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Paul Magnus at 12:32 PM on 16 May 2012Climate Change Consequences - Often Unexpected
Here something that may be unexpected... but certainly is shocking.... when we close the border what happens to the animals....? "While the fences around Israel are necessary, according to Soffer, so too are corridors to allow the free passage of animals. Such passages could be monitored by soldiers for days at a time to allow the animals, such as snakes, to cross both ways." Defending Israel’s borders from ‘climate refugees' http://www.jpost.com/NationalNews/Article.aspx?id=269948 -
otter17 at 12:24 PM on 16 May 2012Climate Change Consequences - Often Unexpected
To me, I find mitigation worthwhile if just to prevent large portions of the Great Plains of my home country (USA) from turning into a desert climate. Though, I guess the regional research indicates we may be too late to prevent that, since the region is marginal prairie. Sad, but the farmers and ranchers will have to make due or quit, reducing America's proud farming heritage in the region (and food production). Aside from my sentimental value attached to that, I do not get the ridiculous risk management practices that some contrarians follow. We have a very manageable, human-controlled risk to the economy on one hand, maybe even a benefit to the economy according to some analyses. On the other hand we have a quite likely uncontrollable and irreversible risk to livelihood, ecosystem services, and economies. Sounds like a no-brainer unless you believe in a conspiracy theory that the whole climate change risk portion was made up (a position even my father took for a short while). -
PT_Goodman at 12:24 PM on 16 May 2012Medieval project gone wrong
I'm currently debating a Climate Change "skeptic" (denier would be the appropriate term). He has been using "data" from the CO2 Science web site. So naturally, I've looked at the graphs he links to at that site. [He dismisses SkS and will not read articles here.] My take has been that the CO2 Science misrepresents the data and research done by the actual researchers, such as Mann and Jones, Moberg, etc. I'm happy to learn, by coming to SkS, that I am not imagining things. Still, my skeptic acquaintance clearly will never change his mind about AGW. I'll read this article again; there a strategy for dealing with such people. This comment is no doubt OT. If so, move it. -
skywatcher at 11:37 AM on 16 May 2012IPCC graph showing accelerating trends is misleading
Tom, points taken re FAQ, my bad! Not that I have ever suggested that the graph is anything but scientifically accurate of course. Monckton's chart, complete with its egregious line painting (the "1860-1880" line is particularly misleading as he's drawn a line from ~1852 to ~1885) ... is it the "anti-Escalator"?? According to Monckton's chart, global warming is almost always happening very rapidly (more rapidly than the long-term mean), and periods of apparent hiatus are mere illusions. We should be even more worried! Monckton is an alarmist!!
Does Helena think Monckton's graph is better than the one in the IPCC report?
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Doug Hutcheson at 11:09 AM on 16 May 2012Climate Change Consequences - Often Unexpected
colinc @ 2, the irony is that your scenario also plays for Peak Oil: when energy gets too expensive for the average family to use, the outcome is the same as if that energy was not available at all. Perhaps PO, which is likely to be a creeping crisis rather than a crunch, will give us the incentive to progressively wean ourselves off the fossils and onto renewables, in a time and manner that gives us a better chance of survival. Having said that, your scenario of drought-induced blackouts is apocalyptic, but not unreasonable. This is just another negative impact that the nay sayers are happily blind to. The OP should be a wake-up call to the fact that AGW is likely to have profound and unpleasant effects that, at the very least, balance any possible benefits. -
Steve Case at 11:07 AM on 16 May 2012Climate Change Consequences - Often Unexpected
the 1993 Cryptosporidium outbreak in Milwaukee wasn't "Global; Warming" I drove by the Howard avenue purification plant every day on my way to work. And at that time there was a great deal of construction going on at the plant. I have no idea what it was, but the fact that there was never seemed to make it into the Milwaukee Journal. We talked about that fact at work. I live on the north side of Milwaukee and I wasn't affected. I don't recall that anyone at work was either. The reason for the overflow into Lake Michigan is that cities like Milwaukee have a combined sanitary storm sewer system and when it rains, shit flows into lake Michigan. It's been that way for years. We have the "Deep Tunnel" which is supposed to store water when there's a rain storm, but everyone knew that it really wouldn’t work for "cloud Bursts" which do occur "Global Warming" or not. I remember flying back to Milwaukee in 2008 the airline flew over the Milwaukee harbor on the approach, you could clearly see the sewage line spreading out into the lake. Local State and Federal government didn't want to spend the money to separate the storm and sanitary sewers and we got sold a bill of goods with the Deep Tunnel project which cost billions and really doesn't work. We all knew from the start that a few thirty foot diameter tunnels weren’t going to hold all the water from a big storm -
