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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 113201 to 113250:

  1. More evidence than you can shake a hockey stick at
    James, that's excellent. The powerpoint slides will come in handy, too, thanks.
  2. Confidence in climate forecasts
    JohnD inadvertently presents an argument indicating the reasonably good utility of models we use. Outputs cluster reasonably well around a pattern of similar conclusions. The notion that variance among exact features of various model outputs is a mark of wholesale failure is actually diagnostic of misunderstanding on JohnD's part. Hypothesizing a myriad of other models does not serve as a functional argument indicating we should ignore the congruence among the models we actually do use. "Absolutely right" of course is not the metric used to determine if models are useful. Thus I think JohnD's endorsement of models is accidentally on the mark. Clouds are a bit of a wildcard but progress is in fact being made in that department and meanwhile folks with more expertise than JohnD (or myself) don't seem paralyzed by the fear that they're going to overturn current thinking. Helps to remember, the folks doing the science are way more circumspect than us in the peanut gallery.
  3. More evidence than you can shake a hockey stick at
    Line 4 should read "...on the evidence..."
  4. Three new studies illustrate significant risks and complications with geoengineering climate
    batsvensson - there's also the factor of first presentation. When Creutzen proposed using sulphates as a replication of volcanoes' emissions with their proven cooling effects, there were only bizarre space-mirrors, etc, and ocean fertilization under discussion, so his seemed like a great idea and, (with the aid of coal-burners who foresaw a cost saving) it gained a lot of traction. In reality, regardless of popular assumptions, sulphates are not the automatic choice as distinctly preferable options have since come into view. Yet this is not to criticize Creutzen, who knows full well the potential catastrophe of the runaway feedbacks - against which even serious global sulphate pollution would be relatively small beer. Regards, Lewis
  5. Confidence in climate forecasts
    Whilst the IPCC confines itself to tracking 20 something climate models there are countless other climate models from which they could have chosen. All of the modelers have access to the same range of data available as inputs, as well as, hopefully, the same knowledge of "known" physics as well as "unknown" physics, the big one of course being clouds, feedback in particular. Given that the output of most models differ to varying degrees, there are obviously variations in the assumptions being made by the modelers as to the combination of inputs and the relative importance, or weighting, each of the parameters are given in the equations that the model constitutes. The fact that each model differs somewhat is indicative that there is still a large degree of uncertainty and a wide range of opinions as to how all the known physics relates to the real world, and what all the collected data really means. Perhaps one of the models does accurately track the past and the present, and accurately project into the future, but which one? Only one can be absolutely right, but by being right it then invalidates many of the assumptions made in all of the other models. The only other alternative is that none are right. Given that the physics of cloud feedback is still an extremely large unknown, it is just as likely that a model that incorporates negative feedback into the equations has as much chance of being right as those which model positive feedback, given it is not known physics, but opinion only that is the determining factor in the face of such unknown physics.
  6. Greenland's ice mass loss has spread to the northwest
    In the Northwest of Greenland, just another data point: An ice island four times the size of Manhattan broke off from one of Greenland's two main glaciers, scientists said on Friday, in the biggest such event in the Arctic in nearly 50 years. The new ice island, which broke off on Thursday, will enter a remote place called the Nares Straight, about 620 miles (1,000 km) south of the North Pole between Greenland and Canada. The ice island has an area of 100 square miles (260 square km) and a thickness up to half the height of the Empire State Building, said Andreas Muenchow, professor of ocean science and engineering at the University of Delaware. Muenchow said he had expected an ice chunk to break off from the Petermann Glacier, one of the two largest remaining ones in Greenland, because it had been growing in size for seven or eight years. But he did not expect it to be so large. "The freshwater stored in this ice island could keep the Delaware or Hudson Rivers flowing for more than two years," said Muenchow, whose research in the area is supported by the National Science Foundation. "It could also keep all U.S. public tap water flowing for 120 days." He said it was hard to judge whether the event occurred due to global warming because records on the sea water around the glacier have only been kept since 2003. The flow of sea water below the glaciers is one of the main causes of ice calvings off Greenland. More. U. Delaware release here, includes imagery.
