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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 109551 to 109600:

  1. A detailed look at Hansen's 1988 projections
    NETDR, there are a couple of glaring flaws in your analysis; "From 1988 to present [Aug 2010] the warming has been .53 ° C - .31 ° C = .22 ° C" 0.53 C is the anomaly for JUST August 2010 while 0.31 C is the anomaly for the entire year 1988. Monthly variations are, of course, greater than annual variations. This method is also subject to huge variations depending on the precise timing. If we pick different months, say March 2010 with 0.84 C anomaly minus November 1988 with -0.03 C anomaly we get a +0.87 C increase... MORE than the model predicted. Also, LOOK at the Hansen graph in the URL you posted. The temperature values BEFORE 1988 diverge significantly from the actual temperature record in individual years. For instance, for 1981 scenario B 'predicted' (7 years after the fact) that the anomaly had been roughly double what the actual record showed. From this we can conclude either that Hansen's model was wrong before it was even released... OR we could be remotely logical and realize that these models were never intended to precisely match each and every year... which is the test you are applying. A model is 'accurate' if it matches the long term trend. Picking out individual years (or months) and saying 'the model is off by X% at this moment in time' is meaningless. Through 2005 the model trend lined up with scenarios B & C. Since 2005 it has lined up with scenario C while emissions have actually been just a bit below those assumed for scenario B. Thus, it could be said that the trend isn't matching the model's prediction for our approximate emissions over the past five years... except that is a ridiculously short period of time on which to base a trend.
  2. A detailed look at Hansen's 1988 projections
    I think the article is far too forgiving with Dr Hansen. He got it significantly wrong. From 1988 to 2010 his graph shows his predicted warming to be. 1.0 ° C - .31 ° C = 69 ° C From 1988 to present [Aug 2010] the warming has been .53 ° C - .31 ° C = .22 ° C http://cstpr.colorado.edu/prometheus/archives/hansenscenarios.png Giving Hanson the benefit of the doubt and using GISS’s own numbers: http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt The earth only warmed 31 % as much as predicted. This is less than scenario “C” which is what was predicted for what would happen with stringent carbon cuts. When the “debate is over” you have all of the answers and are expected to be correct. If he got climate sensitivity wrong that is just an excuse, this means his predictions of 2020 and beyond will be way off track and getting worse each decade.
  3. Risky Business: Gambling on Climate Sensitivity
    A few little things that struck me: It seems a little odd to include Royer 2007 in the climate model category, it's a bit of a hybrid but based on past changes in CO2. Also, where does that the top limit for Royer come from? The paper states "GEOCARBSULF simulations cannot exclude the possibility of a high climate sensitivity"? Finally, why not include Lunt 2010 and Pagani 2010?
  4. Risky Business: Gambling on Climate Sensitivity
    Riccardo "My impression is that our time horizon is pretty near, we're not able (or not willing) to consider long term plans." I really think it's a failure of the imagination. I can speculate about my grandchildren's grandchildren. When people talk about this they don't really visualise it, they just hope that they'll be decent people who'll enjoy life in much the same way we do. In this I'm more with Hansen. I see good possibilities if this generation and the next does the right thing. I see nasty stuff if we and they don't. Of course for them, it'll be just the way the world is. But my generation is not too thrilled about the way our predecessors mucked up our forests and agricultural lands and introduced pests of every kind. I'd hope that our descendants will see that we did our best even though it was too little too late for some things they'll never get to see.
