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Helena at 02:16 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
Yes Yes Yes (in general, you can find punctual counterexamples but that's not what we're talking about) but what's important is that the converse is not true i.e you can have "trend-lines starting closer to the present have a steeper slope than those starting farther back" and an underlying function that is not "an increasing and accelerating function" And it is the converse that the IPCC is saying. They say : "Note that for shorter recent periods, the slope is greater" ==indicating=>> "accelerated warming" That is NOT true. And that's because steeper slopes for short period trends and smaller slopes for long period trends is a general statistical fact. "Note that for shorter recent periods, the slope is greater" can also indicate a cooling trend if you want. You cannot deduce anything from the fact that "for shorter recent periods, the slope is greater", it's just a general statistical fact. -
muoncounter at 02:05 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
Helena #28: "concave up would be correct." This is in reference to a graph presented without any selective trend calculation. I note that you did not challenge the accuracy or applicability of the BEST temperature anomaly vs time graph, so we must take that to mean you accept it's use in this context. So let's go to yes/no questions. You have already agreed that the graph in question is concave up: -Do you agree that concave up is defined by a positive second derivative? -If yes, do you agree that when both first derivative (slope) and 2nd derivative (rate of change of slope) are both positive, the graph describes a function that is accelerating? -If yes, do you agree that an increasing and accelerating function is correctly described by "trend-lines starting closer to the present have a steeper slope than those starting farther back"? -
Helena at 02:04 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
KR : on your first point, it's out of topic here and i don't wanna have troubles with moderators. On the second point, don't you agree with me with the fact that, on average, slopes for longer trends are smaller that slopes for shorter trends, no matter whether you are in a warming or a cooling world, but because it's a simple statistical result ? The only data i have been torturing is when i answered Tom's challenge (proving you can have decreasing 25-50-100 year trends). My torturing of the data was the same that the one the IPCC used for their graph. Therefore i guess we'll agree that what i did for Tom is at the same level as what the IPCC did : poor scientific rigor ! -
KR at 01:53 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
Helena - "... read KR response ... What he says is not entirely correct, the exponential of the CO2 is taken care of by the log of forcings, it doesnt really play there (the exponential, not the CO2 !)." Actually, Helena, Tamino has demonstrated that CO2 forcing is increasing at a rate greater than exponential, meaning that CO2 forcing is increasing at a rate greater than linear. Meaning that the CO2 forcing component is accelerating. However, the core of your posts here have been nit-picking, and incorrect, complaints that the IPCC graphic shown in the opening post is somehow proven wrong by cherry-picked short term trends, or by wordplay with longer terms. Your arguments have the appearance of someone torturing the data to support a favored point, rather than considering the data for it's worth - I sincerely hope that's not the case. -
Helena at 01:52 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
Ricardo "you did not show that "on a very general basis, longer trends tend to have smaller slopes." " I did not *show* that because the fact that trends over long time periods generally imply smaller slopes is a simple statistics, especially for a physical phenomenon like temperature. Of course you can find punctual counterexamples, but they are punctual. Just think about it : let's say, i'm sure you'll agree, over the past millenium, global temperature was constrained between 0 and 30°C (so we make it very very general). That means that the largest linear trend you can find if you look for the trend over the last 1000 years is 0.3°C/decade. Now let's look on year to year basis, and let's assume that the maximum year to year variation for global temperature is 0.3°C/yr. That's 3°C/decade, already ten times more than the millenium one (which was calculated supposing a 30°C variation !!!). Anyway, i guess you get it : long time trends are much more constrained that short time trends, and therefore you get on average more big trends on shorter times than on longer times. Are you convinced ? -
