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Tom Curtis at 07:55 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
MattJ @41, while I agree in principle, I have found that when attempting to do exactly that for readers of The Australian, my letters to the editor if even slightly critical of The Australian's reporting are immediately consigned to the trash can. I doubt Forbes editors will be any more generous. -
Tom Curtis at 07:52 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
KR @49, beautifully summarized. -
Tom Curtis at 07:51 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric the Red @39:"Am I alone here in stating that the temperature increase of the naughts was less than the nineties? "
I repeat my point of 47 that you are talking past KR and Bibliovermis in that your respective claims do not contradict each other. However, this claim is fraught with the possibility of misinterpretation. Using Gisstemp, and taking a five year average, the most rapid increase in temperature in the last 20 years occurred in the early 90's. But that is obviously the product of the the 97/98 El Nino following so closely on the reduction in temperature due to the Mount Pinatubo eruption. Clearly a five year moving average is two short to meaningfully discuss long term trends rather than short term effects. Taking a 10 year average, the most rapid increase is in the period 1995 to 2000, but that is followed by two shorter increases of nearly the same slope in the 2000's. While I agree with you that comparing successive, non overlapping ten year averages is not the best way to analyze the data, clearly you are pushing two hard to find significance in short term trends. -
Patrick 027 at 07:47 AM on 27 July 2011How we know we're causing global warming in a single graphic
If the sun was causing global warming, it would cause summers to warm faster than winter, Is this true sufficiently far from the Arctic? My understanding has been that the polar warming will generally tend to be greater in winter than in summer for either CO2 or solar forced-global warming, at least around where sea ice loss is occuring. -
KR at 07:40 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Tom Curtis - "...your claim does not contradict Eric the Red's claim @25." I would agree, except I would note that @25 was a move of goalposts. Skywatcher and I had both noted that decadal averages were increasing faster than a linear rate, which EtR objected to with 5 year averages. Eric the Red - Take a look at the link Albatross pointed you to, try the tool, and look at the nonsense produced by 5 year averages. 15 year trends approach significance, 30 year trends are significant for the raw data. Your 5-year claim is completely true and simultaneously statistically meaningless. -
Tom Curtis at 07:29 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric the Red @19:"Using Tamino's analysis on a sine wave superimposed upon a linear increase yields results wherein the bounds remain within the trend line for 130 years of data."
Have you actually done that analysis, or are you merely asserting it based on the eyecrometer? -
Tom Curtis at 07:25 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Bibliovermis @27 & KR @28, the 2000's where hotter than the 19990's to a greater extent than the 1990's where hotter than the 2000's as you say, but most of that increase in temperature occurred in the interval 1995 to 2005, and since 2005 temperatures have leveled out. That is, of course, of no consequence for interpreting the long term trend, as is amply illustrated by Sphaerica @42. However, your claim does not contradict Eric the Red's claim @25. -
Bob Lacatena at 07:23 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
43, Eric the Red, You are exemplifying my point. Albatross provided a wonderful visualization tool which properly uses statistics incorrectly (i.e. it uses the right techniques to show how one can get a wrong answer by using too short a trend). My eyecrometer method was more intended to show how you can do even better than that, by using bad technique with too short a trend to get anything you want. Any "the last five years" statement is a cherry pick. Look at the amount of noise in the system, and yet how neatly the entire ensemble fits into the curve.That is like saying July is hot, therefore we are warming. The La Nina for the first six months of the year will preclude approaching that high.
