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Comments 127251 to 127300:

  1. Scientists can't even predict weather
    An analogy that I like to make is to the seasonal cycle. For example, if I told you that I could predict with confidence the weather here in Rochester for a day three weeks hence, you would correctly laugh at me. However, if I told you that I could predict with confidence that the average temperature for next January will be roughly 40 F colder than it was in July, I don't think you would give me much of an argument. It is also worth noting that the chaotic behavior of the weather can be tested with the numerical weather prediction and climate models. For example, a numerical weather prediction model will give a specific weather prediction for a day 3 weeks hence, but if you run it again with just small perturbations to the initial conditions, the prediction will be very different. (Actually, such running of ensembles with perturbed initial conditions now plays an important role in weather forecasting, at least for the period out beyond a few days.) On the other hand, I assume that such a model will give a reasonable prediction for the climate in January relative to July and the basic features will not be sensitive to the initial conditions. Likewise, with a particular climate model, perturbed initial conditions result in differences in the "jiggles" of the global temperature but when run out for 100 years, the different realizations all predict roughly the same overall amount of warming. This is true because the warming that occurs is governed by the fundamental issue of radiative balance between the earth, sun, and space. (Admittedly, because of feedback effects, determining how that radiative balance plays out is not easy...but it does not seem to be sensitive to small perturbations in initial conditions.)
  2. Philippe Chantreau at 18:36 PM on 10 October 2009
    How do we know CO2 is causing warming?
    Lorenzo, the Max Planck Institute TSI reconstruction shows a variance of about 0.8 w/m2 since 1885 (0.2 w/m2 on Earth surface), no net increase over the past 35 years. That reconstruction uses an 11 year average that removes the variations from the solar cycle. Both PMOD and ACRIM show cyclic variations no greater than roughly 2w/m2 (no trend over the observation period), which translate into a surface forcing +/- 0.5 w/m2. We're talking total irradiance here, not the IR part. Considering how small TSI changes are and considering how much of TSI is in the IR spectrum and at which wave lengths, I'm wondering how your question #4 can make sense.
  3. Philippe Chantreau at 16:17 PM on 10 October 2009
    Are humans too insignificant to affect global climate?
    Increased CO2 is such a minor factor compared to water availability and nutrients, it's not even worth considering from a practical point of view. Water vapor itself is also very minor. Changes in rain patterns associated to the climate changes brought by increased CO2 are much more likely to affect plants than the level of CO2 itself. We're not talking about a greenhouse or lab where every single parameter can be finely controlled here. Availability of liquid water and nutrients are the real important things. Ther rest is nit picking. I'd like to see the reference on that increase in plant life study, especially to see if there is any attribution to possible causes in the increase. I'm also wondering what exactly is meant by "increase." I believe that land use changes are more likely than any other factor to yield that kind result. I seriously doubt that "CO2 fertilization" (an abuse of language really) can be that effective.
  4. How do we know CO2 is causing warming?
    LorenzoG wrote in #19: "2.) Doubling the CO2 level in the atmosphere will not result in any more energy being trapped in the atmosphere because ALL OF IT IS ALREADY ABSORBED." That myth is ancient--as in the turn of the 19th century to the 20th century. See A Saturated Gassy Argument.
  5. How we know global warming is still happening
    shawnhet, "Cloud formation depends on RH, but also on the specific humidity. The more water in air, the thicker and deeper will be the clouds that form *once that air cools sufficiently*. There will be more water condensed out of air cooling from 16C to 15C (when everything else is equal) than air cooling from 15C to 14C. If everything else were really equal, then this should lead to correspondingly higher amount of clouds." Why is that? At a given specific humidity the relative humidity will depend upon the saturation vapor pressure and that in turn is dependent on temperature. The higher the temperature the greater the saturation vapor pressure and lower the RH at a given specific humidity. The GCM's indicate that as global average temperature rises so does specific humidity in such a way that RH remains nearly constant (Clausius-Clapeyron relation) or maybe a bit lower. The tendency to form clouds begins at around 70% RH no matter the temperature or specific humidity. You are correct that more water can potentially be condensed out at higher specific humidities where clouds do form, but this relates to precipitable water within the column of atmosphere (because the water load is greater), not necessarily to the tendency for cloud formation.
  6. Philippe Chantreau at 12:05 PM on 10 October 2009
    Are humans too insignificant to affect global climate?
    Increased CO2 is such a minor factor compared to water availability and nutrients, it's not even worth considering from a practical point of view. Water vapor itself is also very minor. Changes in rain patterns associated to the climate changes brought by increased CO2 are much more likely to affect plants than the level of CO2 itself. We're not talking about a greenhouse or lab where every single parameter can be finely controlled here. Availability of liquid water and nutrients are the real important things. Ther rest is nit picking. I'd like to see the reference on that increase in plant life study, especially to see if there is any attribution to possible causes in the increase. I'm also wondering what exactly is meant by "increase." I believe that land use changes are more likely than any other factor to yield that kind result. I seriously doubt that "CO2 fertilization" (an abuse of language really) can be that effective.