Tom Curtis at 10:41 AM on 16 May 2012IPCC graph showing accelerating trends is misleading
skywatcher @115, while I agree that the graph was intended to summarize information in a simpler form, it was also in the Technical Summary of the IPCC report. Indeed, the version above is the version from the technical summary, which differs from that in the FAQ in the relative placement of the maps and line graph. Further, the FAQ is still intended to be scientifically accurate, with FAQ's being referenced by other parts of the report. Far more importantly, the IPCC explicitly discusses the rapid warming in the early to mid 20th century in the report. There is no question of their attempting to hide relevant information here. So the question of the appropriateness of the graph realy comes down to two issues - is the "inference" from the graph of accelerated warming justified; and is the graph simple enough to be understood by its intended audience of politicians and policy makers. Some of the utterances of politicians and policy makers give me reason to doubt that any graph could be simple enough for them to understand, but there is no doubt that the "inference", ie, the point it was designed to illustrate, is justified. It is interesting to note that Monckton has given us an example of what he thinks the graph should have looked like:
This graph he calls "the unvarnished truth". Careful examination shows otherwise. To start, the three clearly marked lines, which are given as being "equal slopes" in the legend, are not equal slopes, with the 1910-1940 line being slightly steeper than the 1975-1998 line. In contrast, the actual trend for 1975-1998 is greater than that for 1910-1940 (see table below). What is worse, the duration (length on the x-axis) of the lines do not correspond to their stated duration, with the 21 year 1860-1880 line having the same width as the 31 year 1910-1940 and the 1975-1998 interval. Further, although the 1975-1998 trend is only just greater than the 1910-1940 trend, the 1975-2005 trend, ie, the trend corresponding in duration to the actual "trend line" shown by Monckton is 0.188 C per decade, a difference from the 1910-1940 trend if Monckton had drawn in the actual trend lines.
Being fair to Monckton, he does not call those bold pink lines "trend lines". But if they are not trend lines, then they can have no legitimate purpose on the graph. Their purpose is solely to deceive the eye, which is notoriously bad at estimating trends. By giving the eye a bold target, Monckton seeks to exaggerate the similarity between the three warming periods, both as to duration and slope.
No doubt, as a fair minded person, Helena has noticed these "errors" by Monckton, and can point us to her public criticism of them? Or is she so busy trying to reheat false "skeptic" talking points that she has no time to criticize the genuine errors of fake "skeptics".
HadCRUT3v +/- HadCRUT4v +/-
1860-1880 0.105 0.159 0.109 0.16
1910-1940 0.153 0.056 0.135 0.056
1975-1998 0.156 0.08 0.071 0.077
1975-2006 0.189 0.052 0.195 0.05
1850-2006 0.042 0.007 0.042 0.008
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Glenn Tamblyn at 10:35 AM on 16 May 2012CRUTEM4: A detailed look
Thanks for this post Kevin. I knew CRUTEM3 didn't have as good station coverage in the Arctic, but I was flabbergasted by their land record not being hemisphere-weighted. This update was obviously needed. -
bill4344 at 09:45 AM on 16 May 2012New research from last week 19/2012
Seconded. These compilations are greatly appreciated, Ari and co.. -
Rob Honeycutt at 09:44 AM on 16 May 2012Climate Change Consequences - Often Unexpected
colinc... On SkS it's preferred if you bold or italicize your emphasis rather than using all caps. If you're not familiar with the techniques for doing this you can click on the "Click for tips on posting..." and it will show you the HTML tags. -
colinc at 09:36 AM on 16 May 2012Climate Change Consequences - Often Unexpected
Pardon me, what do you (the "moderator") mean by "all-caps (now converted)"? I did not, and "your" [Preview]-button confirmed, that no more than a half-dozen words were "all-caps."Moderator Response: [Sph] The rule is not "too much all-caps." It is no all caps. If you follow the link to the Comments Policy you will find instructions for how to use bold and italics for emphasis. -
Tom Curtis at 09:05 AM on 16 May 2012101 responses to Ian Plimer's climate questions
scaddenp @21, giving Carbon500 the benefit of the doubt, he (or she) has concluded that because "there are large regions where the oceans are cooling", that there are individual oceans which are cooling, while others are warming. If that is his/her conclusion, then it is false. Every ocean, and every ocean basin on Earth is warming, although small regions within each ocean basin are cooling. This confusion may have been aided by the fact that "oceans"can act as both a mass noun, as in the passage quoted above (in which it refers to all the water within the worlds oceans), and as a collective noun, in which usage it would refer to all of the Earth's oceans (ie, the Pacific, the Atlantic, etc). To suppose there is a contradiction between the quoted passage and the statement that the worlds oceans are warming, one must suppose that "ocean" is used as a mass known in the quoted passage, and a collective known in the statement. -