Um, no, I said this July as compared to any other July is shaping up to be the 2nd or 3rd warmest July ever, to be exceeded only by (potentially) 1998, 2009 and/or 2010 -- all under El Niño influence, and two of those three are in the last 3 years! What does that tell you? Coming right off the heels of a La Niña, without an El Niño to fuel it, the global mean temperature may approach those of previous recent El Niño summer temperatures. But you'll still be able to wait for the next La Niña, then draw a straight or even descending line through the past five or ten years and say "look, it stopped warming!" Any "last five/ten years" comment is a joke. -
Albatross at 07:02 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric, OP = original poster = Dana. -
Albatross at 07:01 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Sphaerica @42, While I appreciate the point you are trying to make. It would best to conduct such an exercise objectively. Use the point can be made using the neat Java tool embedded in this link. And just to be clear that graph is not mine but from a post by Robert Way, see link below graphic @40. -
Eric the Red at 06:59 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Sphaerica, I fall to see the analogy in your last post, and I believe Albatross is correct in not bending a line to meet a particular point. That is like saying July is hot, therefore we are warming. The La Nina for the first six months of the year will preclude approaching that high. The graph also includes several decades before CO2 levels starting rising, so I would not expect to see a similar trend during those years. No, I do not think you would get the same result choosing any 10-year period. Is it a joke, that people are claiming accelerated warming past on the past ten years, when the 5-year moving average has not increased since 2002? Albatross, what is OP? -
newcrusader at 06:38 AM on 27 July 2011Earth's Climate History: Implications for Tomorrow
Hansen and Sato reiterating their paper from earlier this year. Good stuff all. -
Bob Lacatena at 06:35 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
39, Eric the Red,Am I alone here in stating that the temperature increase of the naughts was less than the nineties?
It's a joke to pick the last ten years and to say warming has slowed/stopped/not accelerated. You can pick almost any ten year span and get the exact same result. Just look at the graph Albatross included. I can do it almost anywhere.
But if you go to Dr. Roy Spencer's site, and look at current temps, you see that we are well on the way the second or third warmest July ever, despite the fact that all previous contenders were El Niño years. Albatross is probably being gracious and conservative by not bending that red line up to meet the peak of the end, which is where I personally think global temperatures now sit, and with the exception of La Niña years you won't ever see anything less again in your lifetime.
Ten years from today I have no doubt that you will be saying "well, yeah, warming was fast in the naughts, but it's slowed down in the tens" and then "well, yeah, warming was fast in the tens, but it's slowed down in the twenties."
It's a complete joke of a game to be playing, and if you really believe it, then the only one you're fooling is yourself (and lots of other people who want to be fooled, because making subtle, immediate changes now to solve the problem is abhorrent to them).
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MattJ at 06:01 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Once more, I remind SS readers that being right it one thing, being persuasive with the public and the powers that be is quite another. It is not enough to refuse Michael's nonsense here in this blog, useful though that is: it must be taken to the readership of Forbes, so that they themselves protest to the editor being sold such a pig in a poke. That alone will get Michaels and his disinformation campaign out of Forbes. -
Albatross at 05:47 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric @39, Thanks, but you still did not answer all my questions. Please don't cherry pick which answers you elect to answer. I am (more) concerned with Michaels and the content of the OP post. As for the rate of increase, perhaps folks were thinking of this:
[Source]
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John Hartz at 05:45 AM on 27 July 2011SkS Weekly Digest #8
Byron & mfripp: When I selected this particular cartoon, I was concerned that readers would find it too parochial. I was not aware that the SkS comment policy guidelines addressed political content until I read Byron's note. I will take this into account when I choose cartoons for future editions of the Weekly Digest. -
Eric the Red at 05:30 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Albatross, If you look at some of the previous posts, KR @28 stated, "temperatures are increasing at an increasing (higher than linear) rate." Skywatcher at @21 also referred to the temperature increase as "steeper-than-linear." Bibliovermos @27 is also using 10-year averages to make a similar statement. I have stated my disagreement with them about the manner in which they are using statistics to make their claims. Am I alone here in stating that the temperature increase of the naughts was less than the nineties? This does not equate to a temperature decrease, short term changes aside. I do not agree with Michael's claim about no warming since 1996. However, I will place someone claiming accelerated warming in the past decade, by choosing a particular set of statistics, in the same club as Michael's. I understand that many people here do not like Patrick Michaels. Fine, I do not care for him either. But how can people tolerate someone who is making a claim that is just as bad in the opposite direction? -
