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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 112101 to 112150:

  1. What caused early 20th Century warming?
    cbrock: Maybe it's better to say they are perturbing the climate equilibrium? How many people know what perturb means? They might just understand equilibrium.
  2. What caused early 20th Century warming?
    Nice, brief post. You might want to reword "greenhouse gas concentrations. . . are now dominating the climate system." Maybe it's better to say they are perturbing the climate equilibrium?
  3. What were climate scientists predicting in the 1970s?
    Marcus, 12, 16 Having consciously taken steps to reduce your carbon footprint, does this not reflect ideological posturing? In my own case, I'm just trying to survive as best as I can. My only ideology with respect to the possibility of global warming has been to preserve my own personal sense of objectivity. I have conceded more than once that GHG can affect climate, however this is different from saying that CO2 is causing global warming. You know very well for instance that energy cannot be created or destroyed. You also know that two thirds of the surface of the Earth is covered with water, and that the Earths atmposphere is proportionally thin as the skin of an apple. You know that the extra CO2 man has produced constitutes only 100 ppm above natures 250 ppm. You explain yourself that a GHG problem has been accumulating for the last 100 years, yet you also know that temperature signals are buried in the noise of global statistics. Even the current article explains that thirty years ago, the science indicated we were possibly heading to an ice age. Yet regardless of all this information, you perceive me as being insidious because I question AGW. As you say, "Wow!"
  4. Can't We At Least Agree That There Is No Consensus?
    And more from Poptech : Pielke Jr. does not need "telling" anything as that is simply his opinion even though it is irrelevant, His opinion is 'irrelevant', especially when it comes to his views about his own papers, right ? Lucky you know the 'truth', eh ? Keep 'em coming - I'll help you to discover more about yourself but you may not like what you see.
  5. Can't We At Least Agree That There Is No Consensus?
    More incredible quotes from Poptech : ...it is explaining to them the criteria for their papers being included... Ah yes, the Poptech method of 'explaining' it to the authors how he knows better than they about their own papers. Lovely. Since I created the list, I know why I included them... Of course you do. Shame no-one else does, especially some of the original authors. Never mind, eh, you know why and that's all that matters. There is nothing in my mind... No comment needed. Pielke Jr. explicitly stated that "Assuming that these are Hypothesis 1 type...", which is wrong... Of course Pielke was wrong...because you are right, right ? Harold Brooks again had the same misconception as Pielke Jr... Of course he did, because you were right again, right ? ...his papers support skeptic's arguments against the negative environmental or economic effects of AGW. After this was explained to Brooks... Ah, again - Brooks had to have his own paper explained to him. Good of you to do so. I have never been pulled up on anything and have bullied no one. As long as you believe that, that's all that matters. There was no mistake made in the link you have provided. Of course not, because you don't make mistakes, do you ? I admire your self-important, self-awareness of your own infallibility. My comment is accurate and I stand by it. Of course you do, because you are never wrong and never make mistakes, do you ? Understood. No one has gotten the better of me. Keep repeating that to yourself and things look better, don't they ? I have yet to spam anything... Unfortunately, anyone at all interested in all this can see all the links where you constantly spam the same nonsense, going round and round until everyone else gets dizzy and you proclaim victory. How nice it would be to live in Poptech world. That consensus is still proceeding without you. Have you noticed yet ?
  6. Berényi Péter at 01:05 AM on 21 August 2010
    The Past and Future of the Greenland Ice Sheet
    #47 Dappledwater at 23:47 PM on 20 August, 2010 Doesn't your whale skull match what is known? It does. However, people here are denying both air and sea surface temperatures were considerably warmer in the Arctic during the Holocene Climatic Optimum than they are today just to make the present feeble warming unprecedented and alarming. Their concern being if Greenland has failed to melt down to the bedrock during those millennia, it would hardly do it now. Truth may be tardy, but in the long run it prevails over communication.
  7. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    theendisfar, I think the correct answer to your question: "How many scientists does it take to change a consensus?" is 1. All it would take would be one scientist whose understanding of the climate mechanics was so much better than the others that he/she would be able to put together an argument that none of the others could refute. That hasn't happened yet over the course of about 100 years. In fact, it has happened the other way more and more. The idea that humans could affect the climate of the planet was once very much not a mainstream idea amongst scientists. That was about 100 years ago. More and more researchers have become convinced over the years.