skywatcher at 09:02 AM on 16 May 2012IPCC graph showing accelerating trends is misleading
Agreed Tom, Helena's post smacks of rather desperate trolling, as clearly she has no supportable quantitative substantive issue with the published graph, that was in an FAQ and is correspondingly uncomplicated. Recent warming is faster than earlier warming. -
Tom Curtis at 08:54 AM on 16 May 2012IPCC graph showing accelerating trends is misleading
Helena @113, while interesting that the second draft of the IPCC AR4 included a simpler graph than that included in the final product, your concluding question is simply fatuous. Any revision to the first or later drafts of IPCC reports, by there nature, have not gone full the "full review process". The only way to ensure that everything in the IPCC reports has gone through the full process is to avoid any revisions, so that the final report is identical to the first draft. The more interesting point is, was the graph a product of the full review process, and quite plainly it was. This attempt by you to beat up a fake controversy over the graph shows to my mind that your interest here is only in generating controversy, with the purpose of obscuring the obvious. Your comments are the result of deliberate trolling rather than genuine inquiries or differences of opinion. I suggest readers bear that fact in mind when reading any of your future posts. -
colinc at 08:22 AM on 16 May 2012Climate Change Consequences - Often Unexpected
Molly's observations are quite astute and accurate but fail to grasp the "real" problem with water. Imagine, if you will, 2 consecutive winters (N.Hemi.) in which western US states see less than 1/2 their "normal" precipitation. (Greater than 80% probability w/in the next decade.) Water levels in Lakes Mead & Powell (just 2 out of many) no longer have enough water to drive the turbines in the base of their respective dams. The power goes out, "permanently" (recall that most Americans have the attention-span of a gnat), for roughly 20+ million people from L.A., San Diego, Phoenix, Las Vegas, etc. That means NO water coming from anyone's tap, no pumps to fuel vehicles, no refrigeration... you get the picture, sorta'. The "thing" is, when the bottled-water runs out (off store shelves) there will not be a single "safe" drop of water to drink for anyone within 100 miles or more of those sprawling eyesores. At least 1/2 of those people will be dead within a couple of weeks. Sure, some may be able to haul out buckets from "found-water" and rub 2 sticks together to make a fire to boil the water. However, that will not eliminate all pathogens and does absolutely nothing to remove VOCs. Moreover, that is the situation for the inhabitants of every major metropolis on the face of the planet. If you live in a city, when (not if) the power goes out in "your area," the odds of your survival are not good and diminish exponentially (or at least geometrically) with each passing day. Note, there are a plethora of reasons for power-outages in every region, CME's, "terrorist" attack or another "economic" shock as bad or worse than the one we find ourselves in still. There are more than a few financial bloggers who perceive the latter as a high-probability event within the next decade.Moderator Response: [DB] Please refrain from using all-caps (now converted to lower case). -
scaddenp at 06:13 AM on 16 May 2012101 responses to Ian Plimer's climate questions
Carbon500 - cut straight to point. In what possible way does the IPCC statement contradict "the oceans are warming"? More to the point, do you not agree that the OHC measurement show that the oceans are warming? More to point, the OHC measurements show Plimer is misleading. -
actually thoughtful at 05:57 AM on 16 May 2012Climate Change Consequences - Often Unexpected
I am quite convinced the "negative feedback" that the skeptics keep searching for will be a reduction in human population, most likely from a disease that finds it niche in a warmer, wetter world. The other choice, to voluntarily reduce emissions and maintain the world we have now, is deemed "to risky". This makes me sad. -
funglestrumpet at 05:51 AM on 16 May 20122012 SkS Weekly Digest #19
There is a good series of programmes on BBC R4 Tuesday mornings (over three weeks) covering extinction events. The first one (available on their 'listen again feature') cites global warming as a major player and compares the current meteoric rise in CO2 with the glacial rise during these events. Next week's programme is going to investigate whether we are experiencing another extinction event. It might be an idea to post a link to each of them. As for issue of the week - my answer is 'no', I think this site has a lot to be proud of, especially the courtesy and profesionalism it displays. -
Helena at 05:39 AM on 16 May 2012IPCC graph showing accelerating trends is misleading
It seems that first and second order draft of the IPCC report didn't show the published graph, but this one instead : http://pds.lib.harvard.edu/pds/view/7768990?n=383&printThumbnails=no I cannot find any critics to it, but it takes a while to go through all the comments. I sure wouldn't criticize it. Does this mean that the published graph did not go through the full review process ? Did it go through any ?Moderator Response: [RH] Fixed typo. -
Dikran Marsupial at 01:31 AM on 16 May 2012Global warming stopped in
1998,1995,2002,2007,2010, ????