  7. How do we know CO2 is causing warming?
    This article ignores basic science. 1.) OK, so a CO2 absorbs a photon of infrared. The only ways that molecule can de-energize to be ready for the next photon is to conduct heat away through impact with another molecule, or to re-radiate it out at the same frequency. Either it does one of these or all CO2 molecules will soon reach saturation and be unable to absorb more infrared. If it conducts it to another molecule then that molecule will either conduct it away again or re-radiate the photon, BUT AT THAT MOLECULE'S WAVELENGTHS, not CO2's. O2, N2, H2O all radiate at different wavelengths than CO2, and your chart above doesn't even cover two of the H2O bands. Unless you analyze the total energy exchange by the Earth on all wavelengths you can't begin to come to any conclusions. 2.) Dr. Heinz Hug's work suggests that CO2 is such a good absorber of infrared energy that it absorbs 100% of IR radiated from the ground at your 650/cm region within 10 meters of the ground. Doubling the CO2 level in the atmosphere will not result in any more energy being trapped in the atmosphere because ALL OF IT IS ALREADY ABSORBED. You won't get twice the heating from doubling the CO2 concentration because there is none left to absorb at that wavelength. 3.) The three primary IR absorption peaks of CO2 only cover about 8% of the infrared band, so CO2 is transparent to 92% of infrared energy. 4.) The Philipona paper mentioned above indicates a 1.8W/m2 increase in energy being radiated towards the ground. The sun sends ~1,000W/m2 at the equator. The increase described by Philipona is 0.18% of the sun's output. Can you prove that there has not been 1/5 of 1% variance in the sun's output over the last 34 years?
    Response: If the CO2 effect was saturated, then increasing CO2 would lead to no change in the greenhouse effect. As satellite measurements (Harries 2001, Griggs 2004, Chen 2007) and surface measurements (Philipona 2004, Evans 2006) all find an enhanced greenhouse effect at the CO2 and CH4 bands, this is empirical confirmation that the CO2 effect is not saturated.

    Note that hotter objects emit radiation at shorter wavelengths. Hence the sun emits shortwave radiation while the earth emits longwave radiation. This is the basis of the greenhouse effect - shortwave radiation from the sun passes through the atmosphere, warms the earth which then emits longwave radiation back out to space. This longwave radiation is absorbed by greenhouse gases. The enhanced greenhouse effect observed by the papers listed above are at longwave wavelengths, not shortwave. It's basic science.
  8. Are humans too insignificant to affect global climate?
    The fact is, that plant growth has a number of constraints on it and if you relax a constraint then growth will increase, unless there is another constraint that is blocking it. If the plant is primarily constrained by the amount of liquid water it is exposed to(or the nature of the soil it is sitting in), then adding more CO2 will not help it grow. However, for the plants that are(currently) constrained by the speed/efficiency they can remove carbon from the air, then increasing CO2 will help them grow. This is why commercial greenhouses routinely pump massive levels of CO2 into their structures(they are designed to relax as many constraints on plant growth as possible). Clearly, some plants, in their current environments would grow faster(and, hence bigger) if they had access to more CO2. Further, this is compounded by the fact that warming temps will also yield more WV which also makes it easier from plants to grow, on average. IIRC, this effect has been measured from space, and there has been something approximating 6% increase in plant life on Earth over the last 20+ years. Cheers, :)
  9. How we know global warming is still happening
    WeatherRusty:"It is not a given that there are more clouds in a generally warmer environment. Cloud formation depends very much on relative humidity and also the availability of lift within the atmosphere, warm moist air must rise and cool to near it's dew point. A product of all climate simulations is a near constant relative humidity as the climate warms. Look at the tropics and near tropics today. Most cloud formation is convective in nature and where this is the result of daytime heating the clouds dissipate at night. The tropics receive the vast majority of solar radiation but cloudiness does not prevent that region from being the warmest on Earth. If the climate zones and jet streams are shifted poleward in a warming world why would the dynamics be any different in their displaced positions?" Cloud formation depends on RH, but also on the specific humidity. The more water in air, the thicker and deeper will be the clouds that form *once that air cools sufficiently*. There will be more water condensed out of air cooling from 16C to 15C (when everything else is equal) than air cooling from 15C to 14C. If everything else were really equal, then this should lead to correspondingly higher amount of clouds. The fact that clouds form quickly and easily in the tropics doesn't prevent them form being the hottest place on Earth(on average), but it does help prevent them from getting as hot as land at the same latitude (during the day). Further, it is not a given that RH is, in fact, a constant either. Cheers, :)
  10. How we know global warming is happening, Part 2
    The ocean heat content graph still has some amount of noise in it. I wonder if the total global heat content would be a more monotonic line, since the planet is steadily taking up more heat over time.
  11. dopeydoctorjohn at 02:25 AM on 10 October 2009
    There is no consensus
    Doran then compares this result with a response from the general public......disingenuously. He quotes a Gallup poll that "suggests that only 58% of the general public would answer yes to our question 2." However, if one cares to check the reference, the question asked of the general public was whether they thought human activities OR natural forces were driving climate change. To answer "yes", they had to think not just that human activities were "a" significant factor, but "THE" significant factor driving warming. A climate scientist thinking human activities contribute 1% to warming answers the survey question "Yes" Joe Bloggs, thinking that human activities contribute 49% to warming answers his respective Gallop question "No". Doran knows this, but compares them on the same graph anyway, and concludes that climate scientists need to "spread the word" more enthusiastically. And this website swallows it hook line and sinker.