jdixon1980 at 05:08 AM on 27 July 2011Mars is warming
Moderator, thanks for the nearly instantaneous response to my post #23!Moderator Response: You're welcome, but I forgot to point you to the Skeptical Science post "It’s the sun" for more info about TSI. -
jdixon1980 at 05:04 AM on 27 July 2011Mars is warming
What I am trying to drive at with my last question is that if in fact TSI is relatively constant over the past several decades (which I assume scientists agree that it is, otherwise how could you make inferences about temperature change between 1977 and 1999 based on changes in brightness of a planet?) and is the accepted measure of heat energy emanating from the sun, it would seem that the burden of proof is on the proponents of Mars as a model for Earth to show more than just a laundry list of similarities between Earth and Mars, but rather a complete theory on how "other" solar effects are altering both Earth and Mars in the same ways. In saying that, I am not ruling out that an empirical close correlation in climate trends between Mars and Earth could persuade me that there is something to the solar effects theories, but my impression from the comment thread is that there has been no clear showing that the trends on Mars and Earth have been parallel.Moderator Response: You are correct. There are no clear parallels of trends in global temperature between Earth and other planets. In some limited time periods (pretty much random snapshots) we have some idea of some few other planets' temperatures. Comparing across those too-few snapshots reveals some of those few planets might be warmer and others might be colder. So skeptics who claim "other planets are warming just like Earth" are plain wrong. -
mfripp at 04:59 AM on 27 July 2011SkS Weekly Digest #8
This cartoon does not advance the knowledge of climate change. Instead, the comic feeds the stereotypes that already exist. I agree with Byron, there are better options than this. -
jdixon1980 at 04:47 AM on 27 July 2011Mars is warming
Do I understand correctly that Fenton 2007 was not based on actual measurements of temperatures on Mars, but rather an inference that temperatures must be going up because the albedo was lower? In my crude understanding (I have a bachelor's degree in mechanical engineering, but I work as an attorney and am by no means up on scientific trends in general, much less trends in climate science), the inference is that a lower *proportion* of light energy from the sun was being reflected, meaning a greater *proportion* of light energy from the sun was being absorbed, and therefore temperatures must be rising as a result? If I am getting this right, then to rely on Fenton 2007 as evidence that Mars warmed between 1977 and 1999, wouldn't you have to accept in the first instance that albedo is a reliable measure of Mars temperature, and doesn't that theory imply that the TSI is fairly constant (for the moment passing over StanislavLem's comment about other solar phenomena besides TSI impacting Martian climate)? Otherwise couldn't the perceived decrease in brightness on Mars actually be due to a decrease in TSI rather than a lower proportion of TSI that is reflected? If that were the case, that would undermine the argument that the Earth is heating up *because* of solar changes, as the Earth would be heating up *despite* a decrease in TSI. Of course, if we are actually measuring TSI directly, then the foregoing line of reasoning is irrelevant, and please forgive my ignorance. Turning to StanislavLem's comment about other solar phenomena causing dust storms on Mars, reasoning that those are "possible" on Earth as well, is anybody putting forth a cogent theory that dust storms on Earth actually are happening, that they follow the patterns of dust storms on Mars, and that they impact Earth's climate in a significant way? Is there a general consensus that the only actual significant heat energy from the sun is from TSI, even if other solar phenomena might have other impacts (gravitational/magnetic?) that could indirectly affect climate?Moderator Response: TSI is indeed measured by directly, by spacecraft. -
Albatross at 04:40 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric @35, "People are going to great length to "prove" that warming has increased during the 2000s. The data does not show it." Perhaps I missed something, but this looks like a strawman argument to me. Who is going to great lengths to prove that the warming has increased during the naughts? You seem intent on entirely missing the point of the OP and turning a blind eye to Pat's transgressions. And I would very much appreciate an answer to my questions. Thanks. -
Bibliovermis at 04:28 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric the Red, The 5-year moving average was also discussed back on the "Why Wasn't The Hottest Decade Hotter?" article. Stop eyeballing the charts and moving the goalposts. -
KR at 04:19 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Back to the topic - Patrick Michaels statements on "no rise in temperature" are indeed statistically meaningless. Short term data is far too noisy to draw such conclusions from, as we've discussed here. I have to say that the discussion has only emphasized how deceptive these unsupported "no warming since..." claims are. But then, Michaels runs New Hope Environmental Services, described as "an advocacy science consulting firm", as well as being associated with the Cato Institute, the George Marshall Institute, and other advocacy/lobbying groups. He's focused on advocacy, not science. -
