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Comments 106751 to 106800:

106751. DSL at 01:38 AM on 15 October 2010
        Do the IPCC use alarmist language?
        Let me point out the obvious, RSVP and Robert. We act in life and death situations every day with a pitifully tiny amount of information. We walk, run, drive, and ride, for example, with only guesswork and little hard data. We constantly use the well-it-worked-before logic, even though the conditions have changed. In short, we bet our lives--and the lives of others--on what are often totally unscientific leaps of cheap reasoning. A great many of us, in fact, bet our time, money, and happiness (and the time, money, and happiness of others) on the idea that there is a supernatural being that has ordered the universe in some detailed way, according to a book written some thousand or thousands of years ago or according to someone who clearly has a vested interest in having us believe such a thing. And yet that's ok. Then we have the IPCC, which has collected the research and input of thousands of scientists, carefully weighed the significance of the data, modeled it in several different ways, checked and re-checked and re-checked the results, and published the information complete with error bars, recognition of weaknesses, and a host of caveats. If the IPCC had simply collected the data and published it all together without providing any models, people would be beating down the doors demanding models--with all their weaknesses. Do we have to stick our hand in the fire to know that doing so will hurt? Not as adults, we don't. We could stick our hand closer and closer to the fire, but we never know that the feeling of heat will not plateau at a certain point. We have theories, and we use the proxy of a stick, noting that the stick is destroyed (as a stick, not as matter) and that the same will likely happen to us. Children have a hard time understanding proxies, and so they stick their hands in the fire, get burned, cry, and get angry (and then end up projecting that anger on the people who warned them not to do it).
106752. Chris G at 01:06 AM on 15 October 2010
        Explaining Arctic sea ice loss
        RSVP, Regarding, "If the problem were only due to CO2 the effects would be symetrical, and they are not. " I don't believe you'll find any claim that the variability of sea ice is only due to CO2. Weather patterns, changes in salinity, oscillations of current and upwelling flow, albedo feedbacks, etc. all interweave to produce the variability. Wind patterns are driven by differences in energy content, which is also effected by the radiative properties of the atmosphere (CO2 influenced). It's like a multi-body problem in Newtonian physics. If you move one body, the forces acting on the other bodies change; so, they move, which changes the forces acting on the original body, and so on. There is some evidence that the increase in sea ice around Antarctica is driven by some combination of increased snowfall (If you warm the ocean, it gives off more moisture. If it is still below freezing, that moisture will precipitate as snow, which changes the albedo of the surface water, etc.), lowered salinity, and increased outflow of the land ice.
106753. Yvan Dutil at 00:50 AM on 15 October 2010
        Do the IPCC use alarmist language?
        Roger A. Wehage, Your exemple about the rectangle is the typical calculation we do when we calculate error tree and Monte-Carlo methos can catch it very easily. By the way, you confuse risk management with quality control, which are quite different beast. When doing risk management, you put your brain in the paranoid mode. Your exemple from NASA are typical case of how exactely NOT doing risk management. For both Challenger and Columbia, the risk was identified but dismiss because it was annoying to adress it. Hum, looks like climate change debate for me. Also, NASA estimate for risks were too low. In the beguining of the program the estimate was 1/300 failure, while observe rate is more like 1/66. But administrators, put it at 1/10000 but it has to be that way.
106754. RSVP at 00:39 AM on 15 October 2010
        Do the IPCC use alarmist language?
        #30, #31 There are no risk-free alternatives.
106755. protestant at 00:30 AM on 15 October 2010
        New temperature reconstruction vindicates ...