  12. dopeydoctorjohn at 02:07 AM on 10 October 2009
    There is no consensus
    Didn't Doran design this question in order for it to be almost impossible to answer "no" to? Didn't he do that in order to generate the highest "yes" answer % possible, in order to create a paper purporting to demonstrate a consensus in excess of the "real" consensus that may exist? Didn't Doran fail to follow up on non-responders? Didn't Doran select out, for special attention, not necessarily the most knowledgeable (why not select out PhDs, or professors, specifically?) but specifically those most likely, undoubtedly, to agree with the premise of his question, and then did he not ask the most inclusive, weakly-framed question possible, just to generate this mighty figure of 97.4%
  13. dopeydoctorjohn at 02:01 AM on 10 October 2009
    There is no consensus
    Doran asked these climate scientists this question: "Do you think human activity is a significant contributing factor in changing mean global temperatures?" 1) "A" factor, not "The only" factor. Not even "the most". 2) What does a climate understand by the word "significant"? In medicine, a relationship is said to be significant if there is a less than 5% chance that it can be explained as random. If sample sizes are large enough, "highly significant" relationships can be calculated that actually mean zip to any given individual. If a given subject is important enough, a 1% contribution to it may be significant. Schizophrenia affects just 1% of the population: anyone think it is an insignificant illness? 1% of the US population lives in Chicago City: is Chicago's contribution to America insignificant? So if human activity contributes 1% to global warming, and if a climate scientist lives and breathes climate, he or she would have to say that 1% contribution is significant, no?
  14. dopeydoctorjohn at 01:41 AM on 10 October 2009
    There is no consensus
    97.4% is an awfully consensus-like number. Practically unanimous. But there are two parts to a fraction or, in this case, a percentage Numerator; and denominator Let's look at the denominator They are "those who listed climate sci- ence as their area of expertise and who also have published more than 50% of their recent peer-reviewed papers on the subject of climate change (79 individu- als in total)." Hmmm. 1) If your gut feeling, after finishing your B.Sc., was that the climate wasn't changing, would you study climate change? Probably not. You'd be thinking it would be pretty boring, because you'd be not expecting it to change. If your gut feeling, after finishing your B.Sc., was that AGW threatened mankind, would you study climate change? You betcha! Here's your chance to save the world AND get the girl! 2) If a climate scientist is doing research on climate change, and he or she finds no change occuring, do we think it is still going to get published? Publication bias in clinical research The Lancet, Volume 337, Issue 8746, Pages 867-872 So doesn't that mean published research, and therefore published researchers, must be biased to those reporting change? 3) When we are talking about "the subject of climate change", isn't it understood that we are usually talking about AGW? 4) SO, that impressive number 97.4% tells us that 97.4% of climate scientists studying climate change and publishing primarily on climate change believe in.......climate change. Exploring the denominator renders the numerator much less impressive. Is that a statistic, or a tautology?
  15. dopeydoctorjohn at 01:07 AM on 10 October 2009
    There is no consensus
    In Australia, if a doctor A thinks another doctor B is impaired to the point of being a danger to society, then doctor A must report doctor B to the Medical Board Medical Practice Amendment Act 2008 (NSW) (Section 71A) If 90% of Earth scientists think the world is at threat from climate change, and 10% of their colleagues are going around unable to agree even on warming, shouldn't the 90% move to get the 10% dismissed? Or, isn't it actually quite that "cut and dried", even amongst Earth scientists?
  16. dopeydoctorjohn at 00:56 AM on 10 October 2009
    There is no consensus
    Doran's survey population included "more than 90%" PhDs and 7% Masters degrees in earth sciences. They were asked: "When compared with pre-1800s levels, do you think that mean global temperatures have generally risen,fallen,or remained relatively constant?" 90% said "risen". Everyone here would be pretty sure as to why that answer would have been given. But, as we all know, truth isn't a democracy. so..what about the other 10%? Here are 300+ PhDs and Master's degreed folk who don't even think warming has occurred. Wouldn't it be good to know their reasoning?
  17. dopeydoctorjohn at 00:45 AM on 10 October 2009
    There is no consensus
    Does anyone think the opinions of the 7111 non-responders might be different to the opinions of the responders? I Googled "Non-response bias" (under the Scholar listings) and found oodles of studies on the subject. It seems to be particularly important when the subject matter is controversial. Like climate change. It seems that if a researcher is keen to know what the surveyed group really think, the researcher will do a followup small randomised study from the target group to try to demonstrate no statisticlly significant difference between the thoughts of the survey responders and the non-responders. Can anyone see where Doran did this?
  18. dopeydoctorjohn at 00:21 AM on 10 October 2009
    There is no consensus
    Hi John. Great site!! Extremely helpful from both sides I know diddly-squat about the environment, so all I can do is ask questions. Regarding the Doran 2009 study, so extensively quoted above, it is written "The authors surveyed 3146 earth scientists" but when I look at the actual link I find 10257 earth scientists were surveyed, and only 3146 responded. So, really, if you survey 10257 earth scientists and ask them "Do you think human activity is a significant contributing factor in changing mean global temperatures?" you find (10257-3146=) 7111 don't find 2 minutes to answer your survey. If I were an Earth Scientist and I thought global warming was about to destroy the planet, I'd be pretty keen to get the message out. I'd find 2 minutes to answer an "up to 9" question survey to help get the message out. Especially if I thought the survey was going to get as much publicity as this Doran study. Why do you think those 7111 Earth Scientists didn't answer the survey?