  5. Climate sensitivity is low
    A common misconception that people have about Climate Sensitivity is that it is a fixed value over a wide range of climatic conditions. This leads to some quite bizarre 'analyses' in the denialosphere, attempting to show that CS couldn't be that high because that implies that CO2 contributes far too much of the 33 DegC of extra warmth attributed to the Greenhouse Effect. The fallacy they make is projecting the same CS value back through lower and lower CO2 levels and temperature regimes. Climate sensitivity is an idea used to encapsulate how the planet IN A PARTICULAR CONFIGURATION - temperature, distribution of land masses, ocean currents, air movements, ice cover, vegetation patterns etc - will respond to a change in radiative forcing from whatever source - GH Gases, Solar changes, Aerosols. So Climate sensitivity will certainly be different at different times. In fact sensitivity to a warming pressure would likely be different to the sensitivity to a cooling pressure in the same climate. So sensitivity to a warming pressure at the bottom of an ice age would be higher than at the top of the ice age; with ice down to lower latitudes, any retreat of that ice due to temp rise exposes a larger area of land and sea and thus has a bigger effect on albedo than the same distance of retreat when the ice is only at higher latitudes. However given the thickness of the ice sheets, the time lags in responding to the warming will be large as it takes time for the ice to melt away. Conversely sensitivity to a cooling pressure coming out of an inter-glacial is likely to be high since even modest cooling can quickly increase the area and duration of snow fall; 1 metre of snow has much the same albedo as ice sheets kilometers thick. The time lag responding to any such cooling is thus also likely to be quicker. In an Ice free world, CS to a warming pressure might be much lower since Ice based albedo change doesn't occur. Similarly in a world with very low CO2, a Snowball Earth, CS might also be low. If the world is literally covered in ice, modest warming may not be enough to cause any ice melt - going from -18 DegC to - 15 DegC for example may not cause any ice cover reduction. It would only be when enough warming pressure has occurred that ice cover retreat begins that change might be rapid. In effect, CS would change when the climatic conditions change enough. This is also important when considering the oft cited figure of 33 DegC of warming due to the GH effect. The calculation that arrives at this number is based on the Earths current Albedo; that around 30% of sunlight is reflected away and isn't part of the energy balance. However in a world that is -18 DegC ON AVERAGE, Ice Cover would be much greater, more even than an Ice AGe which still has a positive average temp. At minus 18 DegC, ice cover sufficient to cause 50% of sunlight to be reflected is quite conceivable. The calculation for this albedo gives 53 Deg extra warmth: -38 DegC
  6. The contradictory nature of global warming skepticism
    archiesteel. I'm honest! It's a rarity these days. That's why it actually really annoys when someone says I'm a liar or dishonest. No, I'm completely open about my scepticism, my confirmation bias, my 'illogical' choice of 10 years of data. As I tried to point out (and I'm sure I don't need to!) I'm not a scientist or in any science field. I'm what Americans call a regular Joe - I'm indicative of the vast majority of people out there (I know because in my job I get to talk to lots of people). We don't see what you see. Maybe seeing it scientifically is wrong. Sometimes it takes an outsider to see something an expert has been staring at for some time. You might see noise and incomplete data, I might see something entirely different. Give it just a passing thought, at least. If I get time later I'm going to pop back and show you what my experience was like on here. But if I don't get time then, have fun - and stay healthy Archie!
  7. Risky Business: Gambling on Climate Sensitivity
    Apart from the die-hard skeptics, I think that for the general public is not even a gambling. My impression is that our time horizon is pretty near, we're not able (or not willing) to consider long term plans. In this sense we are culturally limited to the financial-style next quarter results. These considerations does not apply just to climate or global resources limitation but even to our everyday life. And it's the prologue for the disaster.
  8. Risky Business: Gambling on Climate Sensitivity
    I thought the entire article was well written, Graham, thanks. Regarding the above comments on gambling, and stressing the potential disastrous outcomes - I guess it's a fine line to be walked, between over-caution on the one hand, which may lead to complacency, and alarmism on the other, which will of course lead to dismissal by the denialosphere. (Mind you, the skeptic tendency to leave zero space between 'alarmism' and 'nothing to worry about' makes that a particularly difficult task...) If the more pessimistic results from the climate models are at all correct, it's not just gambling - it's more like playing russian roulette, but with nuclear weapons... if you're wrong, it doesn't just affect you, it affects everyone else as well. Sure, it may just be a sub-kiloton tactical nuke, that 'only' takes out your neighbourhood. Then again, it might be the launch code for the world's entire arsenal. The sad bit is that some people look at that problem, and see that it might not be their neighbourhood, but, say, a neighbourhood in Bangladesh, or a low-lying island nation, and they think "Meh, it doesn't affect me" and push the button anyway...
  9. Risky Business: Gambling on Climate Sensitivity
    I thought the last sentence was already pretty good. It really doesn't need the "before it is too late" kind of thing huntjanin proposes. In fact, I was pretty pleased with the way it built up carefully to the pivotal and climactic statements, "Even such a small rise would signal many damaging and highly disruptive changes to the environment. In this light, the arguments against mitigation because of climate sensitivity are a form of gambling." That is the essential point of the post: it is a form of gambling, and a particularly foolish one, like that game 'chicken' middle schoolers play -- but on a planetary scale. In fact, if I were to ask to any change at all, it would be right here, rather than at the end: something to make it clear that we are not talking about just any 'gambling', but such a particularly reckless one, one where the odds are not only heavily against us, but the price paid is unimaginably high compared to any other form of gambling. So I might, for example, change "a form of gambling" to "the worst sort of gamble, with planetary disaster for the price of losing."
