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Comments 25451 to 25500:
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There's no correlation between CO2 and temperature
SOMMERSWERD - See CO2 is saturated for a discussion of this. The real effects of greenhouse gases take place in the upper atmosphere when the concentrations drop to the level that IR can escape to space, and increased levels of CO2 just raise that altitude. There is no 'saturation' issue.
Moderator Response:[PS] Fixed link
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SOMMERSWERD at 01:25 AM on 29 February 2016There's no correlation between CO2 and temperature
Hi from Spain. I have a question:
"How much of the thermal radiation energy from the Earth in the band centered on the 14.77micron wavelength that is resonant with the vibrational mode of CO2 has already been affected by the current atmospheric CO2 concentration, and how much energy remains to be affected?”
A greeting and thanks in advance
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tcflood at 15:48 PM on 28 February 2016How Exxon Overstates the Uncertainty in Climate Science
It seems to me that the main problem is that the graph (at least at the scale in the online postings) is illegible for *anyone* and so it invites misrepresentation. It would best be presented as a set of five graphs: four that show all the model results for a each of the four RCPs so as to give a good impression of the scatter of the models; then one graph that shows four *averages* of all the results for each of the RCPs. Such a presentation would be much harder to misinterpret and misrepresent.
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sidd at 14:07 PM on 28 February 2016Earth is warming 50x faster than when it comes out of an ice age
Interesting. Alley says "decades" for Thwaites ... possibly. First time i heard him say decades. -
Gingerbaker at 07:41 AM on 28 February 2016Earth is warming 50x faster than when it comes out of an ice age
"... a doubling time from a 1mm per year ice sheet contribution to sea level in the decade 2005-2015 would lead to a cumulative 5 meter rise by 2095.""
SLR doubled in 2015 from 4.1mm/year in 2014 to 10mm in 2015. Just sayin'.
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swampfoxh at 06:58 AM on 28 February 2016How Exxon Overstates the Uncertainty in Climate Science
Up is still up. All of the RCP are "up". I think some of the problem has to do with a person's perception of the impact of a "couple degrees of temperature. With respect to the climate in the dining room on the night your boss is coming over for dinner, a couple of degrees means nothing. Climate scientists know that a, "couple of degrees of global averaged higher temperatures is a "big deal"". So, let us not fret much about the Exxon folks or anyone else that doesn't get it. Keep plugging away at the scientific efforts and the peer-reviewed results and more people will "sign on" to solutions, even if we "extinct-ify most of the human race before we "get there". After all, the globe could use a drastic population reduction...think how much CO2 we wouldn't be pumping into the atmosphere? (There, I've said it) Sorry.
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Glenn Tamblyn at 15:27 PM on 27 February 2016Earth is warming 50x faster than when it comes out of an ice age
wili
Roughly yes. He did think there was still some uncertainty about whether Thwaites is committed to going, and he also thought that it was possibly a century or 2 before is really ramps up, but then it is a multi-decadal rather than multicentury process for the WAIS.
The description of including the fracture mechanics of high ice-cliffs and how that can drive retreat was fascinating/horrifying. And that including that into the ice models 'solved' the Plioscene was telling.Like the best discoveries, once the original realisation that a mechanism needs to be included has been made, in hindsight it can seem like 'well, of course'. But in reality those are important advances in understanding.
It is probably one of those things a layman doesn't question when they see that land terminating glaciers taper down to their end while sea terminating glaciers end in ice cliffs. But when you think it through and realise the implications a lightbulb moment happens. -
michael sweet at 12:36 PM on 27 February 2016Earth is warming 50x faster than when it comes out of an ice age
Why leave out the Arctic Sea ice which is also setting a new record every day for lowest sea ice ? Alan Motorman is using last year's denier meme, there is a reason the deniers are not using it this year.