Riccardo at 01:23 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
No Helena, you di not show that "on a very general basis, longer trends tend to have smaller slopes." You can easily find short term trends with smaller slopes if you change your start point. Again, you are misinterpreting the meaning of what you calculated. -
Riccardo at 01:20 AM on 14 May 2012Turbines in Texas mix up nighttime heat
Nick I think I see what you're saying but the derivation of the Betz's law you quoted assumes a purely laminar flow along the turbine axis, no turbulence whatsoever. If that is the ideal case, heat dissipation due to turbulence damping has to be part of the about 10% overall losses. Then, muoncounter's number is largely overestimted. -
Helena at 01:19 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
small trend = trend over a small time period long trend = trend over a long time period -
Helena at 01:17 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
Moreover, the evolution of the slope does not indicate anything about what the record is actually doing : the record can be going down while the slope of the various trends can be increasing simply because the trends get calculated on smaller time periods. -
Helena at 01:14 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
Ricardo, what i am showing is that, on a very general basis, longer trends tend to have smaller slopes. And therefore what the IPCC shows as an indicator of accelerated warming is merely a statistical artifact. They start with a long trends small slope and end up with a small trend large slope (accelerated warming). I start with a small trend large slope and end with a large trend small slope (decelerated warming). -
Riccardo at 01:01 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
Helena I didn't follow the discussion but at a cursory reading of your claim I find it like a world upside down. You start at an early time and go forward while the IPCC goes the other way around. Are you surprised that you get different or even opposite results? The problem is the meaning and that's what (it seems to me) your're missing. -
Helena at 00:56 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
(therefore your trends don't indicate anything for the behavior of temperature, as i said) -
Helena at 00:54 AM on 14 May 2012IPCC graph showing accelerating trends is misleading
Well, first the trends you calculated are NOT the ones shown on the IPCC. Second, you can easily imagine a temperature record with, as shown by IPCC, a greater slope for shorter periods indicating accelerated warming but where the temperature is in fact cooling. -
Helena at 23:32 PM on 13 May 2012IPCC graph showing accelerating trends is misleading
Eric most of what you say is out of topic we're not discussing natural or man-made acceleration here. We're just discussing the IPCC graph and their use of trends as an indicator of accelerated warming or to support their specific statement.Moderator Response:[DB] Actually, most of what Eric has stated is on-topic and germane to this discussion. You are tortuously arguing against a very simple point:
Using Woodfortrees, this is easily seen, thusly:"Note that for shorter recent periods, the slope is greater, indicating accelerated warming."
[Source]
Or just the trends themselves:
[Source]
Where is the disagreement from the statement to the graphics? It really is that simple.
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Eric (skeptic) at 22:46 PM on 13 May 2012IPCC graph showing accelerating trends is misleading
"concave up would be correct. Nobody is saying it didn't warm here." Helena, your phrasing is regrettably imprecise. Muoncounter pointed out that the warming is accelerating by a concave graph. "You can easily imagine records where linear trend fits to the last 25, 50, 100 and 150 years (and even 75 :) ) increase but where the is no warming." Again the issue is acceleration of warming, not simply "warming". The IPCC caption is"...Linear trend fits to the last 25 (yellow), 50 (orange), 100 (purple) and 150 years (red) are shown, and correspond to 1981 to 2005, 1956 to 2005, 1906 to 2005, and 1856 to 2005, respectively. Note that for shorter recent periods, the slope is greater, indicating accelerated warming".