        #154: "I understand Ljungqvist's comment that you cite ("a very cautious interpretation of the level of warmth since AD 1990 compared to that of the peak warming during the Roman Warm Period and the Medieval Warm Period is strongly suggested") and have no problem with that." But your reconstructions DO have a problem with that. Your post maybde had an intention of also vindicating the original hockey stick shape and that the current temperature trend would be unprecedented. The original study doesnt support that. If you want to be credible also in the eyes of us sceptics', next time, when someone publishes a new proxy-reconstrucion, please cite the graphs used in the papers ant not making your own with your own undocumented un-peer-rewieved methodologies. "However, the key point of my post is to assess the degree to which Ljungqvist "vindicates" Loehle (2008) vs "vindicating" other reconstructions. Loehle's reconstruction is supposed to be a global reconstruction, yet it shows a greater amplitude for NH-centric episodes than actual NH reconstructions (Ljungqvist, Mann, Moberg). To me, that suggests that insofar as Ljungqvist 2010 "vindicates" anyone, it's a much better match to Mann or Moberg than Loehle." And if you add temperature data to Loehle, you get basically same results as Ljundgqvist. She shapes on both are remarkably similar. Some differences occur - like Loehle fails to show RWP and also shows LIA a bit colder. It does NOT vindicate Mann, except with the apples-to-oranges comparison you just did and which was justifiedly strongly critisized on my last posts. The shapes of the original studies simply DO NOT agree. #155: "I don't understand that strategy. Crests are, by definition, noise from short term phenomena. Connecting the dots from 1998's crest to 2009's crest is just as arbitrary as connecting the dots from 1993's trough to 2007's trough. The conclusion that 'there's no statistically significant warming 1998-2010' is to use two and only two data points. How is that not cherrypicking?" Since 1998-2010 ENSO has no significant trend (well it HAS a slightly POSITIVE one). Any other short-term trend will get biased by ENSO (La-Nina to El-Nino trendis 4 example). #156: A running decadal average (red below) would be better at extracting underlying trends with minimised ENSO influence, but as this clearly shows the underlying rising trend few deniers would recommend this methodology." Ok, first of all, you cant calculate running 10 year average to 2010. The graph must end on 2005 since you dont know the avg of 2011 yet (needed for calculating 2006 etc.) Seconly, the warming happened until 1998 until it halted to the "high" level. You are trying to debunk a 12 year trend with a 10year average which is almost as long as the whole trendline which was in question. That doesn't really address my argument, really. Even if 2000 decaedal averge is higher than 1990avg it does not mean the temperatures couldn have halted in the end of 90's. If they just stay on the same level they rose to, the decaedal avg will be simply higher. What if the halt lasts also next 10 year, will you be then using 20yr avg to prove "warmest 20 years in the recorded history!"?
106756. Johnny Vector at 00:16 AM on 15 October 2010
        Do the IPCC use alarmist language?
        This is getting off-topic, but since comment #7 is still there... Roger Wehage says NASA spent billions of USD on reliability analysis for the shuttle and still couldn't get an answer that was in the ballpark. First of all, as for the claim of billions spent on risk assessment, [citation needed]. A billion dollars will buy you 4000 years of full-time work from senior engineers; that's a lot of Probabilistic Risk Assessment. But more to the point, he provides a link which destroys his own argument. Follow the link he gives in comment #7 to see that the median reliability of the STS, across numerous studies, ranges from about 1/80 to 1/130. Huh, pretty much exactly the observed reliability. So whence the claim that PRA is impossible, Roger? Yes that's right, the risk assessment by the experts was correct. Remember, in the case of Challenger, all the engineers said "don't launch" until they were overruled by management. Seems to me this whole story does nothing but support the notion that the experts are quite capable of risk analysis of even complex systems, and are to be ignored at your own peril.
106757. Berényi Péter at 23:49 PM on 14 October 2010
        Climate Cherry Pickers: Falling sea levels in 2010
        #107 kdkd at 12:02 PM on 11 October, 2010 there don't seem to be claims about accelerating sea level rise Of course there is one in this very thread. It is based on a post from the same author. "In point of fact, observed sea level rise is already above IPCC projections and strongly hints at acceleration" Or here is another one, this time from Peter Hogarth. "there is a significant weight of evidence of a recent acceleration in rate of sea level rise [...] The weight of peer-reviewed evidence for this acceleration in sea level rise is robust" The meme at this site must have been started by John Cook himself, with an even stronger claim. "So a broader view of the historical record reveals that sea level is not just rising. The rate of sea level rise has been increasing since the late 19th century" Here is a fairly recent one. "Sea-level rise is accelerating faster than the IPCC predicted" These claims are not supported by evidence, still, they keep popping up, undebunked. They are usually connected to alarming projections of even more acceleration in the future (yes, projections, whatever that's supposed to mean, never predictions), based on the alleged accelerating ice loss over Greenland. That acceleration is computed using eight years of GRACE data. Now that's cherry picking. But I can't see it'd meet much opposition here. As for the "scientific approach", University of Colorado at Boulder sea level data are next to useless. They lack error bars completely and the sampling interval is 9.9156 days (several samples missing). It is about one third of a synodic month, but not quite. The difference is 6230 sec (1 h 43' 50''). As the signal itself must contain strong components at multiples of lunar cycle frequency, it looks like an odd choice. The gradual phase shift makes up a full lunar cycle in about 11 years, so on timescales significantly shorter than that it can introduce false trends. This is why Steve Goddard's four month sea level trend does not make sense, not because it is "cherry picking" (it is not, it's just some recent data). It is actually a bit worse than that. He shows data with no inverted barometer correction. If correction is applied, there is no trend whatsoever. Of course in the long run barometric correction should not change the trend at all, because mass of atmosphere is given and there are limits to how uneven its distribution can get before strong winds restore uniformity. But this time span is not sufficiently long. Otherwise there is nothing wrong with the idea that the ocean itself can be used as a global thermometer to check ocean temperature and heat content measurements. This is what Trenberth is trying to do, with not much success so far. The main problems with this ocean thermometer idea is that as we have seen it is not reliable in the short term (neither its long term precision is good enough) and volumetric thermal expansion coefficient of seawater is highly dependent on both temperature and pressure while ocean mass also keeps changing.
