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glhoffman at 07:53 AM on 16 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
With regard to post no. 34, there are more fundamental problems with current models in making projections because they are largely unverifiable.
Moderator Response:[PW] Discussion of 'models are wrong' are veering a bit off-topic for this thread: further discussion should be posted here.
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KK Tung at 07:35 AM on 16 July 2013The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.
In reply to MA Rodger at post 188: I had trouble understanding your original posts---that was the reason I didn't respond to them then. I may still not be understanding it; so please correct me if I misinterpret your points. You are looking at the interannual variation of the original data in HadCRUT4. This was shown in Figure 4A, not Figure 5A of Tung and Zhou (2013), PNAS. Figure 5A is the result of one round of MLR, after removal of ENSO, vol and solar influences. Figure 5B is the adjusted data, and it contains everything that remains after removal of ENSO, sol and solar, plus AMO influence. It should contain anthropogenic response plus climate noise ideally. In reality it also contains errors in observation and the interpolation that was used to come up with the global mean, especially in the early decades in the 20th century; the 50 years prior to that was especially bad, datawise. You can see that after 1970s, the variations about a linear trend do look smaller and like random noise.
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KR at 07:22 AM on 16 July 2013Trenberth on Tracking Earth’s energy: A key to climate variability and change
Phil - Actually, a 2.9 W/m2 top of atmosphere forcing should directly raise temperatures by about 0.877 C, not including feedbacks.
Calculation: start with the Stefan-Boltzmann relationship of
or Power = emissivity * SB constant * Area * Temperature4
The Stefan-Boltzmann constant is 5.670373*10-8 Wm-2K-4, surface temperature in Kelvin averages 15 C + 273.15 = 288.15 K, and for area we can assume one square meter.
Starting effective Earth emissivity = Power / (SB constant * T4) = 240 W/m2 /(SB * 1 * 288.154) = 0.6139
With 2.9 W/m2 missing, effective emissivity = 237.1 W/m2 /(SB * 1 * 288.154) = 0.60652
To radiate 240 watts with a lower effective emissivity, and remove the energy imbalance, a higher temperature is required. T = (240 W/m2 / (SB * 0.60652)) -4 = 289.03 K = 15.877 C. That's a direct, pre-feedback temperature difference of 0.877 C.
Moderator Response:[DB] updated image link per request.
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Brett N at 07:13 AM on 16 July 2013Global warming games - playing the man not the ball
Twenty years ago I thought the science was complete enough to begin a plan of action to slow the advance of climate change. Sadly, I was naive enough to think our politicians would do the right thing and start to implement the changes required. Silly me, while I went off and lived my life a drama of truly epic proportions was being played out. Heroes and villains, dark forces pulling the strings of puppets ensnared in a web of greed, subtext and innuendo abounding. Shakespeare be dammed, scientists rock!My thanks go out to all of you who have advanced our fight for survival. More than once, I have descended into the twisted rabbit hole of a denier site. Such a pretty argument, so simple, so easy to be sucked in, only to find myself lost in a maze of half truths and sound bites. Yes, more than once, a lifeline thrown by the posters on this site have saved me. Your selfless dedication to the truth, and boundless patience in educating even the slow ones such as myself, should be recognized by all, as truly heroic. -
Phil at 06:56 AM on 16 July 2013Trenberth on Tracking Earth’s energy: A key to climate variability and change
The 2.9 Wm-2 surplus doesn't heat the atmosphere; it heats the entire planet. My back-of-envelope calculation (literally !) suggests that should result in an annual temperature rise of 0.0082K
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supak at 06:52 AM on 16 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Tom Curtis @ 17
While some of what you said went over my head, I appreciate your input and will definitely try to hunt down some of the information you offered.
jdixon1980 @ 36
"so that I wouldn't end up having a financial stake in "rooting" for the human race to continue to drive itself into devastation."
That's funny, and what my wife often laments about my propensity to want to gamble on the future of the human race. I don't have these qualms because I don't have to root for a bad outcome. It's already going to happen.
My guess is that even if he has millions in the bank, he has no plans to pay out on any such bet, so I'm probably wasting my time. But I am keeping what he's saying and plan to make a blog post out of it at some point. I'm just looking to get some input from you guys so I don't look like a fool.
See, while I understand a lot of this stuff, I'm really just a gambler who is always looking for a sure thing. I cannot think of anything much more sure than the fact that we are going to see significant warming of surface temps in the next 25 years.