Mastzdj wrote "Now please help me understand what is steadily increasing in response to the accelerating atmospheric concentration of CO2 ." The key here is to realise that the observed climate is a combination of a deterministic response to a change in the forcings (e.g. CO2 radiative forcing), known as the "forced component", and the chaotic variability that does not depend on the forcings (e.g. the El-Nino/La Nina oscillation - ENSO), known as the "unforced component" or "internal variability of the climate" or simply "weather noise". It is difficult to see the effect of one element of the forced component in a graph that shows both the forced and unforced component. If you want to see the effect of CO2 more clearly, then first you need to control for the effects of things like ENSO and changes in other forcings. If you do so you will get a plot like this:
Where the effect is clearly evident (click the "intermediate" tab for an explanation and a link to the journal paper).
"Are you willing to open this site to not only beating down the stupid comments made by the right wing talking heads on TV, but to honestly looking at the experiments, the data, the interpretation of that data, and the alternative conclusions that can be drawn?"
Yes of course, however do bear in mind that the interpretation of the data and allternative conclusions may not be as strong as you may think. A pysical explanation for a step change would be a bit start, I am a statistician, so I am much more impressed by statistically significant evidence and a plausible physical explanation than I am of subjective interpretation of data with no statistical support or physical mechansim.
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Dikran Marsupial at 01:12 AM on 16 May 2012Global warming stopped in
1998,1995,2002,2007,2010, ????
There are statistical tests that can be used to determine if there is evidence of a step change in time series data, and when used correctly show that there is little evidence for a step change. IIRC this has been discussed in detail at Tamino's blog. It seems to me that the step change is essentially the eye being fooled by the spike caused by the 1997/98 el-nino event. If you plot the UAH data without that blip, it looks to me rather like the warming has continued at pretty much the same rate throughout, certainly it no longer looks as if there has been a step change.Our eyes are very easily fooled into seeing structure in data that simply isn't there, which is why we have statistics. While there are problems with statistical hypothesis testing, it is very useful for guarding against incorrect intuitions. If the evidence for an hypothesis is not statistically significance, then you should not promulgate the hypothesis on the basis of the observations alone. If you also have convincing theoretical justification, that is a nother matter.
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dana1981 at 01:03 AM on 16 May 2012Global warming stopped in
1998,1995,2002,2007,2010, ????
The 'step change' myth is addressed here. -
Composer99 at 01:02 AM on 16 May 2012101 responses to Ian Plimer's climate questions
Carbon500 @17: You appear to be confusing or conflating linguistic accuracy with precision. As long as there is a global-scale energy imbalance causing accumulation of energy within the world ocean (causing the ongoing increase in global oceah heat content), then the statement The oceans are warming is entirely accurate. Increasing resolution and documenting or discussing temporal or spatial variation in the accumulation of ocean heat content adds to the precision of this statement but does not change its accuracy. As far as encouraging investigation & critical thinking in the classroom goes, Plimer's How To Get Expelled From School is a decidedly inferior tool. Indeed, the way the questions are worded it appears to encourage disruption in the classroom and thoughtless contrarianism among students - rather than a spirit of critical inquiry based on reviewing theoretical, experimental and empirical findings in the sciences. -
dana1981 at 01:01 AM on 16 May 2012101 responses to Ian Plimer's climate questions
Carbon500, people often simplify complicated issues when communicating with non-experts. Sure, there are some regions of the oceans and some regional land areas which have cooled, but on average, the oceans and land have warmed a lot. We're talking the equivalent of detonating two Hiroshima atomic bombs per second in the oceans, every second over the past 50 years. So yes, it is entirely accurate to say the oceans have warmed as a whole, even though some small ocean regions may have cooled. Sometimes when you try to get too nuanced you lose sight of the big picture. -
Bob Lacatena at 23:18 PM on 15 May 2012101 responses to Ian Plimer's climate questions
17, Carbon500, "Were I a school teacher, I’d be getting my class to investigate this further..." I'm a little surprised you didn't take this advice to heart before posting, because all of the questions you posed are easily answered with just a little research. Really, Plimer was spewing nonsense, and you are reinforcing it here as if there is some grave doubt about the reality of the answers. Why? If you yourself don't understand and know the answers to the questions, why are you defending Plimer's untenable position (or attacking the response)? -
muoncounter at 23:14 PM on 15 May 2012IPCC graph showing accelerating trends is misleading
It is interesting that the word 'accelerated' is not present in the WG1 discussion of this graph. They merely state the obvious: The rate of warming averaged over the last 50 years (0.13°C ± 0.03°C per decade) is nearly twice that for the last 100 years. If the underlying temperature-time function is linear with random noise, trends calculated from any starting point and over any time period long enough to deal with the noise are all very close. This is distinctly not the appearance of the IPCC graph, clearly indicating that there is some curvature to the function. In this case, the curvature is up. -