106758. Anne van der Bom at 23:28 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Roger A. Wehage, RSVP, in the words of my father, "Your guess is as good as mine." Then I'll take an educated guess over yours or RSVP's. I prefer to use the best available information instead of willfully keeping myself in the dark and pretending the world is just a big blob of unknowable uncertainties.
106759. MichaelM at 23:07 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Roger @22: Indeed, if the population of the planet was only 7 million, instead of billion, and was projected to rise to 9 million then the imperative to act on the projected change in climate would be less. There would be plenty of space and resources to deal with, at best, a 2C change in temperature. But our population is so great, our use of resources so profligate that to continue on the present path is reckless.
106760. SRJ at 22:24 PM on 14 October 2010
        Tai Chi Temperature Reconstructions
        Peter Hogarth, I have a question for your original post. The approach you describe for averaging the proxies seems in my view to be very close to the Composite-Plus-Scale (CPS) method. Especially as it is applied in Ljungqvist, 2010. What are your thoughts on this?
106761. Roger A. Wehage at 21:36 PM on 14 October 2010
        Do the IPCC use alarmist language?
        JMurphy @22: I believe that one should not use the severity or lack thereof in individual events as arguments for or against global warming or climate change. For example, about two hundred years ago the mid Mississippi valley had a powerful earthquake that changed the course of the river. Only a few people died then because only a few people lived in the area. If that same quake were to occur today, hundreds of thousands could die. The same goes for floods and heat waves. Their frequency and severity certainly appear to be increasing. At the same time their impacts on the human population are becoming more severe because of artificial changes we've made to the environment and because of increased population density. For example, heat waves are most severe in paved-over cities that consume hugh amounts of energy to run millions of air conditioners. The unlucky ones are the poor and elderly who cannot afford air conditioners. Many flood disasters are similar. Man has destroyed most of the world's hummus and forest cover and built giant levees to hold back the surging water, only to worsen the situation. Over many decades the U.S. has naively spent many billions of dollars through the Corps Of Engineers to mess with nature; now it is spending many more billions to fix their first mistakes.
106762. Roger A. Wehage at 20:53 PM on 14 October 2010
        Do the IPCC use alarmist language?
        RSVP, in the words of my father, "Your guess is as good as mine."
106763. JMurphy at 20:29 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Come off it, chriscanaris. You start off on natural disasters and then move on to some early heatwave records, posting some material from WIKIPEDIA but ignoring everything that followed on from the bits you liked - 10 to 15 times more information from the 1970s onwards with lots more records.
106764. RSVP at 19:57 PM on 14 October 2010
        Do the IPCC use alarmist language?
        It is redundant to say something is very possible. A thing can either be or not be,... it is either possible or impossible. If it is possible, you can then move on to consider its likelihood (i.e., probability). We know that global warming, for instance is 100% possible, however the probability is indeterminant as the sample space is one.
106765. Riccardo at 19:55 PM on 14 October 2010
        Do the IPCC use alarmist language?
        chriscanaris yes, there has been heat waves, cold spells, floods, forest fire, etc., in the past. Then what? You're completely missing the meaning of probability, which is what James Wight is talking about. Your pedantic list of extreme events is useless as far as the probability of these events is concerned.
106766. Riccardo at 19:48 PM on 14 October 2010
        The sun upside down
        Joe Blog you're right, it was poorly worded. What I wanted to say is that the effect of UV by itself is not new, as clearly stated before when I cited the two papers; though, it may be larger than previously thought. On the contrary, the anti-phase change in the VIS is new.
