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Comments 67751 to 67800:

67751. muoncounter at 05:00 AM on 25 December 2011
       IPCC Reports: Science or Spin?
       mace#29: "it is proving difficult for the general public to unequivocally accept that warming is happening in general" Let's rephrase that: It is proving difficult for the general public to unequivocally accept that warming is happening because there is an active, well-financed, very powerful lobby working against that acceptance, actively spreading disinformation and distrust. This op-ed is not about climate science, but the first two paragraphs easily could be. Repetition is all-important to spreading a Big Lie.
67752. Dikran Marsupial at 04:56 AM on 25 December 2011
       IPCC Reports: Science or Spin?
       John, my main issue with the bite would be the implication that AGW were likely to be of similar severity to a large asteroid impact (e.g. Chicxulub), which seems to me to be greatly overstating things. Such an impact would be likely to result in the deaths of the majority of humans in a pretty short timespan. I doubt the consequences of AGW would be anything like that severe as there is more time to adapt to the disruption in food supply. I'm willing to admit that I may not be the best person (c.f. Mr Logic) to ask on public communication of science. ;o)
67753. John Hartz at 04:49 AM on 25 December 2011
       IPCC Reports: Science or Spin?
       @mace #29: Your propensity to insert climate deneir memes into your posts, e.g., "...and indeed as we've recently experienced, it's been some 13 years since we had the maximum global mean temperature on some measures," suggests to me that you may have a hidden agenda in posting comments.
67754. Dikran Marsupial at 04:47 AM on 25 December 2011
       IPCC Reports: Science or Spin?
       mace, if the population are not going to accept AGW other than in hindsight ("practical experience) then we are doomed, because by that time we will be committed to more warming than to which the world has the resources to adapt. The purpose of the IPCC scientific reports is to summarise the science, not to provide soundbites that will convince the irrational. A better approach is to explain why waiting for proof by practical experience is unreasonable and fundamentally wrong-headed. If more people understood why the "no warming since 1998" canard to which you referred is is a canard, it would be a start in explaining why the attribution of warming since 1978 not being unequivocal is not justification for doubt of AGW. Now, as I said, please learn about internal climate variability before commenting on this issue further, so that you realise why your line of argument is faulty.
67755. John Russell at 04:20 AM on 25 December 2011
       IPCC Reports: Science or Spin?
       @mace You've explained why people don't believe (though I would suggest some of your facts are out); so that's why it's so important to help people understand the science. Only by understanding the science will people realise the importance of action to prevent dangerous climate change. That's why this site exists. If you really want to convince other people that global warming is a problem, then I suggest you point them at NASA's site where everything is explained in simple terms. Why would anyone believe that NASA doesn't know what they're taking about?
67756. doubtingallofit at 04:07 AM on 25 December 2011
       The End of the Hothouse
       If everything happens for a reason, then there has to be a reason for the Big Bang, a reason for the reason for the Big Bang, etc. Causation is a tenet in science, but that does not mean everything has a cause. It means we search for the cause as a function of the discipline called science. Also, the statement says "no particular reason", not no reason. Maybe wording it differently would have helped, since all attention went to that statement rather than the entire post. As for calling a belief that things can be random or without causation believing in magic, I would reply that magic requires violation of physical laws and unless there's a physical law with mathematical verification that there cannot exist a phenomena with a cause, my belief is not magic.
       Moderator Response: [muoncounter] Your 'beliefs' are of little general interest. Please confine your commentary to the topic of this post. Off topic comments are deleted.
       Please note that posting comments here at SkS is a privilege, not a right. This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum. Please take the time to review the policy and ensure future comments are in full compliance with it. Thanks for your understanding and compliance in this matter.
67757. mace at 04:05 AM on 25 December 2011
       IPCC Reports: Science or Spin?
       @Dikran Marsupial. In science, nothing can be 100% proven, but for most people, it needs to be proven in terms of their practical experience. So, looking at the analogy, I provided earlier, sticking my fingers in an electric socket will cause at least burns and possibly death may not always prove true e.g. a fuse could blow, or a general power cut may exist, but fundamentally, anybody whose experienced an electric shock is aware of the danger. Now, the problem that we have with climate science is that it takes place over a long period of time, so people's experiences of how warm it is today compared to how warm it was in the 1970s, say, is subjective, and because it doesn't warm up in straight lines, and indeed as we've recently experienced, it's been some 13 years since we had the maximum global mean temperature on some measures, it is proving difficult for the general public to unequivocally accept that warming is happening in general, let alone that man is responsible for it.
67758. John Russell at 03:42 AM on 25 December 2011
       IPCC Reports: Science or Spin?
