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Comments 26 to 50 out of 120:

26. KR at 10:24 AM on 15 November, 2010
    Norman, you do not appear to have looked at the definition of a chaotic system. A chaotic system shows extreme sensitivity to initial conditions. Weather does exhibit this behavior (the "butterfly effect"), but climate, as defined by long term averages, does not. A small variation in cloud cover doesn't affect global temperatures 20 years out by +/- 5 degrees. The albedo changes of parking lots in Europe don't determine whether we're heading into meltdown or an ice age. The climate simply doesn't have divergent behavior based upon small condition changes - rather, it has a straightforward (albeit non-linear) predictable response to changes in conditions. As Tom Dayton stated, until you understand the definition of a "chaotic system" your statements will not be relevant to this topic.
27. Norman at 11:39 AM on 15 November, 2010
    #23 scaddenp Your questions: "Lets suppose that climate IS chaotic. Now what is the time scale for predictions to fail for imprecisely known systems? For weather, its about 4 days. For the solar system?? Successful model predictions would suggest that it is not chaotic on scales so far worked on. Do you seriously think that your questions about albedo etc. are not built into the climate models? Could be time to study them" The last question is not part of this current point. I do not know what exactly are in climate models but the point of discussion is not about models, it is about the potential for climate to be chaotic (as defined in the mathematical view). I am not sure, by the definition of chaos on the links above, that chaos is a time dependent phenomena. Because of the size and momentum of the Earth's system the chaotic changes are slow and won't show up in 30 year study but do seem to show up when the time frame is extended. All of you have looked at these graphs. If you plot a chaotic system point would not it look similar? Forget the time scale and look at the system itself as a whole. Look at the many fluctuations in Global temps in 400,000 years. 5 million years of Global Temp with many unpatterned fluctations but not random which is a sign of chaos.
28. Norman at 12:00 PM on 15 November, 2010
    #26 KR "A chaotic system shows extreme sensitivity to initial conditions. Weather does exhibit this behavior (the "butterfly effect"), but climate, as defined by long term averages, does not" Are you sure about this statement? You can look at the links I posted for scaddenp and explain why the high degree (10 C temp cycle)and relative numerous Global temp cycles are taking place. The graph is jagged with little uniform behavior. Check out this on rapid climate change in the Sahara. Things totally changed in that area the last 100,000 years. Sahara desert climate change. Quote from the above article: "The climate of the Sahara has undergone enormous variation between wet and dry over the last few hundred thousand years." And your proof for this statement is? "A small variation in cloud cover doesn't affect global temperatures 20 years out by +/- 5 degrees. The albedo changes of parking lots in Europe don't determine whether we're heading into meltdown or an ice age. The climate simply doesn't have divergent behavior based upon small condition changes - rather, it has a straightforward (albeit non-linear) predictable response to changes in conditions." You seem stuck on rate of the change to dispel what the longer term clearly demonstrates. A volcano may indeed cause a drastic change in climate but just not on the short time scale of 20 or even 100 years. It may take thousands of years for the intitial effects to demonstrate the chaotic nature of the climate system with all its complex feedbacks.
29. Norman at 13:05 PM on 15 November, 2010
    #24 muoncounter I am still looking for a way to demonstrate my point... You state: "The earth's average albedo is given here as 0.30 or 30%. We do not go 'from one extreme to the other'. Here is a prior SkS article on the question of albedo. Look at the graph (figures 2 and 3) of measured albedo anomalies in that article; a big anomaly is on the order of 1%. That limits the plausible range of your slider bar considerably. We do not live in a world that is all desert one day, all ice the next, all forest the day after that." You, like the others, seem to think a chaotic system must happen really fast or the system is not chaotic. Why do you think this? I thought a chaotic system was a particular characteristic and I was not aware it was time dependent. I am looking for changes in Earth's Albedo. Primarily during known ice ages. The articles I looked at only stated the Earth's Albedo went up during ice ages but they never seem to give an estimated amount. On Science of Doom I found a blogger who gave a number...not sure where he got it from but it may show that albedo is far from constant or stable in the longer time scale of Earth time (not our time). Science of Doom page with post I refer to, name is Bill Illis. Bill's post: "Earth’s Albedo has varied throughout the last 650 million years between 25% to 50% (29.83% today) depending on the continental arrangements and the amount of ice that builds up and spreads out from the poles. That is a big range and the values are capable of explaining the majority of the temperature changes over the period." Thats the best I could do for now. Put 0.25 in the calculator and 0.50 for albedo and see how this variation effects Global Temp.