106767. chris1204 at 19:45 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Heatwaves go back well before the 1980s but this may be purely coincidental: ‘The record for the longest heat wave in the world is generally accepted to have been set in Marble Bar in Australia, where from October 31, 1923 to April 7, 1924 the temperature broke the 37.8 °C (100.0 °F) benchmark, setting the heat wave record at 160 days... The 1936 North American heat wave during the Dust Bowl, followed the one of the coldest winters on record—the 1936 North American cold wave. Massive Heat waves across North America were persistent in the 1930s, many mid-Atlantic/Ohio valley states recorded their highest temperatures during July 1934. The longest continuous string of 100 °F (38 °C) or higher temperatures was reached for 101 days in Yuma, Arizona during 1937 and the highest temperatures ever reached in Canada were recorded in two locations in Saskatchewan in July 1937.’
106768. RSVP at 19:20 PM on 14 October 2010
        Explaining Arctic sea ice loss
        adelady #34 "You're not distinguishing between sea ice and land ice." If you compare the geographies, the poles are almost perfectly inverted. As per links (below), the area contained within the northern 70 degree parallel is ocean, coinciding with the Antartic continent which is also roughly contained with the southern 70 degree parallel. In the one case the pole is at sea level (and encapsulated by land), and in the other, the region is mountainous, surrounded by water. I didnt see anything here about warmer waters causing ice in the north to melt. If anything the water would be cooling as a result. http://geology.com/world/arctic-ocean-map.shtml http://www.lib.utexas.edu/maps/islands_oceans_poles/antarctic_region_pol_2005.pdf
106769. JMurphy at 18:57 PM on 14 October 2010
        Do the IPCC use alarmist language?
        SME wrote : "Lack of planning and foresight by authorities thus seems to be a major factor. A fine example of Murphy at work." It wasn't me, honest ! Anyway, looking at lists of natural disasters, it's curious how most of those involving heatwaves are since 1980. Or is it ?
106770. Joe Blog at 18:36 PM on 14 October 2010
        The sun upside down
        Riccardo specifically this line "But apart from the numbers, there's nothing new in Haig et al. 2010 for the UV range." Maybe i misinterpreted your summary, but it seemed to me you were implying that this articles findings didnt suggest maybe a larger dynamical effect through UV in the stratosphere, rather than a change in short wave forcing at the surface. No question more data is needed to verify these findings. But interesting stuff either way. Obviously more data is needed to draw firm conclusions
106771. Riccardo at 18:20 PM on 14 October 2010
        The sun upside down
        Joe Blog could you please point me to the part of the post that disagree with this quote? I think I've said the same thing.
106772. chris1204 at 18:14 PM on 14 October 2010
        Do the IPCC use alarmist language?
        The Pakistani floods had multiple causes such as: '...unprecedented monsoon rain... attributed to La Niña... Some of the discharge levels recorded are comparable to those seen during the floods of 1988, 1995, and 1997... An article in the New Scientist attributed the cause of the exceptional rainfall to "freezing" of the jet stream, a phenomenon that reportedly also caused unprecedented heat waves and wildfires in Russia as well as the 2007 United Kingdom floods.' Other factors: 'The Pakistani government was blamed for sluggish and disorganized response to the floods... President Asif Ali Zardari was also criticized for going ahead with visits to meet leaders in Britain and France at a time when his nation was facing catastrophe. In Sindh, the ruling Pakistan People's Party ministers were accused of using their influence to direct flood waters off their crops while risking densely populated areas. Pakistani ambassador for UN Abdullah Hussain Haroon called for an inquiry into allegations about rich landowners diverting water into unprotected villages to save their own crops.' Pakistan is no stranger to extreme weather events though these are the worst in its recorded history. The 1931 China floods are arguably the worst in world history with a death toll ranging from 1.3 – 4 million. Not an argument for complacency - mother nature is indeed an angry beast however we understand the recent tragedy.