  19. Frank Schnabel at 21:53 PM on 9 October 2009
    Temp record is unreliable
    Greeting all, When some outfit like Hadley or GISS offers an estimate of the global mean temp for a given year, do they present along with it an error estimate? e.g. In 2008 the average temp was 25 degrees C + or - 5 degrees. Seems like they would have to, given all that goes into coming up with an estimate. How do they assess the range of error, and how much confidence can we place on such estimates? cordially Frank
  20. How do we know CO2 is causing warming?
    "What they found was a drop in outgoing radiation at the wavelength bands that greenhouse gases such as CO2 and methane (CH4) absorb energy." This is a better post than most i have seen here (with a bit of history and hard physics), but i wonder what the radiation band absorption spectra would look like if the oceans were also absorbing radiation wavelengths due to eg less clouds over the oceans?, rather than c02/ch4 doing it?? Just a thought.
  21. Philippe Chantreau at 15:57 PM on 9 October 2009
    How do we know CO2 is causing warming?
    WR, I believe that Chris is right. In short, if a feedback induces a change lower than the one that caused the feedback itself, then there will be no runaway. The system is inherently stable.
  22. There is no consensus
    Chris, I am aware that there are many proxies which can be used to give rough estimates of temperature in the past. I agree that the climate has been warming at least since the start of the 20th century. The Earth's climate can warm and cool over time due to natural factors. My quest for the "truth" centres on finding out: 1) How much of the recent warming is due to man-made CO2 emissions. 2)Is warming necessarily a bad thing. 3) If man-made CO2 emissions are a contributing factor, what can be done to lower the emissions in a way that will have a DEMONSTRABLE effect in reducing temperature increases in the future - maybe having more nuclear power stations would be the way to go. aww However, with regard to your claim that temperature increase since 1850 " most likely already had an anthropogenic component", is it not true that the IPCC climate models can replicate temperature trends prior to around 1970 simply using natural forcings. Also, from the graphs I have seen, there has been no general increase in the rate of recession of glaciers since 1970.
  23. Is the U.S. Surface Temperature Record Reliable?
    Recording the temperatures on the surface of the planet aren't accurate and do not reflect the true participation of urban heat islands related to global warming. Global warming means there is a source of heat atmospherically. Here is a link to advanced temperature work to isolate the cause of urban heat islands. Look at the amount of heat generated in September. http://www.youtube.com/watch?v=1EmBQcXr6ng
    Response: The source of atmospheric heat has been determined empirically by both satellites and surface measurements of longwave radiation to come from greenhouse gases trapping more heat that would otherwise have radiated back out to space. As for urban heat island, see this research into the effect of urban heat island effect on temperature records.
  24. There is no consensus
    neil, you're changing the subject and arguing about something that isn't what my post (#157) was about. I was pointing out that there are quite a few different temperature scales and that these yield a rather consistent interpretation of 20th century warming. No one is arguing that glacier retreat is solely due to enhanced anthropogenic greenhouse forcing. The point is that one can use glacier extent and its temporal variation as a crude "thermometer", and this analysis gives a temporal variation in earth temperature consistent with that determined by analysis of direct measures.. Note that glacier advance due to the so-called Little Ice Age had more or less stopped by around 1800, and the slow retreat from around 1850 most likely already had an anthropogenic component. After all, the preindustrial atmospheric CO2 levels of around 280 ppm, were ncreased through the 19th century to 300 ppm by 1900 and by 320 ppm by 1960. That increase in atmospheric CO2 should give a warming near 0.4 oC within the best estimate of the climate sensitivity (around 3 oC per doubling of atmospheric CO2). And this is consistent with analysis of attributions of 20th century warming. One simply can't reproduce 20th century warming without including this very significant anthropogenic contribution. An example of this attributional analysis can be found elsewhere on John Cooks site: http://www.skepticalscience.com/climate-models.htm
  25. Scientists can't even predict weather
    An analogy that I like to make is to the seasonal cycle. For example, if I told you that I could predict with confidence the weather here in Rochester for a day three weeks hence, you would correctly laugh at me. However, if I told you that I could predict with confidence that the average temperature for next January will be roughly 40 F colder than it was in July, I don't think you would give me much of an argument. It is also worth noting that the chaotic behavior of the weather can be tested with the numerical weather prediction and climate models. For example, a numerical weather prediction model will give a specific weather prediction for a day 3 weeks hence, but if you run it again with just small perturbations to the initial conditions, the prediction will be very different. (Actually, such running of ensembles with perturbed initial conditions now plays an important role in weather forecasting, at least for the period out beyond a few days.) On the other hand, I assume that such a model will give a reasonable prediction for the climate in January relative to July and the basic features will not be sensitive to the initial conditions. Likewise, with a particular climate model, perturbed initial conditions result in differences in the "jiggles" of the global temperature but when run out for 100 years, the different realizations all predict roughly the same overall amount of warming. This is true because the warming that occurs is governed by the fundamental issue of radiative balance between the earth, sun, and space. (Admittedly, because of feedback effects, determining how that radiative balance plays out is not easy...but it does not seem to be sensitive to small perturbations in initial conditions.)