dorlomin at 22:20 PM on 15 May 2012New research from last week 19/2012
Most of the climate science we come across tends to come onto the radar because of some spurious hand waving 'sceptical' effort to claim fraud or conspiracy or the like. Whats so great about these posts is it gives a brief weekly overview of the sheer volume of science and where the latest ideas are heading. The fact that week after week so many interesting papers appear is a testimony the how interesting and dynamic this area of science is. -
Carbon500 at 21:05 PM on 15 May 2012101 responses to Ian Plimer's climate questions
Composer99 and scaddenp: (-snip-). Hopefully it will get their teachers doing the same, instead (-snip-). To develop this further: The government statement that the world’s oceans are getting warmer everywhere is contradicted by the IPCC as I’ve quoted. Were I a school teacher, I’d be getting my class to investigate this further - for example, which oceans? Cooler by how much? Over what period of time? (-snip-)? - in other words, question, investigate and think for yourself – surely a good scientific grounding? The same applies to oceanic pH. The claim has been made that the average pH of the oceans has increased by 0.11 – does the class think this is plausible, and why? The sort of questions I’d be getting them to look into would be: what factors affect pH? Does the pH range of the oceans vary in different parts of the world? Does it change in shallower waters, and at depth? Is there variation with temperature? How important is CO2 in the picture? Can a class experiment be devised to test issues raised? Finally, Sphaerica : given my comments on ocean pH above, I'd need to do some investigating myself before forming an opinion. (-snip-). Naturally I accept that advances in modelling will have been made since the FAR, and have also noted their comments on computer modelling reliability on pages 600-601. However, (-snip-)?Moderator Response:[DB] This thread is about the Australian Governments 101 responses to Ian Plimer's climate questions and the scientific basis for them. It does not delve into the rationale for why Mr. Plimer takes the stance that he does. Nor does it explore the various and sundry conspiracy theories or "alternative explanations to known physics" that are based on little other than poorly-thought-out wishful thinking.
OHC is still increasing in its inexorable response to the radiative imbalance at the TOA. Use the Search function to look up Levitus 2012 from April for further info. The same for Ocean Acidification and modeling. All are off-topic on this thread.
Off-topic, conspiracy theorizing, allegations of fraud and ideological snipped.
Please construct further comments to comply with the Comments Policy as subsequent comments constructed as this one was will be summarily deleted. Thank you for your compliance and consideration in this matter.
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les at 20:54 PM on 15 May 2012IPCC graph showing accelerating trends is misleading
95 - SJR "I think that Skywatchers contribution suffers from the same problem as the IPCC graph, namely comparing trends over periods of different length." Really your post 100 and KR's post 99 answers this. There is not problem - despite the psudo-science from Helena 92 - to have identical periods so long as the uncertainty is treated properly. as 99 shows, the shorter period has higher uncertainness - however the effect is still substantially greater so there's no problem... skywatcher 76's graphs could have +/- bars or lines which would widen as they reached the early/late fixed point... if one doesn't explicitly calculate the error-bars, you are more or less forced to 'fix' the errors by having constant periods as per 100. -
John Mason at 17:05 PM on 15 May 2012Two Centuries of Climate Science: part three - Manabe to the present day, 1966-2012
Well spotted sailrick! There's always one that gets through! Thanks - John -
Nick Stokes at 16:59 PM on 15 May 2012IPCC graph showing accelerating trends is misleading
The Moyhu trend viewer helps here, though it only goes back to 1901. You can click buttons for the dataset and period you want - say Hadcrut from 1901 to present. In the triangle plot, you can see the trends to present along the right hand axis. They do show reddening colours going up untli about 20 years duration; shorter term trends to present are quite noisy and can be negative. If you want to see trends starting 1901, look along the x-axis, Again after some initial noise, there's quite a high trend reflecting the 1900-1940 period, then a dip, and then a rise to the century duration. You can click anywhere to see numerical values, with significance and a graph, and you can click the red square buttons to show significance. And if you want to cherry pick, it's helpful there too. -
skywatcher at 13:30 PM on 15 May 2012IPCC graph showing accelerating trends is misleading
Tom #108 - agreed , it's prefereable to use end point method due to signal/noise issues early in the series. This is seen in my second graph in #78, the early noise is what causes the trend to vary substantially for trends between 1875 and 1920. After that, you have the progressive rise, which tells you nothing more clever than that the overall profile is slightly convex, but it is weak at inferring anything much else. Helena, just saying 'no' will never make you right. Tom's statement is quite correct, as demonstrated multiple times upthread. You have failed to provide any examples, real or conceptual, that demonstrate otherwise. -
DSL at 12:26 PM on 15 May 2012Global warming stopped in
1998,1995,2002,2007,2010, ????