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Tom Curtis at 10:47 AM on 27 February 2016Earth is warming 50x faster than when it comes out of an ice age
KR @10, you forgot the Antarctic Sea Ice area, which is currently below the 1979-2008 mean:
And global sea ice area which is currently setting a record minimum area in absolute terms, and one of the lowest anomalies on record:
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Earth is warming 50x faster than when it comes out of an ice age
Alan_Motorman - What do you mean, the arctic ice caps are increasing? Antarctic land ice is decreasing at ~134 billion tons per year:
[Source]
(see GRACE data up through this year here, only one paper in disagreement, Zwally et al, and there are potential issues with that methodology), Greenland ice decreasing at 287 billion tons per year, Arctic ice is on a steep downward trend (albeit with yearly variations that do not reach statistical significance):
[Source]
There is no way anyone can seriously assert that the ice caps are increasing.
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Alan_Motorman at 05:03 AM on 27 February 2016Earth is warming 50x faster than when it comes out of an ice age
The artic ice caps are increasing. Water levels will stabilize or even get lower over the next 50 years.
What can offset this trend of cooling is volcanic or methane gas leading to greenhouse affects.
I'm particularly concerned with methane gas pockets under the oceans. Slight temperature variations or earthquakes can lead to these "bubbles" releasing into the atmosphere.
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wili at 02:31 AM on 27 February 2016Earth is warming 50x faster than when it comes out of an ice age
Thanks for that link, Glenn.
As I understand it, he's saying that Thwaites could destabilize at any time, and whenever it does, it is most likely to go in a matter of decades, leading to a rather abrupt sea level rise of about a 4 meters in the northern hemisphere. That is pretty shocking. Is that your understanding of the message?
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sailingfree at 02:16 AM on 27 February 2016There's no empirical evidence
We have direct evidence, as the following news article and original paper show.
http://newscenter.lbl.gov/2015/02/25/co2-greenhouse-effect-increase/
http://www.nature.com/nature/journal/v519/n7543/full/nature14240.html
The above describe direct measurement of the incoming and outgoing radiation of the Globe at various wavelengths over a decade, and show that it is directly due to more CO2. -
scaddenp at 12:24 PM on 26 February 2016Human CO2 is a tiny % of CO2 emissions
Can you be more specific about you want? The gory detail can be found in Chapter 6 of the IPCC AR5 WG1 report.
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Clapper55 at 11:37 AM on 26 February 2016Human CO2 is a tiny % of CO2 emissions
this article is very informative showing how humans are contributing to carbon emissions in to our atmosphere. I would be interested in seeing a more complex version of this showing exactly where natural emissions and man made go.
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Glenn Tamblyn at 09:59 AM on 26 February 2016Earth is warming 50x faster than when it comes out of an ice age
wili
You might find this talk by Richard Alley interesting. Particularly later in the talk where he discusses the Thwaites Glacier. -
John Hartz at 06:19 AM on 26 February 2016Models are unreliable
Tom Curtis: I have neither the time nor inclination to get into a protracted discussion about the details of Frank Shann's posts. Having said that, I believe that the word "simulate" would have been a better choice than "predict" in Dana's OP. "Predict" connotes to the average person the foretelling of something that is likely to happen in the future.
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Tom Curtis at 01:39 AM on 26 February 2016Models are unreliable
John Harz @981, Frank Shann's premise of (not argument for) the need for effective communication is valid (and well known, and acknowledged). His belief that using only archetypal meanings represents effective communication is just false, something he conceals from himself by not asking the crucial question - what is misunderstood as a result of the use of the word 'predict' by Dana. The answer is nothing - something his survey does not address and he does not address in counter argument.
In constrast, his preferred word, 'describe' would introduce genuine misunderstanding, and has it happens is also not an archetypal use of the term.
Your link supports his premise - ie, that effective communication is important, but has only one bearing on his argument about whether a particular example of communication was more or less effective than alternatives. In fact, it only has one bearing on the topic. Specifically, he is a scientist, as were (in all probability) his colleagues who he surveyed. From your link we learn that scientists are poor judges of effective communication. That is, the linked article undermines his claim to relevant expertise on this issue.
I was prepared to allow his courtious granting of himself the last word @967 to stand, but not if you are going to step in and misrepresent the discussion in his favour.
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John Hartz at 00:21 AM on 26 February 2016Models are unreliable
Framk Shann has, in my opinion, made a sound argument for improving the way SkS and others communicate the science of climate change. His central point is butressed by a just published editorial by Nature Climate Change, Reading science.
The tease-line of the editorial is:
Scientists are often accused of poorly communicating their findings, but improving scientific literacy is everyone's responsibility.