  8. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    Improving the analogy. Let's say the homeowner added in some of the wiring himself. Let's say it was an electrician who first said that what he had done was potentially dangerous. Let's say that the 97 said that it was much more likely than not that the new work would cause a fire. Let's say that none of the 100 would be the ones to do the repair work. This might be a point of contention; so, I'll say that I really don't know how much stock in alternative energy companies the typical climate scientist owns.
  9. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    theendisfar, I think you'll find that most climate scientists don't care what the consensus is. It's mostly people who can't do the research for themselves who care what the consensus is of those that can. What, there wasn't convection before we starting adding more CO2 to the biosphere? All the forces in play now have existed for longer than we care about. What we are doing changes the balancing point of the forces.
  10. NASA-GISS: July 2010-- What global warming looks like
    Argus, you seem keen to lessen the impact of the recent rain on Pakistan for some reason. Is it, perhaps, their own fault for living too close to a river; or are there too many of them ? Whatever your reasons, and with regard to your list, perhaps you should try to differentiate between those countries which are more used to receiving a lot of rain (e.g. Cherrapunji, which is one of the wettest places on earth; the Choco Department in Columbian, where Lloro is, which is one of the wettest and most humid places on earth; Guadeloupe and Reunion, which annually receive 178cm and 154cm rain per year respectively - as compared to the UK, which we all consider to be a wet country and which receives an average of 59cm); and those countries like Pakistan (49cm per year, even with the monsoon) which aren't so used to these amounts in such a short space of time. (All these can be checked on Climate Temp) Perhaps Pakistan's total of 30cm in 36 hours IS quite unusual after all, eh ?
  11. How climate skeptics misunderstand past climate change
    Eric, your arguments contain so many false assumptions that I can't even follow what you are trying to say half the time. To start with... water vapor feedback definitely DOES depend on the amount. It is just like any other 'greenhouse gas'. The greater the quantity in the atmosphere, the more it will act to prevent heat escape to space and warm the climate. No, atmospheric water vapor is not maintained at a constant level worldwide... but as global temperature increases the global total amount of water vapor does as well. Higher total water vapor = greater greenhouse warming. BTW, you also said that 'clouds dominate albedo'... most studies show that to be the case SO FAR. However, there has been very little change in albedo due to ice melt to date. Only a tiny percentage of the planet's surface which had ice now does not. As time goes by and the large areas of ice on Greenland, Antarctica, the Arctic ocean, et cetera disappear the albedo effects of ice loss will become much greater. Clouds also trap heat in the same way that greenhouse gases do... creating a great deal of debate over whether their NET feedback effect is positive or negative. What we CAN say with a fair degree of confidence is that the net effect is SMALL.
  12. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    Argus et al, Your arguments are roughly analogous to someone discovering that that the electricity in their house is acting unusually, and it happens that 100 electricians to take a look at it. Ninety-seven of them report that there is a problem with the wiring that has reasonable potential of starting a fire at some point. Being able to prove that there will be a fire and what the damages from that fire would be has little to do with whether or not it's a good idea to fix the wiring.
  13. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    How many scientists does it take to change a consensus? What an odd question for a scientist to ask. A consensus is nothing more than a majority of opinions. I guess the proper answer is ZERO. Scientific consensus is a scientific opinion. Theories do not deliver opinions, they either deliver a result or they do not. So if you are saying that AGW because of CO2 is a hard fact, then please provide some evidence that can be repeated by a neutral skeptic. Perhaps now is a good time to create a post on 'Convection and Evaporation cooling versus Radiation cooling within the Troposphere'? If it can be shown that Radiation delivers more energy to the Tropopause than Convection, then AGW because of CO2 is the only explanation for the increase in temps the Earth has experienced since the end of the Little Ice Age. This of course creates new questions regarding energy transfer, but science should be able to sort that out, correct? This all reminds of the Clinton scandal when he was trying to hide his indiscretions with Lewinsky using legal arguments when all it took was a blue dress to make the relationship clear. Everyone has an opinion, where is AGW's 'Blue Dress'?
  14. How climate skeptics misunderstand past climate change
    Cruzn246 #25: "OK if CO2 is such a strong positive feedback, as claimed, how does the earth dramatically cool when it is about 250?" At present CO2 is a human induced climate driver rather than any sort of significant feedback. In order for CO2 to become a major feedback effect you'd need to see something like extreme heat causing massive wildfires without resulting increased plant growth elsewhere... or rising temperatures causing the oceans to expel excess carbon... in short, heat causing a rise in CO2 which causes more rise in heat. I suppose it could be argued that we have something like that now with extra fossil fuels being burned to run air conditioners more due to increased temperatures... but for the most part the increase in CO2 is due to human industry in general rather than being a feedback effect as you describe. As to how the earth cools when CO2 decreases... that seems so obvious that the mere existence of the question indicates some sort of profound misunderstanding of the situation. CO2 and other greenhouse gases 'trap' heat within the climate system. If the quantity goes down less heat is trapped and it gets colder.