106773. Joe Blog at 18:13 PM on 14 October 2010
        The sun upside down
        Thanks TOP for the link. Riccardo at 19:12 PM With the benefit of having read the article in question, id have to disagree with your summary of the conclusions of Dr Haigh. I believe in her own words, this better sums up the findings. "The SORCE observations are, however, consistent with a solaractivity-dependent change in the temperature gradient of the solar photosphere4, suggesting that the offsetting irradiance trends with wavelength seen in SIM should appear in each solar cycle. If this is the case, then it is necessary to reconsider the current understanding19 of the mechanisms whereby solar cycle variability influences climate: the impact on the stratosphere is much larger than previously thought and the radiative forcing of surface climate is out of phase with solar activity. At present there is no evidence to ascertain whether this behaviour has occurred before, but if this were the case during previous multi-decadal periods of low solar activity it would be necessary to revisit assessments of the solar influence on climate and to revise the methods whereby these are represented in global models." So basically this is suggesting that the sun may influence climate in the troposphere, through varying UV effects in the stratosphere.
106774. Anne van der Bom at 18:13 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Roger A. Wehage "Because the space shuttle is a nightmare. A little O-ring failure here a little insulation impacting a tile there. A gas leak here a stuck valve there. I've a feeling Earth's climate is no different." Well said. A very good motivation why we should be careful not to change the composition of the atmosphere while we are in the dark about what the exact consequences are. Humanity at the controls of the climate feels about as safe as Homer Simpson at the controls of a nuclear power plant. ---------------------------------- Since you are an expert on models, that is the subject you concentrate on. That is a pitfall. The predictions are based on more than just models. Ice cores for example are another line of evidence that point in the same direction wrt climate sensitivity. Look at the full body of evidence.
106775. Riccardo at 18:07 PM on 14 October 2010
        The sun upside down
        Joe Blog I fixed the Haigh 2005 link, thank you. UV impact, as we noticed before, is (almost) not questioned by anyone; some details may not be clear but scientists essentially agree that the effect is there. On the contrary, the GCR hypothesis is still missing a strong confirmation and it is anticipted that GCR have a small on our climate, if any.
106776. alan_marshall at 17:17 PM on 14 October 2010
        Do the IPCC use alarmist language?
        I must admit I have been frustrated by the conservatism of this projection, not so much now, but particularly when it appeared in earlier IPCC reports with a lower degree of certainty. “Most of the observed increase in global average temperatures since the mid-20th century is very likely (greater than 9 in 10) due to the observed increase in anthropogenic greenhouse gas concentrations.” With the mechanism for heat capture by greenhouse gases proven in the laboratory and confirmed by satellite measurements; with no other mechanism demonstrating sufficient forcing to account for the observed rise in temperature; with temperature and CO2 tightly coupled in paleo-climate data - what other explanation justifies the remaining 1 in 10 uncertainty? An alien secret weapon perhaps? I get annoyed that scientists are expected to prove that the warming is outside the bounds of “natural variation”, as if the latter were an independent phenomenon. It is clear that the natural variation in average temperature in both paleo and human history is predominantly driven by changes in CO2, even if initially triggered by smaller forcings such as variation in solar radiance. Yet the skeptics use the term as if it provides a valid alternate explanation. The rise in CO2 in the second half of the 20th century is obviously anthropogenic because we can make fairly accurate estimates of the oil, coal, peat and wood that has been burnt. When you have a proven relationship between cause and effect, and clear evidence for the cause, denying the effect is pure folly.
106777. SME at 17:13 PM on 14 October 2010
        Do the IPCC use alarmist language?
        As a "truth seeker" (that's a person who is attacked and criticised by people at both extremes :-))I found that comment reasonably OK. I'd have minor quibbles but they are not enough to be worth raising. The addition at the end re Pakistan was unfortunate as it doesn't make the overall point at all well and the argument would have been better with the example excluded. While events such as the Pakistan flooding are complex and cannot be simplistically categorised, a major point is that this disaster was NOT driven by an especially extreme weather event. The overall rainfall is reported to have been in the 20 year flood to 30 year flood range. High - but within the range that people reasonably expect to have to deal with in a sensible manner. Damage would be expected, but not catastophe. In this case other factors appear to have been responsible for turning what should have been a modest disaster into a major one. The biggest apparent factor is a change in land use and irrigation practices in relatively recent times, so that drainage has been routed much more efficiently into areas requiring irrigation, and water which was previously wasted for this purpose is now channelled to where it is most wanted. Usually. Alas, as with many man-made optimisations, when the 25 year flood comes the drainage system does not drain as it did before and instead places the water where it is most unwanted, on this occasion, and fails to "waste" it by sending it to sea as it used to do. Lack of planning and foresight by authorities thus seems to be a major factor. A fine example of Murphy at work. SME
106778. gpwayne at 15:43 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Good to see this covered properly - thanks James. Understanding the nature of predictive science, which can only deal with probabilities, is key to appreciating the nature of the problems we face and the overwhelming likelihood that our actions are storing up great and disruptive problems for the future.