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wili at 23:38 PM on 25 February 2016Earth is warming 50x faster than when it comes out of an ice age
Thanks for the clarification, KR. IRRC, Hansen somewhere also said we couldn't competely rule out a doubling time of 5 years. But I don't have the source at my fingertips, so maybe that's my memory playing tricks on me.
I still wonder why one shouldn't just multiply 50 (or 20, or whatever) to the rates given in #s 1 and 2 in my first post to get an approximation of the rates we should expect going forward. I know that there was a lot more ice then in the northern hemisphere, but as I understand it, the Antarctic ice sheet wasn't really in play then. And in any case, wouldn't a lower starting point just be another element to put into the same equation?
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mwsmith12 at 23:19 PM on 25 February 2016Earth is warming 50x faster than when it comes out of an ice age
The title says "Earth is warming 50x faster than when it comes out of an ice age," but the article says "We’re already warming the Earth about 20 times faster than during the ice age transition, and over the next century that rate could increase to 50 times faster or more."
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scaddenp at 12:45 PM on 25 February 2016Models are unreliable
I just had a quick look at Mann 2015 where this all started and at CMIP5 website. According to website, the runs were originally done in 2011. The CMIP5 graph is Mann, is the model ensemble but run with updated forcings. To my mind, this is indeed the correct way to evaluate the predictive power of a model, though the internal variability makes difference fom 2011 to 2015 insignificant. The continued predictive accuracy of even primitive models like Manabe and Weatherall, and FAR suggests to me that climate models are a very long way ahead of reading entrails as means of predicting future climate.
I wonder if Sks should publish a big list of the performance of the alternative "skeptic" models like David Evans, Scafetta, :"the Stadium wave" and other cycle-fitting exercises for comparison.
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FrankShann at 11:53 AM on 25 February 2016Models are unreliable
scaddenp: thanks for taking the trouble to reply, and for the very useful link.
Despite the difficulties, it would be great to have a Skeptical Science resource page that was kept up to date with previous IPCC models (or even just two or three of them) and their forecasts (given the forcings that actually occurred), which would show that the models are accurate. I accept that's very easy for me to suggest, but a lot of work for someone else to do.
I agree about the wilfully ignorant, but surely we need to keep trying. It's one of the important functions of Skeptical Science. Most deniers don't read Skeptical Science, but it's a very useful resource for people trying to persuade the deniers and (more realistically) the undecided. Climate scientists will win in the end - because they're right. Let's hope they win soon enough to prevent catastrophe.
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scaddenp at 11:06 AM on 25 February 2016Models are unreliable
Rerunning the actual climate models is not a trivial process. Serious computer time for version 4 and 5 models. Hassles with code for pre-CMIP days. However, outputs can be scaled for actual forcings. "Lessons for past climate predictions" series do this. Eg for the FAR models, see http://www.skepticalscience.com/lessons-from-past-climate-predictions-ipcc-far.html
However, I am very doubtful about the possibility of changing the minds of the wilfully ignorant. It seems to outsider, that in USA in particular, climate denial is part of right-wing political identity.
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sailingfree at 11:05 AM on 25 February 2016Greenhouse effect has been falsified
Direct evidence of CO2 causing warming is in the following news article and original paper.
http://newscenter.lbl.gov/2015/02/25/co2-greenhouse-effect-increase/
http://www.nature.com/nature/journal/v519/n7543/full/nature14240.html
The above describe direct measurement of the incoming and outgoing radiation of the Globe at various wavelengths over a decade, and show that warming is directly due to more CO2.Moderator Response:[PS] Fixed link. Please learn to do this yourself with the link button in the comments editor.
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FrankShann at 10:47 AM on 25 February 2016Models are unreliable
KR and scaddenp: I understand the role of the RCP scenarios, and that controlling emissions is key - I am not suggesting that either be abandoned.
However, many people don't distinguish between uncertainty in the climate models and uncertainty in the forecasts of forcings - and this is exploited by deniers ("the IPCC forecasts are flawed/too vague/too complex"). In addition, because cycles in some forcings cause a stepwise rise in temperature, deniers are able to pretend that temperature has stopped rising (a pause, or even a permanent pause). Climate scientists explain all this in advance and at the time (and produce The Escalator graph), but many of the public are not convinced (or are misled), and this delays reduction in emissions.