Muon beat me to it, matzdj. The theory of AGW did not start with measurement of temperature. It started with physics. If you or Roy are going to propose a step change, you'll need to provide a consistent physical mechanism. I second Sphaerica's recommendations as well, particularly Foster & Rahmstorf, as it is the kind of basic analysis ignored by those who start and end their analyses with a string of uncontextualized data. -
Mike3267 at 12:09 PM on 15 May 20122012 SkS Weekly Digest #19
Hate to be a wet rag, but some of our denier friends will spin the cartoon into some kind of death threat. In any case, I don't think calling people stupid is the best way to win them over. -
Dragonwyst at 11:57 AM on 15 May 20122012 SkS Weekly Digest #19
Help - edit - "out" not "our" -
Dragonwyst at 11:57 AM on 15 May 20122012 SkS Weekly Digest #19
Not intimidated - just a tad our of my depth. I'm aware of how little I know, and don't know that my 2c can actually add anything worthwhile. However, I think I want to start asking people on both sides of this non-debate what their childhoods were like. I think the "religious fervour" aspect has it's roots way back... -
sailrick at 11:27 AM on 15 May 2012Two Centuries of Climate Science: part three - Manabe to the present day, 1966-2012
"other non-condensing greenhouse-gases had exterted" typo in last word and another typo in the bottom graphic - lower right It reads "CO2 sourcees identified" an extra e Excellent series. delete or edit this, if you will -
Tom Curtis at 11:08 AM on 15 May 2012IPCC graph showing accelerating trends is misleading
skywatcher @107, thanks for the clarification. We should note that it is still preferable to used the end point method rather than the start point method in this case. That is because the HadCRUT3v temperature index typically covered around 20% of the globe in the 1850's, compared to around 80% in the 2000's. The result is that the temperature record has a much lower signal to noise ratio early in the record, particularly prior to 1880 which would defeat the technique. (It may show the correct pattern, I have not checked. But it would be illegitimate to draw any inference from it.) -
skywatcher at 10:51 AM on 15 May 2012IPCC graph showing accelerating trends is misleading
Tom #106, I see your point - the clarifying statement is this - whether you fix the start or end point, always read the trend changes forwards in time. So fixing the 1850 point begins with short trends and ends with longer ones, the later trends being larger than the earlier (2nd fig in #76). Fixing the 2005 point (as done by IPCC) begins with longer trends, that get progressively shorter through time (1st fig in #76), and in both cases the positive trend rises over time. That feature is unique to the rising, accelerating curve, and not present in a falling or decelerating curve. The rate of trend rise is lower if you fix the 1850 point than if you fix the 2005 point, due to the increasing amount of data involved in the longer trend (so the acceleration is less pronounced for the 1850 fix), but the trend still rises. -
muoncounter at 10:37 AM on 15 May 2012Global warming stopped in
1998,1995,2002,2007,2010, ????
matzdj: Your proposed 'step change' has been discussed here before. The problem is that there is no physical mechanism that can make that happen. You'd need an 0.3 degree step, which is about the size of the '98 el Nino (refer to the departure from linear in fig 3). That el Nino ended, as all of these cyclic events do. That leaves your 'step' unsupported. No, the scientifically unsound analysis is the one that does not look at all the data, does not take into consideration the noise and creates effects without cause. -
Tom Curtis at 10:33 AM on 15 May 2012IPCC graph showing accelerating trends is misleading
Skywatcher @102 writes:"The patterns produced in both graphs in #76 are indicative of a temperature profile that is broadly concave, rather than convex or flat. I think that general point is mathematically defensible, as with Tom Curtis' sketches. Mathematically, whether you start in 1850 or in 2005, both will show increasing gradients for a concave profile, but one will have rapid increase near the end (2005 fixed point), and one will have slower increase at the end (1850 fixed). But both will increase."
