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Cool visualization. It's worth keeping in mind that the modeled data lines up with reality because it's supposed to. That's how you calibrate your model, by m
by jasonkester 11y ago
Cool visualization.
It's worth keeping in mind that the modeled data lines up with reality because it's supposed to. That's how you calibrate your model, by making sure it fits reality.
The real trick is to see how well your model extrapolates from the data you have out into the future. As in, if you feed it data up to, say, 1990, will it correctly spit out 2015 temperatures that fit the reality of 2015, or will it spit out crazy 2015 predictions like the models that were built in 1990 did. And, the bigger question: How will its predictions for 2040 (given 2015 data) match up to the reality over the next 25 years.
We seem to be getting a lot better at the modeling side. That's a good thing, since the first couple decades of watching people panicking and fighting each other over whatever scary results came out of the first generation climate models wasn't any fun to watch.
- tosseraccount 11y agoIs there a scorecard for which models have performed well?
- natermer 11y agoNone of the models have performed very well. You probably won't find a scorecard because it's embarrassing.
- ThisIBereave 11y agoCitation needed.
- cholantesh 11y agoProbably a long list of ExxonMobil shill sites.
- jasonkester 11y agoHere's a good one: http://www.drroyspencer.com/2013/04/global-warming-slowdown-the-view-from-space/ http://www.drroyspencer.com/2013/04/global-warming-slowdown-... 44 Climate Models all fighting to out-panic one another, not a single one guessing low enough to predict the actual values for 2012 (when it seems the dataset in question ended) ... and a seemingly more reputable one showing roughly the same thing: http://phys.org/news/2015-01-peer-reviewed-pocket-calculator-climate-exposes-errors.html http://phys.org/news/2015-01-peer-reviewed-pocket-calculator...
- Roodgorf 11y agoThe first graph on that second link is a bit confusing and seems pretty disingenuous. It has the "observations" region stretching to 2050. The rest of the article seems much more factual and interesting, but why start with something so misleading if your supposed goal is to debunk misleading projections?
- cholantesh 11y agoI wouldn't call a paper whose lead author is a well-established denier with no scientific training (https://en.wikipedia.org/wiki/Christopher_Monckton,_3rd_Viscount_Monckton_of_Brenchley https://en.wikipedia.org/wiki/Christopher_Monckton,_3rd_Visc...), and which is co-authored by a known practitioner of large-scale scientific fraud for pay (http://rationalwiki.org/wiki/Willie_Soon http://rationalwiki.org/wiki/Willie_Soon) particularly reputable.
- marcus_holmes 11y agoad-hominem. Who cares who wrote it, what does it say?
- cholantesh 11y agoReally? You think it doesn't matter that the primary author on a paper about climate science doesn't even have an undergraduate-level education in the subject? That the second one credited has a history of accepting large sums of money to write papers endorsing spurious claims DIRECTLY RELATING to climate change?
- Aloha 11y agoAre you going to tell me that every person who has ever written a paper on computer science needs to have a degree in it? While I won't question this guys qualification might be questionable - making a blanket statement that someone must be specifically educated in a subject to write a good paper on it is specious.
- replicatorblog 11y agoNot the most credible looking site, but the graphic seems well cited: http://www.drroyspencer.com/2013/04/global-warming-slowdown-the-view-from-space/ http://www.drroyspencer.com/2013/04/global-warming-slowdown-...
- cholantesh 11y agoSpencer is pretty out there. He's gone on record to say that warming proponents are advancing an argument that will lead to more deaths than the NSDAP's policies did, and is a signatory to the Evangelical Declaration on Climate Change, which suggests that this is largely a matter of faith for him...
- dnautics 11y agoHe does also maintain one of the satellite records, which does show global warming over the period 1960-2000 (not so much the last 10 years because of the global warming hiatus).
- cholantesh 11y agoAnd other records do not show such a hiatus (http://www.skepticalscience.com/global-warming-not-slowing-its-speeding-up.html http://www.skepticalscience.com/global-warming-not-slowing-i...).
- dnautics 11y agoDid you even read the article? look at the university of York dataset, which clearly shows the 1960-2000 warming followed by the 2000-2010 hiatus. Note the York dataset is strictly observationally independent of the UAH dataset.