I merely proposed (@974) an extra tool (that complements The Escalator) to remove variations in the forcings from forecasts of temperature, and enable climate scientists to say that the models they produced 10 or 20 or 30 years ago have accurately forecast temperatures in advance given the forcings that subsequently actually occurred.
Would it be possible to go further and calculate what temperatures the FAR model predicted for 1990-2016 given the forcings that actually occurred each year, and the SAR model for 1995-2016, the TAR model for 2001-2016, AR4 for 2007-2016, and AR5 for 2013-2016? Perhaps it's not possible do this - but if it were, it would contribute greatly to answering the question posed by the title of this thread - "How reliable are climate models?" (It might be a good student research project.) And doing it again each year in the future would keep on showing that the models are accurate. Would it be possible to do this?
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sailingfree at 09:31 AM on 25 February 2016Hansen predicted the West Side Highway would be underwater
When I read the relevant comments on WUWT, I note how successfull his propaganda is. That is, no one seems to notice (or maybe care) that Hansen had a contingency, that is, that CO2 must double.
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sailingfree at 09:24 AM on 25 February 2016Republicans' favorite climate chart has some serious problems
KR @13 Your RATPAC data for 11,000m is the "Goldilocks Layer"!
Interpolation between the upward slope at the Surface, and the downward slope in the stratosphere, we should expect such a "Goldilocks Layer" with a trend of zero. That is why Christy, Curry, and Cruz cherry-pick the middle troposphere, to claim "not much warming".
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sailingfree at 08:33 AM on 25 February 2016Surface Temperature or Satellite Brightness?
The preference of Christy, Curry, and Cruz for the mid-troposphere can be explained:
The Earth's surface temperature is in an upward trend. Above the troposphere, the stratosphere is in a downward trend. So by interpolation, in the troposphere is a "Goldilocks Layer" with a level temperature graph. So, "No warming forever!"
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Tom Curtis at 08:13 AM on 25 February 2016A Response to the “Data or Dogma?” hearing
sailingfree @6, and unnecessarilly repeated @7, there is no such goldilocks layer. The reason is that part of the stratospheric cooling has been due to the impact of CFCs destroying ozone. When manufacture of CFCs was restricted, a regime in which both increasing CO2 and increasing CFCs combined to cool the stratosphere was replaced by one in which decreasing CFCs warmed the stratosphere while increasing CO2 cooled it slightly more. That means the stratospheric trends vary significantly over time, while the tropospheric trends are more or less constant. From that in turn it follows that the goldilocks layer in one time period is not the goldilocks layer in the second. In the moderately near future we will have a third regime of near constant O3 (due to the lack of CFCs) coupled with increasing CO2.
Further, as can be seen in this RATPAC data, the rate of cooling is different in different levels of the stratosphere:
We can compare that with the weighting profile of the TMT MSU channel:
We can then see that, first, in recent years the lower stratosphere has had a flat trend, or possibly even a slightly warming trend. Second, we see that TMT only significantly samples the lower statosphere. It follows that while lower stratospheric temperatures reduce the measured trend from 1979-2015, they have little effect on the measured trend from 1998-2015.
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sailingfree at 08:13 AM on 25 February 2016Ted Cruz fact check: which temperature data are the best?
AuntSally @9 and BBHY @19. Yes, BBHY. Think about it.
The Earth's surface temperature is in an uptrend. Above the troposhere the stratosphere is in a downtrend. Interpolation would show a "Goldilocks Layer" somewhere in the troposhere with a level temperature plot.
As this article says, "The satellite data are best … if you want the data that show the least warming."