Eric the Red at 04:16 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Guys, When you average a 10-year period and compare it to the previous 10-year period, and an increase occurs, your data is too limited to tell if the increase occurred predominately in one 10-year period, the other, or was dispersed equally. A 10-year moving average cannot tell whether temperatures increased through the 2000s until the entire decade can be analyzed, which would require data out to 2015. A 5-year moving average would at least get to the end of 2008. The GISS 5-year moving average is similar to where it stood in the summer of 2002, while CRU is slightly lower. Not what one would expect is if temperatures were "rising faster than linerar." People are going to great length to "prove" that warming has increased during the 2000s. The data does not show it. When looking at the moving averages, the greatest increased occurred between 1993-7 for UAH and RSS, 1993-98 for GISS, and 1993-9 for CRU. In all four datasets, the greatest decadal increase occurred from 1993-2002. I am not making the claim that no warming has occurred since 1995, as that is obviously not the case. But I will disagree those who claim that warming has increased above the long term trend.Moderator Response: [Dikran Marsupial] The data doesn't show that warming has not increased either; see Tamino's analysis shown in this post. Note that Tamino uses tests of statistical significance. As you have been told repeatedly, decadal trends are not robust and it is a mistake to draw any firm conclusions from them in either direction. Decadal averages on the other hand are much more robust. -
Albatross at 03:56 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric @29, "Taking long average may suffice to convince the naive,..." I cannot believe that you elected to post that, especially after people in the know have counseled you and why it is necessary to look at long-term averages to discern statistically significant trends in noisy datasets such at the GAT record. Wow, just wow.Moderator Response: [Dikran Marsupial] Please can everybody refrain from responding to Eric's inflamatory posts. I have had to drop out of active discussion on this thread as moderation has become necessary. -
Eric the Red at 03:55 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
KR, Once again, you are showing the increase that occurred in the 1990s. I agree with the numbers. When you calculate the decade by decade difference you are exemplifying the rise that occurred in the 1990s. [inflamatory deleted]Moderator Response: [Dikran Marsupial] O.K., I will have to drop out of this discussion. Eric, enough of the inflamatory tone. It has been pointed out to you more than once that decadal trends are not robust, if you want to draw a conclusion from them you have a responsibility to detemine if there is statistically significant evidence for your hypothesis. Please note that posting comments here at SkS is a privilege, not a right. This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum. Please take the time to review the policy and ensure future comments are in full compliance with it. Thanks for your understanding and compliance in this matter. -
Dikran Marsupial at 03:54 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric the Red It is sheer hypocrisy for you to comment "You can play with statistics all you want until you arrive at your desired conclusion" when that is exactly what you are doing. Go and formulate a test of statistical significance for your hypothesis and see if the evidence actually does support it. P.S. I should avoid the tone you have taken in your most recent post. Were I not taking an active part in the discussion I would have deleted it as being inflamatory. -
Albatross at 03:53 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric, "Taking long average may suffice to convince the naive, but do not try to sell the snake oil to the rest of us." Sigh, now you are engaging in slander and innuendo. Please try and focus on the science. I look forward to your answers to the questions that I posed to you at #30. -
Albatross at 03:52 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
EricRed, "In every one of these plots, the increase is significantly less in the past decade, and approaching zero." Ah, there is the rub Eric-- "the last decade". I know that you know better than now. Please do not insult us here with such tired old games and canards. You need to up your game. Now are you here to defend (or distract from) the mendacious acts and distortions of Pat Michaels? It certainly seems so. In fact it appears that you are very much in agreement with him. If not, please state clearly which of his statements/claims you agree or disagree with and why. I'll help, Dana found that: 1) "Michaels committed the dishonest act of equating 'no statistically significant warming' with 'no warming'." 2) "He relied exclusively on CRU temperature data to make his arguments, even though he has previously criticized this same data, because the other temperature data sets do not support the arguments Michaels makes." 3)"Michaels' portrayal of Kaufmann's study was not very accurate, nor were his assumptions about the geographic distribution and effects of aerosols." Number 2 is priceless. After all the claims of fraud etc. made by "skeptics" against CRU by "skeptics", the CRUT data has suddenly become the darling of the "skeptics". Could it have anything to do with the fact that it is known to run cool....nah ;) But then again, recall how the "skeptics" were big fans of the UAH data until it started showing warming. -
Eric the Red at 03:47 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Bibliovermis, I agree with the statement that greater warmer was observed in the 1990s. That is exactly what you are protraying with your 10-year moving average. The 10-year moving average peaked in July 2002, with the greatest increase occurring from 1/1995 - 1/2000. You can play with statistics all you want until you arrive at your desired conclusion. [-Snip-]Response:[DB] Inflammatory snipped.
