February 6th, 2012, 11:53 AM
hi all,
I like to read Slashdot and I read a summary article there claiming that the computer models used by Climate scientists to predict temperature and other changes during the last 10 years have been seriously off. However the claimant offered no proof of her claims. Is this accusation true, partially true or false and where did you learn that? If you don't know, do you know where I might learn the real situation? Thanks
This looks like a good overview: How reliable are climate models?
No model is perfect. predictions are difficult, especially about the future. But models are constantly being tested against the available data and improved as a result. Note that there are many different models, using different assumptions and techniques. They all produce generally consistent results.
And most of the models have underestimated the actual temperature increases...
And I think the best point about the models, is even if they were completely perfect in any detail, they can't predict the immisions of future economies, changes of agricultural methane production crops, population fuctuations of flatulating cows, super vocanic eruptions and any number of other things that effect climate. That's why they are run against various scenarios that consider those things; which turns out to be closest is only known after the fact.
Lastly, other than for sea level rise, getting global average change isnt' all that useful. The changes at local and regional level is of the most interest and unfortunately doesn't get enough attention in the media. Knowing the Maimi will most likely be abondoned by mid century and Atlanta will only have half it's current available water is of a lot more urgency and interest then Just knowing it's going to be a few more degrees warmer.
Over and over climate scientist stress that 10 years within real world climate isn't long enough to average out variabilities of surface temperatures and expose any genuine underlying climate trend. That's true with the most advanced modelling too. Averages of many models may show a steady warming, individual model runs don't. Some causes of those variations at year to decade to multidecade scales may be known, quantifiable and to some extent predictable. Others are not so predictable. ENSO alone remains well know and the strongest single variable that causes year to year and decade to decade variation. It is difficult to accurately predict and can make one decade's surface temperatures look different to another and mask a trend; the most recent decade (2001-11) has more el Nino near the beginning and strong la Nina at the end. In the absence of an underlying warming trend there would be clear cooling in surface temperatures over that decade. There isn't.
Have those making the claim that climate models are wrong made any effort to subtract out ENSO or have they deliberately - or out of deep ignorance of the subject - failed to mention it? Ignoring known natural variations like that just shows the lack of intellectual honesty and/or ignorance of those who are determined to convince us that it's climate scientists rather than themselves that are out to mislead. Have a look at Foster and Rahmstorf for temperatures with known natural variables, including ENSO, removed.
If you want to make climate science look bad to an ignorant anti-scientific audience, the common approach is to cherry pick really short "trends" and claim it shows those models are all wrong. The Watt-up-with site is full of this kind of argument.
thanks people, I am a science person and I'm a bit troubled by the increase using of computer models because one of the basic things I learned in math is DON'T EXTRAPOLATE TOO FAR. I am fine with reviewing historical climate data and concluding from that that we are experiencing Climate Change; but it seems unwise to rely on computer models when the datasets are incomplete and the math algorithms imperfectly understood for these situations. It is good to know though that the majority of the models seem accurate or at least the real world data match the upper or lower extremes of the projections.
It is important to note that the error margins and limitations are fully acknowledged and represented in the IPCC reports.Originally Posted by ballyhoo
If anyone has any particular excerpts that would encapsulate this topic I'd like to read it (excerpts being no more than ~5 pages) if you have a link to any longer document then I would download it and read it later. thanks
An 'excerpt' that clearly demonstrates the problem you talked about in the OP is here - http://www.skepticalscience.com/graphics.php?g=47excerpts that would encapsulate this topic
There are 2 clear demonstrations here. Firstly, you can extract contra trends from a long time series if you just pick your start and end points carefully. All you have to do to check whether the extract is valid or not is to look at the whole, or a least a longer segment, of the series.
Secondly, the trend is up and it's staying that way. The Foster & Rahmstorf paper referred to earler is terrific for showing how to take out the noise of ordinary variations and leave the warming trend to show itself more clearly.
And, into the bargain, the record of the last 10 years temperature is within the uncertainty bounds of earlier projections. But the Arctic sea ice projections are a different story. The observations are way, way off the projections of just a few years ago. http://climatecrock.files.wordpress....troeve2big.jpg and for volume http://psc.apl.washington.edu/wordpr...hp echo time()?
thanks, sorry about that. Somehow I did not process that the Foster paper was a hyperlink. I downloaded it for later reading.
I wanted to ask your opinions on work by a group of scientists who disagree with climate change. I am skimming their papers on this link here http://nipccreport.org/reports/2011/...emperature.pdf particularly the graphs on page 68 and p. 71 which present 1500+ years background. I read the associated paragraph but felt that the support samples were too few for p68 but the p71 figure data seemed more to support climate change. As a last note, although I am scientifically trained and tend to agree that climate science has identified global warming climate change - I am open to any new analysis/data which might change the current scientific view. It is extremely counterproductive to describe people who question the conclusions as ignorant and anti-scientific. Question their ulterior motives only if you know they aren't scientists or interested in science. Businessmen using a minority view in the scientific community is one thing. General public questions and doubts another.
Last edited by ballyhoo; February 7th, 2012 at 07:37 AM.
The real situation is that the only reason for the existence of the IPCC is to predict disaster- therefore it is not surprising that the IPCC invariably predicts disaster. Another aspect of the real situation is that questions of this sort are very unwelcome generally and on this forum. Proceed with caution, is my advice- the official story is that there is consensus, so you had darn well better consent!