  7. Three new studies illustrate significant risks and complications with geoengineering climate
    Because they're desperate, batsvensson. The exact nature of their desperation varies from case to case. One person might want to continue a lifestyle, another an income stream, yet another may be concerned about other problems and failing to think it all the way through. Or a mixture of all three.
  8. Waste heat vs greenhouse warming
    I will do more research before posting further. A contrite acknowledgment from VoltairesDistantCousin that ought to be exemplary, could well stand some emulation. Has the level of rational debate degenerated so much that we are having skirmishes over basic facts such as this? Actually it's much worse than you may think. Read through ~200 comments and you'll get the picture.
  9. Three new studies illustrate significant risks and complications with geoengineering climate
    Why would anyone sane like to suggest to pump something we been working very hard to get rid off for very well known reasons into the atmosphere?
  10. Has Global Warming Stopped?
    The analysis of Fdykstra doesn't seem proper to me. Of course, if one adds extra variables, the R2 increases - by definition. R2 should only be interpreted if several models have the same number of variables - without any multicollinearity and heteroscedasticity. Representing a number of observations with any line is no science. The error he mades is that R2 should only be used if one has a theory (explanatory mechanism whatsoever) to be tested - whereas in this case the analysis is aiming at observation - is it getting warmer or not. R2 is then unnessecary - significance level is the only relevant thing and as remarked before, the 5 or 10% significance level is a convention. It are the outer parts of the normal distribution for the number of times somethings is happening. And, as Phil pointed out, the time span is too short to fall within the outer borders of any significance level. I guess that some denialist with good statistical knowlegde has given this question to the reporter. Because everyone knows that the period is short in proportion to the increase of temperature. But Phil gave the possible answer and he stayed within the right area. Right he was, regarding the guns that were targeting him. He couldn't permit any mistakes.
  11. Remember, we’re only human
    daisym @43, "The U.S. government seems hell bent on passing Cap and Trade but, without a full-time alternative energy source, how would it force manufacturers to stop using carbon fuels?" If that is a true statement, then why was the Power Bill dropped in the US Senate, without a vote, and without a squeak from the White House? In the 1980s and 1990, "Cap and trade" was touted as the "free market" solution to pollution and global warming. Now it is derided as "cap and tax" and is ideologically off-limits for any aspiring Republican politician, and many Democrats. I thought Jim Hansen has a good proposal in his book Storms of My Grandchildren. This was for a carbon tax to be paid at the point of extraction or import of carbon fuel. The tax would be paid as a dividend to taxpayers, which they could spend as they please (on carbon fuel, for example, if they so wished, but then they gain nothing). An alternative would use the money collected to offset payroll taxes, thereby creating jobs. This version has been adopted in British Columbia, and is working well. Carbon Tax Cap and trade just has too many complexities. Cap and Trade
  12. VoltairesDistantCousin at 07:13 AM on 7 August 2010
    Waste heat vs greenhouse warming
    Ned, BP: My apologies. Temperature does increase in the stratosphere due, I think to ozone's absorption of UV radiation. I was too quick with my correction. I will do more research before posting further.
  13. Talkin bout the Skeptical Science phone apps
    Buying by scanning? That's nothing; I've been buying by impulse for years now!
  14. Talkin bout the Skeptical Science phone apps
    Nokia phones? What about other Symbian phones? They are not all Nokia phones, you know. And as for buying by scanning, that is on both Android and iPhone now. Has been for a while, too.
  15. Remember, we’re only human
    BP:
    No, we are not just any remarkable species, one of millions, but spiritual and immortal souls, an absolutely unique kind, created in the image of God, given freedom and responsibility. We must remember that.
    BP's belief, shared by billions, is at The Historical Roots of Our Ecological Crisis. I'm now convinced it's also at the root of his relentless denial of AGW.
  16. More evidence than you can shake a hockey stick at
    Thanks for this posting, John. The sources of the slides, the script, and a PowerPoint set for the video can be found at my website. As John anticipated, several commenters on ClimateProgress and YouTube noted that I did not spend much time, or any time, or the evidence that humans have caused global warming. But I did cover that in the slide that starts at 1:27 of the video with the chart of carbon emissions, CO2 concentrations, and global temperatures from the Arctic Climate Impact Assessment. I also discuss the significance of that chart on my website.
  17. Grappling With Change: London and the River Thames
    Michael you might also look at the item linked from here which integrates the 2007 IPCC stuff.
