -
Gilles at 17:38 PM on 7 March 2011A Real-World Example of Carbon Pricing Benefits Outweighing Costs
OK Marcus, so how is the electric car of your friends working ? Dana : "we must find a new energy source to replace carbon fuels. Period. So, why aren't we looking?" We are looking. There's solar (PV and concentrated thermal), wind (offshore and onshore), geothermal, tidal, etc. etc. gasp. Oil is no more used for electricity, at least in the countries that can afford these expensive means of productions. Oil is needed for transportation, heating, carbochemistry, and all this won't help much. "Californians use less per capita energy than most of the rest of the USA, " mainly because climate is hotter, maybe ? "The scientific evidence is what it is, and it clearly shows that carbon is a threat to humanity." The first scientific evidence is that ALL indicators or wealth and welfare are POSITIVELY correlated with the use of fossil fuels, and that without carbon, there is nothing but the poorest life you can imagine. Mucounter : "You seem to be arguing against doing anything because in your opinion, nothing will be an equitable fix. " You misunderstood me : I am arguing that we MUST do anything we can to spare FF, first because they are being exhausted (and even if CO2 had no IR absorption line), but that this will not reduce the overall amount we will extract in the future. -
Bern at 17:33 PM on 7 March 2011The Climate Show Episode 8: Kevin Trenberth
Chemware - yes, I'm well aware of the energy costs - I would expect the capturing & cracking to be powered by nuclear or solar means (I seem to recall watching a video of a concentrator dish that was used in experiments to crack CO2). I completely agree that the carbon capture & storage (CCS) is a fool's errand that will consume enormous resources (both in money and engineering resources) that would be better spent on developing alternative energy supplies. After all, a reduction of, say, 10% emissions now (due to CCS) might cost as much as developing alternate energy sources that can cut emissions by 90% in the near future. It seems that, given limited funds, we should take the longer-term view - especially as, after spending the money on CCS, we'd then need to spend it *again* on the alternate sources anyway... -
Gilles at 17:23 PM on 7 March 2011Icing the Medieval Warm Period
"The second graphic Tom Curtis shows here is the result of multiple model runs using various forcings. " Another strange thing : it is unusual to cover an experimental curve with a set of DIFFERENT models. Through the use of multiple wrong models, I can always cover everything in their interval. What does it prove ?Moderator Response: [Dikran Marsupial] It isn't at all unusual (in fact it ought to be standard operating procedure). The purpose is to show the uncertainty in the projection/hindcast based on our current understanding of climate physics. Climatologists are generally very happy to talk about model uncertainty; if they only showed the best model fit, they would be accused of cherry picking. BTW GEP Box said "all models are wrong, but some are useful"; you have asserted they are wrong, but have provided no evidence that they are not useful. -
Gilles at 17:21 PM on 7 March 2011Icing the Medieval Warm Period
Mucounter : Tom and myself were obviously talking about the first graph (the NZ trend), because he introduced the sentence just before showing it. Concerning the "conspicuous rise " in the high southern latitudes between 1930 and 1940, I don't see how to blame anthropic forcings for it : did anthropic forcings really rise more in this period ? KR : as you probably know, all these models have free parameters, especially for clouds, and the outputs are selected by some kind of "best fits". So it's not the same to do a "best fit" without anthropic forcings, and to do a best fit with anthropic forcings and THEN substract them. Now you may also know that if I had added new free parameters, I would always improve the fit. I could improve the fit with natural forcings only by adding the position of Jupiter, Saturn, and Pluto, and then argue that if I substract these influences, the fit is worse. That is mathematically perfectly correct - and yet physically absurd. This is not a correct way of reasoning.Moderator Response: [Dikran Marsupial] No subtraction is being done. The breadth of the error bars tends to be due to the variability in model runs, not the variability in parameters. GCMs are not statistical model fits, they are models of the physics, that allow you to find out the consequences of a set of assumptions regarding climate physics. The degree to which they can be tuned is fairly limited. If you (or anyone else) think the observed 20th century climate can be modelled without anthropogenic climate by adding a few parameters, go for it, the source code of the GISS model E is publically available as a starting point. If you had to include the positions of Jupiter etc. to do so, that would just indicate that anthropogenic forcings are important; there is good evidence that carbon dioxide is a greenhouse gas and affects climate; that is not the case for the position of Jupiter! -
Timothy Chase at 17:18 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
nofreewind wrote in 76:Are the graphs of global relative humidity here right? http://www.friendsofscience.org/assets/documents/The_Saturated_Greenhouse_Effect.htm
"The Saturated Greenhouse Effect?" The greenhouse effect wouldn't be saturated if CO2 were more than 50X its current concentrations. But for the crayola colors and line thicknesses and the exaggerated scales they appear to be similar to what you found at Climate4You. However, even if one takes at face value a drop in relative humidity that absolute humidity would appear to rise. Moreover, Chris Colose has pointed out that the reanalysis products this is based off of aren't of the highest quality. He states:Radiosondes provide water vapor information in the atmosphere since the 1940′s, but earlier products had a lot of biases, and since then changes in instrumentation have taken place which may lead to discontinuities in the data, and problems arose especially for upper atmospheric data. Is the atmosphere drying up? June 23, 2008 http://chriscolose.wordpress.com/2008/06/23/is-the-atmosphere-drying-up
Furthermore in the AR4 WG1 it shows that data is consistent with increasing humidity in the upper troposphere and that relative humidity has shown little change. Please see:In the absence of large changes in relative humidity, the observed warming of the troposphere (see Section 3.4.1) implies that the specific humidity in the upper troposphere should have increased. As the upper troposphere moistens, the emission level for T12 increases due to the increasing opacity of water vapour along the satellite line of sight. In contrast, the emission level for the MSU T2 remains constant because it depends primarily on the concentration of oxygen, which does not vary by any appreciable amount. Therefore, if the atmosphere moistens, the brightness temperature difference (T2 − T12) will increase over time due to the divergence of their emission levels (Soden et al., 2005). This radiative signature of upper-tropospheric moistening is evident in the positive trends of T2 − T12 for the period 1982 to 2004 (Figure 3.21). If the specific humidity in the upper troposphere had not increased over this period, the emission level for T12 would have remained unchanged and T2 − T12 would show little trend over this period (dashed line in Figure 3.21). 3.4.2.2 Upper-Tropospheric Water Vapour http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-4-2-2.html
The reanalysis is using the very same sondes that have proven problematic in the past with respect to the so-called "missing tropospheric hot spot." So it should come as no surprise that "The Friends of Science" bring up the hot spot only a little further down the page:However, the Hadley Centre's real-world plot of radiosonde temperature observations shown below does not show the projected CO2 induced global warming hot-spot at all. The predicted hot-spot is entirely absent from the observational record.