I do, however, like the comment from Ken in Oz @ 16 that going by surface temps alone is a fool's errand. We shoud be sure to always mention that the vast majority of the warming has gone to the oceans. If only there were some accurate measure of ocean warmth I could get Micheals to agree on, then I'd include that as a seperate bet.
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michael sweet at 06:43 AM on 16 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Ray,
If the best you can come up with for the IPCC exaggerating AGW is an obvious typographical error I take that to mean you agree that the IPCC has not exaggerated AGW at all. A non-skeptic scientist found that typo and the IPCC has publicly acknowledged that they copied an error from another publication.
I dare say that all of the regular posters here agree with Gavin on the "science is settled" statement. Your post here implies that at Skeptical Science we claim the science is settled. Perhaps you need to write your posts more carefully so that you are not misunderstood.
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Kevin C at 06:03 AM on 16 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Ray: You comments are based on a simple but common misunderstanting of statistical significance. We have been meaning to do an article on this, but there never seems to be time. See Misuse of Statistics for an overview.
A statistical significance test on a trend can only disprove the null hypothesis, it cannot prove it. Therefore the fact that the trend on some arbitrary short period can never falsify the hypothesis of continuing warming. That's a simple statistical fallacy.
The confusion arises from the fact that the test is not symmetric. It can falsify the hypothesis of 'no trend', but it cannot falsify the hypothesis of 'continuing trend'. For that you need to change the test.
That may seem counterintuitive, but it's really very simple. If a trend is not statistically significant, it's telling you one of two things. Either
- There is no trend, or
- You don't have enough data
But it doesn't tell you which, so you have no more information than when you started. On the other hand if the trend is statistically significant, then you know that both
- You have enough data, and
- There is a trend
(subject to the given confidence intervals).
Thus, whenever you hear someone quoting the lack of statistical significance of a trend as evidence for a hypothesis, you can immediately conclude that they don't know what they are talking about.
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KR at 04:34 AM on 16 July 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
old sage - Yes, GHGs share energy back and forth with the surrounding atmosphere.
The electron relaxation time for a CO2 molecule is on the order of 10-6 seconds before radiating a photon, while at sea level pressures each gas molecule will collide ~109 times per second - meaning that a CO2 molecule will average roughly 1000 collisions before it can radiate. Therefore the GHG molecules and the surrounding atmosphere are at the same temperature.
The thing is, at thermal equilibrium the absorption spectra of an object (including a volume of gas) is equal to the emission spectra - and as much energy leaves as enters. Note that this doesn't mean the same molecules radiate as absorb, just that statistically as much energy is radiated as absorbed by radiatively active molecules in that volume. And those that radiate do so becase they have the energy to do so, because they are warm enough.
Again, you are presenting Arguments from Incredulity, in contrast to facts, to measurements. Your personal inability to get your head around those facts does not invalidate them.
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old sage at 04:07 AM on 16 July 2013Trenberth on Tracking Earth’s energy: A key to climate variability and change
TD - high time the calibration of spectrographs was investigated if measured.
I cannot get my head round 3 kgs of CO2 absorbing and emitting 350 watts of energy surrounded by 3000 times as many other molecules - do they all agree not to bump into them. I also cannot get my head round the alleged 2.9 w/m2 surplus from GG's. That's equivalent to raising earth's atmosphere 10 degrees p.a. - I think we would notice that!
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old sage at 03:58 AM on 16 July 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
I have been directed to this thread but could not even start to question it, there are too many lacunae in the reasoning starting from the car engine analogy. The engine boils even if the pump keeps pumping because the heat is transported by the pump and has to be dissipated by conduction/convection through the vanes of the 'radiator' - where radiation is irrelevant, just stop the fan to find out. Radiator is a misnomer for a domestic device for conduction and convection of heat - physicists should know that.
I cannot get my head round 3 kgs of CO2 molecules accepting and re-emitting 300 watts of radiant energy in the presence of three thousand more numerous molecules of N2 O2 H2O etc - do they all agree not to collide with them so as not to convert the energy to kinetic?
I cannot get my head round the 2.9 w/m2 said to be the surplus greenhouse heating - that equates to raising the atmosheric weight of air through10 degrees p.a. - I think we would have noticed it somehow.It's time someone addressed their energies to the way spectrographs are calibrated.
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jdixon1980 at 03:20 AM on 16 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Supak @14, 15: Any bet that I made, I would want to bet on different outcomes for different emissions scenarios, so that I wouldn't end up having a financial stake in "rooting" for the human race to continue to drive itself into devastation. But I'm not a climate expert - maybe 25-year predictions don't depend much on which emissions scenario happens during those 25 years, in which case I applaud your denier tax.