106779. scaddenp at 15:39 PM on 14 October 2010
        Quantifying the human contribution to global warming
        John - the IPCC WG1 report. You have read this I hope. However, you comment is somewhat amnbiguous. A 50-100W/m2 FORCING would be deadly. More like 3.7 I think. Are you asking though about the amount of change in radiation from surface being absorbed by CO2 or the change in the amount of back radiation received by the surface from the amount of change in CO2 alone? You might want to look at Philipona 2004 or liberation.fr.
106780. muoncounter at 14:36 PM on 14 October 2010
        Models are unreliable
        Continuing from here. "The algebra of probabilistic distributions is extremely complex ... Extrapolating complex environmental data described by complex statistical relationships into the future is indeed a difficult process" What you've described (in the linked comment) sounds like a fairly routine problem in particle physics. And yet we build devices that rely on the motion of electrons through semiconductors; we manage to collide protons and anti-protons with statistical certainty (and avoid hysterical claims that we'd be creating mini black-holes in the process). We can even make sense of the results and produce a very competent model of the sub-atomic world. Your argument suggests that if a problem is too complex, we can't put any faith in a model solution. The implication is that it's a waste of time and money to begin that process. Yet that is a challenge that has been met successfully in other disciplines. Some of the comments above suggest that it can work here as well.
106781. Doug Bostrom at 14:31 PM on 14 October 2010
        Medieval Warm Period was warmer
        Heidi, the trouble with simplified, nontechnical explanations is that they must leave out the very details required to make them fully articulate. We can distill and digest but it's a lossy form of compression. In the final analysis, to have understanding and more particularly fully justified confidence in perfect synchrony with the research, one has to dig into literature and end up on a parallel plane w/researchers themselves. Normally this is not a problem. I can give you a broad brush treatment of how a parachute works, I can point to the success of parachutes. You could walk away from such a conversation w/a reasonable degree of confidence in parachutes based on a lossy description. But such a treatment is not durable against concerted resistance. Compared to climate research, I don't have to worry about a bunch of parachute skeptics insisting that parachutes don't work because you and I do not have understanding of their aerodynamic principles up to NASA-Ames standards.
106782. RSVP at 14:30 PM on 14 October 2010
        Explaining Arctic sea ice loss
        Philippe Chantreau #22 "I don't know what you're trying to say there." Comparing the Artic with Antartica, I was saying that the Artic ice is mainly at sea level, and that Antartica ice is mostly mounted on land. Not sure if you ever noticed, but it gets colder as altitude increases, so without doing any reasearch, I made the not so unreasonable speculative comment that the Artic is more predisposed to what is actually being observed than Antartica for this reason. As for your question about my use of quotes around "water" and "land"... these refer to the substrate, whereas the surface is actually ice.
106783. muoncounter at 14:20 PM on 14 October 2010
        Do the IPCC use alarmist language?
        #14: "The algebra of probabilistic distributions is extremely complex" Switching to Models are unreliable as per Mod request.
106784. scaddenp at 14:03 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Well I would have to agree with you on need to explore all parameter uncertainty, and I think (but dont know for sure) that they dont have computer power to explore full model. Annan has paper coming out on model ensemble determination. However, note the approach in climate sensitivity estimation.
106785. Composer99 at 14:01 PM on 14 October 2010
        Newcomers, Start Here
        As one of the newbies here, might I make a suggestion (this being the introductory thread for newcomers)? It would seem to me that the blog posts on this site comprise three types: (1) The 'meat and potatoes' of the site: parsing and skeptically analysing the generic arguments posited by climate contrarians/skeptics (2) Critical analysis of specific instances of (to borrow from Ben Goldacre) 'bad science' on the part of contrarians/skeptics (e.g. blog posts on WattsUpWithThat, or by Goddard or Nova, or posts describing takedowns of Monckton) (3) New and interesting research in climate science Is there a possibility of the other two categories of post getting their own meta-posts, with some sort of permanent link on one of the menu bars?