  10. Risky Business: Gambling on Climate Sensitivity
    Good post but in my opinion it needs a last sentence, along the lines of "remedial measures should therefore be adopted befor it is too late."
  11. A South American hockey stick
    Looking at the link identified in #19 is quite interesting if one takes the time to examine the records from around the globe. Unless I'm mistaken it appears that the mini ice age was widespread and not confined to Europe as sometimes asserted.
  12. A detailed look at Hansen's 1988 projections
    A slightly pedantic point ... in the calculation the input figures are 3 or 4 significnat figures. Please make them two. eg. 389 ppm -> 390, 329 -> 330, 1788 -> 1800. The rounding will not affect the final 2 sig fig result.
  13. Global warming and the unstoppable 1500 year cycle
    GC - how many times have you brought this up here? How many times has it been explained to you that your conclusion is totally faulty (CO2 can be forcing and feedback and you cant make the maths come out any other way)? What is so hard about you understanding this?
  14. Global warming and the unstoppable 1500 year cycle
    thingdonta, Your words shine like "...a good deed in a naughty world." Merchant of Venice, (William Shakespeare). 1. OK, climate change is happening. 2. The atmosphere causes average temperatures to be ~33 Kelvin higher than without the atmosphere. Let's call that the "Greenhouse Effect". 3. CO2 has an effect on global temperatures but not enough to to explain the observed variations on any time scale. What thingdonta says is totally vindicated by the Vostok ice core records but just for light relief here is Richard Alley's lesser known ice core data going back only 50,000 years for central Greenland. This data set shows the recent "Hockey Stick" but also the warm period that allowed Vikings to colonize Greenland and the subsequent cold period that destroyed their mini-civilization: http://www.foresight.org/nanodot/?p=3553 For those who are inclined to doubt the Foresight Institute, you can make your own analysis by retrieving the raw data from NOAA: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/isotopes/gisp2_temp_accum_alley2000.txt
    Moderator Response: #3 is covered in the post CO2 Is Not the Only Driver of Climate.That's where you should discuss it.
  15. Arctic sea ice has recovered
    Stop the presses, this just in: Mayans were right! North Pole to be ice-free (well, except for various edges) September 2012! From Neven's blog. Gimme lemons, I'll make lemonade... The Yooper
  16. A detailed look at Hansen's 1988 projections
    I did like your comment on adding the actual 2010 GHG concentrations to Table 1, Sense Seeker, and have updated the post accordingly.
  17. Hansen's 1988 prediction was wrong
    Also while actual temps are in the range of Scenario C, greenhouse gas emissions have not followed those in that particular projection. It makes more sense to focus on Scenario B, which has been very close to actual emissions, and then determine why the actual temp change has been lower (mainly the climate sensitivity factor difference).
  18. A detailed look at Hansen's 1988 projections
    Sense Seeker - you can't get to a surface temperature change from a GHG change without determining the associated forcing (and knowing the climate sensitivity parameter). I'm a big proponent of 'show your work', so I don't want to skip that step. Personally I think the logical process in the advanced version is reasonably clear, but the intermediate and basic versions are less detailed for those who just want to get the general gist.
  19. A detailed look at Hansen's 1988 projections
    archiesteel - you are correct. Joe Blog, you have missed the point entirely. The point, once again, is that yes, Hansen's model's sensitivity of 4.2°C for 2xCO2 is too high (in the short-term), but it also tells us that 3.4°C for 2xCO2 is approximately right. This sort of inability to see past the conclusion you want to see is exactly what I was talking about - "a common reaction to Hansen's 1988 projections is 'he overestimated the rate of warming, therefore Hansen was wrong'...This is obviously an oversimplified conclusion, and it's important to examine why Hansen's projections didn't match up with the actual surface temperature change. That's what we'll do here..."
  20. A detailed look at Hansen's 1988 projections
    Joe... You have to bear in mind this is coming from a study done in 1988 and it's an incredibly complex model. Given that Hansen managed to closely predict warming for the following 22 years is astounding. As well, give how much less was known at the time about climate sensitivity it's amazing that he settled on a number that is so close to reality. The scenario C is actually not as close because (I believe) it used more optimistic GHG emissions rates that didn't come to pass. B has the right GHG emissions and is only off on climate sensitivity by 0.8C. It's also impressive that his middle scenario is the closest. It's what you'd be aiming for in a study like this. Think of it this way. What if you had to guess what global temperatures would be 22 years from now. How close could you get? This is essentially Hansen hitting the first ring outside the bulls eye from a very very very long distance.