  18. michael sweet at 06:25 AM on 7 August 2010
    Grappling With Change: London and the River Thames
    Doug, I posted a little fast before. The report was from 2006 and estimated a 25 cm rise in sea level by 2100. Still too low in my book. They suggest defending all developed areas. They do not estimate protection costs. Will it be economic to defend? For how long? It will be interesting to see what is done when the next IPCC report comes out much higher than the last one. I hope that action is taken before the rise is so fast we have no choice but to move.
  19. Communicating climate science in plain English
    I think this is a great idea. It will allow people to get the intuition before they get into the nitty-gritty. In my experience as someone who loves learning about science, having that intuition explained in simple terms before diving into the real deal can really help steepen your learning curve, because when thrown in at the deep end, some people might struggle to understand the issue and give up in frustration, or at the very least, take a lot longer to figure out what is being said. It's something I frequently wish more textbook authors would do.
  20. Grappling With Change: London and the River Thames
    Michael the functional difference between the British approach to informed policy and ours in the U.S. is visible. We like things to be a little more like Mogadishu, the British less so. It costs money to be less like Mogadishu and lack of funds for doing things that can't produce a profit on a private balance sheet shows up in details such as knowing whether your air tube should be 10cm or 1m. In my humble opinion, heh!
  21. michael sweet at 05:54 AM on 7 August 2010
    Grappling With Change: London and the River Thames
    Galloping Camel, One problem in Florida, compared to Holland, is Holland only has to defend one side from the sea. In Florida we have the sea on two sides. In addition hurricanes, which occur frequently, have high storm surges which overtop levies. We all know what happens once levies are overtopped. It is a question of how long before we have to start moving everyone out of Miami- it cannot be defended from 2 meters of sea level rise. Hopefully sea level rise will be at the lower end of estimates, although those estimates keep rising. Tampa is higher.
  22. michael sweet at 05:31 AM on 7 August 2010
    Grappling With Change: London and the River Thames
    Doug, Thanks for the references. The Nature Consorvatory piece was interesting, although I expect that in the US people will say don't listen to the greenies. It is hard to see how they can keep the road above water after 40 or 50 cm sea level rise. The Tampa planning document uses a 1995 (!!) EPA publication that says there is a 50% chance of 10 cm rise in sea level by 2100 (the Antarctic is not expected to contribute to sea level rise until after 2100). Since current sea level rise is measured at 2.2 mm/yr here that seems a bit conservative to me. It is good to see that city planners are keeping up with the science. --> They have not even obtained the latest EPA documents.
  23. Confidence in climate forecasts
    Pete Ridley @58 -"Until that has happened climate models have no more validity that the fortune teller’s crystal ball." So crystal balls predicted planetary features such as stratospheric cooling, the polar ice asymmetry and oceanic stratification too?.
  24. It's the sun
    GnDoty - read Do volcanoes emit more CO2 than humans for some info on relative CO2 rates. Volcanoes emit at a time averaged ~1% of current human rates - they aren't similar. As to solar influence - that's really pretty well understood. It's been decreasing since the 1970's, but over geologic/cosmic time it's been brightening, as per its life cycle. Stellar evolution is considered to be very well understood - we've got, after all, billions of examples to look at. There's a nice image of the solar life-cycle on Wikipedia.
  25. It's the sun
    GnDoty, if a tree falls in the forest and nobody is there, nobody can be crushed by the tree. We've no experience with having 7+ billion people on the Earth during (for instance) the Deccan flood basalt events, which in any case took far longer to mutate the climate than what we're doing. I'm a firm believer that we're not going to go extinct any more than are cockroaches, but by ignoring what we're doing we're going to end up living a little bit more like cockroaches. Why would we want to do that? Folks raising their hands "aye" to enjoying our present living standard should pay heed. Just ask President Medvedev of Russia. He's got a fresh perspective on "adaptation."
  26. Waste heat vs greenhouse warming
    That said, I'm not sure why BP refers to emissions at 15 μm. Adding CO2 to the atmosphere causes relatively little additional reduction in OLR at 15 μm, and thus relatively little change in the height at which emission occurs. Most of the change from increased CO2 is at 13-14 and 16-17 μm, and overall it's going to lower the effective radiating temperature rather than raise it.