    Response: Norman, it sounds like you still have not read the Intermediate version of this post. You should read it carefully, because it describes chaos and explains why climate is not chaotic. If you are not really trying to assert that climate is chaotic, but only that climate cannot be predicted, then you should read the different post Models are unreliable--both the Basic and Intermediate versions--and you should comment on that post rather than this one that is devoted to the technically defined "chaos."
30. scaddenp at 14:02 PM on 15 November, 2010
    Norman, "I am looking for changes in Earth's Albedo. Primarily during known ice ages." You can save yourself a lot of time trying to find things about climate science but just going to the ipcc WG1 report. (Why dont you just read it). Radiative forcing estimated at -3.2W/m2 for effects of ice and lowered sealevel. Vegetation change estimated at -1W/m2. GHG changes are estimated to contribute -2.8W/m2 for comparison purposes. See the report for references (many) on which these numbers are based. However, this has nothing to do with chaos. Albedo is straightforward and well-behaved. Also, remember your calculator is for airless earth. "It may take thousands of years for the intitial effects to demonstrate the chaotic nature of the climate system with all its complex feedbacks. " What is lacking is any evidence for your assertion. On the contrary, climate seems to behave instead as function of net forcings. If you are waiting for some effect in from say pinatoba to influence climate, then you are in for a very long wait.
31. scaddenp at 14:10 PM on 15 November, 2010
    Also, just noticed your earlier point. "It looks like the output of a chaotic system". If you look at the instruments for just about any component of a power plant then they "look" chaotic too. You cant tell chaos by just looking at the graph. One feature of chaos is quasiperiod cycles, but milankovitch cycles are not quasiperiodic as analysis would show you. You would get a better feel for cause by plotting global temperature against estimated net forcing through time. Please, please try reading and understanding the science rather than reading to try and find an excuse to reject the conclusions.
32. Norman at 06:52 AM on 18 November, 2010
    Moderator I am still working on the possibility that Climate is indeed chaotic and the reasons I feel it may be so I think I am still on the correct thread. I have read your intermediate version of chaos and see you do not include albedo as a means to induce a chaotic climate. Here you state "If the sources and sinks of CO2 were chaotic and could quickly release and sequester large fractions of gas perhaps the climate could be chaotic." Forget about CO2, what about albedo? A change of 1% in the albedo is equal to the effect of CO2 doubling. The reason I still suggest climate may easily be chaotic is because the major climate variables (temperature and precipitation) will have an effect on albeo and albedo in turn can easily change these two variables so it makes for a very unstable situation.
33. Norman at 06:59 AM on 18 November, 2010
    #30 scaddenp Your statement "However, this has nothing to do with chaos. Albedo is straightforward and well-behaved." Does not seem valid in the material I have looked into. Wonder why you believe this statement to be true. I have another calcualtor for you. It is on a site you probably do not like but the calcultor is still valid. It includes the atmosphere and the Greenhouse effect in the calculator. Small albedo changes can cause large climate changes. This seems to fit the concept of sensitivity into the climate system. Very sensitive to small changes and the changes to climate can then effect the albedo, very nonlinear effect. Global Temp calculator that includes atmophere for scaddenp.