  15. The Strange Case of Albert Gore, Inconvenient Truths and a Man in a Powdered Wig
    TOP @14 The judge seems to be saying that the film is being used for political purposes. There have been other politicians that have used science and technology for political ends. Political uses of science such as Gore is doing tend to create a situation where science can be codified into law. This is against science. No, the judge was saying the film was encouraging a particular political agenda, driven by the scientific evidence presented. This is not codifying science into law, but using scientific findings to help drive policy. I wonder what you would have drive public policy ?
  16. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    There is a lot of fuzzy language so far in this post, two examples: - 'many lines of empirical evidence' - is not the same as scientific proof. - saying that the consequences 'could' be catastrophic - is not the same as saying that they 'will' be catastrophic .
  17. gallopingcamel at 23:54 PM on 20 August 2010
    What were climate scientists predicting in the 1970s?
    Marcus (#17), Humanity's efforts to change the planet are pretty feeble compared to what has already been achieved by other life forms. For example, have you ever wondered where the oxygen we breathe came from? Do a little studying and perhaps you will see humanity in a new perspective.
    Moderator Response: This thread has drifted ("lunged," actually) off topic. Everybody please check against the thread topic before you post, and if appropriate go look through the Arguments list on the left side of the page to find a more relevant thread.
  18. The Past and Future of the Greenland Ice Sheet
    BP, doesn't 7500 years ago put it smack dab in the middle of the Holocene Optimum, when Arctic temperatures were much warmer than now?. Doesn't your whale skull match what is known?.
  19. Eric (skeptic) at 23:45 PM on 20 August 2010
    How climate skeptics misunderstand past climate change
    Dappledwater, thanks for link to the other thread. The discussion was all gummed up unfortunately by long tangents into anthropogenic water vapor forcing (in a word: negligible). Feedback works locally on the entire quantity. The climate in any location cannot possibly know or care that the CO2 caused a small amount of global warming, it simply reacts to whatever local warming or cooling is caused by whatever anthropogenic and natural factors are in that location. CO2 warming is almost always going to be the least of those factors. Where it is not (e.g. hot and cold deserts), the feedback will probably be positive (added WV) but limited by lack of water and those being a small portion of the earth.
  20. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    cruzn246, have you looked at the link given to you, to do with empirical evidence ? When you have, try these too : 10 Indicators of a Human Fingerprint on Climate Change 10 Key Climate Indicators point to same finding - Global Warming is unmistakable Then, come back and detail your arguments against. In the meanwhile, from your Oregon Petition link, in what way do you think that Figure 1 (showing Sea Surface temperatures in the Sargasso Sea) argues against anthropogenic global warming ? How did they get their 2005 figure, since the study referred to only went up to 1975 ? How does that Figure 1 prove "George Washington and his army were at Valley Forge during the coldest era in 1,500 years", as they state ? Why does the link to the data behind that Figure 1 not work ?
  21. Berényi Péter at 23:26 PM on 20 August 2010
    The Past and Future of the Greenland Ice Sheet
    #45 KR at 13:32 PM on 20 August, 2010 a bowhead whale skull as evidence for a warmer Arctic is both meaningless and misleading - they like it cold, and live in the Arctic year round According to NOAA Fisheries Office of Protected Resources this is where they live: The site of the skeleton is 500 km away from the present day margin of their habitat, only accessible through heavily ice laden narrow channels. They do like it cold, but being mammals they also need breathing. They can break through 20 cm thick ice with their heads, but not thicker.
  22. How climate skeptics misunderstand past climate change
    Eric, you seem to have a rather confused understanding of climate, such as your claims regarding water vapor
  23. The Good, The Bad and The Ugly Effects of Climate Change
    batsvensson The malaria parasite needs a bare seven days to develop in a mosquito. If mosquitoes live a shorter life then you can bet yout biology textbooks that evolution will find a way to get the cycle a bit shorter. Whether it's the parasite itself or the mosquito or both, one way or another it'll happen.