       OK, Dikran, I take the point. Sorry to be sloppy! Unfortunately sometimes you scientists say things in ways which are not totally understandable to those not versed in science. I try to be an interpreter, because I do have a little knowledge; but it's difficult. Please bear with me! I'd be grateful for any comments on the 'bite' I refer to in my previous comment to 'Skept.fr', (above).
67759. John Hartz at 03:39 AM on 25 December 2011
       Updating the Climate Big Picture
       Dana: Figure 1: "Indicators of Warming" ought to be expanded to include severe dought/desertification and severe rainfall/flooding. These two indcators should be mentioned in the text as well.
67760. John Russell at 03:36 AM on 25 December 2011
       IPCC Reports: Science or Spin?
       Skept.fr writes: (on 'Updating the Climate Big Picture' thread)... "I dislike analogies, but if you want absolutely use some, they must be convincing." Well, we must agree to disagree over whether analogies can be effective with the right kind of person, but I agree completely that they must be convincing. Of course, analogies can never be totally convincing -- how could they when they are not 'the real thing' and therefore will fall over at some point of detail? I agree about the 90% point and in fact when I developed this analogy further I dropped it. I'd be grateful if you could take at look at this new 'bite' I put together on ClimateBites (a development of this train of thought) and tell me whether you think it works, or how I might improve it. Perhaps it would be better to use the comments here rather than on ClimateBites -- unless of course you think it's great! Please understand that I'm keen to get the facts right, though with metaphors or analogies it's also important to simplify in order to be understandable and convincing. And we're not aiming at people who have your knowledge of the science. I just want to get to a point where if a reader is clever enough to see any flaws, then they're clever enough to see why it's wrong to be in denial over AGW.
67761. Dikran Marsupial at 03:25 AM on 25 December 2011
       IPCC Reports: Science or Spin?
       John Russell As I understand it, absolute proof of a causal relationship in the real world is indeed impossible via empirical means. Observing the rise in temperatures expected by AGW theory does not prove that the theory is correct, as the prediction might be correct by coincidence and the rise in temperatures is actually due to aliens bombarding the earth with unknown forms of radiation to make the Earth more suitable for their purposes. There is no reason to think the latter theory is correct, of course, but it is also consistent with the observations, and so the observations do not absolutely prove the theory. This is a deliberately extreme example, there are more plausible non-anthropogenic theories, but the point remains. In maths you can have absolute proof, in science you can only have absolute disproof, which is why most modern science operated by falsificationism. The IPCC are very careful and very scientific in their presentation of the strength of the evidence for the mainstream position. Generally those who don't like their terminology (e.g. Judith Curry) seem not to understand probability adequately well. It is ironic that the "skeptics" complain on one hand about claims that the "science is settled" (an argument that the scientists tend not to actually make) and on the other hand complain about the lack of absolute proof, which the philosophy of science tells is that there is no absolute proof of any scientific theory. I think we need a post on philosophy of science.
67762. John Russell at 03:08 AM on 25 December 2011
       Updating the Climate Big Picture
       Sorry if I have misunderstood something, Dikran, but won't we have absolute proof of the consequence of our actions in 50/100 year's time, when we are experiencing the results of putting another ~200ppm of CO2 in the atmosphere? Or are you arguing that nothing can ever be 'absolute' proof? (I've also posted this comment on the 'IPCC Reports: Science or Spin' thread) [Moderator: by all means delete this post if it's O.T., but if you do, please delete my earlier post as well. Thanks.]
67763. John Russell at 03:07 AM on 25 December 2011
       IPCC Reports: Science or Spin?
       Continued from thread, 'Updating the Climate Big Picture'... "John Russell wrote "As I know you know, absolute proof is possible," This is incorrect, I don't want this thread to descend into yet another discussion of the philisophy of science, David Hume showed that we can have no certain knowledge of causal relationships in the real world. Instead, as Hume suggests, we should apportion our belief according to the evidence, but this falls well short of "absolute proof". The point is that the original statement referred to a warming trend since 1978. One could argue that the warming we have observed is due to deep ocean currents redistributing heat within the climate system. Our knowledge of deep ocean currents in the 1980s is unlikely to improve much on what we already know as we don't have a time machine to go back and take more measurements. Thus there will always be irreducible uncertainty on the attribution of warming over that period. What mace fails to understand is that there is a difference between what we can say "all things being otherwise equal" and what we can say about specific observed events. " Sorry if I have misunderstood something, Dikran, but won't we have absolute proof of the consequence of our actions in 50/100 year's time, when we are experiencing the results of putting another ~200ppm of CO2 in the atmosphere? Or are you arguing that nothing can ever be 'absolute' proof?