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KR at 03:42 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric the Red - "the increase is significantly less in the past decade, and approaching zero." From the GISSTEMP data: Temp. anomaly from 1951–1980 mean: 1980–1989 0.176 °C (0.317 °F) 1990–1999 0.313 °C (0.563 °F) [ +0.137 °C ] 2000–2009 0.513 °C (0.923 °F) [ +0.200 °C ] The decade by decade numbers say otherwise - temperatures are increasing at an increasing (higher than linear) rate for the last 30+ years. The year by year slope isn't meaningful - decadal averages are better, 30 year trends are statistically useful. You are incorrect, again, on this subject. -
Bibliovermis at 03:31 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric the Red, This is a broken record. Stop eyeballing a few pixels and crunch the numbers. We went round and round on this topic back on the Why Wasn't The Hottest Decade Hotter? article. The 2000s were warmer than the 1990s by a larger margin than the 1990s were warmer than the 1980s. Using a 10-year moving average with annual frequency, the last 10 decadal-periods have been the hottest ten with 8 of those 10 having an above average (of the past top 28) temperature change. As Dikran points out, short term trends are not robust. Temperature charts are not Rorschach tests.Moderator Response: [Dikran Marsupial] Link fixed -
Dikran Marsupial at 03:14 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric the Red the human eye is very good at finding what it wants to see in noisy datasets, which is why we have statistics. Given the level of noise in the dataset I suspect the decrease in the slope of the trendline is unlikely to be statistically significant. I can't believe that people are still using variants of the "no warming since 1998" canard. Short term trends are not robust, so you can't reliably detect a genuine decrease in slope from one decadal trend to the next.Response:[DB] ETR has tried to pull this wool over SkS eyeballs several dozen times now, without success. It grows tiresome.
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Eric the Red at 02:57 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
KR, You may want to look at this. http://www.cru.uea.ac.uk/cru/info/warming/ or this. http://data.giss.nasa.gov/gistemp/graphs/Fig.A2.gif or maybe this one. http://www.woodfortrees.org/plot/wti/from:1975/to:2011/plot/wti/mean:60 In every one of these plots, the increase is significantly less in the past decade, and approaching zero. -
garethman at 02:26 AM on 27 July 2011Gripping video of Arctic sea ice melting away before your eyes
It’s a great piece of video and technology. Wattsupwiththat also posted it a couple of weeks ago, though puzzlingly without any contention by posters, just a sense of wonder. Some of the bouys however have stopped working and some give a good view of a workshop. Hopefully they will be up and running again soon. I wonder if they float the right way up? -
dana1981 at 01:52 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Loehle and Scafetta would benefit from reading Dikran's comment #20. The physically baseless curve fitting we're discussing here, and which was done in Loehle and Scafetta's paper, will be the subject of a future post. -
KR at 01:34 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric the Red - The differences in decadal temperatures are increasing since the 1970's: see the plot here. That's a faster than linear increase, contrary to your post here. Secondly: "The data would best be described as a sine wave about a linear trend." Actually, no. The data would best be described as the response of the climate to multiple changing forcing factors. "A sine wave about a linear trend" is a descriptive term, but absolutely not an explanatory statement, as it has no ties to climate physics whatsoever. That's an eyeball judgement (eyecrometer?), not an understanding of the processes involved. Tamino's term for this, having actually analyzed whether there are periodic behaviors in climate from unknown sources, is Mathturbation. I find that quite accurate. Fitting arbitrary periodic functions to the data shows really poor statistical agreement, and has roughly zero predictive power. Unlike considering the physics involved... -
ranyl at 01:26 AM on 27 July 2011Earth's Climate History: Implications for Tomorrow