  24. How climate skeptics misunderstand past climate change
    Cruzn @ 25 - the ice core data seem to disagree with your assertion. See also CO2 lags temperature
    Moderator Response: Cruzn, in addition to that link, see CO2 is not the only driver of climate.
  25. Eric (skeptic) at 22:53 PM on 20 August 2010
    How climate skeptics misunderstand past climate change
    CBDunkerson, it would still be nice to see a model output that didn't have temperature rising indefinitely using capped CO2. The argument that CO2 will increase forever is probably discussed in another thread which I will have to look up. skywatcher, running out of ice with high albedo to melt is great example of a physically limited positive feedback. Unfortunately it is negligible since, according to the albedo page here, cloud albedo dominates. But I would like to see that type of physical limit demonstrated for water vapor. It won't come from GCMs which lack the resolution to model small scale convection and that impact on latent heat transfer (negative), clouds (positive and negative), subsidence (negative), or lack of convection (positive). The amount of positive water feedback depends on the distribution of water vapor, not the amount. So formulas using amounts of increase in water vapor based on warming from CO2 won't work. The answer lies in how the weather changes in a world slightly warmed by CO2. I have read theories here that the amount of extreme climate (concentrated heat and rainfall) is increasing. Climate extremes are negative feedbacks but need to be quantified (and I'm not convinced that they exist). Thanks for the link James. First, in the lapse rate discussion, low latitudes show negative feedback (as I implied above). In the middle and higher latitudes, the feedback is positive. What they don't mention is that the coverage of negative feedback will expand during global warming. Second, in the cloud discussion they mention increases in storm intensity and poleward shifts in storm tracks and other negative feedbacks without seeming to recognize them. Otherwise that section is just muddled and inconclusive. It is actually very simple to use climate models to determine the sign and strength of feedbacks. Concentrated convection is warming, diffuse is cooling. High clouds are warming, low are cooling, mid are ambiguous. Tropical cyclones cool (mainly from subsidence surrounding them). None of this is difficult to understand. One interesting question is how much current measurements match up to the positive and negative feedbacks. A much harder problem is determining the overall evenness of water vapor in world warmed by CO2. Uneven water vapor is cooling, a negative feedback. Evenly distributed water vapor, especially at high altitudes is a positive feedback. Models will not help much until they figure out better ways to integrate small scale weather models into the coarser climate models or computer power increases enough to model small scale weather in climate models. That should not take more than 10 or 20 years IMO.
  26. How climate skeptics misunderstand past climate change
    One thing most folks don't realize is that we are heading to a place most of us are not going to be comfortable with without any help from CO2. If we don't head back into an ice age we will keep melting. there is no static perfection here. It goes one way or the other and it usually goes till things are quite a bit different than now. The coast of FL will go under water again (along with many other places). It is just part of the cycle we have been in for close to 1,000,000 years. Plants and animals will extend their ranges N. It is simply the way it is. Then the ice will come again. That happens when sea currents get so screwed up that warm waters do not make it far enough N anymore. The N hemisphere really controls all of this. Weather is not constant. Get used to it.
    Moderator Response: The rapidity of the current warming does not give us enough time to "get used to it." See "We’re heading into an ice age."
  27. How climate skeptics misunderstand past climate change
    OK if CO2 is such a strong positive feedback, as claimed, how does the earth dramatically cool when it is about 250? It has before. In fact before we slipped into our last ice age CO2 hung on rather stubbornly as temperatures fell dramatically. Seems it isn't quite the force some may think. Let's put it logically. If CO2 is the big dog we should be warmer now than we were at any time in glacial history. We are not even close. What gives?
  28. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    cruzn246, if you believe that, then it merely proves that you haven't bothered to look at all the evidence. All the evidence shows a roughly +0.16 degree per decade warming at a time when the inputs from the sun have been largely trending downwards. This temperature rise has an almost 80% correlation with the rise in CO2 over that same period. If you or any of your denialist mates can point to strong scientific proof that this would have occurred naturally, then I'd be interested to hear it-because such proof has been greatly lacking up to now. Instead, the Denialist Industry has chosen to focus its energies on ludicrous publicity stunts like the one described above!
  29. The Good, The Bad and The Ugly Effects of Climate Change
    (I am still waiting for you to explain the Texas/Mexico case in terms of climate.) Well, you have completely lost me now. Perhaps you have been arguing with yourself all along. As long as you recognise that you are correct, you should be able to finish the discussion with yourself amicably.