  27. Peter Hogarth at 05:16 AM on 7 August 2010
    Confidence in climate forecasts
    Pete Ridley at 02:23 AM on 7 August, 2010 Try to keep it short Pete. (I'll also try to follow my own advice). I think data and objectivity is fundamental to the debate rather than semantics and hyperbolics. "Because of those unfounded assumptions made as a result of the significant uncertainties in the underlying sciences upon which the models are based, any attempts at predicting global climates are little better than fortune telling through gazing into crystal balls" Please be explicit and specific, with science based references rather than opinions (or those of others).
  28. Remember, we’re only human
    The cap and trade mechanism is a way of setting a cost on C02 thus bringing it into our accounting system so we no longer consider C02 pollution to be a "free" resource. As long as we ignore the accumulating cost of C02 while relying on the market to choose fuels we're not going to reduce emissions or provide sufficiently strong incentives to find alternatives to the biggest elephant in the room which is coal. Burgeoning exports of coal from Australia are an indicator of this very simple economic fact, one that even most economists themselves can agree on. Australian Coal Industry - Coal Exports Details Predicting the efficacy of cap and trade seems complicated, does not seem very amenable to simple scientific predictions because it collides with economics and politics(understatement!). I found these writeups pretty informative. They're both policy focused but have scads of references. CBO's An Evaluation of Cap-and-Trade Programs for Reducing U.S. Carbon Emissions (long in the tooth but the basics of this approach are old) A meaningful U.S. cap-and-trade system to address climate change
  29. It's the sun
    I'd be interested in data on current CO2 output caused by fossil fuels versus the CO2 output of an active volcanic period. Both rapidly increase CO2 levels. Would everyone agree that if the output was similar, the earth and life would simply adapt as it has before? This is assuming we as a species will advance technologically to the point of becoming far less dependent on fossil fuels. In my opinion, we can't come to any realistic conclusion when too many variables such as solar influence are not fully understood. This leads a person with an open mind like me to wonder why such drastic measures are being proposed when the situation is still not factually conclusive.
    Response: Here is a comparison of CO2 levels and volcanic activity. The 3 largest volcanic eruptions over the past 50 years had an almost negligible effect on CO2 levels:


  30. Hockey stick is broken
    Eric - please read the last two paragraphs of this posting for an answer to that question.
  31. Waste heat vs greenhouse warming
    VoltairesDistantCousin: BP was right and your "correction" of him is wrong. Temperature decreases with altitude in the troposphere, increases in the stratosphere, decreases in the mesosphere, and increases again in the thermosphere:
  32. Waste heat vs greenhouse warming
    I'm afraid, RSVP, that you are not following the analogy I presented. I DID state that the water pressure drove the outflow rate, with "if the water level rises, it drains faster, if it drops, it drains slower...For fun we can set the output rate to scale with the 4th power of water level". Your analogy of two buckets makes no sense - as has been covered before (repeatedly, by several people), there is only one bucket, one set of energy. It really doesn't matter if the AHF energy comes in fast, slow, through convection, radiation, conduction - the AHF rate is 0.028w/m^2, and it ends up depositing that energy into the mass of the Earth/water/atmosphere at 0.028w/m^2, or 0.028 joules/sec/m^2. That's a rate of energy input to the total Earth/water/air energy. Adding AHF to sunlight, in the analogy I gave, means adding to the water inflow. If 100 gallons per minute are pouring in from the sun, and you add 1 gpm of AHF, well then the water level/pressure (and by analogy temperature) will rise a bit until the output increases to match. If you reduce the outflow rate at the current water level to 90 gpm, water level and pressure will rise until the outflow is again 100 (or 101 with AGH) gpm. Again - there is only one system receiving energy; the sum of Earth+water+atmosphere. There is only one output for that energy, radiation to space. And changes in either the rate of input or output will change the radiative equilibrium temperature of the system. If you cannot understand that, and continue to insist that AHF somehow acts differently than solar energy (does it somehow produce a different flavor of joules - chocolate, perhaps?), then you have a conceptual issue I cannot help you with.