Worrying times unless we stop CO2 emissions. Peak 400pmm as a suggestion for safety? In figure 1 the early Pliocene (CO2 330-400ppm), is 2C hotter but I pressume it still had 20-25m higher seas, poles 19-21C hotter, warmer Eastern Pacific temperatures, wider tropical belt and generally different climatic zones when compared to the present as other researchers have reported. (Lunt D.J. et al, “Earth system sensitivity inferred from Pliocene modelling and data”, Nature Geoscience, VOL 3 , JANUARY 2010, Pagani M et al, “High Earth-system climate sensitivity determined from Pliocene carbon dioxide concentrations” Nature Geoscience VOL 3 , JANUARY 2010, Seki O. et al, “Alkenone and boron-based Pliocene pCO2 records” Earth Planet Sci Lett (2010), Schneider B. “Global warmth with little extra CO2”, Nature Geoscience, VOL 3, pg. 6-7, 2010, Csank, A.Z., et al., “Estimates of Arctic land surface temperatures during the early Pliocene from two novel proxies”, Earth Planet. Sci. Lett. (2011)) The Early Pliocene is most often reproted to be 3-5C hotter (ref. above) than pre-industrustial times making the 100yr climate sensitivity for a doubling of CO2 to be alot higher at 4.5-7.5C (70ppm is 0.4 of a halving if the initial CO2 is 350ppm, 70/(350/2)), whereas if 2C is correct then CS 3C is correct as above. Basically though over the long term 350ppm gets you to the Pliocene whatever its temperature was and you gets about 60% along the way in 100years (unless there is a significant hystersic effect in the way which seems unlikely as Greenland is likely to melt and Antarctica has been a stable albedo for much longer) and if it was only 2C hotter, 1.4C is 100 years looks a lot more relevant and we've already gone ~0.7C. Wonder how much effect an summer ice free arctic will have on the rate melt of Greenland? Ignoring the possibility of at least 2m sea levels rise by 2100 would seem poor planning to me. -
muoncounter at 01:21 AM on 27 July 2011CO2 is not a pollutant
davidh#21: "gets even more problematic when you have to reconcile industrial emissions with natural emissions (e.g. "Am I polluting by breathing?")." That's just silly; we inhale much of the same CO2 we exhale. See the prior thread on breathing (use search). On the other hand, consumption of fossil fuels produces a waste product; on human time scales, it's a one-way process. -
Eric the Red at 00:56 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Sky, I am not sure exactly what you mean by steeper than linear, but assume that you are implying that the linear trend is increasing. That is simply not occurring, as the greatest increase in the past 40 years was observed in the 1990s, with the smallest occurring in the past decade. -
skywatcher at 00:31 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
#19, Tamino has a not very polite word for that kind of unsupported analysis, and has written about that kind of thing several times. I would describe it as climastrology, and not based on any mechanism or forcing factor. It fails miserably as you go further back in time, and has no predictive value. With enough degrees of freedom you can fit anything, but it does not mean you have found anything useful! There are good reasons to think the long-term trend is of different gradients at different times, as it follows from the sum of forcings, including CO2, aerosols and solar elements. On a shorter timescale, such as within an individual decade, forcings such the slight nudge from an individual solar cycle, or a series of El-Ninos transitioning into La Ninas over about a decade, will cause smaller wobbles in the larger trend. It happens that the past 40 years has an approximately linear trend. In fact it appears steeper-than-linear, as the temperature difference between the 2000s and the 1990s is larger than the temperature difference between the 1990s and 1980s, or 1980s and 1970s. -
Dikran Marsupial at 00:25 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric the Red however that does not mean that the observed temperature is the result of a periodic physical process. Computing a linear trend over a period where the changes in forcings have been fairly simple is a sensible thing to do. Curve fitting without taking into account what we do know about the underlying physics is pretty pointless. You comment "The data from ~1975-2005 falls on the increasing portion of the sine wave, and hence, appears linear." implicitly assumes that there actually is a sine wave in the data, rather than the observed temperatures being due to multiple changes in a range of different forcings. -
Eric the Red at 00:16 AM on 27 July 2011Michaels Mischief #1: Continued Warming and Aerosols