34. muoncounter at 01:59 AM on 19 November, 2010
    #33: "Small albedo changes can cause large climate changes." So can small GHG changes, as this calculator clearly demonstrates. And this calculator demonstrates that temperature response to albedo is nearly linear -- systems described by linear function are hardly chaotic. Do you have any idea what it would take to change the planet's average albedo by a few percent for a significant period of time? Even the Pinatubo eruption produced only a short term climate effect. While the global cooling after Pinatubo was not surprising, the observed winter warming over Northern Hemisphere continents in the two winters following the eruption is now understood as a dynamic response to volcanically produced temperature gradients in the lower stratosphere from aerosol heating and ozone depletion, and to reduced tropospheric storminess. To obtain the kind of albedo change you keep postulating, how many Pinatubos would you need? On the other hand, we have measured the increase in GHGs. The junksci calculator you reference shows how effective that is as a control know on global temperature, as do articles here. What part of this isn't clear?
35. DSL at 02:36 AM on 19 November, 2010
    Interestingly, Norman points us to a website--junkscience.com--that was created by tobacco money to promote industry-friendly "science." At the same time, Frederick Seitz is under fire in another thread for his role in promoting the idea that tobacco use is healthy.
36. Norman at 04:33 AM on 19 November, 2010
    #35 DSL I am not promoting the webpage. But the calculator is probably sound. It matches well with the one I linked to. I have that one for scaddenp because it includes atmopshere as well as GHG effects.
37. Tom Dayton at 05:31 AM on 19 November, 2010
    Norman, see RealClimate's Chaos Theory and Global Warming, and Butterflies, Tornadoes, and Climate Modelling.
38. Norman at 09:07 AM on 19 November, 2010
    #34 muoncounter I agree with your statement: "So can small GHG changes, as this calculator clearly demonstrates. And this calculator demonstrates that temperature response to albedo is nearly linear -- systems described by linear function are hardly chaotic." Temperature response to albedo is linear as is temperature response to GHG levels. Look at it the other way, that is where I see the nonlinear and chaotic response. How does temperature effect albedo? This is a harder question to answer. Cooler Northern climate generate the snowfall that is highly reflective and will drastically increase the local albedo in the local area. Globally it may decrease the albedo by 1%. However the bigger albedo effect would be with the clouds. If the climate cools in the Northern regions (higher albedo from increased snow) like during an ice age but the oceans are still fairly warm (from the previous warm cycle) you may get an increase of cloud formation all around (still plenty of water vapor from the warm oceans but now a lot colder air to lift the moisture up to form clouds as a cold front moves through). This increased cloud cover acts to cool the Earth more and the decline in temp becomes steep and drops several degrees in a relative short time frame. As the Earth's overall temperature goes down the oceans begin to cool. Due to the heat capacity of water, the time lag is long. Once the ocean's are cool enough, less water evaporates and cloud formation really becomes significantly less and the albedo drops to much lower levels allowing much more solar radiation in to be absorbed by oceans gradually warming them and ending the ice age. When the oceans get warm enough the cloud formation reaches levels we see today and the albedo averages out to around 0.3. I am not saying this is what happens or takes place, I am using the above scenerio to point out how temperatures could have a nonlinear and drastic effect on albedo, which then will feedback and greatly effect the temperature.
39. Norman at 09:10 AM on 19 November, 2010
    #37 Tom Dayton I did look at the Real Climate explanation of chaos. They do not talk about how temperature can effect albedo. If the only effect on temperature where GHG then the point would be valid. Small changes in albedo (the sensitivity response to determine if a system is chaotic) also have a large effect on temperature. As far as I have read the effect of increasing temperature on albedo is not worked out. There will be more water vapor in the air...will this form more clouds and increase albedo a few % points driving temps down?