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mancan18 at 08:11 AM on 25 February 2016Fossil fuel funded report denies the expert global warming consensus
One Planet Only Forever @7 and Jeff T @6
To evaluate a source of information you not only have to understand who the author is, but you need to pay careful attention to the language used, the style of writing and the material used to support the argument. Now, I suspect that some of the Heartland material is not written to seriously participate in the scientific debate. It is written to give a scientific veneer to the reference material used in non-scientific articles written by those who oppose the climate change argument in the popular media. These articles make it easier for denier motivated journalists who have a non-scientific background to make simple dismissive climate change denier arguments in the popular media. I have seen articles, particularly in the Murdoch press and some conservative journals like Quadrant, that use the word "discredited" when referring to John Cooke's Consensus Project. When reading opinion pieces in the Australian Press by the likes of Andrew Bolt, Miranda Devine, and Piers Ackerman, they often use a combination of words that are dismissive of the whole scientific basis for Climate Change without providing any real evidence. When they do provide "evidence", which is not very often, it is from institutions like Heartland and a few scientists attached to Australia's Institute of Public Affairs. I am sure that it is the same with the popular media in Canada, the US and the UK. It is very easy to make dismissive statements in this debate in the popular media. It is very difficult and not so easy for scientists and like minded journalists to refute those dismissive statements in the popular media. It requires the reader to have some understanding of scientific reasoning. Of course in scientific circles, where scientists argue in a scientific manner, dismissive arguments are not so easily made. They require evidence and logical argument. In science, it is the strength of the scientific argument and supporting evidence that wins the day, not necessarily who the author is.
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sailingfree at 07:56 AM on 25 February 2016A Response to the “Data or Dogma?” hearing
6. Sailingfree I get why the troposhere for a denier:
The Earth's surface is warming. The stratosphere is cooling.
So somewhere in the troposphere, by interpolation, is a "Goldilocks Layer" with a level temperature graph. So "No warming since forever!" can be truthfully proclaimed.
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Earth is warming 50x faster than when it comes out of an ice age
wili - In that Hansen and Sato 2011 they point out that we shouldn't ignore outlier estimates, noting that "...a 10-year doubling time was plausible, pointing out that such a doubling time from a 1mm per year ice sheet contribution to sea level in the decade 2005-2015 would lead to a cumulative 5 meter rise by 2095."
Note that they don't claim that is likely, but that it is plausible, and in the next paragraph note that "...more plausible but still accelerated conditions could lead to sea level rise of 80 cm by 2100." Note "more plausible" in that sentence. They then go on to discuss strong negative feedbacks as well.
The point they were making in that paper was that we can't at this time exclude extremely high sea level rise, and that more study is needed. They weren't claiming 5m by 2100 was the likely outcome, just that it wasn't impossible - despite multiple out of context claims by climate denialists, which seem IMO to be poor attempts to discredit Hansen.
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wili at 07:02 AM on 25 February 2016Earth is warming 50x faster than when it comes out of an ice age
Thanks, scaddenp. I had seen the RC piece, but not the other one you linked to.
What do you think of Hansen and Sato's claims that we could see a doubling rate of ten years over this century with a resultant ~5 meter rise by 2095?
www.columbia.edu/~jeh1/mailings/2011/20110118_MilankovicPaper.pdf
pages 15 -16
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scaddenp at 06:40 AM on 25 February 2016Earth is warming 50x faster than when it comes out of an ice age
While warming is faster, there is a lot less ice to melt. It is certainly an interesting question. You might like to look at new paper on it here. Some discussion about it over at Realclimate.
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wili at 06:34 AM on 25 February 2016Earth is warming 50x faster than when it comes out of an ice age
So, with:
1) the meltwater pulse that happened about 8000 ybp raising sea levels 1-2 meters per century, people.rses.anu.edu.au/lambeck_k/pdf/262.pdf
2) and the Meltwater Pulse 1A at the end of the last ice age 13,800 years ago, raising sea levels over 5 meters per century,
3) and with current warming happening 50 times faster than during those events...
What rates of sea level rise should we be expecting, exactly. And how soon?
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scaddenp at 06:30 AM on 25 February 2016Models are unreliable
The whole point of current focus on climate models is to inform policy with regard to emission strategies. That is under human control, not something you "forecast". We are only peripherally interested in effects on climate from variations in natural forcing because a/ they are either short term or small, and b/ there is nothing we can do about them. We can however control emissions and we really do want to know whether models will accurate predict future under various emission scenarios. For evaluating an older models, you can simply rerun with actual forcings (without changing the model code) and compare to what we actually got.
The hard bit in communication is having public understand the difference between a physical model and statistical model in terms of value in hindcasting.