- cholantesh 11y agoEvidently we were reading different articles,because the author emphatically doesn't concur with your interpetation of the York dataset.
- wnewman 11y agoI think http://judithcurry.com/2013/10/30/implications-for-climate-models-of-their-disagreement-with-observations/ http://judithcurry.com/2013/10/30/implications-for-climate-m... is a reasonably representative informed article on this.
- Retric 11y agoDepends, overall predictions from the mid 1980's where high and a lot of research has gone into why. A significant part of the difference disappears if you adjust for CO2 produced vs predicted. Granted, you can argue that the older models needed to account for both, but what we want to validate is predictions of impacts not predictions of fossil fuel use. It's extremely disingenuous to show a single line as the 'prediction'. There have been plenty of projections that include possible reductions in temperature. As well as a wide range of types of measurements. PS: You can also do a lot of cherry picking on both sides: http://phys.org/news/2012-04-climate-eerily-accurate.html http://phys.org/news/2012-04-climate-eerily-accurate.html
- hackuser 11y agoGreat points. To add a little more detail, predicting the results of greenhouse gasses in the atmosephere is science. Predicting the amount of gasses in the atmosephere requires predicting human economic activity in detail (how much, in what form, etc.), which is impossible, especially on longer timescales (imagine how many investors would love to know how to do that!) The predictions I've seen, at least in the IPCC reports,[1] show not lines but confidence intervals that widen over time. [1] https://news.ycombinator.com/item?id=9772353 https://news.ycombinator.com/item?id=9772353
- ocschwar 11y agoThey've not performed well based on criteria chosen by global warming denialists. For example, you'd be hard pressed to find a climate scientist making any solid predictions about annual global temperature averages. You will, however, see predictions about decadal averages, and those have borne out.
- merpnderp 11y agoBorne out? Compared to what? The RSS and UAH 6.0 lower troposphere predictions? What other measurements do we have that don't have uncertainty bands as large as the measurements? And the zero trend from May 2015 extends back to 1996 for RSS and UAH 6.0.
- ocschwar 11y agoThat "zero trend" is only there if you use annual averages. Again: use decadal moving averages, and an entirely different picture comes up.
- merpnderp 11y agoHow do you use decadal moving averages from satellite data that has only existed since 1979? You'll get roughly the same trend as the full data set. Even so, the last two decades would still be flat, or very nearly so.
- ocschwar 11y agoHint: decades don't have to start with year 10*n+0.
- merpnderp 11y agoWe already know the full data set has a 1.2K/century trend (this is annual trend most commonly used to represent the data). Decadal moving averages aren't going to shed more light than that. We also know that if you just grab the last 19 years and 6 months, or any smaller subset of that, you'll see 0 to negative trends.
- deleted 11y ago[deleted]
- noobermin 11y agoAs someone else shared above: http://www.skepticalscience.com/lessons-from-past-climate-predictions-ipcc-far.html http://www.skepticalscience.com/lessons-from-past-climate-pr...
- bhauer 11y agoHere are some images that you could review. https://www.google.com/search?q=1990s+climate+models+versus+actuals&tbm=isch https://www.google.com/search?q=1990s+climate+models+versus+...
- hackuser 11y agoThe IPCC, probably the best source overall for climate info, has in their reports visualizations showing predictions, and I think historical results, of multiple climate models. (Sorry but I don't have time now to find links and page numbers. Try the Summaries for Policy Makers.) http://www.ipcc.ch/ http://www.ipcc.ch/ Just reading their summaries, which are meticulously prepared and reviewed by hundreds of scientists, will make you more informed than 99.9% of the population, and more than most reading this thread.
- jfoutz 11y agothe grandfather from 1981 seems to hold up pretty well. simple linear models, very readable paper. http://www.realclimate.org/index.php/archives/2012/04/evaluating-a-1981-temperature-projection/ http://www.realclimate.org/index.php/archives/2012/04/evalua...