On the other hand, is Michaels making enough of these bets that he is liable to go bankrupt and leave you unable to collect?
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JasonB at 02:36 AM on 16 July 2013Empirical evidence that humans are causing global warming
Earthling,
That would have to be a record-breaking transition from "It's not us" to "It's good". Well done. Now you just need to familiarise yourself with the consequences of AGW before deciding that it's a good thing.
Thanks to all who replied, I'll consider the possibility that humans have caused somewhere around 74 to 122% of warming and compare it to the IPCC WG1AR5:
"It is extremely likely that human activities have caused more than half of the observed increase in global average surface temperature since the 1950s."
"The greenhouse gas contribution to the warming from 1951–2010 is in the range between 0.6 and 1.4°C. This is very likely greater than the total observed warming of approximately 0.6°C over the same period. {10.3.1}"
I'm not sure what you mean by "compare", do you think your statement is inconsistent with the two quoted? The first is talking about all human activities, the second is specifically talking about greenhouse gasses and echos the comment I made earlier as well as reflecting the most recent scientific literature (which is what the IPCC is actually doing, after all), pointed out already by Daniel Bailey.
"If it doesn’t get warmer over the next years, then it likely will be blamed on the increased share of anthropogenic cooling."
Note that this statement is not from the IPCC WG1AR5. Although it was indented differently, I found the fact it was included in quote marks immediately afterwards and in the same font to be misleading. It's actually a translation of a comment on a blog post!
It also displays a desire not to understand how the system actually works and even criticises genuine scientific attempts to do so when the results don't fit the simplistic strawman that had been constructed.
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Bob Loblaw at 01:35 AM on 16 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Ray:
No, I was not under the impression that you did the statistical analysis. I was hoping that you understood the analysis well enough to know what it really meant. That hope is currently dwindling.
I am still at an impass, with insufficent observations to distinguish between two hypotheses. Those were listed in my last paragraph of the comment above, but I will reword them here, perhaps a little more directly (or bluntly):
1) are you unfamiliar with the proper way of determining a null hypothesis and incoporating that into the "expected value" of a statistical significance test (e.g., t-test)? If this is the case, then are you willing to learn about it before you make any further uninformed comments about significance testing?
2) If you are familiar with how to appropriately choose an "expected value", then why are you making statements that are not supported by the statistical tests that other have done? - e.g., the incorrect idea that a non-significant difference from zero means that the trend is zero? If you do know the meaning of such tests, and are deliberately twisting them into something that they do not actually mean, then that raises questions as to your sincerity.
There may be another explanation that I am not considering, so feel free to provide alternatives. For now, if I had to bet, I'd go with option 1, given that you do not seem to know what null hypotheses others have used in their trend calculations.
To try to keep at least a bit of this on-topic, Pat Michaels seems to often fit into option 2: I think he knows better, but he realizes that many casual readers/observers do not. Consequently, he twists the science into something it is not, makes grandiose statements that lead people to where he wants them to be, and to hell with what the evidence really says. I would not buy a used car from him.
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barry1487 at 01:32 AM on 16 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Despite all this however I do wonder why, in the face of ever increasing CO2 levels, the trends for all the major global temperature data sets are at best showing increases that are not statistically significant and more recently are, apparently, flat
A warming climate does not preclude weather events, and at short time periods the 'noise' can obscure the signal.
There is no statistically significant warming for the last 3 years. Do you think that represents a trend in climate?
You need a premise with which to begin assessing climatic changes rather than the variance within the system. One of the first things to ask is, "how long is enough determine global climate change?" Obviously a few days or months or a handful of years isn't enough. So how long do you need before the short-term effects roughly balance and a climate signal emerges?
Robert Grumbine attempted a mathematical estimate some time ago.
http://moregrumbinescience.blogspot.com.au/2009/01/results-on-deciding-trends.html
The following is worth reading, too.
http://tamino.wordpress.com/2012/07/06/how-long/
(In the 7 to 8 years I've been browsing the climate debates, not once have I come across a 'skeptic' doing analyses like these. It is obvious why that is so)
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rockytom at 01:07 AM on 16 July 2013Climate Change Denial now available as Kindle ebook
"Climate Change Science: A Modern Synthesis" may also be available in your local library. If not, you can request that they order it. I think that Springer offers a special discount to libraries.