THIS is the sort of thing LF is talking about when he describes "cherry picking". But there IS good news, the link will give you a bill of materials so you can run your OWN "high school physics" experiment, and see whose results approximate yours more closely- Enjoy!
Al Gore and Bill Nye FAIL at doing a simple CO2 experiment | Watts Up With That?
From Bill Nye's response(and my observations):
"The Climate Project people used jars with lids that were too thick, the thermometers were not well placed, and the volume of gas in each vessel was greatly diminished by the presence of handsome, but voluminous globes and pedestals. When I’ve done this in the past, my apparatus did not have any of these shortcomings, so I got different results."(Silly Bill, the important thing is that the equipment was the SAME, only the atmosphere was different in each case. THAT WAS THE POINT OF THE EXERCISE. Also, the globes were not present in at least one case. And I notice that you did not specify what apparatus you DID use, not very helpful, that.)
"As the famous Boeing test pilot Tex Johnston remarked, 'One test is worth a thousand expert opinions.' Try it; try your own version, and see if you measure a temperature difference."(Agreed, Bill, but since the rival presentation has specific guidelines, you might want to put up the ones YOU used.)
Not quite.the official story is that there is consensus, so you had darn well better consent!
What you need to do is to look at the preponderance of data, evidence, scientific theory, scholarly analysis. When you do this, you find that the IPCC review of the scientific papers available up until that time (remember the last report is now a bit out of date) pretty well represent the great majority of the evidence and analysis available. My approach is simply to accept that this is probably as good as it gets ... .... ... for the time being. Until something better comes along.
When I come across something which claims to contradict something important in any area of science, I do what any sensible person does. Firstly, I withhold judgement for a fair bit longer than I might do for something that does line up with accepted physics or medicine or seismology or the data, statistics or other knowledge set for that discipline. If I'm really interested in a scientific publication which goes against the accepted view, I try to track down other papers or commentary by people more knowledgeable than I am who have reviewed and contrasted the conclusions or data with the rest of the field.
Disaster prediction is one thing the IPCC reports go out of their way to avoid. Remember the reports have to be signed off by every single country involved. So what the IPCC comes up with is often reduced to 'motherhood' statements because one or more countries refuse to accept the wording the rest of the world is willing to publish. As for the scientists, this quote from National Geographic is worth remembering .... .....it is not surprising that the IPCC invariably predicts disaster
I disagree with with Huber that "we know what that's like" - most of us don't know.Climate scientists don't often talk about such grim long-term forecasts, Huber says, in part because skeptics, exaggerating scientific uncertainties, are always accusing them of alarmism. "We've basically been trying to edit ourselves," Huber says. "Whenever we see something really bad, we tend to hold off. The middle ground is actually much worse than people think.
"If we continue down this road, there really is no uncertainty. We're headed for the Eocene. And we know what that's like."
The article is here - National Geographic Magazine - NGM.com
I'm not sure what you're getting at here. Are you saying that CO2 is not a greenhouse gas?you can run your OWN "high school physics" experiment, and see whose results approximate yours more closely- Enjoy!
Or just that some people are not as good as teachers or lab assistants at setting up demonstrations.
If you really want a properly run demonstration of CO2 absorbing radiation there are dozens - Professor Iain Stewart's is one of the best known. Iain Stewart demonstrates infrared radiation absorption by CO2 - YouTube
Or are you running the other argument, that CO2 in the atmosphere has different radiative physical properties from the CO2 in a laser? Always seems a bit strange to me, but some people apparently think this.
What I am saying is that the Watt's up website example makes it relatively easy to replicate the "high school physics" demonstration cited by Gore. This is not true of the Nye or the Stewart demonstrations. None of these involve lasers.
The most important thing to remember is that ANY deviation from "normal" conditions is attributable to global warming: Wetter than usual? Global warming. Drier than usual? Global warming. Colder than usual? Global warming! And of course, hotter than usual...
Global Warming: The Origin and Nature of the Alleged Scientific Consensus
Sorry, I ran two different arguments together. Didn't mean to. I'll separate them.
(1) What's the point you want to make about replicating the experiments? They're only there as a visual demonstration of what happens to infrared radiation intercepted by certain gases, of which CO2 is the best known. Doing the demonstration badly simply fails to show the phenomenon clearly. If you want to see it clearly, watch someone do it well.
It doesn't matter how many people do it well, badly or not at all , it has no effect on the known physics of greenhouse gases.
(2) Lasers. There are occasionally people who seem to want to argue that CO2 in the atmosphere behaves differently from CO2 used in the technological applications that rely on its radiative properties. Lasers, heat-seeking missiles and the like. Deeply weird in my view. It's an eat your cake and have it too argument. Yes, CO2 is marvelous when its properties allow technological applications. No, it can't possibly work the same way when it's running about in the atmosphere over our heads. Weird.
(1) Or do it yourself. That way you can see who is telling the truth and who is LYING, in this particular case, with wider implications for credibility generally.
(2) CO2 as a component of the lasing medium is about 10-20% of the gas mixture, which is a significantly greater than the 0.035% in which this gas can be found in the atmosphere, which latter, you will note, is "quite transparent to infrared light", per the link.
Carbon dioxide laser - Wikipedia, the free encyclopedia
The laser light is the product of electrical discharge, which, I suppose, like everything else, can be attributed to- global warming.