- jameshart 11y agoYes there is! In fact, this very visualization which you are commenting on is based upon the data produced by NASA Goddard from their climate model by running a historical data prediction, as their contribution to precisely such a comparison/consensus building study sponsored by the IPCC, called the "Coupled Model Intercomparison Project Phase Five". There are links to the sources for all of this in the original article. This information, which I'm sharing with you now, is in the first three paragraphs of endnotes on the actual article. So.... please don't believe other posters who might come along and try to get you to believe that historical comparisons haven't been performed, or the results haven't been published, or that the IPCC ignored them, or whatever else they might choose to argue today.
- bcheung 11y agoEven if there is a model that performs well, how do you account for survivorship bias? And how accurate are models without a clear understanding of the physical reasons why behind them? Seems like we should be concentrating on understanding the physical relationships and less on trying to come up with abstract models. It kind of feels like a bunch of astrologists and just picking the one that seems to perform better. Unless I understand the why, I have a hard time accepting what anyone says. Anyone can fit a model to the data.
- reitzensteinm 11y agoIt's not my field, but I'd be very surprised if models were not also calibrated by extrapolating earlier known years and comparing to later known years. You can really only judge models on days that was not yet available when they were created.
- wnewman 11y ago"The real trick is to see how well your model extrapolates from the data you have out into the future." That is the most common way to show the modeller is not shamelessly overfitting.:-| Another way, though, is less common but not vanishingly uncommon: the model may be so much simpler than the data it fits that overfitting is not a plausible explanation. (Roughly there are too many bits of entropy in the match to the data to have been packed into the model no matter how careless or dishonest you might have been about overfitting.) E.g., quantum mechanics is fundamentally pretty simple --- I can't quantify it exactly, but I think 5 pages of LaTeX output, in a sort of telegraphic elevator pitch cheat sheet style, would suffice to explain it to 1903 Einstein or Planck well enough that they could quickly figure out how to do calculations. Indeed, one page might suffice. And there are only a few adjustable parameters (particle/nucleus masses, Planck's constant, and less than a dozen others). And it matches sizable tables of spectroscopic data to more than six significant figures. (Though admittedly I dunno whether the non-hydrogen calculations would have been practical in 1903.) For the usual information-theoretical reasons, overfitting is not a real possibility: even if you don't check QM with spectroscopic measurements on previously unstudied substances, you can be pretty sure that QM is a good model. (Of course you still have to worry about it potentially breaking down in areas you haven't investigated yet, but at least it impressively captures regularities in the area you have investigated.)
- possibilistic 11y agoDo you happen to have this one to five pages of QM equations somewhere as reference? I would be very interested in reading that.
- GlueChemist 11y agoI believe he is referring to the 'postulates of quantum mechanics', you can find several formats from a quick google search. Dirac, 1929: "The fundamental laws necessary for the mathematical treatment of a large part of physics, and the whole of chemistry are thus completely known, and the difficulty lies only in the fact that application of these laws leads to equations that are too complex to be solved."
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- croddin 11y agoExactly. When modeling most data, you would hold back a validation set, but that doesn't really work as well in this situation. The only thing holding back the validation set is time.
- 300bps 11y agoCool visualization. I agree, but I have to say their imagination on what other things might be causing warming is not very robust. For just one example, there are at least two major effects of burning: 1. Release of chemicals into the atmosphere (ex: carbon dioxide) 2. Directly heating the atmosphere There are literally billions of air conditioners, heaters, cars, factories, etc that all generate heat. The effect of these billions of heaters throughout the world definitely increases global temperatures. After all, this effect is a reason why cities are warmer than their surrounding rural areas (1). This is relevant because direct heating should be temporary while greenhouse gas increases are cumulative. Honest question - has anyone calculated the effect of the direct heating on the atmosphere from the billions of heaters we use vs greenhouse gas increase? ---- (1) http://www.smithsonianmag.com/science-nature/city-hotter-countryside-urban-heat-island-science-180951985/?no-ist http://www.smithsonianmag.com/science-nature/city-hotter-cou...
- murbard2 11y agoThe primary yearly energy consumption is about 155,000 TWh and the volume of the ocean is around 1.33e9 km^3, so back of the envelop, the heat dissipated by energy consumption yearly is enough to raise the temperature of the ocean by 0.0001 C. Doesn't seem very substantial.
- deleted 11y ago[deleted]
- Roodgorf 11y ago> this effect is the reason why cities are warmer than their surrounding rural areas. Anthropologically produced heat is certainly a contributor, but as the article itself says, I believe the majority of the difference is more accurately attributed to the large amount of concrete in cities which takes much longer to dissipate heat.