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barry1487 at 00:52 AM on 16 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Himalayan glaciers vanishing by 2035
Not an exaggeration, an error, which IPCC acknowledged when it was pointed out. AR4 has a few other errors in it.
You're better off choosing the first or second assessment reports (FAR 1990, SAR 1995), Ray, because projections from the TAR (2001) or AR4 (2007) generally can't be tested owing to the short time span since.
If you want to focus on surface data, 20 years is a fairly good minimum time period, and a bit more for satellite data - if atmospheric temperatures are the metric you prefer.
Skeptical Science has a handy tool for that - here. The trend results come with uncertainty estimates. You can get an idea of how much data is needed to achieve statistical significance by changing the time period length. You might want to test claims you've read about by plugging in the time periods, and seeing if the trends are greater than the uncertainty. It's a useful bookmark for the climate debates.
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John Hartz at 00:47 AM on 16 July 2013It's waste heat
Old Sage:
The Science of Doom is a "go to" website for anyone seeking to better understand the mathmetics of climate science. The site is devoted to evaluating and explaining climate science in a very structured manner. It has a 13-part series about Atmsophereic Radiation which you should carefully study.
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Tom Dayton at 00:41 AM on 16 July 2013It's waste heat
Old Sage, I have replied to your comment on an appropriate thread. If you want to continue this conversation, do so over there, not here.
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Tom Dayton at 00:39 AM on 16 July 2013Trenberth on Tracking Earth’s energy: A key to climate variability and change
Old Sage (from an inappropriate thread), you are ignoring what KR pointed out: The numbers in that energy budget are based on actual measurements by hundreds of scientists, refined over many years. You can read about their methods by following the links to the original peer-reviewed papers. That budget does not violate any laws of physics. Really, it does not. It's not even hard to understand. But first you must actually try to understand it. It is clear from all of your comments on Skeptical Science so far that you are not really reading, let alone really trying to understand, anything. You would fail an Introductory Climatology class simply by refusing to read and try to understand.
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old sage at 00:22 AM on 16 July 2013It's waste heat
Very interesting chart that KR, it rewrites the laws of physics replacing that of conservation of energy with conservation of radiation and as for the kinetic theory of gases, forget it. Hardly a joule from conduction and not an erg from the radiative shell surrounding earth.
Hey ho.Moderator Response:[TD] Put your comments about the energy budget somewhere more appropriate, such as the post by Trenberth. Put your comments about the basics of the greenhouse gas mechanism somewhere more appropriate such as the post Tom Curtis pointed you to. In all cases, you really need to read the original posts before commenting.
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tmac57 at 00:08 AM on 16 July 2013Global warming games - playing the man not the ball
I don't know that the story contains "witches",but it most definately has witch hunts as an element.
My contribution will be sent to PEER today.Thanks John Abraham.
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Ray at 00:02 AM on 16 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Michael Sweet Himalayan glaciers vanishing by 2035. I'm fairly that's not an "absurd claim" Sorry but I don't know if there is a link to "The science is settled" at SkepticalScience but here's one to Real Climate in a piece written by Gavin Schmidt. http://www.realclimate.org/index.php/archives/2009/12/unsettled-science I thought this comment of his was very relevant: "The reason why no scientist has said this is because they know full well that knowledge about science is not binary – science isn’t either settled or not settled". Too true
Bob Loblaw you appear to be under the impression that I did the statistical analyses of the temperature data. I didn't You'd have to ask those that did to find out what their null hypothesis was. Hope that is explanation enough but I don't recall seeing it specifically stated
Moderator Response:[TD] The Himalayan glaciers error is covered here.
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John Hartz at 00:01 AM on 16 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
@Glenn Tamblyn, Tom Curtis, Bob Loblaw:
It would be extremely beneficial to all of our readers if you guys were to meld your responses about statitiscal significance into a blog post article.
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DSL at 23:53 PM on 15 July 2013Global warming games - playing the man not the ball
And you can add this to the lovely correspondence the cro-mags have defecated toward climate scientists.
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DSL at 23:47 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
And finally, Ray, if you come up with a period of statistically insignificant warming, or even a period with a negative trend, so what? What does it mean? Is it "aha! gotcha!"?
David Rose of the Daily Mail thinks that it means that "global warming has stopped," and he's quite willing to use his power to spread that message far and wide. Do you think a sixteen year statistically insignificant warming trend in global average surface temp means that global warming has stopped? If so, what does a sixteen year trend of .286C per decade mean (1992-2007)? Do you think it's good methodology to use the surface trend to claim a theory has been demolished, and to do so without performing a component analysis, and without accounting for ocean heat content and the energy used in (accelerating) global ice mass loss.