They would appear to be cherry-picking their unreliable datasets. In contrast others appear to be finding the "hot spot" with little problem. See for example:Insofar as the vertical distributions shown in Fig. 3 are very close to moist adiabatic, as for example predicted by GCMs (Fig. 6), this suggests a systematic bias in at least one MSU channel that has not been fully removed by either group. The discrepancy could in principle be explained by a surface temperature trend greater from that at 850 hPa, but this trend would have to be nearly 1.0 C decade −1 , which is far greater than indicated by surface records. Steven C. Sherwood et al. (2008) Robust tropospheric warming revealed by iteratively homogenized radiosonde data, Journal of Climate, vol. 21, issue 20, p. 5336
... and:We find that tropospheric temperature trends in the tropics are greater than the surface warming and increase with height. Our analysis indicates that the near-zero trend from Spencer and Christy's MSU channel-2 angular scanning retrieval for the tropical low-middle troposphere (T2LT) is inconsistent with tropical tropospheric warming derived from their MSU T2 and T4 data. Qiang Fu and Celeste M. Johanso (26 May 2005) Satellite-derived vertical dependence of tropical tropospheric temperature trends, Geophysical Research Letters, Vol. 32, L10703
... but then Friends of Science aren't exactly a science organization, are they? Please see:In an August 12, 2006, article The Globe and Mail revealed that the group had received significant funding via anonymous, indirect donations from the oil industry, including a major grant from the Science Education Fund, a donor-directed, flow-through charitable fund at the Calgary Foundation. The donations were funnelled through a University of Calgary trust account research set up and controlled by U of C Professor Barry Cooper. [2] [3] The revelations were based largely on the prior investigations of Desmogblog.com, which had reported on the background of FoS scientific advisors and Cooper's role in FoS funding. SourceWatch: Friends of Science http://www.sourcewatch.org/index.php?title=Friends_of_Science
Here are some other organizations you might not want to get your science reporting from:For those who are interested, here is a list in alphabetical order of 32 organizations involved in both the denial campaign surrounding tobacco and that surrounding Anthropogenic Global Warming. I also researched the organizations to see which would appear to be libertarian, including a source for each. Blowing Smoke: 32 Organizations
Anyway, to answer your original question, the graphs of trends in global averaged relative humidity at specific altitudes has little to say about whether or not the humidity of saturation increases roughly as an exponential function of temperature. But that didn't seem to be what you were really focused on so I turned to consider what you were concerned with. -
johnd at 16:37 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
KR at 10:48 AM, re "Evaporated water carries heat into the upper atmosphere, where condensation releases heat to the cooler air, warming it. The resulting precipitation has less energy, or it would remain vapor." Lets think about this. The evaporated water, now a gas, has become an integral part of the atmosphere, thus the heat it carries then becomes accounted for as part of the total carried by the air, does it not? When the water molecule condenses into a water droplet, ie. ceases to be a gas and hence part of the air, even if it gave up all of it's carried heat, then logically there should be no change to the air. Therefore, any heat energy carried with it will mean a loss of heat energy from, and thus a lower temperature of the air it has ceased to be a part of. Does that make sense? -
johnd at 16:17 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
Tom Curtis at 15:17 PM, whilst the IOD alone determines weather patterns across perhaps half of Australia from the north-west to the south-east during it's negative (wet) phase, during it's positive phase it's influence covers about 2/3 of Australia, hence the difficulty in correlating droughts in Australia with El-Nino alone. However, as we have seen recently, the widespread flooding has been due to a -ve IOD coinciding with a La-Nina pattern, the last such unique coincidence being 1975, that period likely the wettest time since first settlement, definitely since official records begin. -
Tom Curtis at 15:17 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
JohnD @55, as a Queenslander, I can tell you that ENSO absolutely dominates weather patterns in Queensland. They are also significant in NSW, Victoria, and across northern Australia. Weather patterns in WA and across the southern states are also affected by events in the Indian Ocean, with a seasonal component as to which is most dominant in the South. -
Tom Curtis at 15:14 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
RW1 @47:The bottom line, for me at least, is net positive feedback is an extraordinary claim that requires extraordinary proof, especially since solar energy is not amplified to anywhere near such an extent and since net negative feedback is far, far more logical for a system stable enough to support life as the Earth is.