  21. A detailed look at Hansen's 1988 projections
    archiesteel Yes, so Hansen was wrong, in his climate sensitivity. It certainly doesn't prove Hansens projections were accurate, or disprove criticisms of his projections, as the article claims to do.
  22. A detailed look at Hansen's 1988 projections
    @Joe Blog: "how can this mean anything other than an overstated climate sensitivity" Isn't that the conclusion of the article, i.e. that Hansen overestimated climate sensitiviy (4.2C instead of 3.4C)?
  23. A detailed look at Hansen's 1988 projections
    Youve lost me with this analysis... in the top graph, the closest is scenario C to observations... A and B appear to clearly over estimate climate sensitivity... Now B is the closest to observed emissions clearly, But C is the closest to observations, how can this mean anything other than an overstated climate sensitivity? Now it dosnt matter one iota what anyone's opinion is on what the temps "will be" in a decade, all that matters for testing the model is a straight comparison between projected and observations. It may be due
  24. The significance of past climate change
    Posted by John Cook on Wednesday, 21 April, 2010 at 19:56 PM Climate changes when it’s forced to change. When our planet suffers an energy imbalance and gains or loses heat, global temperature changes. You mean surface temperature, of course. However, surface temperature depends not only on the heat content of the climate system (atmosphere+hydrosphere+soil), but also on surface pressure (via lapse rate). If surface temperature is increased by 1%, surface temperature goes up by 0.5°C. Therefore while it is true a positive energy imbalance implies surface warming, it does not work in the reverse direction. You can have warming with no net heat energy gain, just by increasing pressure. It has no direct consequences on our present situation, for the volume of atmosphere is pretty stable on historic timescales. However, on geologic timescales the situation is radically different. In the late Carboniferous - early Permian atmospheric oxygen level is assumed to be much higher than today, perhaps as high as 35% per volume. If N2 partial pressure is held constant (at 0.754 atm), it implies an overall atmospheric pressure 24% higher than today. This pressure increase alone would make surface temperatures some 12°C higher. Of course according to the Standard Solar Model luminosity of the Sun was 2-3% lower 300 million years ago than it is today. But it would make surface temperatures only 2°C cooler at most. On the other hand we do know surface temperatures in that epoch were about the same as they are today (with slightly more CO2 in the atmosphere). We have 10°C unexplained lack of warming here (and a permanent polar ice cap). That's more than we asked for. The only way out is to assume surface pressure was also about the same as it is today. However, in this case N2 partial pressure must have been about 20% lower than its present value. As average residence time of N2 in the atmosphere is ~20 million years (due to biological nitrogen fixation) and there is about sixty times more Nitrogen in the crust than in air, it seems to be entirely possible, especially because sequestration of organic detritus was particularly intense in those times. However, if N2 partial pressure can vary on a multi-million year timescale, we should be extremely cautious in interpreting the paleoclimate record, for as far as I know, there is no reliable reconstruction in the literature of past atmospheric pressure changes so far. The upshot is that it is rather difficult (or should we say impossible?) to derive climate sensitivity from paleoclimate data while one of the major ingredients is indeterminate. Understanding the nitrogen cycle should be given high priority.
  25. The contradictory nature of global warming skepticism
    pbjamm.... Science journalist Peter Hadfield (aka PotHoler54) does a really good job of explaining it here. In fact, he has a series of videos on climate change that is really good. Highly recommended.
  26. A detailed look at Hansen's 1988 projections
    A night's sleep does help. I can see what you were trying to do. You are comparing the inputs of Hansen's scenario B (translated into forcings) and the actual changes in the input variables (as 'observed' forcings), and then compare Hansen's output (= projected temperatures) with the real output (= realised temperatures). From that you conclude that Hansen's model was 24% too sensitive. It is a pity that the detour via forcings is there, but I guess that is the best way to summarise all different emissions? (I cannot judge that.) You could consider explaining why the translation into forcings is necessary and justified; it was not obvious to me when I first read it. To guide the reader, you could also consider indicating somewhere in the beginning of your explanation what you are going to do, in broad terms. (Determine difference in input values (GHGs) and compare to differences in output (temp) between Hansen's model and reality.) PS: typo "global surface temperature (dF)" should be (dT)?
  27. Global warming and the unstoppable 1500 year cycle
    @thingadonta: You've just commented on a website dedicated to countering with scientific evidence 121 largely disparate, mostly contradictory, and definitely not unified "arguments" placed against climate science ( http://www.skepticalscience.com/argument.php ) -- often made by the same people. The contrast between that situation and the one found in the present state of climate science that unifies wide-ranging physical phenomena and finds multiply converging lines of evidence is utterly striking. If there is any confusion concerning the state of "skeptical arguments", it's certainly not John Cook's fault.