I agree that a single long-term trend does not reasonably characterize the data for the entire century. The data would best be described as a sine wave about a linear trend. The data from ~1975-2005 falls on the increasing portion of the sine wave, and hence, appears linear. Using Tamino's analysis on a sine wave superimposed upon a linear increase yields results wherein the bounds remain within the trend line for 130 years of data. -
Tom Curtis at 23:54 PM on 26 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric, the supposition you are making that there is one privileged long term trend to which the trend always returns is not warranted. You can generate a least squares linear trend for any set of data. It does not follow that it means anything. The data may be random, or quadratic, or logarithmic, or a succession of distinct trends. Consequently, the only thing you can conclude if the long term trend falls outside the 95% confidence interval of shorter trends in the series is that a single long term linear trend does not adequately characterize the data. If you then want to fit a linear trend plus long term cycle to the data, you can certainly attempt to do so, but no amount of analyses of graphs such as that in 13 will justify that attempt. As it happens, a single long term trend does reasonably characterize the data from 1975 to present, but it does not do so for the entire 20th century. -
Eric the Red at 23:33 PM on 26 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Tom, The former. The actual range would be determined by how far back the graph is extented. I suspect that if one were to go back to the late 19th century and start the trend at this time that there would be periods whereby the bounds fall above and below the trend line. The period you describe would be one of them. The short-term trends changed during these periods, but did not last, as it returned to the long term trend. The implication is that the long term trend is not static, but fluctuates above and below. Using Tamino's analysis, the fluctuations are not noise, but are real. Since the fluctuations occur about the long-term trend, and have always (so far) returned to the trend, there appears to be no reason to believe that it has changed recently. -
Bob Lacatena at 23:10 PM on 26 July 2011Are you a genuine skeptic or a climate denier?
...first that it confiscates the property of the fossil fuel investors.
Cries of stealing profits or property from FF producers reminds me of asbestos. Would anyone argue that we should have let asbestos miners/manufacturers continue to ply their wares, despite the dangers... because it would be unfair to steal their property/profits from them? The Daily Show News article Really... what's the difference? -
Tom Curtis at 22:47 PM on 26 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Eric the Red @15, I am not sure what you are saying here. You may be considering an extension of Tamino's graph back to 1961, such that the longest trend and hence the red dotted line is drawn from the 1961-1911 trend. In that case, you claim (and I well believe) that at some point the bounds of statistical significance for some shorter term trends, presumably in the range 1975 to 1993 do not intersect the long term trend. That is an unsurprising result (if it is what you are claiming) and represents significant evidence that there has been a genuine (ie, long lasting) change in trend between 1961 and the present. Alternatively (and unlikely) you mean that the short term trends at the end of the figure fall outside the bounds of statistical significance for the long term (50 year) trend. Well, yes. They also fall outside those bounds for the 1975 trend. And that is entirely inconsequential, as it represents an incorrect use of the technique. In either event, I don't see any problem for the method of analysis. -
Eric the Red at 22:25 PM on 26 July 2011Michaels Mischief #1: Continued Warming and Aerosols
Tom, Tamino's analysis works for the time period and trend indicated indicated. However, if one uses a longer term trend (50 years or more), then the bounds fall outside the trend line. I am not arguing that a change has occurred in the long term trend, but that shorter term trends fall above and below his bounds. -
Sarah at 22:23 PM on 26 July 2011OA not OK part 8: 170 to 1
Doug, Correct. I'm was trying to simplify to the crux of Jeff's concern, which seems to be CT plus water. Additional contributions to alkalinity are critical for real world calculations, but the basic (and acidic!) chemistry ideas can be understood with a simplified mixture.
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