Given that mean global surface temperatures have fluctuated over a 4 degree range (at least) in the recent past, and that over period in which life has existed on Earth has fluctuated over a 20 degree range (at least), the notion that the climate system is dominated by negative feedbacks has been refuted. Given that the 0.1 w/m^2 variation in total solar forcing has a detectable effect on climate (although difficult to detect), the idea that negative forcings dominate under current circumstances is also shown to be false. -
Chemware at 15:03 PM on 7 March 2011The Climate Show Episode 8: Kevin Trenberth
@Bern: the scale of the proposed carbon capture plants is indeed immense - each plant is about 30-50% of the size of the source coal (or gas) fired power plants. Then there is the volume of recovered CO2 to consider - think of burying one Lake Michigan every year ! Forget about capturing CO2 directly from the atmosphere: capturing CO2 from flue gas (10-15% by volume) is hard enough - capturing it from the atmosphere at 0.0390 % is completely uneconomic, taking more energy than you get from burning the fossil fuels in the first place. Entropy is against you. Also forget about converting pure CO2 back into C + O2. Also takes more energy than you get from burning it in the first place (again, Entropy, but slightly different). -
catfish at 15:01 PM on 7 March 2011Roy Spencer’s Great Blunder, Part 1
Probably the article should also mention something about the previous huge blunder that we have seen from Roy Spencer - the one in which for a long time he also claimed that his data is correct and the thermometers and other people's models are all a giant conspiracy - a story which was only debunked when external reviewers have inspected his data and found serial error in his data analysis - more details here! Re: More details here! Many remarks, but no real scientific critique. -
nofreewind at 14:32 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
Are the graphs of global relative humidity here right? http://www.friendsofscience.org/assets/documents/The_Saturated_Greenhouse_Effect.htmModerator Response: See "Humidity is falling." -
nofreewind at 14:22 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
Timothy Chase said: We know that for every degree Celsius you increase the temperature the humidity of saturation has to increase by 8%. We know that for every 10°C it roughly doubles. And we know that water vapor absorbs radiation, just like carbon dioxide, and are able to satellite image that, too. Water vapor doesn't condense to form clouds unless it exceeds the humidity of saturation -- and the humidity of saturation increases with temperature. By a factor of 2 for every 10°C. --------------------------- How does this correlate with the climate4you humidity graphs? http://www.climate4you.com/GreenhouseGasses.htm -
Philippe Chantreau at 14:11 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
"Does the angle of insolation and subsequent distribution not change significantly?" What do you mean by significantly? You use a lot of adverbs. If you were talking with Poptech, he would altogether dismiss you for being "subjective." Of course, that would be another sterile rethorical trick. "The Paleo data also shows previous interglacials, with lower CO2 levels, being warmer than the one were are in now. This is a strong indication that CO2 is not a significant driver of these cycles. If it were, temperatures would be even warmer than previous interglacials - not cooler." That argument would hold only if the current temp was equilibrium. It's not. In any case, that is a different argument than your original one in #61, which was that CO2 was not acting as a positive feedback. Once again, ill defined words such as "strong indication" or "significant driver" push your argument more toward the rethorical. I'm not sure what you mean by driver. If that would be initial cause, it is well accepted that the orbital changes are the driver and that CO2 is a feedback. Your argument in post 61 that the lag shows that CO2 is not a feedback is no more valid now than it was before. Perhaps it was just poorly formulated. Your assertion that CO2 levels and interglacials do not coincide is false, as shown in the graph in your post #67. -
RW1 at 13:33 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
I wrote in #58: "Plus the amount of incrementally reflected sunlight from clouds. According to Trenberth 2009, the total reflectivity of clouds is about 79 W/m^2, and the total reflectivity of the surface is about 23 W/m^2. Clouds reflect away over 3 times as much incoming solar energy as the surface for a loss of of about 56 W/m^2 for each additional m^2 of cloud cover." Actually, I don't think this is the right way to do this. Clouds cover about 2/3rds of the surface, so 341 W/m^2*0.67 = 228 W/m^2 average incident on the clouds. 79 W/m^2 divided by 228 W/m^2 = 0.34 average reflectivity of clouds. 1/3rd of the surface is cloudless, so 341 W/m^2*0.33 = 113 W/m^2 average incident on the cloudless surface. 23 W/m^2 divided by 113 W/m^2 = 0.20 average reflectivity of the cloudless surface. 0.34-0.20 = 0.14. 341 W/m^2*0.14 = 48 W/m^2 loss for each additional m^2 of cloud cover.Moderator Response: [muoncounter] Sounds like its time to go to an Albedo thread. From that thread, you can link back to originating comments here if necessary. -
scaddenp at 13:20 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
Well claiming that is "minor" amplification compared to albedo is pretty close, especially when in fact albedo and GHG component are of same order. Perhaps we should takes this "CO2 lags temperature" if wish to continue to argue that GHGs are unimportant for glacial/interglacial cycle. -
Timothy Chase at 13:18 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
Inline to comment 56 the moderator wrote:Moderator Response: [muoncounter] Missing link for 'absorption spectra'. [Daniel Bailey] Tim, I took a shot at what you meant to use for your absorption spectra link. If I was wrong, please let me know what the correct link is & I'll update it.