  26. How do we know CO2 is causing warming?
    WeatherRusty, I thnk the answer is simply that the water vapour response to increased atmospheric warming is small enough that its additional forcing results in a temperature rise that is quite a bit smaller than the temperature rise that induced it. The water vapour feedback applies to anything that enhances (or reduces, of course) the atmospheric temperature. So if the sun became a bit brighter such that the direct atmospheric warming was 1 oC, and the resulting water vapour feedback adds an additional x of additional warming then the total warming from the solar enhancement + water vapour feedback is something like 1 + x + x^2 + x^3 + x^4 ... which is 1/(1-x). So if the water vapour response to a 1 oC warming is 0.5 oC then the total warming when everything comes to equilibrium is 1/(1-0.5) = 2 oC. The same argument applies for the enhancement of atmospheric CO2 concentrations. If the atmospheric CO2 concentrations rise by an amount giving a 1 oC of warming then the water vapour feedback will result in a total warming of 1/(1-x). In some ways it's better to describe the feedback as an "amplification" to avoid the connotation with a "runaway" positive feedback.
  27. dopeydoctorjohn at 00:50 AM on 9 October 2009
    Less than half of published scientists endorse global warming
    Quietman Your link on post 5 should be added to the consensus thread where it may get more attention. It's a great link! Cheers
  28. How do we know CO2 is causing warming?
    Can anyone explain why the positive feedback involving water vapor is not a runaway condition? More water vapor=increased warmth=more water vapor=increased warmth etc....etc..... I would start with the fact that water vapor is not a well mixed gas. What would happen if a magic wand where waved and water vapor concentration were approximately the same everywhere such as is the case with CO2?
  29. How do we know CO2 is causing warming?
    RSVP, Very simply in response to post #13, the greenhouse effect slows the loss of out going thermal radiation both day and night. A stronger greenhouse effect results in warmer nights, the energy of which is carried over the the next day. The atmosphere radiates energy all night long, thus preventing a drastic drop in surface temperature, especially over land, in the absence of sunshine. The energy input of the previous day is not totally "discharged" at night as you assert, it only slowly trickles out due the the atmospheric greenhouse effect. Adding greenhouse gases slows the loss even more.
  30. How do we know CO2 is causing warming?
    Aside from the heat directly released, just as CO2 plays a role as a catalyst in global warming, underground nuke testing may have upset Earths hotspots. Why not. The non skeptics arent concerned with this however, even if it were true. All they want to do is ramrod the idea that CO2 is doing everything. This paper for instance "proves" that CO2 is responsible for global warming, since more IR energy around a band of CO2 IR emission is now greater as compared to 25 years ago. If the data is good, about all it proves is that there is more CO2, which we already know. The data is insufficient because even if more heat is being trapped during the day due to CO2, it is the stored energetic carry-over from one day to the next that matters. (Night and winter has an important role in global cooling, yet never mentioned in these discussions.) Energy stored in land and sea. If the total conditions during the 24 hr cycle are enough to "discharge" the energy, even if you have an instantaneous increase in heat retention from CO2, (as is typically illustrated in greenhouse energy budget diagrams), about all you can say is that CO2 makes it hotter during the day (and under specific conditions). That is a lot different from saying that CO2 is the main cause of global warming. Never mind the possibility that you allude to about nuclear testing. Never mind the possibility that air pollution causes more clouds, and clouds as any farmer knows keeps things generally warmer. The concept that CO2 is doing everything however has been institutionalized, and opening up people's minds on the subject appears about as difficult as getting rid of excess CO2 itself.
    Response: This is not the first time you've raised the strawman argument that we claim "CO2 is doing everything". It is not - I've even posted a reply to your previous comments to clarify that CO2 is just one of several anthropogenic forcings - it just happens to be the most dominant forcing and of all the positive forcings, it's bigger than the others combined:



    The studies above also confirm the amplified greenhouse effect from methane but as there is much less methane in the air than CO2, it's radiative forcing is much smaller. Any comments repeating this strawman argument will be deleted.
  31. Sea level rise is exaggerated
    A recent ( June 2009 ) scientific paper by Cliff Ollier of the School of Earth and Environment, The University of Western Australia, states as follows : Abstract: Graphs of sea level for twelve locations in the southwest Pacific show stable sea level for about ten years over the region. The data are compared with results from elsewhere, all of which suggest that any rise of global sea level is negligible. The Darwin theory of coral formation, and subsidence ideas for guyots would suggest that we should see more land subsidence, and apparent sea level rise, than is actually occurring. Sea level studies have not been carried out for very long, but they can indicate major tectonic components such as isostatic rebound in Scandinavia. Attempts to manipulate the data by modelling to show alarming rates of sea level rise (associated with alleged global warming) are not supported by primary regional or global data. Even those places frequently said to be in grave danger of drowning, such as the Maldives.
  32. How do we know CO2 is causing warming?
    Has there been any studies of nuclear weapon testing's impact? There only has been a ban of nuclear testing after 1993. I read there was one nuclear test every nine days prior.