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Nick Palmer at 02:52 AM on 25 February 2016The Uncertainty Handbook: Download and Translations
I confirm SteveS's observations, but on a PC using Adobe Acrobat, Windows 10. I can't say I like the main font they use in the text. Several letters, eg a,r,v,u, x, are smaller/less tall than the others and I find it uncomfortable reading the words!
As far as the inherent uncertainty in climate science prognostications go, there has just been an important paper published in Nature which apparently firmly establishes and quantifies causality for CO2/CH4 increases and changes in GMTA ((global mean surface temperature anomalies) from 1850 onwards and previously back 800,000 years
http://www.nature.com/articles/srep21691 -
One Planet Only Forever at 01:10 AM on 25 February 2016Fossil fuel funded report denies the expert global warming consensus
Jeff T @ 5,
The Critical Thinking course I took as an option when I pursued my MBA identified understanding who wrote something to be one of the first steps in evaluating a source of information.
That understanding does not 'bias' a review by a conscientious responsible pursuer of better understanding. It helps establish the type of effort that should be put into the review. How much careful exclusion or deliberate deception to expect can make the effort to evaluate the information much more effective.
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Joel_Huberman at 23:50 PM on 24 February 2016The Uncertainty Handbook: Download and Translations
I'm confirming SteveS's observation. Furthermore, Adobe Reader also shows the last two pages as being blank.
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Models are unreliable
FrankShann - That's the entire reason for the various Representative Concentration Pathways (RCPs) evaluated in the models, to bracket potential emissions. Shorter term variations (which include emergent ENSO type events), volcanic activity, solar cycle, etc, are also incorporated, but as those aren't predictable they are estimates.
Which doesn't matter WRT the 30 year projections from the models, as the natural variability is less than the effects of thirty year climate change trends, and the GCMs aren't intended for year to year accuracy anyway - rather, they are intended to probe long term changes in weather statistics, in the climate.
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ajadedmug at 18:44 PM on 24 February 2016The Uncertainty Handbook: Download and Translations
SteveS - Thanks very much: that is worth a deal, and is exactly the sort of response that I was hoping to get. I shall now amend my draft email to Climate Outreach and explain that the problem appears not to exist on a Mac for the most recent versions of OS and Preview. Then I shall send it :). CO can then judge whether it wishes to investigate further.
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One Planet Only Forever at 15:28 PM on 24 February 2016Republicans' favorite climate chart has some serious problems
HK,
The real problem is not Capitalism, Competition, Free Markets, or Marketing (or Communism or Socialism). The real problem is the tendency for some people to want to personally get away with something they can understand is unacceptable.When people choose to pursue personal interest without responsible conscientious regard for the consequences of their chosen desires and actions, they can have a competitive advantage in any game (Those economic and political things are all games made-up by humans. And the problem gets worse when those callously self-interested types win the right to make-up the rules or make-up how the rules will be enforced).
And the misuse of the powerful science of Marketing can allow those type of people to get more undeserved advantage through the drumming up of undeserved popular support from others who are easily impressed, willing to believe unjustifiable claims in support of unacceptable actions.
That is what is going on, and not just in the US.
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FrankShann at 14:25 PM on 24 February 2016Models are unreliable
A very tentative suggestion...
In addition to @972 and @973: to convince most people, climate models need to be able to forecast *future* temperatures, and not just accurately describe *past* temperatures (I am avoiding the word "predict").
Unfortunately, you then need to forecast all the forcings for a given future year, as well as have a good climate model. Errors in your forecasts of the forcings may be at least as great as the errors in your climate model.
What about taking the current Best Available Model (BAM-2016) and saying "we forecast that global mean surface temperature (GMST) will be Z if the CO2 is V, El Nino is W, aerosols are X, volcanic activity is Y etc (with reliable sources for the values of the forcings defined in advance, such as the appropriate values from www.esrl.noaa.gov/gmd/ccgg/trends/global.html#global_data for CO2)? The model would be published in advance and the results updated each year. New models could be introduced over time (such as BAM-2020 in 2020) while still calculating the forecasts from previous models (such as BAM-2016).