What an utterly useless comment. :|
You mean it isn't?What an utterly useless comment. :|But maybe you are right, mentioning lasers in threads devoted to climate science could turn out to be a gratuitous distraction to begin with. Sorry it came up.
Maybe Kalster will like this one better: Would you say that the trends in the period from, oh, say, 1912 to 2012 A.D. are "short term" compared to the entire geologic history of the planet?
Are you being deliberately obtuse again? The point about CO2 lasers is how it demonstrates CO2's radiative characteristics. I am sure you know that, but instead prefer to make some deliberately ignorant jibe at climate science. Useless post.You mean it isn't?What an utterly useless comment. :|
Again, surely you know better already, and if you don't, why the taunting tone? If you don't understand climate science enough to even know the answer to this, what business do you have adopting that tone? Can't you discuss things like a normal person? The result is that a significant portion of your posts only amuse yourself and is useless otherwise. Are you fine with that? Do you want to be taken seriously or not?Maybe Kalster will like this one better: Would you say that the trends in the period from, oh, say, 1912 to 2012 A.D. are "short term" compared to the entire geologic history of the planet?
No WAY anthropogenic global warming advocates could resort to alarmist scare-mongering crackpottery, absolutely no WAY, and this one mentions the dreaded methane hydrates too, coincidence or fact?
Over 4.5 Billion people could die from Global Warming-related causes by 2012 | Watts Up With That?
Taunt, what taunt, I was trying to improve the quality of my comments- evidently I need to do better, since nobody wants to answer my questions- or perhaps it is all moot since the Apocalypse is here, funny I didn't notice...and incidentally, the next "normal person" I meet on this forum will be the first one.Are you being deliberately obtuse again? The point about CO2 lasers is how it demonstrates CO2's radiative characteristics. I am sure you know that, but instead prefer to make some deliberately ignorant jibe at climate science. Useless post.You mean it isn't?What an utterly useless comment. :|
Again, surely you know better already, and if you don't, why the taunting tone? If you don't understand climate science enough to even know the answer to this, what business do you have adopting that tone? Can't you discuss things like a normal person? The result is that a significant portion of your posts only amuse yourself and is useless otherwise. Are you fine with that? Do you want to be taken seriously or not?Maybe Kalster will like this one better: Would you say that the trends in the period from, oh, say, 1912 to 2012 A.D. are "short term" compared to the entire geologic history of the planet?
And if I have amused myself I have achieved my objective. What is yours?
Who?No WAY anthropogenic global warming advocates could resort to alarmist scare-mongering crackpottery, absolutely no WAY, and this one mentions the dreaded methane hydrates too, coincidence or fact?
Over 4.5 Billion people could die from Global Warming-related causes by 2012 | Watts Up With That?
Martians are going to kidnap tonight....I read it in the newpaper.
Now is that a scientific view, or a populist view which could in the right hands be a media/entertainment story.
--
It is true that methane hydrate release (the same stuff that caused the BP distaster) is a subject of significant research--mostly because there is so much methane locked up in on the ocean floor. It's also researched in paleoclimatology as a possible reason the planet recovered from what's popularly known as "ice ball earth," a particularly cold climate earth had in its distant past.
But do you have the scientific papers which contend that anything like discussed in the paper is likely in modern context...or even a serious possibility....or anything sounding like the "entertaining" story your linked to? I think the strongest papers you'll find explore it as a possible feedback into a warmer world--far short of the alarmism you're proposing. The climate change we likely face is alarming enough without the methane release. It does seem likely at least some methane will provide positive feedback to make things a bit warmer.
Bottomline you can't use media hype to support your positions against the science. Only science can do that.
God dammit! How old are you? It's not about being normal, it's about having at least a measure of maturity and actually contributing to the forum. Your childish antics contributes nothing. In fact, it takes away from the quality of the forum. I'm not saying be a stiff, but for goodness' sake.Taunt, what taunt, I was trying to improve the quality of my comments- evidently I need to do better, since nobody wants to answer my questions- or perhaps it is all moot since the Apocalypse is here, funny I didn't notice...and incidentally, the next "normal person" I meet on this forum will be the first one.
And if I have amused myself I have achieved my objective. What is yours?
Can't you be serious for one second?or perhaps it is all moot since the Apocalypse is here
If you want to amuse yourself, go to another forum. I, and the majority of other people here want to learn and discuss interesting science topics. You, on the other hand, are like a hyperactive kid in a supermarket. What does your tone accomplish? You don't seem to know even basic stuff, yet taunt people with nearly every post. Do you think that is constructive in the least? Your conduct is disrupting. Shape up please.And if I have amused myself I have achieved my objective. What is yours?
As it happens, real scientists have recently been discusing this online. And surprise, surprise, the people who know what they're talking about are much less concerned about methane than they are about CO2 release. (Well, it's surprising if you don't really know what the experts usually say.)the dreaded methane hydrates
RealClimate: An Arctic methane worst-case scenario
and if you want to play at being a climate scientist yourself here's something handy for your
leisure hours ....... RealClimate: An online model of methane in the atmosphere
You know, I don't recall being called "immature" or "disruptive"(both subjective, ad hominem comments) on the UFO thread. I suppose it is all a function of whose ox or sacred cow is getting gored, correct?
Anyway, lasers emit radiation in response to electrical discharge, the Apocalypse has not arrived in the time frame projected, and the best source of materials for the "high school physics" demonstration touted by Al Gore is on the "Watt's up with that" website. You have not provided information to the contrary and neither has anyone else.