Actually that particular link was to a copy of the well-known graphic showing downwelling and upwelling radiation at Top Of Atmosphere as well as the absorption due to different greenhouse gases including nitrous oxide: http://climate-guardian.agilityhoster.com/avatar/index.php?inner_page=transmission Not a big deal, though. While I have made a number of my own graphics using web-based tools, mapping to spheres, etc. that particular graphic is from Global Warming Art. Unfortunately it seems to be having trouble today. Something involving the MySql database I believe. -
RW1 at 13:06 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
scaddenp (RE: 69), "How does a change in DLR due to change in GHG NOT have an effect on surface temperature? I make no claim that it doesn't, but we are getting off topic here. Moderators - any suggestion where this discussion should go? -
Bob Tisdale at 13:01 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
Timothy Chase at 09:34 AM on 6 March, 2011: Thanks for the link to Tamino's mistake. He used the wrong North Atlantic SST dataset [Kaplan] for his comparison to GISS LOTI. http://wattsupwiththat.com/2011/02/03/tisdale-tasks-tamino/ or at my blog if you'd prefer: http://bobtisdale.blogspot.com/2011/02/comments-on-taminos-amo-post_03.html And thanks for the link to DiLorenzo 2010, but I have read it.Moderator Response: [Daniel Bailey] If you feel Tamino used the wrong dataset why have you not corrected him? I note, having read the entire post Tim linked to for you, you were absent from the discussion therein. By definition, Kaplan is THE dataset to use for NA SST's. -
scaddenp at 12:51 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
RW1 - all sorts of wonderful explanations work if you dont worry about arithmetic. The problem with the milankovich theory from day one is that variation in solar and insolation alone are insufficient. You need the GHG feedback as well make it work. You also need a means to turn a NH effect into a global effect - which GHG feedbacks manage nicely. As to idea, that previous interglacial temperatures should depend only on CO2 - we ALREADY agree that milankovich forcing drive this and they are different for each interglacial. How about a model run with ALL the forcings and feedbacks included? To say nothing of also ignoring the physics. How does a change in DLR due to change in GHG NOT have an effect on surface temperature? This is an extraordinary claim that I want to see the evidence for from skeptics. -
Timothy Chase at 12:51 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
I had written in 56:We can't explain the warm interglacials and ice ages without the amplification due to carbon dioxide (which is released by the oceans when they warm like a warming soda losing its fizz but absorbed when the oceans cool), ice sheets (due to their melting and growth) and water vapor feedback.
RW1 responded in 61:Sure we can. The glacial and interglacial periods in between are driven by changes in the Earth's orbit around the Sun, which in turn changes the distribution of the incoming solar energy immensely. This is enough to overcome what appears to be a very strong net negative feedback operating on the system. CO2 lags or follows these cycles - it does not coincide or precede them.
CO2 lags warming by no more than 1000 years, likely as the deep ocean gives up carbon. And when I stated that carbon dioxide (under these circumstances) is a feedback that implied a lag of sorts. The warming from a glacial to interglacial takes several thousand years. Therefore the carbon dioxide actually coincides with much of the warming. Which is why the curves appear to be almost on top of one-another. Looking at just the warming due to solar insolation you can't explain the saw tooth structure of the temperature and CO2 trendlines. Things warm rapidly, with the warming period appearing to be perhaps 7000 or 8000 years. But the cooling takes perhaps 100,000 years. Orbital forcings can't explain why this asymmetric pattern appears time and time again. But the rapid decay and slow growth of ice sheets as well as the rapid degassing but slow absorption of carbon dioxide by the oceans and ultimately it minearlization can. For the sawtooth structure please see Figure 1 here: CO2 lags temperature - what does it mean? http://www.skepticalscience.com/co2-lags-temperature-intermediate.htm In the review article: C. Lorius (13 Sept 1990) The ice-core record: climate sensitivity and future greenhouse warming, Nature, Vol 347 ... Hansen and coauthors state:The orbital forcing is, however, relatively weak when considered on an annual globally averaged basis (the total insolation received by Earth has varied by 0.7 W m-2 over the past 160 kyr). The amplification of this forcing, the observed dominant 100-kyr cycle and the synchronized termination of the main glaciations and their similar amplitude in the Northern and Southern Hemispheres cannot easily be explained despite developments including the nonlinear response to ice sheets to orbital forcing.