I have probably misunderstood what you said, however, with an accelerating (concave upward) curve a sequence of progressively longer trends with a common start point would each have a progressively greater trend, ie, the longer trends would be larger. In contrast, sequence of progressively longer trends with a common end point would have progressively lower trends, ie, the longer trends would be lower. -
Tom Curtis at 10:25 AM on 15 May 2012IPCC graph showing accelerating trends is misleading
In my concluding paragraph of 104, I should have said her assumption is false of any data with an accelerating slope and a signal to noise ratio sufficient to allow determination of the underlying signal. If Helena has wanted to argue that the technique illustrated by the IPCC can work in some cases, but that in the particular case used by the IPCC, the noise is to great for it to be valid, she may have had a point. There are relatively simple mathematical methods for determining that, and I believe they would show that she was incorrect. But you do actually have to look at the data to know if she would have been incorrect or not, if that had been her contention. Instead, Helena has argued that the technique cannot work under any circumstances, even as a statistical inference. She thereby demonstrates that she does not even understand the basic maths of the situation. -
Tom Curtis at 10:15 AM on 15 May 2012IPCC graph showing accelerating trends is misleading
Two points for Helena: 1) I believe I have finally figured out what you mean be a decreasing decelerating curve. It is a curve which below the x-axis, ie, negative, but in which it approaches the x-axis over time such that curve satisfies the condition that slope(t) < slope(t+a) where a is greater than 0. That, however, is mathematically just an accelerating curve. Over time, the slope of the curve gets larger. The situation is described as - it is cold, but it is getting warmer, and over time it is getting warmer faster. So, yes, the IPCC technique will detect acceleration in this case - and so it should, for the situation is one of accelerated warming. If I have misunderstood your phrase (which is as clear as mud), specify what you mean mathematically, or plot the curve on a graph and show it to us. 2 Helena @93 said:"In the same way, when you start in the present (his graph1 and the IPCC), you're not being "fair" to the past as its trend gets mechanically diluted. You "force-flaten" long trends. That's why you can't compare trends that have different T. "
This theme that increasing the length of the trend will always flatten it is a constant theme of Helena's, and (so far as I can tell) the core of her argument. Indeed, SFAICT, apart from a few failed counterexamples and constantly reiterating that she disagrees, she has no other argument. And it is simply false. Consider the function such that If x < or = 0, f(x)= 0; else f(x)=x^2. We can consider two series of progressively longer trends. In the first series the trends are all centered on 1. In this case, each successive trend will have a higher slope than the previous trend. That directly contradicts Helena's contention. In the second series, the trends all terminate at 25. In this case, each successively larger trend will have a lower trend than the preceding one. This is the case that parallels the IPCC diagram. Helena's central assumption is in fact false of any data with an accelerating slope (and in some other cases as well). By sticking rigourously to her "intuitive statistics", Helena simply starts with an initial premise that no data can show acceleration. -
Tom Curtis at 09:48 AM on 15 May 2012IPCC graph showing accelerating trends is misleading
SRJ @86, the question under discussion here is not, "What is the best method to analyze temperature trends over the last 150 years?" The IPCC's analysis did not consist of just the illustration under discussion, which as Dikran Marsupial has pointed out, only appears in summaries of the data, not in direct analyses of the data. In FAQ 3.1 where a similar figure to that above appears, the IPCC says:"Expressed as a global average, surface temperatures have increased by about 0.74°C over the past hundred years (between 1906 and 2005; see Figure 1). However, the warming has been neither steady nor the same in different seasons or in different locations. There was not much overall change from 1850 to about 1915, aside from ups and downs associated with natural variability but which may have also partly arisen from poor sampling. An increase (0.35°C) occurred in the global average temperature from the 1910s to the 1940s, followed by a slight cooling (0.1°C), and then a rapid warming (0.55°C) up to the end of 2006 (Figure 1). The warmest years of the series are 1998 and 2005 (which are statistically indistinguishable), and 11 of the 12 warmest years have occurred in the last 12 years (1995 to 2006). Warming, particularly since the 1970s, has generally been greater over land than over the oceans. Seasonally, warming has been slightly greater in the winter hemisphere. Additional warming occurs in cities and urban areas (often referred to as the urban heat island effect), but is confined in spatial extent, and its effects are allowed for both by excluding as many of the affected sites as possible from the global temperature data and by increasing the error range (the light grey band in the figure)."
Clearly, therefore, the IPCC makes people aware of the high trends in Global Mean Surface Temperature (GMST) in the middle of the 20th century. These high trends correlate with high trends in total Top of Atmosphere (TOA) forcing, although the forcings do not completely explain it. Because of that correlation, it would be an embarrassment to the IPCC if there where not high trends in GMST in the middle of the 20th century. As the IPCC makes people aware of the mid 20th century trends, their purpose in the diagram we are discussing is not to conceal them. Rather, it is to illustrate the general tendency to higher trends as the century progresses. If that illustration is not to be misleading, then an inductive inference from the pattern shown to the acceleration of the warming over the period in question must be justified. That is what has been questioned by Monckton and by Helena. So, while I agree that the additive model is better than the IPCC's chart, that is not relevant to this discussion. Further, while I agree that for most purposes comparing trends of different length is unwise, that is also not relevant to this discussion. What is relevant is the question as to whether or not, if