  28. A South American hockey stick
    John, can you correct the mis-spelling of Moberg's name in the article, please.
    Response: Fixed. You'd think I'd have noticed the correct spelling in the graph :-(
  29. The contradictory nature of global warming skepticism
    @Baz: " I have said before that I display confirmation bias (a perfectly human trait)" So, you recognized you are biased, but will not try to correct that bias? And you wonder why we don't take you seriously? It's human to be biased, but it's rather stupid to continue being in the wrong once your errors have been pointed out to you.
  30. The contradictory nature of global warming skepticism
    "KR. I didn't agree with the 20-30 period at all, I accepted that's what the general consensus of opinion is on this site." Umm, but the 20-30 year period is determined objectively from the statistical study of internal variability. I notice that you have given links to this long ago. The point of doing such studies is to have an objective basis for that "consensus opinion". Can you think of a better way?
  31. The contradictory nature of global warming skepticism
    @Baz #314 You have stated:
    "KR. I didn't agree with the 20-30 period at all, I accepted that's what the general consensus of opinion is on this site. I have said before that I display confirmation bias (a perfectly human trait), but I'm in good company here."
    Will you also accept that the reason this is the general consensus on this site is because this is how the term "climate" is defined within the scientific community? Specifically, here is the definition of climate from the AR4 Synthesis Report Glossary:
    Climate "Climate in a narrow sense is usually defined as the average weather, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period for averaging these variables is 30 years, as defined by the World Meteorological Organization. The relevant quantities are most often surface variables such as temperature, precipitation and wind. Climate in a wider sense is the state, including a statistical description, of the climate system. In various parts of this report different averaging periods, such as a period of 20 years, are also used.
    Scientific dialog is most meaningful when participants are using well-established terminology in a consistent manner. There may be other web sites that would be more amenable to your redefining established terminology to suit your argument. Confirmation bias may be a perfectly human trait, but it is poison to scientific reasoning. I don't know to what degree any other bloggers at this site might be guilty of this offense, but if you, personally, are guilty of it AND aware of it, then you relinquish any credibility to valid scientific reasoning. This site is supposed to be about scientific evidence, not to validating preconceived conclusions.
  32. The contradictory nature of global warming skepticism
    Baz, why dont you look at individual model runs? - (predictions for climate are made from average of many runs because it isnt possible to accurately initialise models and the internal variation in models is highly dependent on initialization). An individual run shows you an example of what normal climate physics will produce on a year by year basis. And surprise, you have periods of cooling, slow warming - and rapid warming, but giving 30 year trends. Nothing that contradicts model going on.
  33. Skepticalenergyguy at 07:02 AM on 21 September 2010
    Human CO2 is a tiny % of CO2 emissions
    I agree that we need to be more environmentally responsible, no I'm not an industrialist, I am an engineer. My job is to reduce energy usage for my clients, increase energy awareness, promote environmental stewadardship, and develop creative ways for my clients to do all of these things economically. Thank you all for your input, it gives me stuff to think about.
  34. The contradictory nature of global warming skepticism
    Re: pbjamm (317) I, too, came to his defense to allow him more time to make his case. As you state, I believe he has now made it. I would, however, make the point that most skeptics do not necessarily disagree with the scientific method or even some of the basic tenets of global warming or the greenhouse gas effects; they usually differ in terms of interpretation of various niggling points. There is a different term for those who make an unscientific case for their position. But thank you for taking the time to make your voice heard here. New voices, and the different perspectives they offer, are always welcome. The Yooper
  35. Video update on Arctic sea ice in 2010
    CBD: Clearly, this is more evidence of how warming has stopped (or is flat or is taking a few years off) or whatever. :) At least some people are taking things seriously. "Russia has no plans to deploy troops in the Arctic. We want to strengthen Russia's means of securing maritime security in the region," the Russian Foreign Ministry's Arctic representative Anton Vasilev said at the press conference.