  33. Confidence in climate forecasts
    I'm curious to know what Argus is really arguing about. W/reference to model predictions versus observations, Argus said: [dubious proof omitted] these climate 'forecasts' over-predict global temperatures when compared with observed temperatures. I am guessing there is a purpose behind this. What purpose do you believe that to be, Argus? I ask because this has a lot of bearing on the topic of this post. Quite a large body of research tells us that a given person's confidence in and ability to integrate new information is often dictated not by the quality of that information but instead how it comports with their beliefs about things not directly related but which instead may be affected by actions indicated by the new information. In this case you're harboring some misunderstandings about models that happen to allow you to dismiss them as having no utility in helping us to decide whether to change our actions. Your remark about "purpose behind this" sounds superficially like an irrational buttressing of your misconceptions about models. That's why I'm wondering about the specifics of the "purpose" you see in errors of models.
  34. Remember, we’re only human
    Do scientists believe that carbon derivatives trading will make significant reductions in carbon fuel usage? The U.S. government seems hell bent on passing Cap and Trade but, without a full-time alternative energy source, how would it force manufacturers to stop using carbon fuels? Should industrialized counties jointly conduct R&D to find a full-time energy source that would replace carbon fuels?
  35. More evidence than you can shake a hockey stick at
    Moscow's been like that for weeks, too. Conditions at 22:00 Moscow time: 81 °F Smoke. Interesting analysis of the Russia phenomenon here by Wunderground's Rob Carver. Jeff Masters has an update here.
  36. More evidence than you can shake a hockey stick at
    Of course, weather events should be treated as data points and not proof, but here are some spooky data-points! -- http://www.tutiempo.net/en/Weather/Moscow_Domodedov/UUDD.htm Projected daytime highs for Moscow, RU: 6-8-2010: 40C (104F) 7-8-2010: 40C (104F) 8-8-2010: 38C (100F) 9-8-2020: 39C (102F) That's Moscow, not Cairo -- Moscow, not New Delhi. MOSCOW, not Riyadh!
  37. Grappling With Change: London and the River Thames
    Dorlomin, I think you hit the nail on the head quite nicely. A non-tidal example. At the bottom of my yard there is a creek that has been heavily channelized over the decades. Along this creek we've had some flooding events recently having to do with unusually intense rainfall. The channeled river has very little capacity to handful large excursions in flow and meanwhile the channelization itself was done so that development could cover what used to be the floodplain. When the channel capacity is exceeded the result is nearly instantaneous arrival of water in homes, practically no advance warning in the face of rapid swings due to paving having reduced permeability so much. There's no way to wish the water away so another solution is needed. The upshot is that a number of local structures have been condemned, the flood plain where those buildings stood is being connected to the creek again along a portion of the banks. This will somewhat improve the probability of the remaining homes along the channel remaining dry. A statistical improvement. Oddly enough my particular problem is with groundwater, not the creek itself.
  38. citizenschallenge at 04:07 AM on 7 August 2010
    Communicating climate science in plain English
    Excellent, Excellent!!! I love the evolution of this site. Even if I don't own anything besides an ancient cell phone and my trusty MacBook. I totally support you making information available at three levels. Keep on truck'in :-)
  39. Peter Hogarth at 04:03 AM on 7 August 2010
    The Past and Future of the Greenland Ice Sheet
    Arkadiusz Semczyszak at 23:03 PM on 3 August, 2010 (With apologies to moderators for the length of comment). The papers you cite are all interesting and recent papers but none of them appear to be directly concerned with the recent warming of Greenland, though some are very relevant to the paleo record. They do not support your conclusion. The related papers of Swingedouw 2010 and Servonnat 2010 use a state of the art model to examine the effects of TSI, CO2, and orbital changes on temperature and NAO over the past thousand years, and they support the prevailing view from IPCC AR4. They also explicitly provide support for the conclusion from Kaufmann 2009 (which Chris mentions) that the Northern Hemisphere has experienced a slow cooling over the past millennium (- until the recent century when this trend has abruptly reversed). From Swingedouw 2010 when discussing pre-industrial asymmetric NH/SH response to warming: “This type of response is comparable to a certain extent with the temperature response to greenhouse gases increase during the last 50 years (Trenberth et al. 2007), with a large warming