I'm DEAD serious here, but guess what? It is no fun at all, and it isn't changing your minds about the issue any more that the tired old feud between skeptic and iceaura is changing either of THEIR minds- ain't gonna happen, it's just that simple.
Bottom line is that your boy cried "wolf", which makes a lot of folks wonder if the rest of you are as well.
who the hell are you talking about?
Come ON, it's a FULL CENTURY- vs. a couple of billion years. Anyone wanna take a crack at answering this one? Anyone at all?Maybe Kalster will like this one better: Would you say that the trends in the period from, oh, say, 1912 to 2012 A.D. are "short term" compared to the entire geologic history of the planet?
Some jerk who wrote the story in the Canadian newspaper, follow the link if you want. You can find it if you Google "Brad Arnold + global warming", it is on other sites too- such is the glory of the Internet. I am beat, sleep well everybody, and cheer up, the year isn't over, maybe we'll have a global thermonuclear war after all...who the hell are you talking about?
Ballyhoo, scientists have been set a very difficult task - to make projections and predictions about how human activities impact climate. Modeling has proved itself to be a powerful tool for doing so. Validation has been, and remains, a crucial element in their development and use. Models are consistently attacked by those who are opposed to the science based understanding that we are changing our planet's climate, because computer models can be made to give whatever results their makers want of them. There may be an element of truth to that but alleging climate scientists want any results other than better understanding of climate processes and improved accuracy for predictions is unsubstantiated slander with no element of truth to it. There's no evidence that computer models ever been used by climate scientists to exaggerate the impacts of GHG emissions. You shouldn't be going along with calls to deprive climate scientists of their most useful tools.
Successive independent panels at the world's leading science advisory bodies have endorsed the methodology and broad conclusions of climate science about the impacts of emissions. It ought not be a surprise that those who are opposed to the kinds of policy the reality and seriousness of climate change demand of us want climate scientist to not only appear to be unable to provide useful predictions but want to discredit and deprive them of the means of doing so. I understand that James Hansen's predictions of more rapid and extreme change - multi metre rises in sea levels within this century for example - was on the basis of paleoclimate data of natural climate change events of the past. But those kinds of methods embody greater uncertainty, not less. They make serious policy action more difficult, not easier. The achievement of climate scientists are jewels in the crown of human achievement, the more so for giving us the window of opportunity to avoid extremely dangerous climate change. That we've squandered 2 decades of that window is not the fault of faulty computer modeling.
No, no answer, but a couple of relevant points.
1. Continental positions.
How relevant are the conditions of umpty million years ago when NH and SH climates were split apart by water circulating directly around the equator? Modern climate is hugely affected by the fact that North and South America have joined up enough to stop this flow. One example, ENSO. There would not be any ENSO effects of any kind if cool or warm water in the Eastern Pacific could flow or drain or whatever technicalish sounding word you'd like to use to describe the phenomenon of water travelling smoothly, unimpeded, between the Pacific and the Atlantic. (Add in the lack of a Gulf Stream to warm Western Europe and any other effects that occur to you.)
2. Sun brightening.
If you're talking billions of years and climate, you need to account for the fact that the sun is now much, much brighter than it was back in the days of CO2 concentrations in the omg range.
Apparently you haven't taken the time to understand the first thing about the current state of climate modeling. It's not really based on billion year histories. And it's not just one model, it's dozens, running on supercomputers and distributed computing platforms. It's based on simple physics, what are called primative equations (don't get your panties in a bunch, look up what it means) These are basic undeniable physical principles. What history does, is provide verification that the approximations that are used to allow computation in less that centuries is valid.
In general they all agree that the future is grim, and in fact as stated above, the most dire predictions (which are also valid) are filtered out by the need for everyone to sign off on it. There are no low end scenarios that are filtered out, only the worst case scenarios.
True enough, the continents have been playing at bumper cars the whole time and the sun has been getting brighter and the equinoxes have been exhibiting precession like mad the whole time. All frightfully interesting. Has any of it caused your "methane worst case scenario"? What could cause such a thing to occur?
Nothing, it is just another hypothetical disaster. The author admits as much and presents not even a shred of evidence regarding the etiology of this "scenario".
How very UNUSUAL for the climate "science" crowd- idle speculation, scary and utterly divorced from reality. For what it's worth, your NG article is also pretty indefinite about the causes of this PETM, but it wasn't too many SUVs, this at least we can all agree upon.
We do not have to model billions of years, maybe a few million or even thousands would be less of a "short term trend" compared to a century, wouldn't it now? Yet the only episode cited on the thread by you so far is the PETM- of course this is not cherry picking...
Last edited by Arthur Angler; February 7th, 2012 at 10:32 PM.
Why bother with models when you've got ice cores?We do not have to model billions of years, maybe a few million or even thousands would be less of a "short term trend" compared to a century, wouldn't it now?
Richard Alley on Earth's Biggest Climate Control Knob
You might like Alley's style. Apparently he's a brilliant teacher.
(I'm afraid it takes a real effort for me to tolerate him until I get used to it.)
Below is a somewhat lengthy critique of the computer models involved and the issues affecting the error probability. Hope you find it useful. As you can see, opinions differ here on the forum, so to a degree you are on your own.
Skeptic » Reading Room » A Climate of Belief
Climatic changes have had historically quite powerful impacts on humanity on scales much shorter than Arthur's billion year scale.