  36. The contradictory nature of global warming skepticism
    re: Rob Honeycutt (315,310,etc) Thank you for making the math of this clear. I am neither a statistician nor mathematician so the notion of what constituted "statistical significance" was never completely clear to me until reading your last few posts. re: Daniel Bailey (316) I was one of the first to come to the defense of Baz but after reading this ENTIRE thread I am having a hard time believing that he is a genuine skeptic. It has become tiresome rehashing the same points over and over. Despite that I feel I have learned a great deal in the course of the discussion so I thank all who contributed. -pbjamm
  37. Should The Earth Be Cooling?
    Re: Ken Lambert (63) Dude, I have to offer up a concession. You usually DO have sources to back up your contentions, unlike others who post here with only opinion for a wingman. I was reminded of this a bit ago when Baz said you were wrong. As his accuracy meter has flat-lined, it was actually a testimony on your behalf! Anyway, where were we? Oh, yeah. In your post #56 above, you focus on a statistically insignificant period of time (i.e., too short of a time period to base any scientific supposition on) and also refer to: "SLR flattening by nearly all analyses". Those were the two points I objected to. If you want to make the statement that it is your "opinion" that there is a "flattening" of temperatures in such a short period of time as you reference, then fine. Baz will make room for you. SLR is what it is. If you wish to contend with The University of Colorado, then go for it. There are various areas in which you have demonstrated a clear understanding of the subject at hand in your various comments I've read on Skeptical Science. I wish there was a way to get around the disconnect on these two items I objected to in my original comment. You are clearly an intelligent person, so I hope that at some point we can work to figure it out. Oh, one other thing. Upon re-reading my comment at 58 above, it comes across a little more strident than I meant it to. I apologize for that tone. I was a little worked-up still from sorting things out with a, um, different commenter; I will try to be more even in tone in the future. The Yooper
  38. The contradictory nature of global warming skepticism
    Re: Baz (305) It is truly difficult to take you seriously anymore. Your contention that Phil Jones introduced the period 1995 to the present is contradicted by your source. Here's Harrabin's questions to Jones:
    "A - Do you agree that according to the global temperature record used by the IPCC, the rates of global warming from 1860-1880, 1910-1940 and 1975-1998 were identical? B - Do you agree that from 1995 to the present there has been no statistically-significant global warming C - Do you agree that from January 2002 to the present there has been statistically significant global cooling? D - Do you agree that natural influences could have contributed significantly to the global warming observed from 1975-1998, and, if so, please could you specify each natural influence and express its radiative forcing over the period in Watts per square metre."
    Nowhere in his response to question A does Jones introduce the period 1995 to the present. Therefore, it is Harrabin who introduces your period in question into the interview, not Jones as you contend. This has become completely tiresome. I leave it to the reader to decide if you have said anything germane or of value at any point. At the very least, it is to be hoped that someone, somewhere, has picked up something of value from this exchange. The Yooper
  39. The contradictory nature of global warming skepticism
    Baz... Yes, that is exactly right. Given the general noise in climate you need 20 to 30 years of data to rise above a 95% confidence level. 1995 to 2009 falls just short of statistical significance, not because of the 0.12C figure, but because it's only 14 years. That's why the question was framed with that specific time frame. That does not mean that there has been any statistically significant warming or cooling (or flattening) in the past 10 years. It can't yet be reliably distinguished from the noise. This was my point. You call out the warming of 1995 to 2009 as not being statistically significant but at the same time you're telling us that the last 10 years are showing us that global warming has stalled or stopped. In this case you can't have your cake and eat it too.
  40. The contradictory nature of global warming skepticism
    Rob, actually he said, "Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods." KR. I didn't agree with the 20-30 period at all, I accepted that's what the general consensus of opinion is on this site. I have said before that I display confirmation bias (a perfectly human trait), but I'm in good company here. CBD. Genuine thanks for all your input. If I wanted to be like some on here are to me, I'd have to say you cherry-picked those time-frames to start from the Little Ice Age ending. But of course, I'd never do that! http://www.co2science.org/articles/V12/N10/EDIT.php Ooh, I bet some here are going to love that link! JMurphy. See graph at terrible website link above. Thanks all. I think I'll conclude my contributions here. However, I'm afraid I will be back. :)
  41. Climate change: Water vapor makes for a wet argument
    johnd - IR is more dominant as an energy pathway than latent heat (evaporation/condensation). Latent heat moves 80 W/m^2 into the atmosphere, while IR moves 356 W/m^2 into the atmosphere (Trenberth 2009). Atmospheric emissions of IR to space are 169 W/m^2, with an estimated 30 W/m^2 from clouds. Evaporation is not the dominant energy pathway, not by a factor of 4. Your statements contradict the actual measurements.