  33. How do we know CO2 is causing warming?
    As someone who only has limited access to full contents of papers, I thank you for giving us a peek at the Harries et al. (2001). It's too bad we don't have much papers like Evans & Puckrin (2006) who measure the change in DLR by each gas. A new paper by Wang & Liang (2009) mentions the possible reason why we don't have much of them: "While surface shortwave radiation has long been measured globally [Gilgen and Ohmura, 1999], Ld is not conventionally observed due to the higher cost of pyrgeometers used for Ld measurement, and more difficult challenges of instrument calibration and quality control [Enz et al., 1975; Udo, 2000; Sridhar and Elliott, 2002; Duarte et al., 2006]." (Ld being the surface downward longwave radiation.) http://www.agu.org/pubs/crossref/2009/2009JD011800.shtml
  34. How do we know CO2 is causing warming?
    I'm not a scientist, but I do understand basic logic. What's interesting to me about Leonard's assertions is not that many of them are wrong, but how he draws the wrong conclusions from the facts he gets right. What it shows is a lack of ability to do "systems thinking": the type of reasoning that involves understanding of stocks and flows, time delays, nonlinearities, and feedbacks - exactly the concepts important to understanding climate science. Leonard makes logical errors in each of these areas. His argument about water vapor being a much more potent GHG is a stock and flow error. The notion that decreasing temperatures during a period of CO2 increase disproves AGW fails to grasp nonlinearities and time delays. He talks about "water vapor feedback," but based on the incoherence of the sentence, I'd guess he doesn't know what a feedback is. But even highly-educated people with technical backgrounds can fail to grasp these concepts intuitively. A study called "All Models are Wrong" (John Sterman, System Dynamics Review, Winter 2002) found that even most MIT grad students couldn't grasp basic systems thinking concepts like stocks and flows. I'd argue that, aside from political bias, the inability to do systems thinking is the second biggest driver of climate denial. People like McIntyre and Plimer may be highly educated and skilled at performing calculations, but their brains' intuitive grasp of systems concepts may be under-developed. This is why you don't have to be a technical expert on all the details of climate science to still respond to denier talking points. Most of them aren't errors of fact so much as errors of logic. (John - Sorry to steal your thunder on the previous post. There must have been some water vapor feedbacks or something :)
  35. Water vapor is the most powerful greenhouse gas
    I would like to see all energy inputs and outputs and also the real estimates of the amounts of water in oceans water in atmosphere carbon sources ,co2 production from nature and man methane from nature and man i would lke to see evidence of temperatures in the distant past with co2 levels and if possible water vapour levels say over millenia. my expectation is that atmospheric carbon and water vapour levels are tails of very big dogs in the oceans and carbon sources. that we are dealing with small numbers in a system of much bigger numbers so conclusions we reach about global warming based on atmosheric gases are very problematic. what does co2 energy absorption in its narrow absorption band really have on energy balance.could it be it is reradiated at another frequency to space ? please explain how the green house effect of a gas actually works in detail I can appreciate the effect of WV in that clouds capture heat energy from the sun and nett radiate convect and reflect more heat than if the clouds were not there.water vapour that is not in a cloud presumably is causing a radiation block from the earth. i am not sure of the deatil
    Response: I've recently posted about an analysis of all energy inputs and outputs. and posted on man's co2 emissions. For more on the carbon cycle, see this page on human versus natural co2 emissions.

    Examination of past temperature change alongside CO2 change is examined on the CO2 lags temperature page as well as empirical determinations of climate sensitivity.

    The conclusion that atmospheric gases are causing global warming is based on empirical observations. Satellite observations of radiation escaping to space find that less radiation is escaping at wavelengths that CO2 absorb. This is confirmed by surface measurements of downward longwave radiation that also find increasing downward radiation at CO2 wavelengths.
  36. Philippe Chantreau at 10:00 AM on 8 October 2009
    Are humans too insignificant to affect global climate?
    I meant to say the temperate rainforests, which I believe to be the richest terrestrial biome outside of tropical rainforests.
  37. Philippe Chantreau at 09:54 AM on 8 October 2009
    Are humans too insignificant to affect global climate?
    Plants grow best where there is plenty of water available. Indeed that seems to be the most important factor since, with time, even poor soil will be enriched by plant life, which will then recycle itself leading to more abundant and diverse life. The African forest is a case in point; much of it sits on a thin layer of rich soil built over time by decomposing organisms, the original soil underneath is nothing but red dust, called laterite. Laterite is quite good to build roads. With proper sun exposure throughout the day, allowing it to dry, a laterite road is likely to last longer than a paved one. Strangely enough, plants don't start growing on laterite roads nearly as fast or as easily as they do in the cracks of a paved road. The temperate forests are also found where there is plenty of available water, as in Kamtchatka, Pacific Northwest, South Alaska. Of all factors, not a single one is more important than the availability of water, not even nutrients, with enough time given.
  38. Philippe Chantreau at 09:41 AM on 8 October 2009
    How do we know CO2 is causing warming?
    Glad to see the follow up on the Harries paper. A wealth of interesting papers here, from John and posters as well. Nice.
  39. Are humans too insignificant to affect global climate?
    RSVP said: "Do plants generally grow faster in warmer or cooler climates?" There are many more factors to be considered that just rate of growth. Total yield and nutritional quality are much more important. Rice has been shown to be negatively affected by increasing minimum temperatures: "Grain yield declined by 10% for each 1°C increase in growing-season minimum temperature in the dry season, whereas the effect of maximum temperature on crop yield was insignificant. This report provides a direct evidence of decreased rice yields from increased nighttime temperature associated with global warming." PNAS July 6, 2004 vol. 101 no. 27 9971-9975 http://www.pnas.org/content/101/27/9971.full Nutritional quality of wheat declines: "The discovery that staple crops like wheat have less protein when grown in high concentrations of CO2 has already caused concern, but the bad news doesn't stop there. Ramping up CO2 also changes the balance of amino acids and several trace elements, says Petra Högy from the University of Hohenheim in Germany". http://www.newscientist.com/article/dn17617-wheat-gets-worse-as-cosub2sub-rises.html There are many other papers describing deleterious effects of higher temperatures and higher CO2 levels on the plants which are staples in our diet. Thus messing around with our climate and atmospheric chemistry will not be good for our food supply.