40. Norman at 11:51 AM on 19 November, 2010
    muoncounter, Here is some reading to back up some of my thoughts. Clouds effect on Albedo. Selected quote from the above article link: "Clouds, therefore, are responsible for about 55% of the sunlight that is reflected into space without adding heat to the climate system. Clouds alone roughly double Earth's albedo, from 0.15 (no clouds) to 0.31 (including clouds). In short, clouds are the predominant means by which incoming sunlight is reflected back out into space." Put those albedo changes in the calculator and see what a difference it makes. Another quote that supports my current view that Climate is chaotic: "However, water vapor and clouds play numerous roles in the climate system, and the net affect of increased evaporation rates caused by global warming are difficult to predict" Another article that also talks about the albedo effect. MIT article about Cloud effects. Quote from this article stating how much clouds change Temperature. "Recent observational studies show that these effects almost balance, but that the cooling effect is somewhat more important. From the point of view of global change, however, it is crucial to note that this small difference is about five times larger than the radiative effect anticipated from a doubling of atmospheric carbon dioxide (CO2), and that the individual components of the difference are orders of magnitude larger. In existing climate models about one third of the predicted warming due to increasing CO2 arises because of the predicted cloud changes. These predictions, however, are highly speculative because none of the models include interactive cloud physics" Another quote suggesting the difficult nature in predicting future climate: "Clearly, without a proper treatment of both layer clouds and convection, model predictions of climate are uncertain. Cloud effects are so much larger than the anticipated effects of added greenhouse gases, that small changes in the cloud picture can easily alter predictions of global warming. In addition, existing methods of representing convection and clouds are crude, and, in some cases, can be shown even to be qualitatively incorrect"
41. muoncounter at 13:50 PM on 19 November, 2010
    #38, #40: Norman, It sounds like you are trying to run a climate model without benefit of any computing. That's not particularly helpful, as complicated systems don't simplify so easily. Best left to the pros; we can then read their results and form our own picture with the benefit of educated input. What you describe sounds to me a bit like what happens every year, as we move from summer to winter. That alone is neither a net warming nor cooling. Here's one inconsistency in your scheme: "If the climate cools in the Northern regions (higher albedo from increased snow) like during an ice age but the oceans are still fairly warm (from the previous warm cycle) you may get an increase of cloud formation ... This increased cloud cover acts to cool the Earth more ..." Here's what Holland and Bitz 2003 found: ... clouds reduce the strength of the ice-albedo feedback by shielding the planetary albedo from the surface. Furthermore most models predict Arctic cloud cover increases with warming, which increases the planetary albedo Further, drawing comparisons to glacial stages is too tricky to do on the back of an envelope. Burt et al showed that the increased albedo due to glacial ice is moderated by the accompanying lowered sea level: Although the positive ice-albedo feedback acts to amplify the climate change ... , due to the melting of sea ice and ice sheets in the Northern Hemisphere, the ice-albedo feedback is actually negative over large regions of the high-latitude Northern Hemisphere, due to changes in the size of the Arctic Ocean basin. Both of those mechanisms do not enhance change, they moderate change: Cloud cover moderates the increased albedo of surface ice; warming air causes clouds which cool. These act to reduce the 'chaotic' nature that you seem to want to find. There are no sharp changes in temperature in this system. What is needed to explain sharply increasing or decreasing temps? Some other agent: We know its not the sun, as TSI is down while temperature is going up. We have a known warming agent in increasing atmospheric GHGs. Insisting that "Clouds alone roughly double Earth's albedo, from 0.15 (no clouds) to 0.31" is possible and should be put into the calculator makes no sense. We do not go from no clouds to heavy clouds. Look at satellite photos; there are always some clouds. Finally "the net affect of increased evaporation rates caused by global warming are difficult to predict" doesn't mean its chaotic. Repetition doesn't make it so.
42. KR at 14:12 PM on 19 November, 2010
    Norman - Have you read the intermediate version of this topic? Non-linear does not imply chaotic, although all chaotic systems are non-linear. Weather is highly dependent on initial conditions (you can't predict next July 17th's temperature). Climate, on the other hand, as described in the RealClimate links posted earlier, is a boundary condition issue - when does outgoing energy match incoming energy? Feedback, not incidentally, is a geometric relationship (Forcing / (1 - Feedback Gain)), which is linear. There are certainly non-linear transition points, such as vanishing ice in the Arctic, but it's still not a chaotic system. You've repeated your albedo feedback question, but have not established that there is chaos in long term climate. Unless you do, you have failed to raise an objection.