Anthony McMichael explores what we can learn about how climate impacts human nutrition and health, societies and conflict in "Insights from past millennia into climatic impacts on human health and survival" published by the US National Academy of Sciences. From early migration out of Africa facilitated by low sea levels due to ice age glaciations to the development of agrarian societies during the early holocene during post-ice age warming, climate changes have had profound impacts. The Younger Dryas event devastated early humanity along the Nile and Syria with archeological evidence of prevalence of violent deaths, with subsequent abandonment of settlements. Sumeria grew during the Holocence Climatic Optimum and declined with changed, drier climatic conditions - "Clay tablets and carvings on stone steles attest to growing misery, conflict, starvation, and several epidemic outbreaks" (McMichael citing "Climate Change in Prehistory. The End of the Reign of Chaos"). I think it's conceit and delusion to imagine we will be immune from harm when facing a strong global climate that has no real precedent.
From multi-century scales down to single extreme weather events, humanity is strongly impacted by climate and weather.
He sings, he dances, he waves his hands- yep, he's a knob. Will check it out later, but hey- are you really willing to chuck the IPCC models out the window? If you do you've got company.
And from the same issue of Skeptic magazine, an article from a climate scientist.
Skeptic » Reading Room » How We Know Global Warming is Real
Both of these items are pretty long. If you find the prospect of reading carefully, taking notes, comparing notes then looking up even more references to check things out a bit daunting, try some neatly put together videos from Potholer54. The whole series is here .... Potholer54 Climate Change - YouTube
He can sometimes be pretty snarky if he's debunking myths of various kinds (have a look at some of the evolution versus creation or Golden Crocoduck items for outstanding snark), but he's originally trained as a geologist and has done his time as a science journalist, so he's good at getting stuff across clearly.
Authur the IPCC has no models. And knock off the snarky comments. They are becoming a habit you need to break before you're no longer welcome.
chuck the IPCC models out the window
What IPCC models? The IPCC does no science at all.
The process is a review and collection/collation of the latest and best supported data and scientific publications available at the time. (Though necessarily the cutoff date for acceptance for papers is several months before the reports finally see the light of day.)
It's a hypothetical disaster of fairly epic - even eonic - proportions.
The reason we wouldn't expect a methane meltdown in the past is that all that stuff happened very slowly - methane doesn't last long in the atmosphere, so to set off a meltdown you have to warm a lot of it up very rapidly. Continental drift is not fast enough.
The reasons we are a bit worried at present are that
1)we are already at the warm end of the glacial freeze/thaw, so that a lot of methane hydrate is at the edge of its regime, riding the warm edge of the temp and pressure regime that keeps it solid
2) on top of the high end of the temp cycle, which has brought so much methane to the dissolution point in its little patches on the ocean floor, we are adding CO2 trapped heat to the system at unprecedented rates - faster than ever before in geological history. This extremely rapid heating of already poised hydrate deposits bids to push a lot of methane over the edge at once - enough to feed back faster than it is removed from the atmosphere. That would be different from the past - a sort of explosion of heat trapping gas thawing yet more, doing in a matter of decades what took millenia in millenia past.
I wish to see more data across the 1500 year period (or more if you know about it) besides the ice sheet data. That's important and persuasive but I know that there are other factors too.
Not sure exactly what you're after, but this video is worth watching anyway.
It's important to use full screen - otherwise you'll never be able to decipher the names of the various data sources as they accumulate at the top right. Whenever I go back to this one I like to let it run all the way through first. Then rerun it and stop it at, or a bit prior to, the period I'm interested in. Stopping it a few times at 1000, 500, 0 a couple of others as the graph takes shape. The map's colour coding is handy for checking if your memory for exactly where Vostok or other data sources are sometimes lets you down.
Time history of atmospheric CO2 - YouTube
If you like your videos with music, try this version.
http://www.youtube.com/watch?v=KYLGB...eature=related
well, I know there are other variables that represent climate change besides ice sheet changes such as chemical changes/types of rocks sedimented to ocean bottoms, changes in fossil species diversity and types, changes to ratios of various elemental isotopes - I want to see MORE data for OTHER variables besides ice sheets and across a more EXTENDED TIME such as the 1500 year time frame I mentioned from the scientists challenging climate change theories and models.Not sure exactly what you're after, but this video is worth watching anyway. It's important to use full screen - otherwise you'll never be able to decipher the names of the various data sources as they accumulate at the top right. Whenever I go back to this one I like to let it run all the way through first. Then rerun it and stop it at, or a bit prior to, the period I'm interested in. Stopping it a few times at 1000, 500, 0 a couple of others as the graph takes shape. The map's colour coding is handy for checking if your memory for exactly where Vostok or other data sources are sometimes lets you down. Time history of atmospheric CO2 - YouTube If you like your videos with music, try this version. History of CO2_Inception.wmv - YouTube
That's good! But as you explore the research always keep in mind the vast differences in time scales involved. Co2 and methane changes effect climate over periods of decades to several thousand years, weathering on the order of tens of thousands to millions of years, orbital and other astronomical changes on the order of thousands to a hundred thousand years, a super volcano or huge astoriod can change things in days.well, I know there are other variables that represent climate change besides ice sheet changes such as chemical changes/types of rocks sedimented to ocean bottoms, changes in fossil species diversity and types, changes to ratios of various elemental isotopes - I want to see MORE data for OTHER variables besides ice sheets and across a more EXTENDED TIME such as the 1500 year time frame I mentioned from the scientists challenging climate change theories and models.
oDid you watch the CO2 versus temperature video? That covers 800,000 years.ther variables that represent climate change besides ice sheet changes such as chemical changes/types of rocks sedimented to ocean bottoms, changes in fossil species diversity and types, changes to ratios of various elemental isotopes - I want to see MORE data for OTHER variables besides ice sheets and across a more EXTENDED TIME such as the 1500 year time frame I mentioned
You're not going to see much change in "rocks sedimented to ocean bottoms" in just 1500 years, let alone fossils. If you're looking for an overview of paleoclimatology, there's waaaaay too much for a brief answer.