Perhaps this has already been done, or models such as CMIP5 cannot be applied in this way, or some important forcings cannot be pre-specified in a suitable fashion, or there are other problems. As I say, this is merely a tentative suggestion.
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SteveS at 13:53 PM on 24 February 2016The Uncertainty Handbook: Download and Translations
For what it's worth, I had no problems with the english version on a Mac running OS X El Capitan (10.11.3) and Preview 8.1. Pages 19 and 20 are blank, but that seems like it could be intentional.
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ajadedmug at 12:25 PM on 24 February 2016The Uncertainty Handbook: Download and Translations
BaerbelW - I thought that a more prudent first step would be to establish whether other Mac users in the Skeptical Science community are seeing this issue. If I email Climate Outreach, they may waste time investigating a software issue that is in reality solely related to my MacBook or to Macbooks running older versions of software and OS.
My MacBook runs Mac OS X Lion 10.7.5 (11G63) and Preview Version 5.5.3 (719.31). As a test comparison, I downloaded the latest Adobe reader to compare, and the documents were then perfectly readable. I then deleted the Adobe Reader and tried with Preview again. This time more of the text was viewable, but there are still major gaps. This is something that I have never seen before with Preview. I have tried opening numerous other .pdf files that I have already viewed previously with Preview and there were no problems.
I have written a draft email to Climate Outreach and will wait 48 hours to see if anyone responds before I send it, if I send it. I am probably untypical: most PC or Mac users probably use Adobe reader. I don't, because Preview has worked fine for me over the last eight years...until yesterday. Given most people with a computer will use an Adobe reader, this Preview issue is probably more curious than significant, and may be limited to people like me who are running older versions of operating system and software.
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scaddenp at 12:25 PM on 24 February 2016Models are unreliable
Good points. If you want to look at how past model "predictions" of the future have gone, then you could of course look at how, say, one of the earliest models, Manabe and Weatherall 1975, used by Wally Broecker, is doing now. See here. It would be nice to update this chart. There are other predictions (eg FAR) also in the "Lessons from past climate predictions" series that are worth looking at. Of course any serious evaluation has to compare actual forcings against what the prediction assumed if you want to assess skill at climate modelling rather than guessing emission rates. Broecker overestimated emissions but also looks to have underestimated sensitivity.
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sailingfree at 11:09 AM on 24 February 2016Models are unreliable
KR@968: Thanks, your statement
"The proper question is "Is there evidence to support the assertion that CMIP5 models predict temperatures from forcings?" The answer to that is certainly 'yes', as validated by their ability to reproduce past temperature evolutions on both the global and regional levels."
helps clear it up for this layman.
I do side with FrankShann, though, as it has not been clear to me to what extent past temperatures are inputs to the models. (After all, before Copernicus, anyone could predict a daily sunrise, knowing no physics at all.) It must be made clear that the models do not use past temperatures to predict the future temperatures. (like, Gee, I see a sine wave and a slope, so that should continue in the future.)
A passage like "We wrote the models during 2005 to 2010,(or whatever) and used the conditions and temperature of 1880 and the known forcings from then, like sunlight, CO2, and volcanoes, and then ran the models and successfuly predicted (or descibed) the temperatures from 1880 to 2010." would be more clear to me.
A doubter would still wonder, since we knew in advance the temperatures to describe, to what extent we tweaked parameters to get the right temperatures. So you would have to show him how the tweak was for proper humidity, wind, or what ever, not just to get the desired temperature.
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FrankShann at 09:32 AM on 24 February 2016Models are unreliable
KR @968. My question accurately represented Dana's post. He said "climate models have done an excellent job predicting how much temperatures at the Earth’s surface would warm", and immediately below that showed the graph of CMIP5 and temperature for 1880-2010. Dana did not say "from forcings", so neither did I. The title of the graph includes "using CMIP5 all-forcing experiments" and that was shown - but every person I asked said that the graph did not provide evidence that CMIP5 has done an excellent job predicting temperature - because the vast majority of people use predict to mean forecast. Even Tom Curtis agrees that there is "no doubt that forecast is the archetypal definition of 'predict'".
*If Skeptical Science aspires to explain climate science to the general public, it needs to use words in a way that is understood by the general public (or flag the specialist meaning).*
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