    Response: Norman, you should give up your assertion that climate is chaotic, and instead comment on a different thread to focus on what seems to be your real assertion that Climate Models are Unreliable.
43. Norman at 23:11 PM on 19 November, 2010
    Moderator, Before I leave the topic I will post a link that has evidence of the chaotic nature of climate. Dust patterns in ice cores suggest sudden and dramic changes in Global atmopheric circulation patterns. Article suggest climate is chatotic.
44. Norman at 23:14 PM on 19 November, 2010
    #41 muoncounter "Insisting that "Clouds alone roughly double Earth's albedo, from 0.15 (no clouds) to 0.31" is possible and should be put into the calculator makes no sense. We do not go from no clouds to heavy clouds. Look at satellite photos; there are always some clouds" But what is the percentage? Unfortunately we do not have satellite photos of the Earth during an ice age and cannot empirically determine the percentage of cloud cover during one of these periods.
45. muoncounter at 05:44 AM on 20 November, 2010
    #43: "evidence of the chaotic nature of climate." OK, I'll see your evidence and raise you this bit: Even though climate is chaotic, with weather states impossible to predict in detail more than a few days ahead, there is a predictable impact of anthropogenic forcing on the probability of occurrence of the naturally-occurring climatic regimes. ... it is a false dichotomy to suppose that some recently-occurring drought or flood is either on the one hand caused by global warming, or on the other hand is merely due to natural climate variability. Rather, the correct way to address such an issue is to ask instead whether anthropogenic climate change will increase or decrease the probability of occurrence of the type of drought or flood -- emphasis added All that is similar to the comments here: Weather in a given region occurs in such a complex and unstable environment, driven by such a multitude of factors, that no single weather event can be pinned solely on climate change. In that sense, it's correct to say that the Moscow heat wave was not caused by climate change. However, if one frames the question slightly differently: "Would an event like the Moscow heat wave have occurred if carbon dioxide levels had remained at pre-industrial levels," the answer, Hansen asserts, is clear: "Almost certainly not." So even if we accept your premise that climate has chaotic behavior, that does not mean it is unpredictable. End of story.
46. Ned at 04:13 AM on 5 January, 2011
    In another thread, fdijkstra writes: Scientists should not make any predictions about the climate. No cool predictions, no warm predictions, because the climate is unpredictable. It is a chaotic system with many unknown and ununderstood factors. That is silly, as a moment's reflection would have told you. Would you seriously object to any of the following predictions? (1) On average, in 2011, the Arctic and the Antarctic will be cooler than the tropics. (2) On average, in 2011, regions lying in the Intertropical Convergence Zone will have higher precipitation than regions lying at the poleward edge of the Hadley Cell. (3) On average, in 2011, the northern hemisphere will be warmer in July than in December, while the southern hemisphere will show the opposite seasonality. Those are all very specific, quantifiable predictions about the climate (well, #2 would require some complicated definitions to quantify...). I suspect that virtually everyone who understands the basics of the Earth's climate would agree that all three of those predictions are reasonable. OK, how about these predictions: (4) In the absence of any other countervailing forcings, an instantaneous 25% decrease in solar irradiance, sustained for a century, would cause the Earth's mean surface temperature to decrease and the extent of sea ice to increase. (5) A volcanic eruption or large asteroid impact that injected a large quantity of aerosols into the stratosphere would also cause the Earth's mean surface temperature to decrease. Those are slightly more complicated predictions, but still things that pretty much everyone would agree with. Again, they are based on conceptual or numerical models of the climate system. From here, one could move to more detailed and more complex predictions. Naturally, we will be less confident in our predictions as they get more specific in terms of time, place, and phenomena. That's OK, everyone understands that. The claim that somehow the climate is just too complicated to predict is just plain wrong. We can make simple predictions with a very high degree of confidence, and more specific predictions with correspondingly greater uncertainty.