One really nice piece of evidence I like to look at is the history of the Japanese cherry blossom festival. They've kept super detailed written records for almost 1000 years. http://arnoldia.arboretum.harvard.ed...icles/1893.pdf
If you're looking for answers or counter-arguments to matters raised by the NIPCC or SPPI people, you could try writing down which or their arguments you find most persuasive ("grapes in Greenland" "broken hockey stick" "models are unreliable" or similar summaries) and look at Skeptical Science's list of climate myths to see if they've dealt with it. (The most popular argument at the moment is apparently "climate's changed before", so poor old "It's the sun" has to settle for second ranking now.)
There are a few people advancing lots of theories of wildly varying quality. There's no consistency in the objections to the established science, so you'll need to say which particular papers from which particular scientists you find persuasive. A whole lot easier to deal with one or half a dozen papers than to try and do a general summary of several thousand papers - that's the IPCC's job - in the vague hope that that might answer your specific questions.scientists challenging climate change theories and models.
Back to the NIPCC. It's one thing to say that we shouldn't blindly accept what mainstream scientists tell us. It's another thing entirely to claim that lining up alongside Fred Singer or any organisation he has a strong voice in is a good thing to do. He's been on the wrong side of all the important public policy scientific issues for the last 40+ years. Tobacco, acid rain, the ozone hole, asbestos, DDT, you-name-it. He's been wrong every time.
Last edited by adelady; February 9th, 2012 at 05:40 PM.
For an overview of long and short timescale climate influences, from billions of years down to decades, this is a nicely put together piece.
Why does climate change? Causes and Timescales - Weather and Climate - timesunion.com - Albany NY
Doesn't take long to read. Might help frame your queries.
Though I've started to wonder about this comment
When you're into extended time scales, say 10000 years or more, you're instantly into the realms of Milankovitch cycles, inter-glacials and all. Move into the millions of years and glaciation / de-glaciation are the dominant processes. You'll need to be a bit more explicit for others to really pinpoint what you're getting at.I want to see MORE data for OTHER variables besides ice sheets and across a more EXTENDED TIME
Ballyhoo, climate denialism uses recognisable techniques. Your initial query about models being "seriously off" with respect to the past ten years is an excellent example that demonstrates the use of several commonly used tricks - and they really are tricks intended to mislead and deceive.
First trick is picking a single specific indicator/measure, (rather than that measure in relation to all the others. It's consistency or not with other measures is important). Next, by picking a too short period (within which natural variations can mask or exaggerate underlying trends - in this case masks). Next trick is picking a specific period that, out of the context, shows a skewed result (again because natural influences tend to mask warming). Next by failing to mention or take into consideration known natural influences for that particular, cherry picked measure and period (which had warming influence of el Nino dominating towards the beginning and cooling influence of la Nina at the end as well as declining solar TSI strength).
Being consistent - or not - with other measures and indicators as well as with established understandings of climate processes are important. If it appears inconsistent with continual warming from rising GHG's honesty requires that reasons why be explored. Such as too short period that allow the short term dominance of known natural oscillations or influences to mask of exaggerate. Like ENSO and temporary decline in solar strength. And the climate models being compared to - were they averages of many models or specific ones, how were those influences modeled? Averaging would tend to level out those influences. Do the results better match the corrected temperature graphs such as by Foster and Rahmstorf that adjust for known influences?
What I see from any simplistic attempt to compare models to a single decade, with known natural influences that are masking warming over the short term deliberately left out of consideration is a clear intent to mislead and deceive. Given what's at stake, deliberate intent to mislead and deceive should not be tolerated.
Adelady,
That's a nice intro in your link. Good idea to post it!
Read something today that went right back to the OP.
No link given unfortunately. I tried to find the item on slashdot but couldn't, so I'll take this comment as accurately representing what was said.I read a summary article there claiming that the computer models used by Climate scientists to predict temperature and other changes during the last 10 years have been seriously off.
No climate scientist on earth has tried to predict temperature and other changes "during the last 10 years". That's not their job and they don't have modelling algorithms capable of doing it even if they wanted to fit such projects in among the others that take up so much computing power and time. As it happens, there are dozens and dozens of models with various features, and the climate outcomes of the last few years are entirely within the range of projections - apart from Arctic sea ice.
This item has a neat presentation of results over the last couple of years through to longer periods. The second page is excellent. "Global Warming Has Stopped"? How to Fool People Using "Cherry-Picked" Climate Data - Forbes
Okay then, Mr. Moderator Sir, what DOES the IPCC base the doom forecasts on if not computer models?
Do they have crystal balls or something? If they only USE models constructed by others vs developing said models themselves, is this a truly relevant point regarding the accuracy of same? What have I done, exactly, to merit such threats? I cannot be the only one guilty of the infamous CRIME of "snarkiness" here, can I? Perhaps it is my point of view which you find repugnant, and not the way I express it? Is it the DISSENT you wish to silence, because I MAY have been "snarky" on other topics, and do not draw this sort of commentary?