at the northern high latitudes, while the Southern Ocean experiences a very small warming and even a slight increase in sea ice cover” From Servonnat 2010: “Using a linear statistical decomposition we evaluated that TSI and CO2 have similar contributions to secular temperature variability between 1425 and 1850 AD” & “The amplitude of the temperature secular variability is in agreement with both temperature reconstructions and IPCC AR4 simulations taking into account the impact of the volcanoes”. I have to emphasise that the authors are looking at preindustrial forcings and confirm and add detail to current prevailing thoughts on pre-industrial forcings and effects Capron 2010 is concerned with rapid temperature changes in the last glacial period using the Greenland and Antarctic ice core records, and in brief examines precursor events (a topic I believe I possibly pointed you to recently) which include CO2 changes, possible AMOC changes (as in Barker 2010) as well as probable insolation effects on ice sheet volume. The present scenario is one where CO2 is rising more quickly than in any of the pre industrial ice core records, AMOC is relatively stable, and orbitally driven NH insolation is gently decreasing. These papers do not provide evidence for rapid Greenland melting at this stage in the current interglacial through any mechanism except rising CO2. The estimated long term orbital changes in NH insolation dwarf the insolation changes over recent centuries. The Vecchio 2010 paper is about an influence of nutation (an 18.6 year wiggle in the tilt angle as the earth precesses) on the phase of the global seasonal variations in temperature, the reported results suggesting a shift of 1.74 days towards earlier seasons over 110 years. What relevance this has I am not sure.
  40. VoltairesDistantCousin at 03:44 AM on 7 August 2010
    Waste heat vs greenhouse warming

    In comment #189, it was asserted that

    "...With current CO2 levels at 15 μm it is about 22 km above the surface. At that altitude the higher you go the higher temperature gets. Therefore putting more carbon dioxide into the system increases the effective radiation temperature at that frequency."

    Specifically, the poster asserts that the temperature increases with altitude at 22km. This is incorrect. At 22 km, we would still be in the stratosphere, a layer of the atmosphere in which temperature decreases with altitude. It is only when we reach the thermosphere, above about 95 km that we see temperatures rising with altitude. However, in the thermosphere, the air is so sparse as to be nearly transparent to exiting infrared photons.

    Has the level of rational debate degenerated so much that we are having skirmishes over basic facts such as this?

  41. Waste heat vs greenhouse warming
    KR 188 "Water doesn't leave as fast as it's entering." You yourself acknowledge that energy radiates as T to the fourth. So if the surface warms, it should radiate harder. In the analogy, the leaves slow drainage and this would be a problem if the inflow of water remained the same, but as surface radiation increases with T^4, the analogy seems to break down. Even in the analogy, you could have said that outflow increasing due to increased water pressure, but you didnt. I can also make up analogies... imagine two 50 gallon barrels that are filled with 25 gallons of brackish water every morning for one month. At the bottom of each barrel there are two distinct filters. The first has coursely ground activated charcoal, and the second a much finer grid of activated charcoal. Both are allowed to drain during the day. Everyday, by six in the evening, the first one is empty, whereas the second one takes until midnight. Examining the filters, we see that the distribution of dirt in the first is spread thoughtout the filter, whereas in the second most of the dirt remains in the upper layers of the filter. In this analogy, you can see how the density of the filter (GHG concentration) slows the flow, but that the total energy is release in both cases (no accumulation of energy due to filters). The notable difference is the guck profile in the filters (temperature profile in the atmosphere). So I am allowing for warmer temperatures in the lower atmosphere due to GHGs but I am saying that it must be made up for a cooler upper atmosphere given that the net heat flux is constant. Of course higher temperatures at the surface can mess up the biosphere, and melt ice etc., but in terms of energy storage, it is not clear to what extent this is happening, but even you have said that radiation goes as T^4, so a warmer surface would induce more radiation. We dont want to forget about waste heat... During the night, it rains during the last two weeks of the experiment, but no one realizes it. It is noticed that the barrels take longer to drain. In fact during the last week of the month, they are finding water still draining in the wee hours of the morning. Those conducting the experiment are certain that it is due to the accumulated muck.