        Response: Thanks for the suggestion. However, there's so many (2) and (3) type posts, the margins would be overflowing (besides, I have other cooler plans for the margins)
        
106786. scaddenp at 13:54 PM on 14 October 2010
        Medieval Warm Period was warmer
        Heidi, all proxies have two things that make useful. 1/ Something is dependent on temperature in a known way 2/ Some way of dating the proxy. Now ALL proxies have problems. A temperature reconstruction is no good without estimates of uncertainty which are large. Problems with both the temperature relationship and dating dog both. However, that does not mean they are no use. You can test theory to see whether the proxies match within the uncertainties As to individual proxies - best to look up detail. Ice cores, tree rings, stalagmites etc. have excellent time resolution. The oxygen isotope ratio in ice is an excellent thermometer so ice core is probably best we have - but only tell the temperature of places that accumulate ice. Tree rings and stalagmites are more problematic. Sediments, corals etc add in a dating problem. However, I wouldn't get carried away on paleoclimate - its skeptic fun park because of the uncertainty. AGW is founded in physics but tested against paleoclimate.
106787. Roger A. Wehage at 13:37 PM on 14 October 2010
        Do the IPCC use alarmist language?
        "That's not food for thought, its nonsense. The independent probabilities of multiple events don't add." You are absolutely correct. They don't just add or subtract or multiply or divide; they do all these plus thousands or millions of others. Try this: You have a rectangle whose length and width are each described by a normal distribution with a different mean and standard deviation. How would you describe the rectangle's area, length time width? What if opposite sides weren't parallel, and the angles were described by normal distributions with different means and standard deviations? What if the sides weren't even straight lines? What if the distributions weren't normal, but skewed or lognormal or something else? The algebra of probabilistic distributions is extremely complex and a danger in the hands of people who don't understand it or who pretend to. Extrapolating complex environmental data described by complex statistical relationships into the future is indeed a difficult process and subject to many hazards in the hands of those who don't have the prerequisite background or tools. I know enough to know that I have neither the prerequisite background nor the tools to predict the probabilistic distribution of anything more than simple statistical examples.
106788. Tom Dayton at 13:21 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Roger Wehage, you will be surprised to learn that there is more to decision theory than "six sigma." Many decades more to it. There are societies, journals, academic departments, technologies, and successful commercial consultancies specializing in application of those technologies. Just type "decision theory" into your internet search engine. Specifically regarding the IPCC, you could read the relevant sections of the IPCC reports that describe how the IPCC decided on their published probability estimates. But if that's too technical, then you might be interested in a good poster that was presented at the American Geophysical Union in 2009. It was by a PhD student in philosophy, rather than by a statistician, so it is a good, comprehensible, basic, explanation. It does not seem to be online except for its abstract ("A Defence of the AR4's Bayesian Approach to Quantifying Uncertainty"), but perhaps if you contact the author he will send you the contents.
106789. kdkd at 13:15 PM on 14 October 2010
        New temperature reconstruction vindicates ...
        muoncounter #157 You can demonstrate the effect sizes needed for statistical significance as I explained in this post. A further thing of note, is that if you're doing short-series correlations, and the value of R2 varies wildly depending on the start and end points within the set of data that you're interested in, then you're doing something wrong, and need more context or alternative statistical methods. In Peter Hogarth's (#156) instance, you'd want to control for the effect of ENSO in some way, and then measure the trend.
106790. Roger A. Wehage at 13:09 PM on 14 October 2010
        Do the IPCC use alarmist language?
        "Montecarlo methods are more common in complex model uncertainty estimation." I have been in the computer-based modeling and simulation business for over thirty years. I invented the acronym GIGOSIM, which stands for Garbage In, Garbage Out SIMulation. When using computer-based models to analyze highly complex, nonlinear systems whose accurate response predictions depend on many nonlinear topological relationships, parameters, and input data, it is absolutely necessary to identify and include all significant topological, parametric, and boundary data. Montecarlo methods may have some utility if a model's topological and boundary relationships are fairly well established, otherwise they could "verify" erroneous models whose output may appear to give the expected results. Nonlinear systems can do that. Yvan Dutil said, "I did used to calculate failure risk in space mission. This is not that difficult. All you need is decent estimate of the component reliability." If it is not so difficult, then why has NASA spent $Billions on it and failed? Because the space shuttle is a nightmare. A little O-ring failure here a little insulation impacting a tile there. A gas leak here a stuck valve there. I've a feeling Earth's climate is no different. Just as one can't model part of a space shuttle without knowing thousands of boundary conditions, one can't model part of Earth's environment without knowing thousands of boundary conditions. Too many scientists zoom in on one or a few critical factors while ignoring others in the name of simplifying down to manageable levels at the risk of biased or even incorrect projections. This could lead to GIGOSM, and let the reader beware.