Solar forcing is weak. You can't even explain the extent to which warming to place even when you include the nonlinear response of ice sheets. And you can't explain the synchronicity of the warming of both hemispheres. Both GCM studies and multivariate studies of paleoclimate data suggest that roughly 40% of the warming of the Antarctic from glacial to interglacial was due to the increase in CO2 from 200 to 300 ppmv. (See page 144.) Furthermore, while recognizing that orbital forcing was responsible for the Milankovitch cycles, they predicted that through the analysis of upcoming ice core samples it would be possible to identify the lag time between the initial warming and the rise in carbon dioxide. Please see:This objective is part of the GRIP (Greenland Ice Core Project) and GISP II (Greenland Ice Sheet Project) now being conducted in north central Greenland by Eurpopean and American scientists. These dirllings are expected to reach the bedrock (ice thickness is 3.2 km) in 1992 and to cover the last climate cycle and hopefully more. These cores will allow further documentation of the rapid climate changes discussed here. With a snow accumulation higher than at Vostok they should also allow a better determination of the relative timing (phase lag) of climate and greenhouse forcing. pg.145
But just as importantly there were times when carbon dioxide rose first. The ice cores from Greenland and Antarctica have taken us back the better part of a million years now. During this time temperature always seems to rise first. However, if you look back further in the case of supervolcanoes and their flood basalt eruptions carbon dioxide rose first, then temperature. Examples of where continental and submarine supervolcanoes gave rise to Large Igneous Provinces resulting in mass extinction include: 55 Mya, Paleocene-Eocene Thermal Maximum – North Atlantic Basalts 65 Mya, end-Cretaceous event resulting from a supervolcano that gave rise to the Deccan basalts in India as it collided with Asia at the time of the formation of the Himalayas 183 Mya, Toracian Turnover (a lesser warming and extinction event in the Early Jurassic period) – Karoo Basalts (Africa) 201 Mya, End Triassic Extinction – Central Atlantic Magmatic Province 251 Mya, Permian-Triassic Extinction that resulted from a supervolcano that left behind the Siberian basalts during the breakup of Pangaea. 360-375 Mya, Late Devonian Extinction – Viluy Traps (Eastern Siberia, more tentative according to Rampino below) For a more extensive list, please see: Vincent E. Courtillot and Paul R. Renne (2003) On the ages of flood basalt events, C. R. Geoscience 335, 113–140 For a recent commentary: Michael R. Rampino (April 13, 2010) Mass extinctions of life and catastrophic flood basalt volcanism, PNAS, vol. 107, no. 15, pp. 6555-6556 Here is recent study showing that the eruption of the Central Atlantic Magmatic Province occured simultaneously with the end Triassic Extinction 201 Mya: Jessica H. Whiteside (April 13, 2010) Compound-specific carbon isotopes from Earth's largest flood basalt eruptions directly linked to the end-Triassic mass extinction, PNAS, vol. 107, no. 15, pp 6721-6725 In recent times temperature generally rose first. But if you look further back, in some cases carbon dioxide rose first, then temperature. And those times that carbon dioxide rose first are strongly associated with sudden changes in climate and the resulting major and minor extinction events. -
RW1 at 12:17 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
Philippe (RE: 65), "I don't see how your short paragraph argues against the CO2 feedback in interglacials. The adverb "immensely" used in reference to the change in insolation distribution is more rethorical than accurate." How do you figure? Does the angle of insolation and subsequent distribution not change significantly? "Nonetheless, the fact that CO2 changes follow the initial deglaciation induced by orbital changes does nothing to indicate CO2 does not or can not act as a positive feedback. Furthermore, the radiative properties of CO2 are such that it is physically impossible for the gas to not act as a positive feedback at some level." Yes, the physics do suggest at least some positive feedback effect is likely, but I think the data strongly suggest it's negligible and the main forces driving the changes are the orbit combined with the ebb and flow of surface ice, especially since temperatures at the end of the interglacials continue to fall significantly even as CO2 remains relatively high. "Paleo data show CO2 levels coinciding with interglacials and following the initial degalciation. It also shows temp increasing to a level that insolation changes alone would not explain. If you want to argue against that, make an argument that is at least logical. The fact that CO2 changes follow the deglaciation by itself is not enough to prevent it from acting as a feedback. The Paleo data also shows previous interglacials, with lower CO2 levels, being warmer than the one were are in now. This is a strong indication that CO2 is not a significant driver of these cycles. If it were, temperatures would be even warmer than previous interglacials - not cooler.
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Charlie A at 12:09 PM on 7 March 2011Blaming the Pacific Decadal Oscillation
#47 RW1 says "The bottom line, for me at least, is net positive feedback is an extraordinary claim that requires extraordinary proof,... " Net positive feedback in climate science is not the same as net positive feedback in most other fields. The terminology in climate science are a bit messed up in that a "net positive" feedback per standard climate science convention would still be a net NEGATIVE feedback as long as the positive feedback is less than the increased blackbody radiation from the increased temperature of the earth. Or to put it another way, the increased blackbody radiation from a warming earth is not included in the feedback sums to determine whether there is postive or negative feedback. -
Bern at 11:54 AM on 7 March 2011The Climate Show Episode 8: Kevin Trenberth
zinfan94 - I understand the majority of that CO2 absorption is going into the oceans. As warming continues, that particular sink will decline, and possibly reverse, so we may not be able to rely on natural processes to remove excess CO2 from the atmosphere. Although the required scale of industrial plants capable of sequestering billions of tons of CO2 each year is pretty concerning... are there industrial processes capable of cracking that CO2 back into C + O2? It'd be a lot easier to sequester solid briquettes of C (plenty of open cut mines to backfill, or even dump them on the seabed) rather than liquid or gaseous CO2... -