67764. skept.fr at 03:02 AM on 25 December 2011
       Updating the Climate Big Picture
       #41 John Russell : "I ask them: if there was a 90% chance that the family house they lived in was going to collapse at some time in the next twenty years, would they demand more evidence, or would they get out, fast? " For a skeptic mind, this is typically not a good metaphor or analogy (I've already had this kind of debate with Tom Curtis, by the way). I dislike analogies, but if you want absolutely use some, they must be convincing. In climate sciences' conclusions assessed by IPCC (which form the base for policy advice and citizen reflexion), the 90% level of confidence we're discussing does not concern a "collapse" in a short period (20 years), but an attribution (of past 60 years warming to GHGs as the main cause). See for example confidence levels in the latest IPCC report on extreme events, SREX 2011 (policymakers read the IPCC reports' SPM, not the full report and not some particular work in the abundant literature).
       Response:

       [DB] As previously noted, IPCC discussion is OT here.  Please take this area of the discussion to the IPCC Reports: Science or Spin? thread.

67765. muoncounter at 02:51 AM on 25 December 2011
       Making Arctic Sea Ice Loss Real
       Less technical, but more tasty: Late 1970's minimum volume ~16k km^3, on the left; current minimum volume ~4k, on the right: Our Arctic ice is now 'pint-sized.' Apologies to you metric folks; there are 2 pints in a quart and 2 quarts in a half-gallon.
67766. John Hartz at 02:09 AM on 25 December 2011
       Updating the Climate Big Picture
       Dikran Marsupial & John Russell: Re your exchanges with mace, "Beware of a wolf in sheep's clothing."
       Moderator Response: [muoncounter] Let's go a step further. This posting is a summary article, not a detailed analysis. Protracted argument over exact wording is a distraction; let's make further commentary over shades of meaning of terms like 'very likely' off-topic from this point forward.
       If you would like to continue detailed discussion of specific terminology in IPCC AR4, there are several topic-specific IPCC threads.
67767. Daniel Bailey at 01:49 AM on 25 December 2011
       Making Arctic Sea Ice Loss Real
       

       @ Doug H The mass loss is indeed dramatic. Being volumetric (non-existing in 3-dimensions), it is more difficult to make that volume loss relational. Here are 3 attempts:

        

       

        

       

        

       Note that this final graphic reveals that Arctic sea ice volume has declined in every month of the year, not just the summer minimums.

67768. Dikran Marsupial at 00:28 AM on 25 December 2011
       Updating the Climate Big Picture
       John Russell wrote "As I know you know, absolute proof is possible," This is incorrect, I don't want this thread to descend into yet another discussion of the philisophy of science, David Hume showed that we can have no certain knowledge of causal relationships in the real world. Instead, as Hume suggests, we should apportion our belief according to the evidence, but this falls well short of "absolute proof". The point is that the original statement referred to a warming trend since 1978. One could argue that the warming we have observed is due to deep ocean currents redistributing heat within the climate system. Our knowledge of deep ocean currents in the 1980s is unlikely to improve much on what we already know as we don't have a time machine to go back and take more measurements. Thus there will always be irreducible uncertainty on the attribution of warming over that period. What mace fails to understand is that there is a difference between what we can say "all things being otherwise equal" and what we can say about specific observed events.
67769. Dikran Marsupial at 00:20 AM on 25 December 2011
       Updating the Climate Big Picture
       mace@40 no, we are not in agreement. We can be sure that increasing atmospheric CO2 concentrations will increase temperatures without being sure that the observed warming since 1978 was caused by anthropogenic emissions. Thus your argument that we need to make this link unequivocal implies that a "skeptic" requirement for this linke to be unequivocal is somehow rational or reasonable. When you agree that this requirement is irrational and unreasonable, then we will be in agreement.
67770. John Russell at 00:05 AM on 25 December 2011
       Updating the Climate Big Picture
       @Dikran #37. As I know you know, absolute proof is possible, given enough time for events to unfold. However if we want to avoid potential disaster we can't wait that long. The level of probability that climate cynics demand is way beyond what they would require for any other aspect of their lives. I ask them: if there was a 90% chance that the family house they lived in was going to collapse at some time in the next twenty years, would they demand more evidence, or would they get out, fast? If evidence suggested that there was a 90% chance that our planet was going to be hit by a large asteroid in 30 year's time unless we start work now on a solution; what would they say to me if I told them it was all a scam to raise tax? Moreover it was dreamt up by a conspiracy of scientists: and here's a scientist who used to be big before he retired in the 1990s who's published a paper that shows asteroids don't exist. Anyway, Earth has been hit by asteroids many times before without a problem. And asteroid dust is good for plants. And even if it's true that an asteroid is heading for us, don't to worry -- it'll probably miss us. In the face of so many lines of evidence for man-made climate change, as you say, requiring unequivocal proof is irrational and unreasonable.