Aha! Gotcha! Oh ho! Uh huh!
No. The theory of anthropogenic global warming is not based on the global average surface temp trend. The theory did not start with "hey. it's warming. i wonder what's causing it." It started with "hey, per Tyndall, CO2 is a greenhouse gas. I wonder what would happen if humans increased atmospheric CO2."
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DSL at 23:30 PM on 15 July 2013Empirical evidence that humans are causing global warming
Earthling, I've responded to part of your sentiment here.
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DSL at 23:29 PM on 15 July 2013It's not bad
Earthling: "It would seem that we humans have probably done ourselves a favour by acting to avoid a decline in global temperature."
What, by missing the next glacial period 1500 to 5000 years from now? Sure, the LIA sucked, but so did the PETM and end-Permian. The PETM event involved a change in global average temp of 5C over 12,000 years. That's what extreme looks like. We're doing about 40x the rate of PETM warming. In what shape will we be when the time comes for us to miss the next glacial period? When is the best time to develop sustainable energy and greenhouse management technology? When the world is rich in energy resources and relatively stable politically, economically, and socially? Or when cheap energy is diminishing, food prices are rising, climate is persistently unstable, and many more people are on the move trying to find a better place to live? I think the idea is that we reach the next "missed" glacial period without having gone through the school of hard knocks and instead having shown that we're mature enough to drive the family car.
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kar at 22:58 PM on 15 July 2013Climate Change and the Nature of Science: The Carbon “Tipping Point” is Coming
A general problem far beyond this article, is that too often the horizon of problems into the future is set to be like 87 years or may be couple of hundred years (until 2100 or a couple of centuries more).
Even quite a lot of science article fail to mention what David Archer told us in the The Long Thaw - it will last more than 100,000 years to reach back to preindustrial state of CO2 content in the air ... -
kar at 22:40 PM on 15 July 2013Climate Change and the Nature of Science: The Carbon “Tipping Point” is Coming
Is it not a error in the start of the 6th section? Where it should be to and not from?
There is written:
"... that there are 3.1 billion tons of extra carbon being added from the atmosphere ..."
Should been:
"... that there are 3.1 billion tons of extra carbon being added to the atmosphere ..."
... and it could be also be added in the end of the sentence: ... every year.
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michael sweet at 20:47 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Ray,
I am still waiting for you to provide examples of the IPCC exaggerating the AGW problem. You suggested at 2 above the IPCC exaggerates the AGW problem. SInce you referenced WUWT above I presume you have not seen any posts there that document the IPCC exaggerates the AGW problem. If you provide no examples that would indicate that your suggestion of exaggeration was incorrect.
Please provide a link to a Skeptical Science thread that claims "the science is settled". There is much to learn about AGW. On the other hand, even the skeptics now admit that the temperature is increasing. The greenhouse effect and the contribution of CO2 is also no longer debated by scientists. If you want to suggest that we have to convince WUWT you will have to be more specific about what you claim is not settled. What exactly are you claiming is not settled? Please provide specific examples.
It is easy to make absurd claims if you are not required to back them up with specific examples.
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Paul D at 20:27 PM on 15 July 2013Global warming games - playing the man not the ball
The fact is, climate science undermines the established economics and politics of the 'left vs right' meme for the last 100 years or so.
So it was always going to be a rough ride.Galileo experienced the same problem trying to get the political (religious) establishment to listen.
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MA Rodger at 20:23 PM on 15 July 2013It's waste heat
old sage.
Your argued position here appears to rest on the method used to measure themal conductivity in fluids as described in your physics text book. Radation and convection effects are something such a method would require to reduce to insignificance because if not the measurement method would need amending to account for them.
Thus when you say radiation is only 5% the effect of conduction, that simply demonstrates a well designed method (although 5% due to radiation is actually pretty rubbish, to be honest).
But you are taking this 5% figure and asserting it to be some universal ratio of the relative importance of conduction and radiation. Such a use is nonsensical.
I would suggest you read the rest of that physics text book. This will allow you to make some very basic calculations for the size of radiative energy fluxes through the Earth's atmosphere and you will quickly discover that the 5% figure is entirely inappropriate.
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Cornelius Breadbasket at 19:22 PM on 15 July 2013Global warming games - playing the man not the ball
There are many scientists on this site, and in particular menioned in this article that I'd like to nominate for the John Maddox Prize. I'm hoping that readers here may also make nominations.