        Moderator Response: If you want to discuss the specific topic of climate models' validity, please do so on the thread Models are unreliable.
106791. muoncounter at 12:52 PM on 14 October 2010
        Do the IPCC use alarmist language?
        #7: "more than one billion parts. What is the probability that the shuttle will fail if each part has a probability of 1 in a million of failing?" That's not food for thought, its nonsense. The independent probabilities of multiple events don't add. But we should ask: What is the really alarmist language? The 'very likelys' or 'most likelys' described above? Compare those mild-mannered phrases to 'scam', 'fraud', 'big lie', 'propaganda', 'deceitful', 'snowmageddon', and the like.
106792. barry1487 at 12:30 PM on 14 October 2010
        Do the IPCC use alarmist language?
        

        It's OK to be alarmed when facing extinction

        What does that have to do with climate change or airplanes?
106793. Yvan Dutil at 12:21 PM on 14 October 2010
        Do the IPCC use alarmist language?
        In one of my many former life, I did used to calculate failure risk in space mission. This is not that difficult. All you need is decent estimate of the component reliability. Those have to be crossverified when possible. As for probability assesment, IPCC language has been used to translate scientific uncertainties in layman language. In my mind, this is a combinaison of reported uncertainties (combined pdf) and expert assesment. This is not different of what you see in other field like risk management where similar approach is used.
106794. Heidi at 12:20 PM on 14 October 2010
        Medieval Warm Period was warmer
        So, what I get told often is: How does anyone really know the temperatures during the Middle Ages? There's no data back beyond 30 or 50 years. Scientists are just guessing. It's mumbo jumbo because there's a lot of money in research on climate change. It's a fad. You say it's based on ice core samples, tree rings, coral reefs, and other proxy measurements but how do those work to generate believable information? How can an ice core, for example, tell you the temperature of the earth a thousand years ago? I hope you aren't pulling your hair out right now. It's basic but I get challenged all the time on this in conversations with bright, well-informed, educated people who don't believe in climate change because they don't believe the data. It would be great to have a non-super-technical explanation of why scientists know we are experiencing something truly unique climate-wise; an explanation of the way you measure and why it's accurate. Thanks!
106795. scaddenp at 12:14 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Robert - You could read the papers on estimating uncertainty and probability in various aspects of climate instead of making unsubstantiated suggestions about dart boards. eg Annan and Hargreaves. Montecarlo methods are more common in complex model uncertainty estimation.
106796. Roger A. Wehage at 11:57 AM on 14 October 2010
        Do the IPCC use alarmist language?
        I suppose IPCC have not heard of six sigma. The area under one tail of the normal curve 6 sigma out is approximately 10^-9, which corresponds to a probability of 1 in a billion. The area under one tail of the normal curve 4.5 sigma out is approximately 10^-6, which corresponds to a probability of about 1 in a million. Manufacturing strives for a failure rate of less than 1 in a million. Now some food for thought. The space shuttle has more than one billion parts. What is the probability that the shuttle will fail if each part has a probability of 1 in a million of failing? So where would IPCC come up with their numbers? A dart board? Or let's see; nine papers out of ten said that a doubling of atmospheric CO2 will warm the planet by more than 1.5 degrees, so the probability is 9 out of 10 that it will be more than 1.5 degrees. So which would be more useful to the reader, 9 out of 10, where the numbers were pulled from their butts, or "very" and (un)"likely", which were also pulled from their butts and mean nothing. I claim that the second option is closer to reflecting what the IPCC really knows about their probabilities. $Billions have been spent on computing the space shuttle's probability of failure and probability of catastrophic failure. Here is a little discussion. How well did they do? Miserably. Probably about the same as the old Indian who held up a piece of rope to predict the weather. If it's wet it's raining and if it wiggles the wind is blowing. Probability is all relative. I wouldn't rely on any of their "Three different approaches are used to describe uncertainties..." Astronauts are reckless and know they have a much greater probability of blowing up than passengers in James' airplane. But I'm not, and I won't get on board, especially if he is relying on other sources for his information. How many important inputs were "estimated" (scientific wild ass guesses or SWAGs?) or ignored or left out for simplicity or cost reduction or just overlooked? Back in my college days I computed numbers to three digits with my trusty old Post slide rule. Today, students compute answers to sixteen or more digits and write them all down. Which answer is more accurate? Precise? My advice is, read the information and study the charts and graphs. If something is "very important" to you, then don't take their word for it, but dig deeper into the subject.

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