67771. mace at 00:03 AM on 25 December 2011
       Updating the Climate Big Picture
       @Dikran Marsupial. I think we're in agreement here. If I was told it's 'very likely' that if I cross the road, I'll be knocked over by a bus, I'd be wary of crossing the road whenever I saw a bus. If I was told that it was 'unequivocal' that sticking my fingers in an electrical socket will at the very least cause burns and potentially death, then I'd definitely not be sticking my fingers in the socket. So, there is a big difference between the 2 statements. My original point is that we need to be extremely careful in our use of language.
67772. Dikran Marsupial at 23:41 PM on 24 December 2011
       Updating the Climate Big Picture
       mace You are merely repeating your error. That anthropogenic emissions of GHG will raise global temperatures, all things being otherwise equal is already unequivocal. However that doens't mean that the warming since 1978 can be unequivocally attributed at anthropogenic emissions because of the "all things being equal" part. The doubt isn't due to the link between GHGs and radative forcing or climate sensitivity. It is because of uncertainties in observations of other forcings and internal climate variability. As I said that is no reason to doubt the link between anthropogenic emissions and global warming. Until you understand that point, repeating weakened versions of your original statement is merely contributing to the noise, not the signal. Some of the science IS settled. Some is not. The attribution of the observed warming since 1978 to anthropogenic causes is not completely settled, for the reasons I have given. It is a bit like attributing a particular extreme climate event to global warming, we can't really do this, we can only say that "all things being otherwise equal" a rise in global temperature will make those extremes more common or worse. Does that mean we don't need to worry about global temperatures with respect to extreme events? No, of course not. We don't need to move the evidence anywhere; the evidence is what it is. What we need to do is to act rationally on the evidence that we do have. If someone told you that crossing a busy street with your eye closed is "very likely" that you will be run over by a truck. Is that enough for you to keep your eyes open when crossing the street, or do you need to be told that it is "unequivocal" that you would be run over? The "skeptics" are in the latter position.
67773. mace at 23:26 PM on 24 December 2011
       Updating the Climate Big Picture
       @Dikran Marsupial. Fair point. In my previous post, I should have said we need to move from 'very likely' towards 'unequivocal'. From the table in the IPCC link, you can see that there a lot of areas in which we will be able to move from 'More likely than not', 'Likely', 'Very Likely' and 'Extremely Likely (>95%)' to unequivocal i.e. 100%. In the 5th report, I would expect most of the current gradings to increase in their levels of confidence. I liken our current predicament with that of early cancer scientists. However, we need to keep an open mind ourselves. In 1926, Johannes Fibiger received the nobel prize for medicine for his discovery that a microscopic worm caused stomach cancer in rats, from which he deduced this was a possible cause in humans. http://www.nndb.com/people/172/000126791/ This is why it's dangerous to label things which are 'very likely' as 'settled science'.
67774. Dikran Marsupial at 23:07 PM on 24 December 2011
       Updating the Climate Big Picture
       mace wrote "True, but there are still people that deny the existence of dinosaurs, for example. Our aim isn't to eliminate all deniers but to marginalise them by producing more and more evidence to support anthropogenic causes of global warming." You have just contradicted your earlier post. No amount o evidence supporting anthropogenic causes of global warming will ever make the trend 1978-present unequivocal, for the reasons I gave. The way to marginalise the skeptics (like those who doubt the existence of dinosaurs) is not to add evidence, but to show that absolute proof is fundamentally impossible, as good scientists know. This requiring unqeuivocal proof is irrational and unreasonable. What you have done is suggest that this requirement for an unequivocal link is somehow reasonable, and hence playing into the hands of the "skeptics" rather than marginalising them. This issue has been discussed more than once on SkS, so I repeat my advice, please read more before posting.
67775. John Russell at 22:37 PM on 24 December 2011
       Updating the Climate Big Picture
       This might be off topic (in which case I can repost on any other suggested thread), but as others have brought up the subject... With reference to the use of the phrase 'climate skeptic' (or 'sceptic' if, like me, you're British): I read someone the other day using the phrase 'climate cynic' (I think it was Joe Romm). I must say I much prefer that to the phrase 'fake sceptic'. My reason being that, OK, we know what 'fake sceptic' means, but to a lay-person it needs explanation. As we all agree, to be sceptical of evidence or ideas that appear to contradict accepted science is a good thing; consequently I don't feel it's right give validity to the word 'sceptic' in the context of a person who is ideologically opposed to the concept of man-made warming. Also, given the way in some quarters use of the word, 'denier' is being manipulated to suggest ideological abuse of 'climate cynics', then maybe this new phrase should be run up the mast and given an airing?