  42. Confidence in climate forecasts
    chris at 21:42 PM on 6 August, 2010: So you really believe that a climate model is just a "working replica of the earth" - only it is made from "mathematical equations" instead of "rock and water and other materials"? Just like the "model stream-trains ... are miniature working replicas of real steam-engines"? I am not that easily convinced! I certainly have no personal experience whatsoever of making computer models of the climate, but I have the equivalent of a master's degree in (what in my country is called) technical physics, and I have worked for 25 years as a computer programmer. So I know a bit about how make a program work - you put in what you know, or think you know, for a starter, then test it, compare it to the real world, make some changes, test, change again, etc. Of course the model is based on "known physics" somewhere. I did mention that in my comment. But there must also be a lot of empirical parameters and variables put into it, in order to make its output agree with climate history. And when you achieve that, you are resonably satisfied. In the post How reliable are climate models? a big deal is made out of the fact that the models "successfully reproduce the past". Of course they do. That is what they were made to do. But predicting the future is another matter. To make a really accurate climate model of the earth and its biosphere, in its setting in the solar system, is not like making a model of a microwave oven or a power station. It is immensely harder than that. I imagine it would be almost as hard as making a model of how the human race will evolve during the next million years. We have the physical and chemical laws, we know about natural selection etc, we know our DNA, we can make our model fit the changes of the past million years, but then what?
  43. It's the sun
    GnDoty - you can't ignore volcanic sources of CO2 over the (very) long haul. Temperatures are related to both CO2 and solar input, as described on CO2 was higher in the past. The difficulty now is that we're adding CO2 at an extremely high rate by geologic standards, and the geological weathering feedback and other CO2 sinks are too slow to keep up. We're entering a new domain, as described on On temperature and CO2 in the past. I'm not looking forward to the temperature catching up with current CO2 and solar levels...
  44. Waste heat vs greenhouse warming
    The 'saturation', or rather the GHG emission only range I was looking at on Has the greenhouse effect been falsified?, Figure 1., is the 16-14 micrometer band.
  45. Waste heat vs greenhouse warming
    BP - I found the graph I was looking for. See Has the greenhouse effect been falsified?, figure 1., where the CO2 bands are sending ~1/2 their IR to space, 1/2 back down. Without the GHG blocking the spectra would closely follow the black-body curve at ~267K, or it would until things cooled off. I used "fully saturated" poorly in my posting - what I intended should have been the much wordier "for those wavelengths where there's enough GHG in the atmospheric column to essentially absorb direct ground radiation before it gets out to space uninterrupted, thus preventing direct radiation and only showing spherically distributed thermal radiation from the GHG". Because I, well, thought that was pretty wordy...
  46. Confidence in climate forecasts
    In my previous comment I emphasised the change made by the IPCC to its AR2 WG1 Chapter 5 “Climate Model Evaluation” when replacing “prediction” with “projection”. It is worthwhile considering the important distinction between these two words, clarified in a definition buried in AR3 Appendix I - Glossary. “Projection (generic) 
A projection is a potential future evolution of a quantity or set of quantities, often computed with the aid of a model. Projections are distinguished from predictions in order to emphasise that projections involve assumptions concerning, e.g., future socio-economic and technological developments that may or may not be realised, and are therefore subject to substantial uncertainty. See also Climate projection; Climate prediction.” “Climate projection: 
A projection of the response of the climate system to emission or concentration scenarios of greenhouse gases and aerosols, or radiative forcing scenarios, often based upon simulations by climate models. Climate projections are distinguished from climate predictions in order to emphasise that climate projections depend upon the emission/concentration/ radiative forcing scenario used, which are based on assumptions, concerning, e.g., future socio-economic and technological developments, that may or may not be realised, and are therefore subject to substantial uncertainty.” Climate prediction: 