The IPCC graphic is overly simplistic (IMO) since it does not discuss the extent of natural acceleration and deceleration that could lead to a superimposed natural and manmade acceleration. That would require a paper. But the IPCC claim is that there is acceleration of warming (unattributed) and that the acceleration is current (as of 2005). -
BC at 22:22 PM on 13 May 2012Arctic Winter Analysis
Thanks for the interesting article.It'll take a few reads to absorb. A question in the meantime - how do scientists get the sea level pressure and the surface air temperature measurements for a place like the Artic? -
Nick Stokes at 21:24 PM on 13 May 2012Turbines in Texas mix up nighttime heat
Michael, one could say, why not add in the rotational velocity of the Earth as well? Or is air in a plane hotter after take-off? KE for this purpose would be calculated with mean square velocity - ie square of deviations about the fluid mean velocity. Otherwise it depends on frame of reference. Definition of temperature requires local thermodynamic equilibrium in a volume. That volume would have to be moving with the fluid. If there is flow through the volume, then there is advection - no equilibrium. I don't believe the generator exports 59% of the wind energy - that's a very theoretical max. Riccardo, I agree that the 40% refers to emerging KE. My point is that it's no longer avial flow - it's azimuthal or turbulent eddies, and it can't go anywhere much. When it decays, as it must, it will be converted to heat. But MS's calc says it won't raise the temperature much. -
Glenn Tamblyn at 20:25 PM on 13 May 2012Two Centuries of Climate Science: part three - Manabe to the present day, 1966-2012
LT @3. I love the image that in 'skepticland' they get confused easily. "It would be more accurate to say that greater CO2 concentrations cause the outgoing energy to meet greater resistance as it passes from the surface to outer space." My understanding of ther GH Effect is that most 'outgoing radiation' from the surface gets absorbed - perhaps 99%. What matters far more is how much of this initially absorbed radiation 'eventually' manages to escape. The GH effect is defined, less by how much is initially absorbed, rather than by how much is subsequently re-radiated. It is increased restriction of the re-radiated component that is the main game. -
michael sweet at 19:25 PM on 13 May 2012Two Centuries of Climate Science: part three - Manabe to the present day, 1966-2012
Lazyteenager, You are incorrect. The energy into the Earth system currently does not equal the energy out. The Earth has an energy imbalance caused by human greenhouse gasses. See this post for evidence of ocean heat uptake. Energy in equals energy out at equilibrium. The equilibrium has been upset and the globe must warm to re-establish the equilibrium. -
Helena at 19:08 PM on 13 May 2012IPCC graph showing accelerating trends is misleading
Sphaerica27 : It's really a pain to understand what you're looking for. Everything is done on woodfortrees with HadCRUT3 variance adjusted global mean. First my homework : what i showed, responding to Tom's challenge : "it is not possible to pick arbitrary end points mimicking the IPCC graph, and to show a deceleration over the temperature record as a result. You have no counter example to the IPCC's procedure. " is that there exist a common start point for which it works : 1910-1934 > 1910-1959 > 1910-2009 gives a decreasing trend as you get closer to present : 25yr trend #Selected data from 1910 #Selected data up to 1934 #Least squares trend line; slope = 0.013717 per year 50yr trend #Selected data from 1910 #Selected data up to 1959 #Least squares trend line; slope = 0.00773312 per year 100yr trend #Selected data from 1910 #Selected data up to 2009 #Least squares trend line; slope = 0.00742333 per year The closer you get to present, the smaller the trend. Uhhhhhhhhhh Back to IPCC graph. The second thing i showed it that the not depicted 75yr period 1931-2005 is > the 100yr period 1906-2005, which goes against the increasing trend assertion by the IPCC. 100yr #Selected data from 1906 #Selected data up to 2005 #Least squares trend line; slope = 0.00724928 per year 75yr #Selected data from 1931 #Selected data up to 2005 #Least squares trend line; slope = 0.00659195 per year 50yr #Selected data from 1956 #Selected data up to 2005 #Least squares trend line; slope = 0.0124017 per year muoncounter26 : concave up would be correct. Nobody is saying it didn't warm here. Had it been the statement written in the IPCC, i wouldn't be here discussing it with you. The problem is the IPCC saying that linear trend fits to the last 25, 50, 100 and 150 years indicate warming. You can easily imagine records where linear trend fits to the last 25, 50, 100 and 150 years (and even 75 :) ) increase but where the is no warming. I really don't understand how you guys can defend the idea that the IPCC trend graph & statement support or indicate anything. "Do we really need trends to see what's been happening?" I agree with that. But you should tell that to IPCC. I'm the one criticizing their (mis)use of trends to support a statement. -
John Mason at 18:30 PM on 13 May 2012Two Centuries of Climate Science: part three - Manabe to the present day, 1966-2012
re - #3, a certain amount of IR emitted by the planet's surface does not get back out into space because it is absorbed by the GHGs and re-radiated in all directions, including back towards the surface. To me, that's 'prevented' although some might prefer 'inhibited' I guess. Surely if energy in = energy out the lack of net gain would keep us as a snowball, given our distance from the sun - exactly the problem that got Fourier's interest going back in the early 1800s. -
LazyTeenager at 16:38 PM on 13 May 2012Two Centuries of Climate Science: part three - Manabe to the present day, 1966-2012