67776. mace at 22:36 PM on 24 December 2011
       Updating the Climate Big Picture
       "suggesting that an unequivocal link should be required to silence the skeptics is deeply misguided. The deniers will accept any uncertainty to support their view, no matter how small" True, but there are still people that deny the existence of dinosaurs, for example. Our aim isn't to eliminate all deniers but to marginalise them by producing more and more evidence to support anthropogenic causes of global warming.
67777. mace at 22:33 PM on 24 December 2011
       Updating the Climate Big Picture
       The direct link to the relevant section in the IPCC report is here:- http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-7.html
67778. mace at 22:29 PM on 24 December 2011
       Updating the Climate Big Picture
       @Dikran Marsupial. The reason why the IPCC does not make the link, as you reckon they should, is because we need to unequivically prove that the amount of greenhouse gas produced by man and not re-absorbed in the carbon cycle, is responsible for global warming. At the moment, it's 'very likely', but to move it to be unequivical will, unfortunately, take a lot more proof. The problem that we have is that the climate is obviously very complex, and the interaction between natural and manmade forcing agents and other feedback mechanisms isn't wholly understood. The problem with claiming that we have 'unequivical' proof that the link is made, is that this would mean that the public would expect us to be able to reliably predict the global mean temperature within a short time frame, 5 years, say, to a degree of accuracy comparable to what they expect from other unequivically proven scientific theories. I would expect that with each report publication, our degree of confidence will be raised each time, which will increasingly move public opinion in our direction.
67779. Dikran Marsupial at 22:05 PM on 24 December 2011
       Updating the Climate Big Picture
       mace if 2. That mankind is responsible for the increase in the percentage of greenhouse gases resident in the atmosphere is 'unequivical' and 3. That greenhouse gases trap heat is 'unequivical' How can the direct link between 2 and 3 be anything other than "unequivocal"? GHGs are GHGs whether they are due to anthopogenic emissions or not. Furthermore you do not appear to understand the link between 2/3 and 1. If it is unequivocal that anthropogenic emissions are increasing the amount of GHGs in the atmopshere and that it is unequivocal that GHGs trap heat, then it follows that it is unequivocal that all things being otherwise equal we are causing the Earth to warm. The only uncertainties lie in changes in other forcings and unforced climate variability. The uncertainty due to the former is fairly small; the variability of the latter is enough that scientific honesty means that we should not claim that the rise actually observed can be unequivocally attributed to our emissions. None of this is a rational reason for skeptics to doubt that our emissions are afecting the climate, and suggesting that an unequivocal link should be required to silence the skeptics is deeply misguided. The deniers will accept any uncertainty to support their view, no matter how small. The correct argument to make is that there can be no absolute proof of a causal relationship regarding the real world based on observational or experimental evidence. PLEASE can you read more widely before posting, you are still contributing to the noise rater than the signal.
67780. mace at 21:41 PM on 24 December 2011
       Updating the Climate Big Picture
       @Tom Curtis, I'd be very worried if anybody on here wasn't completely familiar with the IPCC 4th report, which is the basis on which our concensus holds. The IPCC 4th report uses the following strictly defined terms:- 'unequivical' i.e. 100% confidence 'very likely' i.e. >90% confidence 'likely' i.e >60% confidence. The phrase 'settled science' isn't used but could be construed in most people's minds to be closer to 'unequivical' than to 'very likely', whereas they are a long way apart. The IPCC report says the following:- 1. That there has been a warming trend since 1978 is 'unequivical' 2. That mankind is responsible for the increase in the percentage of greenhouse gases resident in the atmosphere is 'unequivical' 3. That greenhouse gases trap heat is 'unequivical' 4. That items 1 and 3 are directly linked to item 2, is 'very likely'. We need to carry on focussing on making the link in item 4, but claiming that this link is 'settled science' means that we have a complete understanding of the climate, which isn't yet the case. We need to continue the work so far, so that we can turn 'very likely' in to 'unequivical' and finally silence the skeptic-deniers.