  42. Video update on Arctic sea ice in 2010
    Some interesting developments the past few days. First, what the NSIDC thought was the end of the melt season after 9/10 turned out to just be a 5 day bump. Since then extent has begun declining again and is now below the 9/10 'minimum' and just a hair's breadth above the 2008 low extent. If it drops any further it will tie 2008 for the 2nd lowest result after 2007. Second, PIOMAS just updated their anomaly graph thru 9/14 and shows an anomaly of about -9,500 km^3. Subtracting that from the 13,400 km^3 September baseline would yield 3,900 km^3. However, that baseline value is a monthly average while the anomaly is a daily value and 9/14 is likely close to the minimum for the month. Thus, when the 2010 monthly average is computed it will probably be around 4,000 km^3... still FAR below the previous record low of 5,800 km^3 set in 2009. I did some math based on various statistics they cite on the main page (e.g. "September Ice Volume was lowest in 2009 at 5,800 km^3 or 67% below its 1979 maximum") and came up with some stats on ice loss rates; Max (1979): 17,600 km^3 Mean: 13,400 km^3 Min (2010): 4,000 km^3 Rate: -425 km^3 per year Given that long term rate the ice would be gone in September in 10 years. If the rate over the past decade (~-1000 km^3 per year) continued it'd be four years. If the rate continued to increase as it has been it's just two years. So, I'm calling 2016 +/- 4 years for the Arctic sea ice to be gone except for a few bits and pieces. If the long term trends continued then there'd be no ice even in APRIL (the maximum extent) in about 50 years.
  43. The contradictory nature of global warming skepticism
    CBDunkerson wrote : "If you look at the graph you can pretty easily come up with alternating periods of about 30 years each with 'increasing' and 'decreasing' temperatures; 1850-1880: increasing +0.1 C 1880-1910: decreasing -0.25 C 1910-1940: increasing +0.5 C 1940-1970: decreasing -0.1 C 1970-2000: increasing +0.5 C 2000-2010+: 'flat'" Actually, and without trying to be sarcastic and belittling, we can use the 'Baz' scale to determine the reaction to each of those trends, just by using the sort of logic Baz has used to assert that he no longer believes the earth is warming : 1850-1880: increasing +0.1 C ("Hm, looks like AGW is real") 1880-1910: decreasing -0.25 C ("Hang on, it's not warming !") 1910-1940: increasing +0.5 C ("OK, it is happening. I'm a 'believer'") 1940-1970: decreasing -0.1 C ("Wait a minute, it's not warming...again") 1970-2000: increasing +0.5 C (Oh, perhaps it is. I'll give it another 5 years") 2000-2010+: 'flat' ("Ah ha - it's not warming. Prove it, using a 5 to 10 year trend !)
  44. The contradictory nature of global warming skepticism
    CBD #309: "The reason I didn't choose 1940 to 1950 is because the first period of warming was entirely natural!" Not precisely accurate. MOSTLY natural yes, but not "entirely" natural. Most of the 1910 to 1940 warming was due to increased solar activity, but the enhanced greenhouse effect was also starting to have an impact during that timeframe. I like to turn the 'natural cycles' bit back on the 'skeptics'. If you look at the graph you can pretty easily come up with alternating periods of about 30 years each with 'increasing' and 'decreasing' temperatures; 1850-1880: increasing +0.1 C 1880-1910: decreasing -0.25 C 1910-1940: increasing +0.5 C 1940-1970: decreasing -0.1 C 1970-2000: increasing +0.5 C 2000-2010+: 'flat' From this, it seems like the 'increasing' periods are showing more warming over time while the 'decreasing' periods are showing less cooling... or in the current cycle NO cooling. Which is the sort of pattern you would see if an accelerating warming trend were overlaid onto a regular oscillation. The temperature varies up and down due to a lot of different factors. If the 1910 to 1940 warming had ONLY been solar forcing then temperatures should have dropped back down to the prior level when solar activity declined... they didn't. That 1940 to 1970 period also had alot of aerosol pollution that is believed to have contributed to the cooling. Sorting out all the factors and how much of an impact they've had is a complicated mess... but if we were only dealing with various natural oscillations overlaying each other the long term average would be flat. Instead, it shows pronounced warming. If we ignore the underlying science you are correct... no one can say from the graph alone whether this is a brief fluctuation like others in the past which will be followed by a return to warming OR if we have now hit a peak and temperatures will begin to go back down. But we don't have JUST the graph alone to base our decisions on. We know from direct satellite measurements that there is currently an energy imbalance with more energy coming in to the climate system than is going out. We know that wavelengths of IR blocked by greenhouse gases are being measured in increasing concentrations at the surface and decreasing amounts in space. We know that long settled (~140 years) physics tells us that the increasing CO2 levels we are measuring will produce continued warming. In short, we know for a fact that the total climate system of the planet is continuing to accumulate heat. It has been settled unquestioned science for over a century and we are getting direct measurements of it happening. The fact that the SURFACE AIR TEMPERATURE hasn't reflected that ongoing accumulation much for the past decade is something we call 'weather'. The historical record shows that such fluctuations happen all the time. Right now the heat mostly isn't in the lower atmosphere (though the poles are an obvious exception)... but we KNOW it is still accumulating and thus it is inevitable that it will eventually impact surface air temperatures.