Bern at 11:50 AM on 7 March 2011The Climate Show Episode 8: Kevin Trenberth
I've really gotta set aside the time to watch these... Although 70 spare minutes is hard to come by with a 5-month-old in the house!Response: I'm learning to find little pockets of time to listen to the long TCS episodes - while exercising, driving, doing household chores, the mowing, etc. There's just so much info packed in an hour or so, it's worth the trouble to find a way to shoehorn it into the schedule. -
KR at 11:49 AM on 7 March 2011Icing the Medieval Warm Period
Gilles - The second graphic Tom Curtis shows here is the result of multiple model runs using various forcings. As per the caption, the blue bar represents the 2-sigma variation range around model runs that do not include anthropogenic forcings (but do include insolation, volcanic aerosols, orbital effects, etc.), the red bar represents the variation range around models run with our forcings, and the black line is the actual temperature record. These are models shown to have considerable agreement with historic temperatures (including some pre-industrials) using recorded forcings. The point made in this graphic is that we have some idea of how forcings drive temperatures, and that we cannot account for current temperature rise without the anthropogenic contribution as part of the physics. -
zinfan94 at 11:49 AM on 7 March 2011The Climate Show Episode 8: Kevin Trenberth
Gareth messed up the information on carbon balance when discussing the carbon that will be released from melting permafrost. We don't have to "suck carbon out of the atmosphere" to reduce carbon dioxide concentrations in the atmosphere. The various carbon sinks, the oceans, soils, and vegetation, are currently taking over half of the carbon from fossil fuels and deforestation... If we reduce fossil fuel emissions 60-80%, then carbon dioxide concentrations in the atmosphere will begin to drop. We do NOT have to begin removing carbon dioxide directly from the atmosphere using a human installed process to get declines in CO2 concentrations. We do not have to get to below zero fossil fuel carbon emissions, as he stated later in this Climate Show.Moderator Response: [Daniel Bailey] Tom Wigley covered that very topic over at Brave New Climate, here. Note that in Tom's study, global zero CO2 emissions are not achieved until 2050, but then held there indefinitely once achieved. Also, AR4 assumptions are used for Ice Sheet melt (and thus are obsolete). And finally note that, even holding global emissions to zero, it will then take over 100 years for concentration levels to drop below 350 (considered the "safe" maximum limit). -
Philippe Chantreau at 11:45 AM on 7 March 2011Blaming the Pacific Decadal Oscillation
RW1 @ 61. I don't see how your short paragraph argues against the CO2 feedback in interglacials. The adverb "immensely" used in reference to the change in insolation distribution is more rethorical than accurate. Nonetheless, the fact that CO2 changes follow the initial deglaciation induced by orbital changes does nothing to indicate CO2 does not or can not act as a positive feedback. Furthermore, the radiative properties of CO2 are such that it is physically impossible for the gas to not act as a positive feedback at some level. Paleo data show CO2 levels coinciding with interglacials and following the initial degalciation. It also shows temp increasing to a level that insolation changes alone would not explain. If you want to argue against that, make an argument that is at least logical. The fact that CO2 changes follow the deglaciation by itself is not enough to prevent it from acting as a feedback. -
KR at 11:38 AM on 7 March 2011Blaming the Pacific Decadal Oscillation
RW1 - My point was that precipitation is not, repeat, not a pathway of energy back to the surface. That energy of evaporation is left in the atmosphere, representing part of the energy transfer to the atmosphere (convection, latent heat, and IR, in increasing order). Latent heat loss certainly cools the surface. Some of that energy returns to the surface as backradiation (not precipitation), some is radiated out to space. -
adelady at 11:27 AM on 7 March 2011Icing the Medieval Warm Period
Gilles "I see a shift in the 1950's, and your glaciers has experienced already most of their melting at this date. Aren't you distorting mere facts ? " No. I see this little factoid as a possible signal of other things. That initial leaning into a downward slope on the glacier mass balance trend indicates 2 possibilities. Firstly, solar irradiance was higher for much of that period and that might just have been a blip in a long term trend if other things had not changed. Secondly, and more importantly from my point of view, I have a lurking suspicion that much of the warming-that-didn't-show-up-until-the-70s went into a couple of dark corners that seemed insignificant at the time. Night-time minimum temperatures. Ice melt. And that ice melt would have predominated in land terminating glaciers rather than those supported by sheets of sea ice buffered by the oceans. Even where the edges of those ice sheets were retreating, however erratically, they didn't lose enough to damage the glaciers at their landward edge. It certainly wasn't large enough or fast enough to sound the kind of alarm bells we're now seeing for Arctic sea ice. But I think there's almost enough data around for there to be a century long trend when we look at the right indicators. -
muoncounter at 11:17 AM on 7 March 2011Icing the Medieval Warm Period
G: "I don't see anything like that in your curve." We are discussing the bottom graph here. Is there not a conspicuous rise from 1930-mid 40s? Is the northern hemisphere 1970s low present in this graph? Please avoid accusations of factual distortion -- that is a violation of the Comments Policy. -
RW1 at 11:08 AM on 7 March 2011Blaming the Pacific Decadal Oscillation