67781. CBDunkerson at 20:39 PM on 24 December 2011
       Updating the Climate Big Picture
       James Wilson, setting aside the points others have made about the lack of factual grounding in your comments... it needs to be pointed out that NASA temperature data is virtually identical to the BEST data. Frankly, your insinuation of 'questionable' data is nonsensical given that BEST was used because it is a 'skeptic' data set. Feel free to use NASA data instead. The results don't change. mace, in addition to Tom's points, you should realize that, "the link between this [humans increasing greenhouse gas concentrations] and global warming" is basic physics, and thus somewhat more than just 'very likely'. If the quantity of greenhouse gases goes up then the greenhouse effect increases (i.e. more IR radiation is retained in the atmosphere) and you have global warming. The only people who dispute that are crackpots and those who have been misled by crackpots. All of the prominent 'skeptic' scientists (e.g. Pielke, Spencer, Christy, Plimer, et cetera) concede that human greenhouse gas emissions are causing global warming.
67782. Doug Hutcheson at 18:47 PM on 24 December 2011
       Making Arctic Sea Ice Loss Real
       Good visualisation of area lost. What about mass lost? Presumably this would be even more dramatic.
67783. Philippe Chantreau at 18:15 PM on 24 December 2011
       Updating the Climate Big Picture
       James Wilson, the strange assertions that you make must be supported, otherwise it's just trash talk about the work of others. What does "scientifically defensible" mean? Who are these "external people" and what have they published in the litterature? What are the "known biases"? In what papers were these biases analyzed? When I say papers, I mean peer-reviewed science papers from serious journals. You talk about getting back to the science but you don't provide any scientific reference to a lenghty set of wild assertions. If you decide to respond with anyting specific, make sure it is on an appropriate thread.
67784. Doug Hutcheson at 18:02 PM on 24 December 2011
       Ocean Acidification Is Fatal To Fish
       John Russell@18 Thanks for the link to the pdf on OA. It really opened my eyes to a problem I have read about, but did not understand at all clearly. Near the end of the document, there is a chart showing various CO2 mitigation strategies we could implement and one of them is shown as 'BECS', which I googled and the best match I found was "Bio Energy to Carbon Sequestration": would that be right? I am alarmed at the lag in OA vs CO2 increase, meaning that OA is going to increase for a long time, even if we stop pumping CO2 into the atmosphere today. Evidently, there are no brakes on our steam-roller. Good thing I am not fond of sea-food: perhaps that is a benign genetic mutation for me (grin). We really are a dangerous species! Sigh.
67785. Tom Curtis at 16:12 PM on 24 December 2011
       Making Arctic Sea Ice Loss Real
       For further comparison, that is: 8% of the area of Asia, or equal to the combined territories of India, Nepal, Bagnladesh and Buhtan; 31% of the area of Africa, or equal to the area of Sudan, South Sudan and Libya; and 20% of the area of South America, or equal to the combined areas of Brazil and Colombia. Sorry, no maps.
67786. Tom Curtis at 15:50 PM on 24 December 2011
       Making Arctic Sea Ice Loss Real
       And for the Land down under: (Original map from wikipedia) The shaded area is actually 3,740,000 km^2 (give or take)or about 4% oversize for the comparison. {That's the disadvantage of not having nice small states like Texas for fine tuning ;)} The area of lost ice represents 47% of Australia's territory including Tasmania, but not the Australian Antarctic Territory.
67787. Bob Lacatena at 15:49 PM on 24 December 2011
       Ocean Acidification Is Fatal To Fish
       27, mace, Actually, there has been no time in the Pleistocene Epoch where CO₂ levels rose above 300 ppm (so "spiked" from 285 to 300 is a bit of a stretch), but it does hint at exactly how deadly what we are doing to the atmosphere may be. From my post a few weeks ago (you should give it a read), (Fahrenheit) 451 ppm:

       During the Eemian, an interglacial period that began roughly 130,000 years ago and lasted 16,000 years, temperatures in Europe north of the Alps were roughly 1-2˚C higher than today. Sea levels were 4 to 6 meters higher. CO2 levels were roughly at 300 ppm. Going further back, during a warm period 3 million years ago within the Pliocene epoch, temperatures were a mere 2-3˚C warmer than today (see here and here and here). Sea levels were 25 meters higher. CO2 levels were between 360 ppm and 400 ppm.

67788. Phila at 15:39 PM on 24 December 2011
       Ocean Acidification Is Fatal To Fish
       mace: skeptic-deniers can point to the spikes that occurred during the pleistocene period as being greater than what happened today, In the first place, "skeptic-deniers" have proven repeatedly that they will believe -- or at least say -- just about anything to avoid confronting the reality of AGW. That being the case, I don't think there's any reliable way to "skeptic"-proof graphs (beyond following existing standards for scientific practice). If all else fails, they'll find a way to attack the attempt to make graphs "skeptic"-proof. Any port in a storm, as the saying is. "Skeptics" who point to the Pleistocene ignore the current rate of temperature change, and they also ignore the fact that the Earth now has a population of about 7 billion people (and growing) who are more or less dependent on the environmental status quo. The proper response to the claim you bring up is to point out that it's irrelevant to modern civilization, its infrastructure, its fisheries, blah blah blah. Anyone who can't see that has a vested interest in not seeing it.