  40. How do we know CO2 is causing warming?
    couple more points re #4
    In addition, the recent temperature leveling off and in fact tending down (last 7 or so years), along with admissions that this may in fact go on 20 more year, seems to disconnect the clear relation between temperature and CO2 level.
    The relation between temperature and CO2 relates to the equilibrium temperature resulting from a raised CO2 level, Leonard. It’s obvious that natural variation will modulate the transition towards that new temperature. Analysis of total heat content indicates that the earth continues to absorb heat under influence of radiative imbalance and this is going to contribute to enhanced surface warming. http://www.skepticalscience.com/How-we-know-global-warming-is-happening-Part-2.html
    In direct response to WAG, the global temperature has risen numerous times as fast and as high over the last few thousand years with no greenhouse cause.
    I don’t think there’s any evidence that supports that assertion. Can you provide some?
    Water vapor is far the largest greenhouse gas and self regulates the system.
    Whatever “self-regulates” means here (can you explain?), the evidence indicates that water vapour is a positive feedback (see papers cited in my post #6 above). Nothing is really “self-regulating” the system. The earth responds to enhanced radiative forcing by absorbing heat and warming.
    The rise in CO2 is real, but has been 10 times large in the distant past with similar temperatures.
    That’s not relevant without considering the steady increase in solar constant since the start of the solar system. 500 million years ago the sun was radiating around 4% less brightly than now. Any particular CO2 concentration will give a much warmer earth now than the same CO2 concentration in the deep past. The relationship between paleo CO2 measures and paleo temperatures in the deep past is quite strong as has been described in a review by Royer: Dana L. Royer (2006) CO2-forced climate thresholds during the Phanerozoic. Geochimica et Cosmochimica Acta 70 (2006) 5665–5675 Abstract: The correspondence between atmospheric CO2 concentrations and globally averaged surface temperatures in the recent past suggests that thiscoupling may be of great antiquity. Here, I compare 490 published proxy records of CO2 spanning the Ordovician to Neogene with records of global cool events to evaluate the strength of CO2-temperature coupling over the Phanerozoic (last 542 my). For periods with sufficient CO2 coverage, all cool events are associated with CO2 levels below 1000 ppm. A CO2 threshold of below 500 ppm is suggested for the initiation of widespread, continental glaciations, although this threshold was likely higher during the Paleozoic due to a lower solar luminosity at that time. Also, based on data from the Jurassic and Cretaceous, a CO2 threshold of below 1000 ppm is proposed for the initiation of cool non-glacial conditions. A pervasive, tight correlation between CO2 and temperature is found both at coarse (10 my timescales) and fine resolutions up to the temporal limits of the data set (million-year timescales), indicating that CO2, operating in combination with many other factors such as solar luminosity and paleogeography, has imparted strong control over global temperatures for much of the Phanerozoic. droyer.web.wesleyan.edu/PhanCO2(GCA).pdf
  41. How do we know CO2 is causing warming?
    Kind of funny how you see a change around 600 cm-1, but no change around 1000 cm-1.
    Response: Different bands react in different ways - observations match theoretical expectations in this case.
  42. How do we know CO2 is causing warming?
    re #4: Not really Leonard. Saying stuff doesn’t make it true!
    Since the upper troposphere hot spot at the tropics is mainly missing, and since the absolute humidity has not increased even as the temperature increased, is in direct opposition to the positive feedback effect being present.
    The absolute humidity certainly has increased. There really isn’t any question of that [*] A recent analysis indicates that the upper tropospheric temperature in the tropics is not inconsistent with predictions from modelling [**] [*] Dessler, A. E., Z. Zhang, and P. Yang (2008), Water-vapor climate feedback inferred from climate fluctuations, 2003–2008, Geophys. Res. Lett., 35, L20704 http://www.agu.org/pubs/crossref/2008/2008GL035333.shtml Gettelman A and Fu, Q. (2008) Observed and simulated upper-tropospheric water vapor feedback . J. Climate 21, 3282-3289 Buehler SA (2008) An upper tropospheric humidity data set from operational satellite microwave data. J. Geophys. Res. 113, art #D14110 Brogniez H and Pierrehumbert RT (2007) Intercomparison of tropical tropospheric humidity in GCMs with AMSU-B water vapor data. Geophys. Res. Lett. 34, art #L17912 Royer DL et al. (2007) Climate sensitivity constrained by CO2 concentrations over the past 420 million years Nature 446, 530-532 Santer BD et al. (2007) Identification of human-induced changes in atmospheric moisture content. Proc. Natl. Acad. Sci. USA 104, 15248-15253 Soden BJ, et al (2005) The radiative signature of upper tropospheric moistening Science 310, 841-844. [**]B. D. Santer et al. (2008) Consistency of modelled and observed temperature trends in the tropical troposphere. International Journal of Climatology 28, 1703 – 1722. https://publicaffairs.llnl.gov/news/news_releases/2008/NR-08-10-05-article.pdf