- Daishiman 11y agoThey did the math already. The amount of directly released human heat is a drop in the bucket.
- omalleyt 11y agoThis visualization is a multivariate linear regression with time trending variables...lol the entire thing is garbage, I could get a better R^2 than the 7 or so variables they used if instead I used variables to explain climate change like: number of gay marriages in the world, murders, abortions, etc...I don't recommend this, I'm just saying trended data can "say" anything
- o_nate 11y agoUm, no it's not. It's a physical model. Read the PDF they link to.
- guelo 11y agoDon't know what you're referring to about crazy predictions, the 1990 models actually did pretty well, http://www.skepticalscience.com/lessons-from-past-climate-predictions-ipcc-far.html http://www.skepticalscience.com/lessons-from-past-climate-pr...
- jandrese 11y agoThey seemed crazy at the time because most people didn't expect the level of warming that we are now seeing.
- ThomPete 11y agoI have absolutely no knowledge about this field, but from what I understand people who study the Sun wouldn't agree as much with the numbers about the suns temperature. I will see if I can find the numbers.
- Tyr42 11y agoReally, I think from what I've read, there was some talk about sun-spots, which actually lower the sun's temperature or something. I'm really not convinced that they are measuring the correct value there at all.....
- lamontcg 11y agoThe shape of the curve is driven by the independent variable (CO2 concentration, volcanic activity, etc). The magnitude needs to get adjusted so that it doesn't produce inconsistent results when extrapolated backwards in time. Which is the problem with explaining the recent spike in temperature as anything other than CO2 concentration. Most of the other variables like solar flux are relatively steady so that if you increase their climate forcing effect you get a really bad fit in the 1900s which is non-physical. There's also additional data like satellite measurements of the broadening of the absorption lines of CO2 and H2O in the IR blackbody spectra that the Earth radiates and the measurement of the shortfall of outgoing radiation in the radiation budget which are consistent with GHG effects and independently confirm these models.
- birdsbolt 11y agoThere's a lovely book called The Limits to Growth published in 1972, through the years authors have updated their book and their models (there's more than 20). It turned out that business-as-usual model extrapolated very well from '70s to '00s. So, even them modelling was fairly good.
- patrickdavey 11y agoYip, great book, good warnings, of which we have done very little about. Another book to recommend is "This changes everything" ... sets out a very reasonable argument while capitalism as it stands is basically incompatible with doing much to prevent climate change. Worth a read.
- frogpelt 11y agoHerein lies the rub. Corrupt politicians will find that using environmental concerns and climate change gives them the proper motivation to say "we need more control and the common man needs fewer freedoms". This is why it's a political issue. Don't expect masses of people to gobble up the idea that climate change is going to ruin the planet when the motivating factor for a good portion of the people selling the idea is that they can seize more control. It's no different than terrorism and things like the Patriot Act. Terrorism is a horrible problem and no one wants armed rebels chopping people's heads off in the streets of our cities. But when politicians start their backroom meetings and connive a way to start chipping away at our freedoms and our privacy (I'm being redundant), you start finding terrorism skeptics. We have to find the proper balance between the rights of the individual and the rights of the community. But all the while the entity that sits between the community and the individual, government, is taking more and more control. And they seem to let no opportunity to do so pass. Climate change is one of their new, favorite vehicles.
- dj_doh 11y agoProbably unintuitive UX. I kept scrolling wanting to read something. But it kept changing graph and then suddenly text appeared.
- MaysonL 11y agoThe thing is, it's not just the temperature measurements fitting the greenhouse gases. It's also all the biological and physical evidence. Bird migrations, plant species ranges, glacier and ice cap shrinkage and growth, permafrost melting, polar vortices occurring, etc.,etc.,etc. Screw the models: look at the reality.
- visarga 11y ago> if you feed it data up to, say, 1990, will it correctly spit out 2015 temperatures that fit the reality of 2015, or will it spit out crazy 2015 predictions like the models that were built in 1990 did Yeah, so they pick models until they find one that fits both 1990 and 2015? That would be using the test data to train the model - like the Baidu approach.