Maybe you can define snarkiness and sort of a scale for me to use to make sure I don't offend again?
Or you could return to the topic.
FALSE ALARM: Why Almost Everything We’ve Been Told About Global Warming is Misleading, Exaggerated, or Plain Wrong » Climate science
A simple model anyone can download:
Simple Climate Model Release, Version 1.0 « Roy Spencer, Ph. D.
Dr. Gleick, cited in #57 above, elected to use GISS data- I wonder why?
Confronting "cherry-picking" in both Northern and Southern Hemispheres:
FALSE ALARM: Why Almost Everything We’ve Been Told About Global Warming is Misleading, Exaggerated, or Plain Wrong » The past decade: warmer or cooler? Response to a reader II
Great. A website by a journalist who admits "I can’t claim to be an expert on climate science". This alone doesn't refute his claims, but something tells me you haven't done any ground work to verify his claims, yet you expect us to go through considerable trouble to refute a sceptic non-scientist? "FALSE ALARM: Why Almost Everything We’ve Been Told About Global Warming is Misleading, Exaggerated, or Plain Wrong" is the title of his new book by the way. What a surprise.
Tell me, Arthur, do you think you are being diligent in your tackling of the climate change issue? Because you seem to have started out with a premise that it is all bogus based not on an understanding of the science, but something else (what?), and have taken to proving your presupposition from then on and with an attitude born out of goodness knows what.
Basically, this is a question about climate 'sensitivity' because releasing greenhouse gases wouldn't matter if the climate didn't respond in any noticeable way.Sir, what DOES the IPCC base the ...... forecasts on if not computer models?
I remember reading that the most important things in determining sensitivity and the resulting outcomes depend on 3 things. First is paleoclimate. Second is physics. Third is models. And paleoclimate is a much, much better guide than either of the other two.
(I can't find this one in my quotable quotes file, so I've gone on memory alone - and I have certainly forgotten the middle bit, it may include data and observations - as well as the name of the speaker.)
The technical issue is that the models have wider error bars than the paleo data. The main problem with the paleo data is relating it to decadal and century timescales rather than the thousands or millions of years involved there.
Back to models. What's the problem? All the temperature outcomes and other indicators are all well within the uncertainty ranges of the multi-model runs so far. (Provided you tactfully avoid mentioning the disastrous results for Arctic sea ice.)
The NASA people have just released their update for 2011. You don't need to read the article, just look at the first graph. RealClimate: 2011 Updates to model-data comparisons
What's wrong with the models there? The observed data doesn't go anywhere near the 95% extremes of the modelled temperature ranges.
adelady, I thank you for providing these links but I'm not sure why you cannot understand what I'm asking - I think it's very clear.
Although CO2 levels and ice sheet areas are important, I want to know what other lines of evidence there are in the fossil record.
Are you a scientifically trained? Do you know anything at all about isotope ratios in sedimentary samples or types of rocks that form in increasing acidic oceans? Or about fossil diversity changes? Types of C4 or C3 plants remains you see in climate change scenarios? Plant wax residues in oceans sediments? Types of ocean microorganism remains that change with changing ocean acidity, oxygen carbon dioxide partial pressures?
You seem to think that simply citing carbon dioxide levels or ice sheet areas suffices to prove global warming.
I disagree - they are major components of the arguments but they don't clinch it. Your answers seem to indicate you are well versed in topics related to climate science but when I ask for details you don't seem as knowledgeable.
I'm not trying to criticize - I'm trying to determine how valid the challenge of that Slashdot claim was really.
Acually, temperatures clearly show global warming over the last 5 decades. What more do you need?
You could also ask on the BAUT forum: Bad Astronomy and Universe Today Forum - there seem to be quite a few people there with a good understanding of climate science (including a few on the more sceptical side).
In the arena of anthro CO2 driven climate change: To the extent it was "valid"it wasn't relevant, to the extent it was relevant it wasn't "valid", would be the answer you have been given.
What are you arguing?
I think what's throwing us is you keep asking about "global warming," which we understand in this conversation as man-made global warming a recent phenomena of the past century, but using and asking for evidence that goes WAY further back, but (and this is important) doesn't have the resolution to tell us anything about the past century. This is why it's important to understand the timeline and resolution of what we call proxy (indirect) data for past climate.
--
I will however try perhaps to fill in the gap by looking a few samples of temperature reconstructions:
The sampling of data used for just the past 2000 years include:
Thermometer data from land, sea surface. (~250 years)
Satellite data (~35 years)
Borehole data (~300 years)
Agricultural harvest date records such as grapes harvest dates (~500 years)
Tree ring data (~2000 years)
Glacier length studies (~150 years)
Coral species and growth ring studies (~1000 years)
Sedimentation and radiocarbon studies of mosses species (~1300 years)
Stalagmite isotopic composition (~2000 years)
Lake sediment studies of temperature sensitive chironomid remains (midges---aka "no see-ums) (~12000 years, many similar studies of other life)
Going back further, into some of the types you mentioned:
Agricultural harvest amount records such as wheat (~2500 years)
Ocean sediment core shell isotope (Mg/Ca) studies (~350,000 years)
Ice core oxygen isotope studies (~800,000 years)
Land glacial extent studies (~3 million years)
Sedimentary rock studies of Boron isotopes, glacial remains etc.... (~ billion years)
These is just a smattering of the range and types of evidence for being used to reconstruct past climates--each having it's own characteristics such as accuracy, time-resolution, locations etc.