  30. What were climate scientists predicting in the 1970s?
    Wow, GC, that post is ludicrous even for you! No one is talking about the next million or so years-we're all simply talking about humanity's obvious ability to greatly impact his environment within the course of our society's history. The fact is that human ingenuity has allowed us to alter our environment in ways no other animal could even dream. From destruction of forests to the alteration of our rivers to the alteration of the the building blocks of life itself-via genetic engineering. By burning material that was absorbing CO2 back when Earth's atmosphere contained more than 10 times the CO2 of today's atmosphere-& when temperatures were a good 6 degrees warmer than today-it doesn't take a Brainiac to figure out that such actions might well be detrimental to our environment in the medium term!
  31. Can't We At Least Agree That There Is No Consensus?
    As for Energy & Environment, well : On our Energy and Environment paper from 1999, had we known then how that outlet would evolve beyond 1999 we certainly wouldn't have published there. The journal is not carried in the ISI and thus its papers rarely cited. (Then we thought it soon would be.) We were invited to submit a piece in 1997 or 1998 and we had this in prep and sent it in. Pielke Jr Looks like he needs telling again, doesn't it, Poptech ? But this is what E & E is really for : "The focus is on energy policy debates in relation to the numerous environmental 'concerns' that have surfaced in recent decades." Sonja Boehmer-Christiansen More from her : (Remember acid rain, the death of Europ'es forests in a few deacdes? Or the death of the global ocean from pollution in the 1970s, the subject of my PhD? Environmental threats have long serves many other agendas, and natural scientists may at least be aware of this.) Hm, familiar so-called skeptical conspiracy-theory nonsense, eh ? But at least she admits to a certain degree of reality : The negative attitudes of the IPCC/CRU people to my often sceptical journal have harmed it. Its impact rating has remained too low for many ambitious young researchers to use it, and even sales may have been affected. Shame about the conspiracy-theory again, though. But her real admission : "I'm following my political agenda -- a bit, anyway," she says. "But isn't that the right of the editor?" That's what being outside the consensus means - political posturing has no part to play in science, so E & E fails as a pertinent, relevant, reliable source of any sort of legitimate science.
  32. What were climate scientists predicting in the 1970s?
    Wow, RSVP, you're truly beyond pathetic-aren't you? Having absolutely *no* real come-back to the evidence I've prevented, you stoop to your usual contemptuous drivel. Pretty much SOP for the Denialists I'd say. The fact is that I don't own a clothes dryer or a car. I walk distances of less than 6km & use public transport for distances of greater than 6km-& yes I source the bulk of my food from local producers. I use energy efficient light-globes, a continuous flow gas hot water system & am on a 50% renewable energy scheme. Yet, contrary to the claims of your fossil fuel industry mates, I'm not "doing it tough"-indeed, because my energy & fuel bills are so low, I probably have more money in my pocket every fortnight than people in otherwise identical circumstances to myself. Which is my point-reducing our CO2 footprint actually isn't "insurmountable", it is only as difficult as it is because your fossil fuel mates-desperate to defend their mega-profits-have convinced the less intelligent amongst us that reducing our CO2 footprint will "Ruin us all". Of course, none of this alters my point from post # 12, which highlights that *all* the available evidence points clearly to how humans are impacting on climate over the last 50-100 years. That you chose not to deal directly with that post, & instead chose to engage in a rather weak ad hominem attack merely reveals the fundamental WEAKNESS of your original position!
  33. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    "The claims made for the OISM petition do not withstand objective scrutiny, and the assertions made in the petition are not supported by evidence, data or scientific research." You could say the same for people who are predicting catastrophic change. There is no scientific proof we are in the process of anything that is not natural at this time.
    Response: There are actually many lines of empirical evidence that we are in the process of "unnatural global warming".
  34. Can't We At Least Agree That There Is No Consensus?
    Poptech wrote : "I told them they were wrong about why their papers were included in the list." Yes, you certainly told them, didn't you, but they still didn't get it, did they ? Maybe you didn't tell them forcefully enough, or is it just that they gave up on you and moved away rather sharpish ? The latter, I think, as can be seen at Pielke's site (the page called, funnily enough : 'better-recheck-that-list' - but you knew better, in your own mind), where you tell Pielke that he is not even aware of what he is talking about ("The fact that you said "assuming" means you are not even aware of why they were listed." - yes, you told him good). Harold Brooks was mystified too : I just noticed I’m the lead author on one of the papers on the list. I have absolutely no idea how that paper could be construed as “skeptical of man-made global warming.” I have no idea how it could be construed as saying anything at all about man-made global warming. And you keep getting pulled-up on the preposterous nature of your little list (e.g. here and here, the latter showing your inability to apologise for your shameful bullying. This site also shows you in your true, nasty colours, and your inability to acknowledge mistakes again. But this comment from you has got to be another classic : I believe a guy with an M.S. in veterinary medicine is competent to review the material concerning AGW and give a scientific opinion on it, yes I do. All the above should be a warning to everyone as to how you work and your willingness to post personal details online about those who get the better of you. Spam away but you will only make yourself look more ridiculous...if that is at all possible !