The fact that carbon dioxide is a 'greenhouse gas' - a gas that prevents a certain amount of heat radiation escaping back to space --------- This is wrong. I know what you intended to mean, but in climate skeptic land they get confused easily. They do crazy things like picking at some analogy or metaphor in the belief that exposing the limitations of a metaphor somehow disproves the greenhouse effect. In case it's not clear the energy in must equal the energy out. This energy is in the form of radiation. It's not prevented from escaping back to space. It would be more accurate to say that greater CO2 concentrations cause the outgoing energy to meet greater resistance as it passes from the surface to outer space. -
Bob Lacatena at 14:48 PM on 13 May 2012IPCC graph showing accelerating trends is misleading
Helena, I did look at your links and graphs, and what I'm saying is that they don't show what you claim they show. Let's try it this way... list the ranges of years, and the slope. Just do that. Let's see you cherry pick the years to make this work. -
muoncounter at 13:22 PM on 13 May 2012IPCC graph showing accelerating trends is misleading
Helena#21: "Increasing trends don't (-snip-) an accelerated warming, and decreasing trends ... a decelerated warming. They don't (-snip-) anything." That has to be a new highpoint in doublespeak. Changing trends don't indicate anything? That requires that 'there's been no warming since xxxx' doesn't indicate anything; nor is there anything indicated by 'there is no scientific basis for saying that warming hasn't stopped'. I suppose 'concave up' doesn't mean anything either. Do we really need trends to see what's been happening?
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Eric (skeptic) at 11:20 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Obviously your post is staying since it got fixed. I disagree with your assessment of the log of the exponential and it is addressed here -
Helena at 11:10 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
In my message 21 "(-snip-)" = "indicate" Sorry for the all caps. -
Helena at 11:09 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Eric : We'll see, if it disappears again i'll get rid of the all caps for the word "indicate". My all caps is Tom's bold (dunnow how to get my text in bold here). Anyway, on your message 20, here we are merely discussing communication skills and scientific rigor, not the reality of warming. Anyone who looks at the temperature trend see that it is warming. I've read KR response on the other thread about linear increase or acceleration in temperature trend and exponential CO2. What he says is not entirely correct, the exponential of the CO2 is taken care of by the log of forcings, it doesnt really play there (the exponential, not the CO2 !). What matters (in a simplified version) is the relaxation time. That tells you whether the response will be linear or quadratic. But it's out of topic here. Anyway, i'll just wait a few mins see if my post stays, then gotta go. Thanks for the discussion. Cheers -
Eric (skeptic) at 11:01 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Perhaps it was your use of all-caps (tat is forbidden) -
Helena at 10:56 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Sphaerica @18 What are you talking about ? I did provide graphs (cf previous posts) Tom @19 1/ As i said, that merely shows that uncertainties on the trends are quite large. 2/ So you do agree with me that the 75yr trend goes against the picture presented of increasing trends, right ? You said yourself : "It is not necessary that the error bars be miniscule for the purported IPCC claim to be correct. It is only necessary that the measured trend be greater." Therefore, according to your own standards, i did show that the measured trend for the 75yr trend was not greater, and that had the IPCC been consistent and depicted all 25yr periods without leaving out the 75yr trend (cherrypicking ?), the IPCC assertion would not have been possible. According to my standards, all i am doing here is pointless because, as i said, comparing trends of different lengths is meaningless. You can find any result you are looking for. 3/ You challenged me by saying "it is not possible to pick arbitrary end points mimicking the IPCC graph, and to show a deceleration over the temperature record as a result. You have no counter example to the IPCC's procedure. " I found the counterexample with an arbitrary starting point (1910) and decreasing trends mimicking the IPCC graph (25, 50, 100yr trends). Again, according to your own standard and following IPCC procedure where, as you say yourself "it is only necessary that the measured trend be greater", i've succeeded. Now that you have it you seem unhappy that it exists. "The reason is that you are, fairly obviously, cherry picking artifacts of noise in an accelerating temperature trend. " Of course I am cherry picking the starting point ! You challenged me by saying that i wouldn't be able to find an arbitrary point and mimick the IPCC procedure with decelerated trends. So i looked for it and found it. Now let's get back to what it all means : what the ipcc says is that their increasing trends (-snip-) accelerated warming. Clearly that statement is wrong. Increasing trends don't (-snip-) an accelerated warming, and decreasing trends (my example) don't (-snip-) a decelerated warming. They don't (-snip-) anything. I don't understand that you guys can defend such a graph. Isn't it easier to just admit that it was not the best chosen graph to depict that warming is accelerating ?Moderator Response:[DB] Please acquaint yourself with this site's Comments Policy (link next to every comment input box). It is noted that, more than anything, you are simply being argumentative for its own sake.