  43. How do we know CO2 is causing warming?
    Leonard Weinstein, There are several assertions crammed into one paragraph, but I'll deal with the prominent assertions you're presenting. Water vapor is a positive feedback, as many direct observations have indicated. http://www.agu.org/pubs/crossref/2008/2008GL035333.shtml The "no tropical hotspot" argument is both a questionable assertion and a red herring. First, the balance of evidence suggests that there is a tropical hotspot. http://www.skepticalscience.com/tropospheric-hot-spot.htm http://www.realclimate.org/index.php/archives/2008/05/tropical-tropopshere-ii/ http://www.realclimate.org/index.php/archives/2007/12/tropical-troposphere-trends/ Second, a tropical tropospheric hotspot is not unique to GHG warming. It should appear with solar warming as well. Lastly, if there truly was no tropical hotspot in observations, it would actually imply, if anything, a higher climate sensitivity. http://chriscolose.wordpress.com/2008/12/20/skepticsdenialists-part-2-hotspots-and-repetition/
  44. Leonard Weinstein at 05:47 AM on 8 October 2009
    How do we know CO2 is causing warming?
    The fact that CO2 is a greenhouse gas and raises the temperature somewhat is not the issue of the technical Skeptics. The issue is water vapor feedback amplifying the result. Since the upper troposphere hot spot at the tropics is mainly missing, and since the absolute humidity has not increased even as the temperature increased, is in direct opposition to the positive feedback effect being present. In addition, the recent temperature leveling off and in fact tending down (last 7 or so years), along with admissions that this may in fact go on 20 more year, seems to disconnect the clear relation between temperature and CO2 level. In direct response to WAG, the global temperature has risen numerous times as fast and as high over the last few thousand years with no greenhouse cause. The current lack of continual rise does not support an unusual level. The fact that CO2 is a greenhouse gas is not the issue. Water vapor is far the largest greenhouse gas and self regulates the system. The rise in CO2 is real, but has been 10 times large in the distant past with similar temperatures. It does not matter where it comes from, only the result is important.
    Response: Kudos for squeezing so many arguments into one small comment. They are addressed elsewhere in this site: Apologies to any subsequent commenters if my links or answers duplicate their responses.
  45. How do we know CO2 is causing warming?
    Back to the basics, I guess. Hard to believe there are folks still denying the impact of CO2. This post brings together a series of important studies that supports one line of very strong evidence supporting the CO2 link to global warming. There's other lines of evidence such as tropospheric warming, more at lower heights, and stratospheric cooling, all consistent with GHG warming. There's more secondary but compelling evidence of the slow changes over the proxy record and the 20th-century spike, and what is the statistical likelihood of recent rapid warming. http://www.sciencedaily.com/releases/2009/01/090109115047.htm Very well done. It's posts like these that start generating the "these government-funded scientists are fabricating evidence" arguments from a fervent crowd that is high on repetition of talking points and short on science.
  46. How do we know CO2 is causing warming?
    Absolutely devastating post. Skeptics' arguments have holes like Bonnie and Clyde. With the evidence here and John's last post, you can bring it all together to make a pretty airtight logical proof for global warming. We know these things to be factually true: 1. Global temperatures have risen. 2. CO2 is a greenhouse gas. 3. CO2's concentration in the atmosphere has risen significantly. 4. That extra CO2 comes from burning of fossil fuels. To logically prove that humans are NOT causing the observed increase in temperatures, you therefore need to prove BOTH of two things: First, you need to show how it could be possible to pump more of a known greenhouse gas into the atmosphere WITHOUT temperatures increasing. Second, if CO2 is not causing the observed warming, you need to show what IS. The link to the full post is below. I challenge any skeptic to prove both these points above. http://akwag.blogspot.com/2009/09/obama-speaks-on-global-warming-what-you_22.html
    Response: Hey, you're stealing my thunder! I was planning to tie together all the latest posts into a single thread compiling the empirical evidence that humans are causing global warming. Now you've gone and spoiled the surprise :-)
  47. How do we know CO2 is causing warming?
    Excellent post! I've not before seen a concise, complete explanation tying together all these particular threads of evidence. Thanks!
  48. Are humans too insignificant to affect global climate?
    "Nice try. You are talking about a desert that has looked like that since Moses. I was talking about the effect of plus 1 or 2 degrees C. " A 1C or 2C change in global mean temperature also changes patterns of precipitation and evaporation, which changes water availability. Some areas will get wetter, and some will get dryer. Even if plants theoretically grow faster at warmer temperatures and higher ambient CO2, that does no good if they're already nutrient-limited or water-limited, as many plants are in the real world. There is lots and lots of research about this.
  49. Are humans too insignificant to affect global climate?
    Ned Nice try. You are talking about a desert that has looked like that since Moses. I was talking about the effect of plus 1 or 2 degrees C.
  50. Are humans too insignificant to affect global climate?
    I am not denying anything. I assume global warming is a reality and would like to know what can be done about it besides drawing a paycheck to crunch numbers all day about how much CO2 is being generated. Denialists, I would say, are those that suggest we can somehow circumvent laws of thermodynamics associated with all form of energy production. Physics aside, while CO2 has something to do with global warming, the phenomenon (as this paper implies) has to do with OVERPOPULATION. Birth control and education, for instance, may be much more relevant towards this cause as compared to the narrow and miopic "scientific" discussion at hand. For purposes of analysis, it is normal and OK to isolate factors, but when you are talking about a system as complex as the Earth, it seems quite ARROGANT indeed to assume you have all the answers, and only be focussing on that one aspect of the problem. and all live in harmony with nature while maintaing unending industrial growth. You cant just focus on one part of this problem, which has been my point since day one.

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