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Earthling at 16:44 PM on 15 July 2013Empirical evidence that humans are causing global warming
JasonB, "(i.e. the temperature would have actually declined without human GHG emissions)."
It would seem that we humans have probably done ourselves a favour by acting to avoid a decline in global temperature.
The LIA, wasn't a time I would have enjoyed living in, for me, the 40s were bad enough.
Thanks to all who replied, I'll consider the possibility that humans have caused somewhere around 74 to 122% of warming and compare it to the IPCC WG1AR5:
"It is extremely likely that human activities have caused more than half of the observed increase in global average surface temperature since the 1950s.""The greenhouse gas contribution to the warming from 1951–2010 is in the range between 0.6 and 1.4°C. This is very likely greater than the total observed warming of approximately 0.6°C over the same period. {10.3.1}""If it doesn’t get warmer over the next years, then it likely will be blamed on the increased share of anthropogenic cooling.".
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Bob Loblaw at 14:56 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Ray makes two statements (in two different comments):
"If the rise is not statistically significant is it really a rise?"
"In my own field of science which is biochemistry, Student's t-test is routinely used as a measure of significance."
The unstated question is: not statistically significant compared to what? If you are as familiar with a Student's t test as you claim, then you will remember that an important step in the calculations is where you determine "observed - expected". In the case of a temperature trend, "observed" is the slope from the regression, and "expected" is the value from your null hypothesis. But what is your null hypothesis?
- if you want to see if the slope is non-zero, then your null hypotheis is zero and your expected value is zero. This is very common.
- if you want to see if the past warming trend has "stalled", or "stopped", etc., then your expected value is not zero, as your null hypotheis is that the trend has not changed. To use zero as the expected value is wrong - you should use the previous trend value as your expected value. This mistake is also very common.
For the case where a calculated trend is neither significantly different from zero, nor significantly different from the previous trend, then the data that you have is insufficient to distiguish between those two null hypotheses. Which is where Glenn and Tom's comments about short time periods become relevant.
If you are unaware that a t-test can use an expected value other than zero, then you've got some learning to do. If you are aware that an expected value can be non-zero, then you've got some explaining to do.
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Ray at 14:36 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
The link is http://en.wordpress.com/tag/werner-brozek/. In the article the author comments on the slope of the lines. As I stated I'm a biochemist not a climate scientist and I acknowledge that comments such as those by Tom Curtis and others are from those with more understanding of the science than I have. That said, the scientically trained layman can see that "the science is settled mantra" may be premature from some the findings reported.
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Tom Curtis at 14:33 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Ray @23, you now show evidence of some statistical sophistication. Given that, I wonder how you can justify parsing:
"The hypothesis of no warming has not been excluded"
as:
"There has been no warming".
To my mind the later is a positive claim, in effect stating that the hypothesis of warming has been excluded by the data. And that is, of course false. In science, no hypothesis gets prefferential treatment. Not even the nul hypothesis, and failing to disprove the null hypothesis is not the same as proving the null hypothesis, no matter how many times deniers pretend to the contrary.
In this case, however, the null hypothesis is only disconfirmed if you cherry pick your start points to limit the data available; and if you exclude other known relevant data (such as ENSO states). I wonder how you would mark a student who, having tested a hypothesis and excluded the null, dropped half of the data and redid the test, then reported only the data used in the second test along with a confident claim that the failure of that data to exclude the null hypothesis showed that the hypothesis being tested was false (ie, "There has been no warming.")
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Tom Curtis at 14:23 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Ray @20, first I'll note that Glenn Tamblyn's response is excellent. If you think carefully about what he wrote I need add nothing (though I'll add it anyway). In particular, he pointed out that for any period in the last forty years, even though the linear trend over that period is positive and significant (0.167 +/- 0.037 C per decade), there is a shorter period in which the trend is not statistically significant. If you interpret "the trend is positive but not statistically significant" as meaning there is no trend, then for each of those periods there both was a positive trend (because it is part of an extended period with a statistically significant rise), and no trend (because it is part of a period without a statistically significant trend). Thus, the common misinterpretation of lack of statistical significance is directly inconsistent. Logically, it cannot be true.
In fact, statistical significance speaks not to whether the observed trend is rising or falling, but rather how confident we can be about that claim. If the trend is rising but not statistically significant, that means there is:
- The observed trend is positive.
- A greater than fifty percent chance that the underlying trend is positive.
- A greater than 2.5% chance that the underlying trend is flat or negative.
That is all it means.