KR, "But the point remains - precipitation has less energy than water vapor, and the precipitation cycle is a major pathway of energy into the atmosphere. Not back to the surface. And calculating global precipitation (and the energy moved in that fashion) is how Trenberth obtains the 78 W/m^2 latent heat figure in his energy balance diagrams." Yes, but precipitation is also still a considerably large pathway of energy back to the surface, and any latent heat energy removed from the surface that isn't returned to the surface in equal amount will have a cooling effect on the surface, reducing surface emitted radiation; thus equally offsetting any latent heat energy radiated into the atmosphere that ultimately escapes out to space. -
Gilles at 10:58 AM on 7 March 2011Icing the Medieval Warm Period
" New Zealand temperatures, after being flat for the first part of the 20th century started to rise in the 1930's" Really, I don't see anything like that in your curve. Why do you say that temperatures started to rise in 1930 ? I see a shift in the 1950's, and your glaciers has experienced already most of their melting at this date. Aren't you distorting mere facts ? -
Gilles at 10:53 AM on 7 March 2011Icing the Medieval Warm Period
" 1) The temperature does not fall outside the confidence interval of combined anthropogenic and natural forcings over the same period;" First you should recognize that it is not the "temperatures" but the "anomalies" with respect to the first half of the XXth century - this by no means surprising that ANY anomaly computed with respect to the same period are comparable, irrespective of the model - the opposite would be surprising ! so the agreement in the first part is of low significance. " 2) The combined anthropogenic and natural forcings predict a higher temperatures than natural forcings alone (thus shown the anthropogenic forcings to be significant); and" actually the graphics has always been unclear for me, but may be you can explain me : is the blue curve a "best fit" obtainable without anthropic component ? or is it a "best fit" WITH anthropic component, after substraction of the anthropic component? that's quite different. If you optimize the model with an anthropic component, and AFTER substract anything , you are sure that the result is worsened. But that doesn't prove that another equally good fit could be obtained with other hypothesis. " 3) The temperature tends to lie near the center of the anthropogenic and natural forcings, but on the extreme limit of the confidence interval of natural forcings alone." see above. How "natural forcings alone" have been adjusted ? " Once you accept these 6 facts, you will find you no longer need to distort science to accommodate your world view." I will not accept these 6 facts before having a clear answer to the previous questions .... -
KR at 10:48 AM on 7 March 2011Blaming the Pacific Decadal Oscillation
johnd - Evaporated water carries heat into the upper atmosphere, where condensation releases heat to the cooler air, warming it. The resulting precipitation has less energy, or it would remain vapor. Energy thus transferred to the atmosphere is then radiated or convected away. This heat of condensation powers thunderstorms and hurricanes - heating the atmosphere, causing updrafts that drag moist air up to where it condenses, releasing more heat, and so on... The energy can then get radiated out to space (partially), or radiated back to the surface (again, partially). But the point remains - precipitation has less energy than water vapor, and the precipitation cycle is a major pathway of energy into the atmosphere. Not back to the surface. And calculating global precipitation (and the energy moved in that fashion) is how Trenberth obtains the 78 W/m^2 latent heat figure in his energy balance diagrams. --- I would suggest taking clouds to one of the cloud feedback threads. -
RW1 at 10:39 AM on 7 March 2011Blaming the Pacific Decadal Oscillation
Timothy Chase (RE: 56), "We can't explain the warm interglacials and ice ages without the amplification due to carbon dioxide (which is released by the oceans when they warm like a warming soda losing its fizz but absorbed when the oceans cool), ice sheets (due to their melting and growth) and water vapor feedback." Sure we can. The glacial and interglacial periods in between are driven by changes in the Earth's orbit around the Sun, which in turn changes the distribution of the incoming solar energy immensely. This is enough to overcome what appears to be a very strong net negative feedback operating on the system. CO2 lags or follows these cycles - it does not coincide or precede them. -
Timothy Chase at 10:37 AM on 7 March 2011Blaming the Pacific Decadal Oscillation
RW1 quotes RickG then writes in 51:"As for clouds, those with small water droplets (lighter clouds) tend to reflect light while those with larger water droplets (darker clouds) tend to absorb more light. Am I wrong?" I'm not sure.
It's pretty obvious in the visible part of the spectrum. Rain clouds -- where the drops are coalescing to form larger drops that are eventually heavy enough to fall -- are darker than the light fluffy clouds. Dark clouds tend to produce especially downpours. However, clouds per se are close to being perfect black bodies in the infrared spectrum. This doesn't matter much if the clouds are close to the surface since they will be roughly the same temperature as the ground and emit radiation at roughly the same rate that they absorb it. But in accordance with Kirchoff's law high altitude clouds absorb radiation independently of their temperature but emit radiation proportional to their temperature taken to the fourth power. So increasing high altitude clouds will tend to warm the climate system as they reduce the rate at which energy escapes to space. As they warm they reduce the rate at which heat escapes from successively lower layers as they decrease the temperature differential until those lower layers warm like the layers above them. Given an enhanced greenhouse effect, whether it is due to higher levels of greenhouse gases or high altitude clouds, an equilibrium will eventually be reached. At some point the rate at which radiation leaves the climate system will equal the rate at which radiation enters the climate system. However the altitude that radiation escapes from will be higher. The greenhouse gases and clouds involved will have to warm in order to radiate energy to space the same rate as the greenhouse gases and clouds at the lower altitudes did before. After the equilibrium has been reestablished the lapse rate -- rate at which temperature falls with increasing altitude -- will be roughly the same. And given the warming of the higher altitudes this will imply a warmer surface. -
RW1 at 10:23 AM on 7 March 2011Blaming the Pacific Decadal Oscillation