  35. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    What methodology do you speak of that is in question in this document? Is the anything wrong with charts or graphs in this? http://www.petitionproject.org/gw_article/Review_Article_HTML.php Did they fudge anything? Is there any false data? Also, the statement you made in the end, that 97% of climatologists support this statement. Several independent studies have shown that 97% of climate scientists agree that humans are causing the climate to change, that CO2 is causing global changes to the climate, and that the consequences could be catastrophic. The use of could here gives a lot of wiggle room. If you change the word of will or is you get a drastically different number. There is barely a majority, if that, that says they know a significant change is taking place.
  36. How climate skeptics misunderstand past climate change
    It is a crucial point to make - positive feedbacks are required to reconstruct past climatic change, and as mentioned that leads to sensitivities similar to those calculated for future warming. Otherwise, you cannot account for glacial-interglacial climate shifts. Also important is that a positive feedback does not equal a runaway positive feedback - if the 'gain' is less than 1, then the feedback is necessarily self-limiting. e.g CO2 rise of X leads to a temperature rise of Y and a feeback of 0.5*X, leading to a temperature rise of Y', feedback of 0.25*X, rise Y'', feedback 0.125X etc etc in a geometric series, which is self-limiting. Our best estimate is that the doubling CO2 leads to a temperature rise of ~1C with the feedbacks summed adding another ~2C. In the short term, warming will cost us a lot in albedo, as we have lots of sea ice and snowfileds that can be melted quickly, and so that feedback will operate substantially at first, but eventually that feedback will slow down as there simply won't be as much snowfields/sea ice per unit temperature rise to drive the feedback. The large ice sheets also have the albedo feedback, but changes in their areas will likely take rather longer to become apparent (still a bad thing as like a heavy runaway train their changes are harder to stop).
  37. Is Arctic Sea Ice 'Just Fine'?
    The latest PIOMAS update puts the mid August ice volume anomaly at about -9,700 cubic kilometers. Given that the baseline for mid August is ~14,500 cubic kilometers that puts the current volume at less than 5,000 km^3... well below the previous record low of 5,800 last September - and with a month yet to go on the melt season. It doesn't look likely that a new minimum EXTENT will be hit this year as the ice is very widely dispersed (though it has started bunching up more the past few days), but the volume has fallen off the bottom of the chart. The way things are going, minimum volume this year will likely be below 4,000 km^3... and if the current trend continues for a few more years the September minimum will have dropped from the 13,400 km^3 long term average down to 0... at which point the extent would also perforce be zero - regardless of how the currents are flowing. Hopefully the extreme melt the past two years has just been a fluctuation and the rate of volume loss will slow down.
  38. How climate skeptics misunderstand past climate change
    I suppose “highly sensitive” is a somewhat subjective way of putting it. I’ll consider rewording that part. gallopingcamel, estimates of climate sensitivity from paleoclimate studies have roughly the same range as estimates based on models. This is discussed elsewhere on Skeptical Science – see here and here. Eric, you’ll find the IPCC chapter “Climate Models and Their Evaluation” here.
  39. How climate skeptics misunderstand past climate change
    Third paragraph, last sentence, 4th word from the end should be "an" rather than "a". Eric, positive feedbacks 'end' when the factors driving them do... which obviously means that it varies by feedback. For instance, increased atmospheric temperatures allow the atmosphere to hold more water vapor... thus, as CO2 (or anything else) drives up the atmospheric temperature the amount of water vapor in the air increases. Water vapor is itself a very powerful greenhouse gas... which means that the increased water vapor causes MORE warming. In short, a positive feedback. This feedback would thus continue until the underlying cause of temperature rise (in this case rising CO2 levels) ended OR the planet ran out of surface water... which we'd pretty much have to be TRYING to kill ourselves off to achieve. One of the other major positive feedbacks is ice albedo... as the temperature rises ice melts, which exposes more dark land and water, which raises temperatures more. Again... the positive feedback continues until the external warming factor (rising CO2) ends or the planet runs out of ice... which couldn't happen for a long time and then only if we burned all available fossil fuels. Thus, the reason models show feedbacks 'continuing upwards indefinitely' is that the planet isn't going to run out of water or ice any time soon. The limiting factor is really fossil fuels. When we run out of or stop using those then positive feedbacks will continue playing out for a few more decades and then temperatures would level off. However, if you assume we go after deepwater oil (check), tar sands (check), oil shale (not yet, though Bush tried), methane clathrates (Russia is starting to), and other 'unconventional sources' we could theoretically be burning fossil fuels for another two hundred years or more. With just conventional sources we'd run out completely by around 2100.