If we know that the trend is positive at the 90% confidence level but not at the 95% confidence level, then:
- The observed trend is positive.
- There is a greater than 95% chance that the trend is positive.
- There is a greater than 2.5% chance that the trend is flat or negative.
The reason it is a 95% chance rather than a 90% chance is because the confidence interval is symetrical, so there is a 5% chance that the trend will be positive, but larger than the upper bound of the 90% confidence interval, which is, of course, still positive.
Of course, those probability estimates are based only on the information in the temperature data alone (plus some well characterized statistical assumptions). If we include other data, such as the known relationship between ENSO oscillations and temperature, and the known ENSO fluctuations over the period, the probability that the underlying trend is positive becomes much greater that indicated the temperature data alone. Indeed, including the information about ENSO and other known short term influences shows the underlying trend since 1997 to by 0.209 +/- 0.085 C per decade (GISTEMP adjusted).
In any event, turning the claim that the trend is positive but not statistically significant, ie, the claim that:
- The observed trend is positive.
- A greater than fifty percent chance that the underlying trend is positive.
- A greater than 2.5% chance that the underlying trend is flat or negative.
into the claim that there is not positive trend can at best be construed as woefull ignorance, but in many cases is more likely to be deliberate misrepresentation.
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Ray at 14:04 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Thank you for the comments in posts 21 and 22. In my own field of science which is biochemistry, Student's t-test is routinely used as a measure of significance. If I get a t value of p<0.5 then I can't claim the results didn't happen by chance alone. Certainly no journal in my field would accept a claim on my part that my finding was unequivocally real. Similarly no journal would accept my use of a 90% confidence interval to validate my findings. Interestingly there has been an evaluation of global temperatures from 6 major data sets (GISS, Hadcrut 3 and 4, RSS, UAH, NOAA) using data retrieved from Skeptical Science and the SkS Temperature Trend Calculator. Statistically significant warming at the 95% confidence limit has not been shown in any of the data sets for periods ranging from 18-23 years.
Moderator Response:[DB] "Interestingly there has been an evaluation of global temperatures from 6 major data sets (GISS, Hadcrut 3 and 4, RSS, UAH, NOAA) using data retrieved from Skeptical Science and the SkS Temperature Trend Calculator. Statistically significant warming at the 95% confidence limit has not been shown in any of the data sets for periods ranging from 18-23 years."
You'll need to provide a proof link for this assertion. As longtime commenter KR has observed many times in this venue:
When examining ANY time-span starting in the instrumental record and ending in the present, note that:• Over no period is warming statistically excluded. NONE.• Over no period is the hypothesis of "no warming" statistically supported WRT a null hypothesis of the longer term trends. NONE.• And over any period with enough data to actually separate the two hypotheses – there is warming. ALWAYS.Therefore, in the absence of a change in trend, the previous warming trend is therefore still in place.
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Glenn Tamblyn at 13:29 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Ray
You are missing the point of Tom's comment. If we are talking about the 'statistical significance' of something, we are discussing how likely that something was to have occurred due to random chance or not. Not whether that 'something' happened at all. Tom is referring to the fact that the concept from statistics - 'statistically significant' - is misleadingly equated with the colloquial English word 'significant' when actually the two terms have very different meanings.
However, if one seeks to mislead people, not pointing out the distinction is all that is needed to con a reader who is unfamiliar with the meaning of the term from statistics.
Lets take Phil Jones' oft mis-represented comment about there hasn't been a statistically significant warming since x (I can't remember the year) He actually said that it wasn't statistically significant at the 95% confidence interval which is the usual standard measure. He also said that it was statistically significant at the 90% confidence interval.
His meaning, in plain English - 'There has been warming; the chances that this observed warming is not random are not greater than 95%; but they chances that the observed warming is not random are greater than 90%'
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Tom Dayton at 13:22 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Ray, if you pick short enough periods in a time series with a low signal to noise ratio, you can get many or even all those periods to lack a statistically significant rise. But longer periods that contain those short periods do have a statistically significant rise. That apparent logical incompatibility is only apparent, when you understand what "statistically significant" really means.
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Ray at 13:01 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Tom Curtis @12
Your comment
"The most typical misrepresentation in this sort of case is misrepresenting "the rise in temperature has not been statistically significant" as "there has been no rise in temperature".
If the rise is not statistically significant is it really a rise? If it is does this make statistical evaluation redundant?
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barry1487 at 12:44 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
There were plenty of predictions made in FAR (mostly Chapter 5) with far less climate data than today. A balanced scorecard, pointing out what they got right and wrong could make a very strong point in the debate. Worth an article at SkS?