Multiple usages of all-caps snipped.
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Eric (skeptic) at 10:55 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
In a previous thread about the graphic above, I basically agreed with KR"s conclusion here. I think the graphic shows a particular type of acceleration over the long term (century timescales). As I noted in that thread they left out the 75 and the 125 year trends which narrows their definition of acceleration and would add noise to the visual. The idea of noise from natural variation is an important part of the analysis of acceleration which this graphic does not attempt to provide. -
Tom Curtis at 09:58 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Helena @13: 1) Nobody who is arguing a case that depends critically on choosing just one of two available temperature indices should be talking about "arguing mere semantics". The Gistemp Land Ocean Temperature Index (LOTI) shows a trend of 0.0169576 C per year from 1981-2005, a trend of 0.0139565 C per year from 1917-1941, and a trend of 0.0134231 C per year from 1918-1942. For what it is worth, HadCRUT4 also shows a reduced trend over the 1910-1940 period, and an increased trend over the 1970-2010 interval, although obviously I do not have precise trends. 2) The 75 year trend is 0.00650795 C per year, compared to 0.00722857 C per year for the 100 year trend. The difference, less than 0.001 C per year is less than the difference in trend you dismiss as merely semantic when it suites you. It is certainly not enough to alter the visual impact of the graph, or to alter the conclusions of the IPCC. 3) The 50 year trend from 1910 is 0.00761979 C per year; the 100 year trend is 0.00749844 C per year. The difference is just over 0.0001 C per year. What was that you said about merely semantic differences again? More importantly, the pattern is not preserved in Gistemp, in which the 50 year trend is greater than the 100 year trend. Clearly, therefore, you do not have an example showing deceleration in which successive trends from the start point are less than each other by a large (although not quite statistically significant in one case) margin. The reason is that you are, fairly obviously, cherry picking artifacts of noise in an accelerating temperature trend. -
Bob Lacatena at 09:58 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Helena, Nothing you are saying makes any sense... or bears out, when I look at the actual data. Up is up, no matter how you try to stand it. Please produce a graph (use woodfortrees.org if you like) that clearly proves your point. And try to do it without cherry picking end points and ranges. -
Helena at 09:21 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
At the end of my first paragraph, replace "cooling" by "decelerating warming" -
Helena at 09:19 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
dana @14 : don't you agree that my assertion stating that, over the 1910-2010 period, the decreasing slope for the linear trends of the first 25, 50 and the full 100years *indicates* cooling is untrue ? Well, in the same way, the assertion by the IPCC that the increasing slope for the linear trends over the last 25, 50, 100 and 150 years *indicates* accelerated warming is also untrue. Moreover, as shown above, the linear trend for the last 75 years goes in the wrong direction, so at the very least it should be considered as cherry picking the trend baseline to pick only the trends that agree with what you want to assert. This has nothing to do with climate science or denying that the world is warming (it is), it's just scientific rigor. Muoncounter @15 : Sorry but i am asking for qualitative reasons, not quantitative ones. "Short" and "long" are quantitative assessments : of course there are order of magnitudes of difference between the two timescales, but that's the whole point of my example. You cannot just say that because there are orders of magnitude of difference, the system has qualitatively a different behavior. Here is an analogy : From 101°C and orders of magnitude up, water is qualitatively the same : vapor. But from 99°C to 101°C, it is qualitatively different (phase transition) even though the temperature changes very little. The underlying question is : in a complex system, how do you know the timescale (if any) over which you can say that "internal variability" (to be defined) is filtered out. But that's out of topic here. -
Riccardo at 06:11 AM on 13 May 2012Turbines in Texas mix up nighttime heat