  40. NASA-GISS: July 2010-- What global warming looks like
    Rain (from Wikipedia): Most in one minute: 38 millimetres (1.5 in); Barst, Guadeloupe, 1970-11-26. Most in 42 minutes: 300 millimetres (12 in) in 42 minutes. Holt, Missouri, USA. June 22, 1947 Most in 12 hours: 1,144 millimetres (45.0 in); Foc-Foc, La Réunion, January 8, 1966, during tropical cyclone Denise. Most in 24 hours: 1,825 millimetres (71.9 in); Foc-Foc, La Réunion, January 8, 1966 during tropical cyclone Denise. Most in 48 hours: 2,466 millimetres (97.1 in); Aurère, La Réunion, April 10, 1958. Most in 72 hours: 3,929 millimetres (154.7 in); Commerson, La Réunion, April 10, 1958 during Cyclone Gamede. Most in 15 days: 6,083 millimetres (239.5 in); Commerson, La Réunion, January 1980 during tropical cyclone Hyacinthe. Most in one year: 25.4 meters (1000 in); Cherrapunji, India. Highest average annual total: 13.3 meters (523.6 in); Lloro, Colombia. In the last 100+ years, U.K. has experienced 19 rainfalls with more than 200 mm of rain pouring down in 24 hours (also Wikipedia). The devastating effect of 300 mm in 36 hours in Pakistan comes because too many people live too close to a big and changing river. Also, man has made violent rains more dangerous all over the world, by deforestation.
  41. Is the sun causing global warming?
    It might be worth distinguishing in the article between direct and indirect solar influences. The article implies solar activity being direct insolation or sunlight. In that respect Eric is 'off topic', however from what I can make out Kirkby suggests an indirect solar influence which is not insolation related. Maybe the article should cross reference the cosmic ray article?
  42. Climate's changed before
    Svettypoo - I'm afraid your analysis is rather simplistic, for instance you fail to account for reduced solar luminosity further back in time, and also new analysis is casting some doubt on the extremely high CO2 levels once thought to have existed. Atmospheric CO2 concentrations during ancient greenhouse climates were similar to those predicted for A.D. 2100 Furthermore, how exactly do you think the estimates for climate sensitivity came about, if not from the study of Earth's previous climates?
  43. Eric (skeptic) at 20:04 PM on 20 August 2010
    How climate skeptics misunderstand past climate change
    scaddenp, do you have a link to ECS/AR4 (I don't know what those are)? Also do you know of a specific physical mechanism that limits the feedback in the models? Is that physical mechanism weather? Doug, what I was looking for is a model output that stops some time in the future at some temperature. The model outputs I have looked at all continue upwards indefinitely. If the models never have an upper limit to temperature, it's hard to take them seriously.
  44. Eric (skeptic) at 19:58 PM on 20 August 2010
    How climate skeptics misunderstand past climate change
    KR, those are fascinating posts. Do you have any physical explanation of how the feedback mechanism always knows to add 0.5 of the anomaly? For example, how does the tropical feedback limit itself to 0.5 of a worldwide anomaly if the tropics expand due to warming? Or are tropical, subtropical, temperate, desert, etc all the same feedback amount? All based on the anomaly and not the absolute temperature? Is this only long term feedback that ignores short term fluctuations? (e.g. worldwide average albedo changes, short term solar fluctuations, etc) see UAH for example: http://www.drroyspencer.com/wp-content/uploads/UAH_LT_1979_thru_July_10.gif
  45. What were climate scientists predicting in the 1970s?
    Marcus Since you dont believe its hubris, I suggest as an individual you not wait for the entire planet get on board. An easy one might be using a clothes line to dry your clothes (if you arent already doing that). If you have room for a garden, start planting vegetables. Sell your car, and when you ride your bike to the store, make sure you buy local products only. I am still not convinced that using solar panels doesnt trap heat that would otherwise reflect back into space, but you can still do your share by reducing energy consumption, turning off lights at night, etc, but the hardest one I imagine is going to be computer down time.