you do compare trends as the IPCC has done, you can validly make an inductive inference that the warming has accelerated. Please note that simply comparing the peak 25 year trend in different periods does not answer that question. Consequently, for this purpose your first chart is worse than the IPCC's. That is because a high trend ending in a particular year may be followed by a low trend shortly thereafter. Consquently you can have more total warming with a lower peak trend which is reached year after year than with a higher peak trend that is reached and simply falls away. Another way of putting that is that that you get greater warming with more robust trends, and hence it is the robust trends which better indicate increased warming. Finally, the attack on the chart above by Monckton is not based on statistical qualms. Rather it is based on a desire to attack the IPCC to undermine action on global warming. You can be sure that had the IPCC used the additive model shown by you, it would have come under equally virulent, and unwarranted assault. If you do not believe this, just consider the continuing unjustified assaults against the validity of the temperature record itself. -
skywatcher at 09:38 AM on 15 May 2012IPCC graph showing accelerating trends is misleading
SRJ - I quite agree on the general point that for a more detailed analysis, using trends of comparable length is preferable, but this is only relevant for detailed analysis, which the IPCC FAQ figure was not. Your numbers in #100 neatly illustrate the point with consistent trend lengths. The reason I produced the figures in #76 was that, as KR says in #99, the IPCC figure was merely illustrating a point. Not proving some part of atmospheric physics, or anything like that. Helena repeatedly implied that there was a kind of cherry-picking going on with the choice of the four trends by the IPCC - my figure neatly demonstrated that this was not the case, given the more-or-less progressively increasing trend rates to the present. Most other choices of four trends spaced across the profile would have given the same result, even if a few choices would have produced slightly different patterns (relevant to Dikrans points about forcing and trends). The patterns produced in both graphs in #76 are indicative of a temperature profile that is broadly concave, rather than convex or flat. I think that general point is mathematically defensible, as with Tom Curtis' sketches. Mathematically, whether you start in 1850 or in 2005, both will show increasing gradients for a concave profile, but one will have rapid increase near the end (2005 fixed point), and one will have slower increase at the end (1850 fixed). But both will increase. There are, statistically, much better ways to support the overall acceleration in temperature (or just look at any of the 'hockey stick' graphs!), but these methods would not be appropriate for an illustrative FAQ answer. Helena #92, a "decreasing, decelerating" profile would have negative gradients. So your point was? There are four possible curve solutions - draw the four possible curves, like the two in Tom Curtis' #77, one has increasing positive gradients, one has increasing (steepening) negative gradients, a third has decreasing positive gradients, and the last has decreasing (flattening) negative gradients. All would show up differently in my figures in #76. -
michael sweet at 09:18 AM on 15 May 2012Global warming stopped in
1998,1995,2002,2007,2010, ????
Mastzdj, I am surprised an engineer would claim "my “eyeball-least-squares-fit” to the data." Any scientist knows an eyeball line is not a least squares line. Using my special Mark-2 ultra-sensitive eyeball your lines are incorrect. They should have an upward slope in both cases where you have flat lines. Please provide a graph with a least squares fit and not an eyeball fit. -
KR at 09:02 AM on 15 May 2012IPCC graph showing accelerating trends is misleading
SRJ - Got it, my mistake on what you were discussing in terms of autocorrelation. While I still feel that varying trend lengths are of some use, if properly considering uncertainties, I would agree that looking at equal spans provides rather more information. -
SRJ at 08:36 AM on 15 May 2012IPCC graph showing accelerating trends is misleading
# 99 KR You misunderstood me, I was referring back to Dikran in post 94 where he suggested fitting a linear trend to the trend estimates from my plot in post 86. Those trend estimates are autocorrelated since they have so much data in common. I should have stated clearer in my post 97 that it was about autocorrelation between the trend estimates of post 86 rather than autocorrelation of the temperature anomalies themselves. The trends you are calculating are again for time periods of different length, and as such comparing apples to oranges. What I would do is to compare trends calculated over time spans of equal length, e.g. 100 years. Using the SKS Trend calculator here is how I would do it: Period _____ Trend Hadcrut3 1850-1950: 0.023 ±0.013 °C/decade (2σ) 1875-1975: 0.034 ±0.013 °C/decade (2σ) 1900-2000: 0.065 ±0.012 °C/decade (2σ) 1912-2012: 0.074 ±0.012 °C/decade (2σ) -
Bob Lacatena at 08:21 AM on 15 May 2012101 responses to Ian Plimer's climate questions
13, Carbon500, "The ocean remains alkaline (pH>7)" Really? So your position is that any change in the concentration of H+ in the oceans that does not actually push the pH below 7 is harmless? A 30% increase in H+ concentration (as evidenced by a pH change of 0.11) is unworthy of wory? On climate modeling: Do you think a single sentence in a five year old report provides a thorough and authoritative review of the state of an important and rapidly advancing aspect of science (climate modeling)? On the matter of ocean heat... Skeptical science will have a few important posts in upcoming weeks on this, relating to the latest research. I hope that you'll accept such findings with as much confidence as you do when quoting a 5 year old report. -
scaddenp at 08:00 AM on 15 May 2012101 responses to Ian Plimer's climate questions
Carbon500. See here for discussion of published total Ocean Heat Content. Note the date of the publication too. I'd say "the oceans are warming" is an accurate statement. What is the OHC data unequivocally shows is that we have an energy imbalance, and that temperatures will continue to rise. With a 101 questions to answer, the response is necessarily brief. If you wanted the detail, then the IPCC report would also make a good start, but good that you have found that.
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