Betz's law says that the horizontal wind velocity can not be zero downwind and that there is a theoretical maximum efficiency of 60%; hence 40% of the "input" energy is still kinetic energy of the wind. If the real efficiency is for example 50%, i.e. it's electricity to be used elsewhere, the remaining 10% goes into heat due to electricity production losses, friction and viscosity due to the increased turbulence. The latter can then be just a few percent. Even that 10%, though, could be locally significant if sustained. But once it gets diluted by natural mixing over relatively large volumes I don't see how it could produce significant warming. I too think, with Nick, that we do not have a clear explanation of the tempemperature rise. -
Bob Lacatena at 06:10 AM on 13 May 2012Increasing CO2 has little to no effect
photeki, Hint... anyone who includes lots of words and graphs and numbers, but no actual mathematics, is being lazy and trusting to common sense and "thought processes" to qualify everything while quantifying nothing. More directly... his perspective and opinions are totally worthless. Is it not peer-reviewed because he's afraid the process is flawed, or just because he's so demonstrably wrong? How often do people get to walk onto the floor of the U.S. Mint and demand their fair share of freshly printed bills, because the money-review system is flawed and unfair and they deserve more? -
muoncounter at 04:31 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Helena#13: "you cannot prove that the impossibility to go from hours to 25 years is qualitatively different than the one going from 25years to 150years. " Really? 150/25 = 6:1 25 years = 219150 hours. Your examples of comparing temperatures 12 hours apart to temperatures 25 years apart yields 219150/12 = 18262.5:1 Comparing temperatures (and temperature trends) over short time frames to long time frames is qualitatively different - and extremely misleading. -
dana1981 at 04:23 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Helena, you seem to miss the point of this post. All the IPCC is doing is saying that in recent years/decades, global warming has accelerated. That is true. It doesn't mean that there can't be prior years with similar warming trends to that in recent years. We have discussed the 1910-1940 warming here and here. There's certainly nothing "misleading" about the IPCC figure. -
Helena at 04:20 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
True, that was a 26year period. So there is a 0.0017°C/year difference in the trend. Well i guess you're right if we stick to semantics, not to science rigor as the statement seems very much sensitive to error bars and to endpoints (ironically the statement would be wrong in AR5 as 1987-2011 is 0.0155809 per year). What about the 75yr trend i was talking about ? And the 1910 thing ? "Finally, with regard to your post 5, 12 hours is not a period long enough to represent a climatology." You know as much as i do that 30yrs it nothing more than a convention. Of course daily temperatures don't define a climatology, but 25year periods don't define one either (except by convention) and you cannot prove that the impossibility to go from hours to 25 years is qualitatively different than the one going from 25years to 150years. That's the whole point i'm making : having similar time periods is the minimum required (but not sufficient) when you compare trends ! -
Tom Curtis at 03:36 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Helena @9, you are obviously grasping at straws. It is not necessary that the error bars be miniscule for the purported IPCC claim to be correct. It is only necessary that the measured trend be greater. And the last datum on the IPCC graph is 2006. However, having just checked FAQ 3.1, I notice the IPCC calculated trends terminate in 2005. So, comparing the 1981-2005 trend (0.0188397 C per year), to that for 1917-1941 (0.0171067 C per year) and 1918-1942 (0.0171202 C per year). The difference is approximately 0.002 C per year. (Please note that 1980-2005 is a 26 year period.) Finally, with regard to your post 5, 12 hours is not a period long enough to represent a climatology. Therefore your analogy is specious. -
Helena at 03:17 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Ouch still a zero missing, sorry -
Helena at 03:17 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
I meant 0.02°C/decade (and 0.0002°C per year) -