  46. Can't We At Least Agree That There Is No Consensus?
    Poptech - impact factor is not about popularity - its a measure of the extent of which papers in those journals influence science. And while it can be abused it as close as you can get as an objective measure for the impact of a journal on science. E&E exists as a "tobacco science" journal so that suspect stuff can be published and claimed as "peer reviewed". If you have something of significance to say in science that will pass the real review of your peers then you would be a complete idiot to publish it in E&E. It won't be read, and wont be cited. It exists for another kind of publication altogether.
  47. Climate's changed before
    Firstly I would like to thank you and your website for generating valuable discussion on AGW. Secondly, I would like to say that I don't think it is impossible for humans to change the climate, but that the change we bring about through AGW will be less significant than claimed by your article. In other words, my research has shown that our climate isn't as sensitive to CO2 as most AGW proponents claim. In your article, you claim that "we" can calculate that a doubling of CO2 will result in approximately 3 degrees centigrade. I hope you can enlighten me on the methodology of this calculation. The empirical evidence does not support your conclusions. You can take any era from history, but I will take the Jurassic and Triassic to make my point. The raw data is taken from encyclopedia Britannica 11'th edition. During the Jurassic Period CO2 concentration was 1950ppm (7 times greater than preindustrial levels of 250 ppm). You claim that for every doubling of CO2 temp increases by 3 degrees centigrade. With that logic, the Jurassic period should have been warmer by 9 degrees. It was only warmer by 3 degrees. Triassic period had CO2 concentrations of 1750ppm and was also only hotter by 3 degrees. I understand that other variables were different during that period as well. But, if you look anywhere on the geological timescale you will have a hard time proving that a doubling of CO2 directly results in a 3 degrees increase in temp. Thank you for the article!
    Response: Thanks for the kind comments. Climate sensitivity is essentially the change in temperature in response to a change in the planet's energy balance. So to calculate climate sensitivity, you need to work out how much global temperature has changed in the past and the changes in the planet's energy balance at the time. So if we can obtain records that give temperature (eg - from ice cores) and couple that with records that give changes in solar activity, atmospheric composition and volcanic activity, it's possible to calculate climate sensitivity empirically.

    Climate sensitivity is around 3 degrees warming for a doubling of CO2. A more technically correct definition is 3 degrees warming for a radiative forcing of 2.7 watts per square metre (which is the radiative forcing from a doubling of CO2). So if you want to look at the planet's energy imbalance over past periods, you need to include other variables which affect the planet's energy balance. Specifically, we find that as you go further in the past, the sun is less bright. So you need to consider the combined effect of a dimmer sun with higher CO2 in past periods. When we do that, we find a close correlation between the net radiative forcing and climate.
  48. Plain English climate science - now live at Skeptical Science
    Thanks for the comment, villabalo. I'll add it to my list of source material and bring it to the attention of any of the authors who could find it useful. You might find it appearing somewhere.
  49. The Good, The Bad and The Ugly Effects of Climate Change
    JMurphy, To continue repeating the same mantra borderline me to again reply with "So what?". Nobody have ever denied that ecology is strongly affected by climate as this is a well established observation, not even the quote you refer to denies this - on the contrary they confirm it. However, to claim climate to be an important factor for the spread of malaria is a completely other issue (called nonsense) and it is a great oversimplify of the problem. To take one(1) oversimplified example (since we now play the game of simplification) to show the absurdity it the claim that higher temperature will lead to a greater spread of malaria: it is known that higher temperature can shorten the life time of insects. If the life span of the vector is shorter than the development time of the pathogen, then trivially the pathogen can not spread. In other words, higher temperature can lead to a reduced spread of malaria, contrary to the claim. (I am still waiting for you to explain the Texas/Mexico case in terms of climate.)
  50. Is the sun causing global warming?
    Eric144: "Kirkby's work shows that the science is not settled. I am conflating scientists and environmentalists because that is how the NASA/Hansen/Schmidt/Mann axis behaves." I think your language is riddled with politicisation. I hope you are open to a possible conclusion that you may be wrong as well as your current belief that you think you are correct. If you are really interested in the science, then an 'axis' is irrelevant.

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