  45. The contradictory nature of global warming skepticism
    Baz - you have been continuing to claim that 10 years of data is enough for you to conclude that warming has stopped. Given the noise in the data, seasonal variations, the Pacific oscillation, etc., 10 years provides very little statistical significance. You agreed with the 20-30 year range earlier in this thread; what happened to that agreement? Essentially you are arguing that the 10 years you have focused on (low statistical significance, very little support for anything but short term noise variations, still within the 2 sigma variations around the previously established trend) is more relevant than the 30 year, highly statistically significant (99.9999 confidence? Way less than a fraction of a percent chance that it's not warming, and we've just picked up noise?) record of a warming trend. That argument really doesn't hold up, Baz. At all. I suspect you're suffering from confirmatory bias. If we don't see warming over 20-30 years, then we'll have strong support for the trend to have stopped or paused. That just hasn't happened yet. What you're looking at is equivalent to a a few cool days in early June (weather) - and from those claiming that summer isn't coming.
  46. A detailed look at Hansen's 1988 projections
    Sense Seeker - I didn't provide the actual atmospheric concentrations of the various GHGs, but I did provide the actual radiative forcing associated with them, which is what matters for these calculations. Also Hansen '88 provided his formulas for dT but not dF, so I used Myhre for the dFs, which are reasonably close to Hansen's values. Ken Lambert - as the GISS forcing link only provided data up to 2003, I extrapolated to 2010 to get a value of approximately 1.06 W/m2. Several commenters have stated that the actual temperatures have run close to Scenario C, which completely misses the point, and I would suggest re-reading the rebuttal. Actual emissions have not been very similar to Scenario C, so comparing to Scenario C rather than B doesn't make sense. Albatross - yes, Scenarios B and C were very similar (perhaps identical, I'd have to go back and look) up until 2000.
  47. The contradictory nature of global warming skepticism
    Baz... What Phil Jones was saying is you'd need a few more years of data to achieve statistical significance, not that the rate would need to be higher.
  48. The contradictory nature of global warming skepticism
    CBD. I've only read the first page so far, but it seems I'm leaning against Ken Lambert at post 12. The reason I didn't choose 1940 to 1950 is because the first period of warming was entirely natural! Man-made warming began in 1975 according to Tamino. When I see this: http://woodfortrees.org/plot/hadcrut3vgl/from:2001/plot/hadcrut3vgl/from:2001/trend ...I see a flattened temperature. I see no warming for 10 years. I see warming stalled, maybe stopped. Now we can argue about one data set, or the 'science' of only using 10 years until we're both blue, but THAT is what I see. I see that black line in the graph above and I wonder if the warming has stopped - and I'm not the only one. If there's no heat in the oceans then me, and others who think 'unscientifically' like me, are going to be right; and you, and others here, are going to be wrong. You cannot say at this stage that I am wrong in that belief, neither can I say you are. Only time will tell the truth.
  49. The contradictory nature of global warming skepticism
    Baz #306: "I don't accept 10 years of flattened temps is conducive to continued global warming." Take a look at the full HadCrut temp graph back to 1850; This clearly shows DECLINING temperatures from 1940 to 1950. Why didn't that 'disprove man made global warming'? Or the 'flat' period from 1960 to 1975? Why didn't the steep rise (0.2 C per decade) from 1980 to 2000 'prove' that we were in for 2 C additional warming by 2100 even assuming no acceleration of warming? Ditto the 0.5 C rise from 1910 to 1940... surely that meant we were in for continued 0.167 C per decade warming, right? Yet the drop in temperatures from 1880 to 1910 clearly indicated that we were heading into an ice age. There have been fluctuations, both up and down, more pronounced and/or prolonged than the 10 year 'level' period you are stuck on... so what is so 'special' about this particular minor fluctuation? Even setting aside the statistical issues... your position just isn't consistent with the historical record.
  50. The contradictory nature of global warming skepticism
    CBD, I need some time to read that!

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