47. muoncounter at 04:25 AM on 5 January, 2011
    "It is a chaotic system with many unknown and ununderstood factors" It was the consensus (bad word) of this thread that weather is chaotic, while climate is not. In each of Ned's examples, there will be times and locations where the weather varies due to local conditions and is therefore difficult to predict. However, the overall pattern and trend is well-determined from the conditions in each case. See the wiki article on chaos theory for other examples and an explanation of the specific meaning of 'chaotic' in the scientific sense. In short, complicated does not equal chaotic.
48. neil at 12:16 PM on 7 May, 2011
    @scaddenp I don't doubt the utility of climate models. However here, and elsewhere you have said that the mathematical systems representing weather (in GCMs) formally display chaos, but that climate models are not chaotic. Since the mathematical system of equations in weather and climate models are practically identical, I don't see any reason why chaotic behaviour should be formally excluded from the latter. The only difference is the length of the integration. Perhaps you can explain what you mean. As a practical example, in the UVic Earth Systems Climate Model we can show sensitive dependence to initial conditions for the MOC strength in long equilibrium simulations (i.e. multiple equilibria in an intermediate complexity climate model in 3000 year long integrations). The MITgcm, set up as a fully coupled AO-GCM with simple geography, has also demonstrated multiple equilbria ( see MITgcm website). There is also a Journal of Climate paper submitted on this. So, it seems to me that chaotic behaviour certainly is permitted by these mathematical systems (climate models). Whether this holds in the real climate system is another question. To me this does not imply that climate models are useless - rather that they warn us that abrupt climate change is a possibility (even if the chances are low).
49. KR at 12:41 PM on 7 May, 2011
    neil - The difference between a chaotic initial value system (weather) and a boundary limited system (climate) is the difference between trajectory details and trajectory averages. Weather is highly susceptible to initial conditions, and predicting weather and it's details (rain or not, where will the pressure systems go?) requires detailed information and a lot of computing power to predict even a few days out. This is a very hard problem, as even a small error or approximation of initial conditions will inevitably cause the prediction to deviate from reality a few days out. Climate, however, is a boundary condition system. We don't know what days in March 2012 it will rain, but we can predict even this far out what the average temperature is likely to be with high certainty. When a particular bit of weather departs from the averages, it will (statistically) return to the average, and spend some time on the other side as well. So why is climate a boundary limited system? It depends on total energies. If energy leaving the climate exceeds energy coming in, we'll get colder, and less heat will leave - back to the average as determined by the insolation and thermal radiation. If we have a hot season, the climate will radiate above the average, and we'll cool down. The weather will vary around those averages in a difficult to predict way, but it will vary around the averages determined by energy conservation! And those averages are what climate predictions are about. Boundary conditions drive any deviations back to the averages for that system. So while we cannot state whether it will be sunny on your birthday - we can still note that winters will be colder than summers, and that reducing the amount of energy leaving the climate at any temperature (with GHG's) will make the average temperatures higher. --- In terms of modeling - regardless of the initial conditions of a global climate model (GCM), it will move fairly quickly to the averages determined by energy flows and conservation. The further you have run a GCM, the less sensitive to initial conditions. This is the reverse of weather predictions, as your prediction of detailed weather, while still within a few standard deviations of the averages, may be anywhere around that average once you've run your prediction for a while.
50. KR at 12:46 PM on 7 May, 2011
    neil - In terms of multiple equilibria, when those have not been observed in nature, I would suspect that either there are some issues with the model, or that if accurate the climate may be moving to a transitional state, such as severe changes in the thermohaline circulation. I don't know the particular models you mentioned - I cannot opine as to which this might be. Although you seem to be stating that these are fairly simple models... If multiple models show several equilibria, given different modeling criteria, complexity, and assumptions, I would watch that particular aspect of climate rather carefully for change.

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