67789. skept.fr at 13:48 PM on 24 December 2011
       Foster and Rahmstorf Measure the Global Warming Signal
       #74-77 : thank you all for the different precisions. Papy is right, FR2011 reference is explicitly this GISS source, dealing with stratospheric aerosols only (so volcanic activity). For tropospheric aerosols, both natural and man-made, interesting regional estimates in Streets et al. 2009 , to read with muoncounter's reference. But this is outside the scope of FR2011. Aerosols are clearly still difficult to constrain, for their emissions as well as their effects, but Bob's explanations for analysis methods are interesting.
67790. Tom Curtis at 12:44 PM on 24 December 2011
       Updating the Climate Big Picture
       mace @24, you need to quote the section of the main article which calls something settled science and the equivalent claim from the IPCC which is called "very likely" (>90% likelihood). Otherwise your sentence is post is meaningless. As it stands I cannot find anything called "settled science" above which the IPCC only calls "very likely".
67791. funglestrumpet at 10:48 AM on 24 December 2011
       Updating the Climate Big Picture
       This is an excellent piece of work, thanks. It is probably the most important information that this site puts out because it will do most to convince those who are confused by the opposing views that they are presented with in the media, yet becoming sufficiently worried about it to seek better information. On a technical note, I would like to see more emphasis on the projected sea level rise and its likely non-linear progression (re. Hanson and Sato). For instance, the U.K. government in its infinite wisdom is spending an absolute fortune, which it can ill afford, on the Olympic Games in a city that is vulnerable to sea level rise. The time will likely come in the not too distant future when the chosen site for the games will only be suitable for water-sports, which will, of course, work wonders for real estate values. Long before then, Canute like, there will need to be a new Thames Barrier unless they, the powers that be, wake up and take London to high ground, which won’t be cheap! (And they think that the current financial situation is bad.) It is amusing to read current plans for a new London airport in the Thames estuary, which, I assume, will be designed to accommodate modern versions of Sunderland and Catalina flying boats. Virtually all coastal cities are vulnerable in their own way. A potential three meter rise in sea level from the collapse of the West Antarctic Ice Sheet should concentrate the minds of many, especially of those that can’t swim. On a practical note, errors in proof reading will, in the minds of some, reflect errors in the science it discusses, which is a pity, considering the effort that has clearly gone into compiling it. Though having done some proof reading on my own publications, you have my deepest sympathy. I found the following: ‘theory?". Well’ ‘Unfortunately there is a there is a very vocal’ ‘Th good news’ ‘not to immeditately take’
67792. Rob Painting at 10:13 AM on 24 December 2011
       Updating the Climate Big Picture
       JamesWilson - "Can we get back to discussing science?" Yes, indeed. Like for instance who is taking the NASA dating apart and correcting mistakes? " If you want to convince a Global Warming skeptic" SkS does not attempt to convince fake-skeptics. The evidence for man-made global warming is overwhelming, and yet they still resist the evidence, throwing up one illogical objection after the other.Trying to convince those people is a futile exercise. Our objective is right at the top of the home page: Explaining climate change science & rebutting global warming misinformation
67793. muoncounter at 10:12 AM on 24 December 2011
       Updating the Climate Big Picture
       JamesWilson#23: Your objections to BEST make no sense; that data set was gone over with a fine-toothed comb. See the several existing BEST data threads. What NASA data are you referring to as 'more scientifically defensible' and how does this differ from BEST? Please be sure to cite your sources for these assertions; this is science we're talking about, not hearsay. In case you hadn't noticed, there are hundreds of posts here discussing specific aspects of science. No one is 'sweeping science away.' Many people think having one 'big picture' thread is a very good idea. If you are looking to discuss a specific point, find the thread that deals with it - and read the posting.
67794. mace at 10:00 AM on 24 December 2011
       Updating the Climate Big Picture
       iPCC use the phrase 'very likely' rather than settled. We should stick to the consensus view. Mankind adding gases to the atmosphere that cannot be naturally balanced is settled, but the link between this and global warming is 'very likely', rather than settled. Terminology is important.