Timothy Chase (RE: 56), ""... especially since solar energy is not amplified to anywhere near such an extent." It is amplified to roughly the same extent." How do you figure? 239 W/m^2 of post albedo solar energy becomes 390 W/m^2 at the surface (390/239 = 1.6), where as 3.7 W/m^2 from 2xCO2 becomes 16.6 W/m^2 at the surface (16.6/3.7 = 4.5). If this much amplification is within the systems boundaries, why doesn't it take about 1075 W/m^2 at the surface to offset the 239 W/m^2 coming in from the Sun (1075/239 = 4.5)??? -
RW1 at 10:14 AM on 7 March 2011Blaming the Pacific Decadal Oscillation
johnd (RE: 54), "The only way to determine the bottom line of the process would be to measure the amount of heat being liberated from the surface by evaporation against the amount of heat that is returned to the surface by rain." Plus the amount of incrementally reflected sunlight from clouds. According to Trenberth 2009, the total reflectivity of clouds is about 79 W/m^2, and the total reflectivity of the surface is about 23 W/m^2. Clouds reflect away over 3 times as much incoming solar energy as the surface for a loss of of about 56 W/m^2 for each additional m^2 of cloud cover. However, the clear sky has an average transmittance of 40 W/m^2 and the cloudy sky has an average transmittance of 30 W/m^2 - making the amount of incremental surface power trapped per each additional m^2 of cloud cover 10 W/m^2. Thus, according to Trenberth's numbers at least, each additional m^2 of cloud cover results in a net loss of about 46 W/m^2, which is quite a bit. -
johnd at 10:12 AM on 7 March 2011Blaming the Pacific Decadal Oscillation
Timothy Chase at 09:57 AM, regarding your comment "El Nino temperatures go up due to the energy that is released into the atmosphere. Then temperatures go down." The energy released into the atmosphere then goes where? Having come from the oceans in the first place it is unlikely to all have gone back there again otherwise conditions would be such that a repeat El-Nino would occur. With energy being released from the oceans by an El-Nino, would more CO2 be sunk as a result? -
Timothy Chase at 09:57 AM on 7 March 2011Blaming the Pacific Decadal Oscillation
RW1 wrote in 47:All I'm saying is if natural oscillations (variations) can cause up to 0.5 C of temperature change in one year, why couldn't natural forces cause most of the 0.6 C of warming over the whole of 20th century?
I believe the subject of this post is the climate oscillation known as the Pacific Decadal Oscillation. Climate oscillations like the Pacific Decadal Oscillation store energy, release it, get recharged then release it again. El Nino is a classic example of this. Just after an El Nino temperatures go up due to the energy that is released into the atmosphere. Then temperatures go down. Climate oscillations are responsible for much of the year to year natural variability in temperature. Another source is solar insolation. But we know that but for the solar cycle output has been flat to falling since at least 1962 thanks to satellite measurements. Climate oscillations can't create energy. They can only store it then release it. The sun hasn't been producing additional energy. Where is the energy for your natural variability being the "cause most of the 0.6 C of warming over the whole of 20th century" supposed to come from? We know that CO2 absorbs thermal radiation. We are able to easily demonstrate this in a lab. See the "CO2 Experiment" video at the top of this page.) We have known this since the mid 1800s. We are able to measure the absorption spectra of carbon dioxide and other greenhouse gases. We know that in terms of its greenhouse effect carbon dioxide acts primariyly in the region of the spectra centered around 15 μm (15 microns), a wavenumber of 667 cm-1 that is due to the quantized bending mode of the molecule -- which acts in accordance with the principles of quantum mechanics to result in the absorption of radiation in this part of the spectra. We know that absorption keeps going up as you raise the levels of carbon dioxide. Using satellites we are able to image atmospheric carbon dioxide. We are able to see the plumes rising up from the heavily populated East and West coasts of the United States. We can image the carbon dioxide because it reduces the rate at which infrared radiation escapes to space. If energy is escaping the climate system at a reduced rate but entering the climate system at the sate rate as before we know that the amount of energy in the system has to increase. We know that the temperatures have to increase. We know that for every degree Celsius you increase the temperature the humidity of saturation has to increase by 8%. We know that for every 10°C it roughly doubles. And we know that water vapor absorbs radiation, just like carbon dioxide, and are able to satellite image that, too. Water vapor doesn't condense to form clouds unless it exceeds the humidity of saturation -- and the humidity of saturation increases with temperature. By a factor of 2 for every 10°C. RW1 wrote in 47:The bottom line, for me at least, is net positive feedback is an extraordinary claim that requires extraordinary proof, especially since solar energy is not amplified to anywhere near such an extent and since net negative feedback is far, far more logical for a system stable enough to support life as the Earth is.
"... especially since solar energy is not amplified to anywhere near such an extent." It is amplified to roughly the same extent. We can't explain the warm interglacials and ice ages without the amplification due to carbon dioxide (which is released by the oceans when they warm like a warming soda losing its fizz but absorbed when the oceans cool), ice sheets (due to their melting and growth) and water vapor feedback. "... net negative feedback is far, far more logical for a system stable enough to support life as the Earth is." Have you ever heard of the Permian/Triassic Extinction? Nearly all life as we know it was wiped out when a flood basalt supervolcano erupted, sending vast quantities of carbon dioxide into the atmosphere. We won't likely reach that level but something resembling the Paleocene-Eocence Extinction may be within our reach.Moderator Response: [muoncounter] Missing link for 'absorption spectra'. [Daniel Bailey] Tim, I took a shot at what you meant to use for your absorption spectra link. If I was wrong, please let me know what the correct link is & I'll update it.
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