(I know there have been articles on FAR surface temp projections, but there were many other predictions made, some of which I mentioned in my first post above) -
barry1487 at 12:36 PM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
There is an unfortunate tendency for using global average surface air temperatures as THE measure of global temperature and it's not confined to laypersons.
I'm guessing that the focus on surface air temperatures is because 1), it is only recently that ocean heat content indicea have been collated, 2) impact of global warming (for humans anyway) will be experienced mostly at the surface.
IPCC reports have a strong (but not exclusive) emphasis on surface temperatures. AR4 Summary for Policy Makers has a few short paragraphs on ocean temperatures, for example, but much more on surface data. There are no ocean heat content projections in AR4, so it's no wonder people from all points of the debate have focussed on surface data.
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chriskoz at 12:30 PM on 15 July 2013Climate Change and the Nature of Science: The Carbon “Tipping Point” is Coming
kmalpede@11,
Hi Karen,I'm interested in this play, however I have no idea if it ever comes to the theatre near me (Sydney AUS) let me know when. Maybe in the meantime, can you give us some info about it (review detailing the action) or perhaps some trailer or link to some online content so that we can watch and have a good feeling about its content. Thanks.
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Glenn Tamblyn at 12:12 PM on 15 July 2013IPCC is alarmist
andrewii
This article discusses the findings by Lee Kump and colleagues wrt the rate of inctrease of CO2 during the Paleocene/Eocene Thermal Maximum, around 55 million years ago.
This period is considered a reasonable analogue for today. The world was originally warmer than today by perhaps 4-6 DegC, then it experienced a doubling or more of CO2 very quickly (in geological time scales). Temps climbed another 4-6 DegC, a small Extinction event occurred and an Anoxic event occcurred in the ocean.
Kump et al found that CO2 levels today are climbing 10 times faster than during the PETM.
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Tom Curtis at 10:50 AM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
Supak @14:
First, you should insist on using HadCRUT4 rather than HadCRUT3.
Second, find out the start year for Michael's predicted 25 years with no warming.
Third, from existing HadCRUT4 data, find the standard error on 25 year trends.
Fourth, bet that on the 25th year, the warming trend will be greater than two times the standard error for HadCRUT4 trends.
Alternatively, find the AR4 multimodel mean prediction with a HadCRUT mask (either version). Bet that the GMST as measured by HadCRUT will be within 0.2 degrees of that plus an adjustment factor based on ENSO as per Foster and Rahmstorf. His position will be that it is within 0.2 C of the 1996-2012 mean. Each year, there is a standard payout from the person the other person to the person where the temperature falls within "their" predicted range. Obviously if it falls in both, there is no payout.
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Ken in Oz at 10:44 AM on 15 July 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
There is an unfortunate tendency for using global average surface air temperatures as THE measure of global temperature and it's not confined to laypersons. ie people who should know better say things like "The world warmed by x degrees" or "The world has experienced no significant warming for x years" (suggesting air temperatures near the surface is equivalent to 'the world', when if fact most of the heat, whether during the periods when "global temperatures" are experiencing there normal (plus a bit) ups or normal (plus a bit) downs, goes into the oceans. And this increase in heat content hasn't slowed or stopped.
Warming of surface air temperatures is not the same as the world warming because air only holds a few percent of the heat the world has gained.
In my opinion climate science communicators who conciously or unconciously use air temperatures as the definitive measure of change to our climate system - or just as shorthand - are contributing to ongoing misunderstandings. If Pauchauri has been one of them I'm disappointed.
Back to scrutinising the 3% - Michaels' actual knowledge of climate makes him more effective at pushing the denialist/obstructionist line. Certainly he would know that the world continued to warm during the past 17 years and that is shown clearly in heat content with most of it in going into rising ocean heat, so therefore, to push his biased conclusion that preceded his formulation of his arguments, he would know to distract attention from heat content and keep the focus strictly on surface air temperatures. When the next el Nino sends that 'stalled' warming back into record territory, he will suddenly rediscover some of the natural processes that make that variability - processes that he currently avoids mention of in discussing why we can have a 17 year 'pause' without global warming having stopped or slowed.
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vrooomie at 09:35 AM on 15 July 2013Understanding the long-term carbon-cycle: weathering of rocks - a vitally important carbon-sink
As a geologist, this thread finally feels like I've found my people....:-)
Thanks to the fellow geologists who've helped me refresh my phase reaction diagrams!
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