Helena at 03:16 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Tom @ 8 Uhh i didn't know you could get the raw data, nice tool. Well, then i switched to to the 1917-1942 25yr-period. slope = 0.0178289 per year For the 1980 to 2005 period : slope = 0.0180092 per year And don't tell me error bars are smaller than 0.0002 °C/decade ! PS : How can the last point on the IPCC graph be 2006 as 2005 is not even depicted ? -
Tom Curtis at 03:06 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Helena @3, the trend for 1982-2006 (the last 25 years of the temperature record used by the IPCC) is 0.0202857 C per year. That from 1915-1940 is 0.014621 C per year, which is substantially less. That from 1980-2005 is 0.0180092 C per year. Of these three trends, that from 1915-1940 is lowest. That fact could easily have been checked by examining the raw data of your own plot. So, what you have shown is not that point number 2 is wrong, but merely that you are prepared to assert that it is without properly checking the data. -
Helena at 03:06 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
To sum it up (sorry for the length of the links, i hope it's not considered as spamming) : - I did find a counterexemple, that is say if you start in 1910 you can find that the first 25yrs trend is higher than the first 50yrs trends which is also higher than the full 100yrs 1910-2010 trend. - The IPCC picture does not work if you take the 75yr trend (1930-2005) that they don't depict (they skip from the 50yrs to the 100yrs) : the 75yrs trend is smaller than the 100years trend. How is taking the 75yrs chery picking, as you are stating yourself that it is based on 25years intervals ? - But maybe you think 75yrs is cherry picked and the 25yrs of your 2nd point applies to any 25yr-period ? Then I also showed you that the past 25yrs (1980-2005) have been warming at the same rate as the 1915-1940 25yrs period. -
Helena at 02:56 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
Ok here it works with a common starting point in 1910 link 1 By the way, isn't it weird that IPCC represents 25, 50, .., 100, and 150 ? They're missing 75 (and 125). Well, that's because with 75 (1930-2005), it doesn't work :). link 2Moderator Response: TC: Edited links to preserve page format. -
Helena at 02:47 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
"More importantly, your argument entirely misses the more important point that Monckton completely misrepresents the nature of the IPCC's argument premised on the graph in question." And you miss the most important point that you cannot compare trends over different time periods. It's all i aimed to show (with wrong numbers possibly, but i gave you a simple counterexample with the midnight thing). Take for endpoint today at midnight, and you'll see that you have a cooling trend over the past 12h but a warming trend of the past 30years. -
Michael Whittemore at 02:45 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
This video at 6mins in shows Monckton explain that the climate system is like a sign wave and that the IPCC are drawing the trend lines on the up ward slop of this sign wave of climate change. He seems to be changing his angle of attack and trying to trick his audience into thinking that the reason he is right and the IPCC are wrong, is that we are going to see a cooling period. -
Helena at 02:44 AM on 13 May 2012IPCC graph showing accelerating trends is misleading
I hadn't done the precise graph. Before I answer on point 1, the tool you used allowed me show that point number 2 ""That the pace of warming over the last 25 years is greater than that in preceding years on the record."" is wrong : linkModerator Response: TC: Edited link to preserve page format. -
Tom Curtis at 01:54 AM on 13 May 2012Increasing CO2 has little to no effect
photeki @127, the linked article immediately demonstrates that Roy Clark is yet another in the long line of supposed "skeptics" who attempt to refute the theory of the greenhouse effect with out first bothering to learn what it is. Specifically, he attempts to show that the CO2 effect is saturated by discussing back radiation only. The greenhouse effect is not based on back radiation, and any discussion that assumes it is shows the author to be in complete ignorance of the theory they purport to refute. You will find a basic introduction to the greenhouse effect here. Read it carefully. Notice how the relevant factors are the Top of Atmosphere radiative balance, and that no mention of back radiation is needed. And for the record, if you work out the radiative physics for an increase of CO2 at the TOA, it does result in significant changes in radiative forcing, of 3.7 W/m^2 per doubling of CO2.
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