A climate prediction or climate forecast is the result of an attempt to produce a most likely description or estimate of the actual evolution of the climate in the future, e.g. at seasonal, interannual or long-term time scales. See also: Climate projection and Climate (change) scenario. As I indicated previously, these distinctions, although conveniently overlooked by supporters of The (significant human-made global climate change) Hypothesis, are by no means trivial. On the contrary, they are fundamental to the debate. As far as projecting changing global climates are concerned the most important words providing that clarification are “assumptions .. subject to substantial uncertainty ..” particularly in relation to uncertainty and assumptions about radiative forcing. Kevin Judd underplays this high level of uncertainty and the associated highly dubious assumptions made by supporters of The Hypothesis. He says “Of course there will always be some doubt and uncertainty about how the details of climate change will play out, but there is no doubt on the basic story that the earth's average temperature is going to rise 2 to 3 degrees over the next 50 to 100 years. Anyone who says otherwise, either does not understand how science works, or is being deliberately misleading..” He is wrong. Those projections of 2-3C rise in mean global temperature are pure conjecture. As Professor Barry Brook (Note 1), Sir Hubert Wilkins professor of climate change at Adelaide University said over a year ago, “There are a lot of uncertainties in science, and it is indeed likely that the current consensus on some points of climate science is wrong, or at least sufficiently uncertain that we don’t know anything much useful about processes or drivers” (Note 2 – please read the whole paragraph for the full context). It is that poor scientific understanding of global climate processes and drivers that forces supporters of The Hypothesis to speculate about future trends and other agenda unrelated to climate change that causes them to speculate about a catastrophic trend. Those Implications by Kevin Judd (is this Professor Kevin Judd of the University of Western Australia?) that today’s computer models are able to predict global climate change are totally misleading. Because of those unfounded assumptions made as a result of the significant uncertainties in the underlying sciences upon which the models are based, any attempts at predicting global climates are little better than fortune telling through gazing into crystal balls. John Cook’s lead article on the “How reliable are climate models?” thread says that sceptics argue “Models are unreliable .. “. This understates what many skeptics say, which is that climate models are incapable of predicting global climates. Specious claims are repeatedly made by supporters of The Hypohesis about the ability of climate models to predict global climates. In a plethora of comments on that thread the claim is made that this is substantiated by mean global temperature change predictions attempted by Dr. James Hansen in 1988. In these, one of the three scenarios produced results that show some alignment with claimed global temperature changes to 2000. The fact that this alignment disappears for the period 2000-2010 is conveniently overlooked. Because of the enormous scientific uncertainties about global climate processes and drivers, no climate model can be considered capable of predicting anything relating to global climates until it has reliably predicted global temperature trends over the accepted minimum period of 30 years. This test run would have to be undertaken under strict control procedures monitored by independent validation professionals before sceptics would accept that the models are reliable. Until that has happened climate models have no more validity that the fortune teller’s crystal ball. NOTES: 1) see http://www.adelaide.edu.au/directory/barry.brook 2) see http://bravenewclimate.com/2009/04/23/ian-plimer-heaven-and-earth/ Best regards, Pete Ridley.
  47. Talkin bout the Skeptical Science phone apps
    ROFL the title of your article is hilarious! XD Nice one.
  48. It's the sun
    "We actually have many lines of evidence that clearly point to the burning of fossil fuels causing rising CO2. " Sorry, I should have stated more clearly I was inquiring about past warming cycles with higher CO2 concentrations (with a cooler sun). I think KR posted above providing a potential cause for rising CO2 levels which cause warming with a much cooler sun compared to present. If I understood your first response correctly, previous warming was caused by increased CO2 levels caused by non-solar forces. I'm trying to understand what causes CO2 levels to rise high enough to cause warming (excluding fossil fuels, volcanic activity, and the sun). This also begs the question: if current global warming is caused by solar forces AND CO2, are we not fast-tracking the earth to provide a natural balance as seen in the past (assuming an origin for increased CO2 is the sun).
  49. Why I care about climate change
    Hi John, thanks for that bit of background. As the ATE advert says "To communicate is the beginning of understanding". About a year ago I started debating on Australian (Family First) Senator Steve Fielding's blog. Steve is a committed Christian but is also a sceptic. Another committed Christian and supporter of The (significant human-made global climate change) Hypothesis, Phil (AKA Stormboy - http://bloodwoodtree.org/category/climate-change) and I had numerous exchanges of opinion on climate change. I approach this subject from the other side of the debate, suspicious of the real motivations of the politicians in driving what I see as a confidence trick. After months of debate neither of us changed our opinions on the issue. Only time will tell whether or not the scientific speculation about our use of fossil fuels is having any significant impact upon global climates or whether such impacts are beneficial or detrimental to the most important form of life on the planet, humans. Best regards, Pete Ridley
  50. Three new studies illustrate significant risks and complications with geoengineering climate
    Thank you for catching that, Jenikhollan. I'll update the post to the right figure when I get home tonight.

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