67795. JamesWilson at 09:46 AM on 24 December 2011
       Updating the Climate Big Picture
       The choice of graphs seem a little questionable. BEST for example is a much poorer source of land data than NASA. Both have known bias but NASA has a lot more external people pulling the data apart and correcting their mistakes. This is likely to produce more accurate data. But more importantly: NASA produces more scientifically defensible data. This article really isn't going to convince *anyone* skeptical of the science behind Global Warming of *anything*. It also makes so many claims that it difficult to even discuss the science behind it. Can we get back to discussing science? If you want to convince a Global Warming skeptic that is the way. Sweeping science away in "the Big Picture" is what makes people skeptical of Global Warming theory in the first place.
67796. Michael at 09:44 AM on 24 December 2011
       Updating the Climate Big Picture
       Thank you Rob
67797. Bob Loblaw at 09:42 AM on 24 December 2011
       Foster and Rahmstorf Measure the Global Warming Signal
       The links to AERONET and GAW that I posted are to networks of ground-based passive optical instruments that use direct sun readings to measure the atmospheric attenuation at specific (narrow range) wavelengths. The filters can be in the UV, visible, or near-IR portions of the spectrum, and are usually selected with particular types of analysis in mind (i.e., particular types of atmospheric aerosols). These sorts of instruments have several characteristics: - the direct sun reading does not tell you whether the attenuation is the result of absorption or scattering or both. - the direct sun reading does not tell you where in the atmosphere the aerosol is. It represent an atmospheric total. - the initial measurement tells you Total Optical Depth. Data analysis accounts for attenuation due to Rayleigh scattering. Depending on the wavelength, other adjustments are made for absorption by other known gases - e.g. ozone, water vapour, etc. The remainder becomes the Aerosol Optical Depth, and it is wavelength-specific. - depending on the purpose, wavelengths will be selected to avoid certain absorption bands, but you can also target them if you are trying to measure a particular gas (e.g., ozone). - how Aerosol Optical Depth varies with wavelength can tell you a lot about the aerosols - e.g., size distribution. - some instruments (AERONET in particular) take readings away from the sun. This allows identification of many other optical properties of the aerosols, including whether they are mainly absorbers (e.g. soot) or scatterers (e.g. dust). - clouds also have optical depths. Thin ones are measurable, but thick ones absorb everything and optical depth becomes infinite (mathematically). To get aerosol optical depth, analysis includes some sort of cloud screening, so that cloud doesn't get confused with aerosols. - all of this will allow some determination of what type of aerosol is present, and perhaps where it is in the atmosphere (e.g., volcanic dust in the stratosphere). There are other methods of measuring aerosols, such as aircraft sampling, or LIDAR. LIDAR is a laser-based active sampling method that sends light beams into the atmosphere, and measures the return signal. They are capable of creating atmospheric soundings of various optical properties. A quick Google search led me to this European network: EARLINET. I hope this helps clarify some of the characteristics of measuring aerosol optical depths.
67798. Rob Painting at 09:14 AM on 24 December 2011
       Updating the Climate Big Picture
       Michael - the figure is around 20,000 visits per day IIRC. And no where near 7 billion people have access to the internet. Billions are currently starving, so blogging is way down the list of their priorities.
67799. Rob Painting at 08:58 AM on 24 December 2011
       Models are unreliable
       JamesWilson -"Oddly the Jason-2 site shows the change and drop starting in 2010 but...... See SkS post: Sea level fell in 2010 And the latest update from AVISO
67800. Michael at 07:59 AM on 24 December 2011
       Updating the Climate Big Picture
       At the risk of being off-topic here goes on big picture: - CO2 cumulates and incremental emissions have an atmospheric life of tens thousands of years [This is so if one assumes the sinks are cleaning up CO2 from many decades ago - the right way to look at it given the impending feedbacks]. - The general public and most politicians thinks CO2 is a smelly Fart that dissipates quickly once we reduce CO2 emissions. Governments are not interested in informing them otherwise. - Nevertheless this means paleoclimate comparisons are valid given CO2 is the main driver of global temperature for a constant solar irradiance. However, given that the rate of CO2 increase is now 10,000 times quicker than in paleoclimate Newton would not hesitate to claim the transition to Pliocene paleoclimate conditions will also be much much quicker. Basically 25m sea level rises for the 2C target and lots of other nasties. http://www.giss.nasa.gov/research/news/20111208/ http://www.youtube.com/watch?v=hK8BbOnvGJU - This wonderful website of yours gets 2 to 3 thousand users a day in a world of 7bn. It has done great work and is a fantastic resource. - But how can we change the understanding of the public to motivate the politicians ? Or is this off topic ? Best wishes.

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