My point being that they only report summations of what the sciences are producing. They do not own, operate, or contract for studies from any models. If you do a book report does that make that book yours? No.Okay then, Mr. Moderator Sir, what DOES the IPCC base the doom forecasts on if not computer models?
"he's a knob. " in a quote containing no content and a factual error about the IPCC is going too far.I cannot be the only one guilty of the infamous CRIME of "snarkiness" here, can I? Perhaps it is my point of view which you find repugnant, and not the way I express it? Is it the DISSENT you wish to silence, because I MAY have been "snarky" on other topics, and do not draw this sort of commentary?
Maybe you can define snarkiness and sort of a scale for me to use to make sure I don't offend again?
Most of your other comments are equally as abrasive and ignorant.
Is it? Or not allowing incivility and seemingly deliberate ignorance such as your continuing to post ten year "climate trends" as dissent, regardless of how many times you've been informed that climate is defined as periods of 30 years. You are out of excuses, and I and the other mods are tired of reminding you how to avoid: making abrasive comments, invalid arguments, insubstantial contributions, inconsiderate comments such as your recent recommendations about suicide, failure to head warnings and numerous other things you've done to foul this forum. (you are one of the most reported members by other members on these boards).Is it the DISSENT you wish to silence,
I'm giving you two weeks off this time, while the mod team reviews your continued membership.
Last edited by Lynx_Fox; February 10th, 2012 at 05:12 PM.
I won't repeat the information Lynx Fox gave you. But 2 comments.You seem to think that simply citing carbon dioxide levels or ice sheet areas suffices to prove global warming.
..... ...... .....
I'm not trying to criticize - I'm trying to determine how valid the challenge of that Slashdot claim was really.
1. Without the words of "the challenge of that Slashdot claim", let alone a direct link, it's pretty hard to work out exactly what collection of which data would best answer your query. I did try to find it. I hoped you'd give it for a bit more guidance here.
2. Climate change in the current era is merely a subset of general climate science. And carbon dioxide levels and ice sheet formation / melting are the biggest evidence items on the climate list. LF gave a pretty good brief summary of some of the supporting data.
If your slashdot item gives you a specific cause for caution about the science generally, or a specific claim about modelling (or statistical analysis or similar technical minutiae), or a particular contrarian paper or body of work, then give the specifics and see if anyone can help you.
Ballyhoo, I think you've been shown clearly why it was not a valid claim. Do you understand why 10 years is too short? Do you understand that none of the science organisations that run GCM's claim that they can predict short term variables like ENSO beyond a rough prediction for the next year? Do you understand that it's variability averages out over longer periods and that's why longer term trends can still be ascertained with confidence where shorter term ones cannot? Pointing out a mismatch between models and real world temperatures over such short scales is misleading. Those that do so are acting out of ignorance or willingness to practice deceit. If out of ignorance they are practicing deceit by claiming a level of knowledge and expertise they don't have. It's possible to have scientific credentials and have no relevant expertise in computer models, their validation or the the full extent of how much is now known about the workings of our climate.
In the absence of deep expertise you can put some trust in the scientific organisations and practices that have served humanity so well, or do as people like Arthur do and choose to disregard them in favour of sources of information on the basis of them telling you what you want to hear. Why he thinks successive independent assessments by the US National Academy of Sciences are suspect but What's Up With That and the CATO Institute are trustworthy is probably clearer to me than to him. Why would you think Slashdot holds a candle to NAS, NCAR, GISS, NOAA, Royal Society, Hadley CRU etc when it comes to reliability and trust on a matter of science? I suggest you look to them and to sources that accurately reflect the body of knowledge these and other genuine science organisations have developed. They are much more trustworthy than Slashdot.
I need to know a longer baseline to be sure it's manmade and not natural long term variations
MUCH better! that's the kind of multiple lines of evidence I want to see!I think what's throwing us is you keep asking about "global warming," which we understand in this conversation as man-made global warming a recent phenomena of the past century, but using and asking for evidence that goes WAY further back, but (and this is important) doesn't have the resolution to tell us anything about the past century. This is why it's important to understand the timeline and resolution of what we call proxy (indirect) data for past climate. -- I will however try perhaps to fill in the gap by looking a few samples of temperature reconstructions:The sampling of data used for just the past 2000 years include: Thermometer data from land, sea surface. (~250 years) Satellite data (~35 years) Borehole data (~300 years) Agricultural harvest date records such as grapes harvest dates (~500 years) Tree ring data (~2000 years) Glacier length studies (~150 years) Coral species and growth ring studies (~1000 years) Sedimentation and radiocarbon studies of mosses species (~1300 years) Stalagmite isotopic composition (~2000 years) Lake sediment studies of temperature sensitive chironomid remains (midges---aka "no see-ums) (~12000 years, many similar studies of other life) Going back further, into some of the types you mentioned: Agricultural harvest amount records such as wheat (~2500 years) Ocean sediment core shell isotope (Mg/Ca) studies (~350,000 years) Ice core oxygen isotope studies (~800,000 years) Land glacial extent studies (~3 million years) Sedimentary rock studies of Boron isotopes, glacial remains etc.... (~ billion years) These is just a smattering of the range and types of evidence for being used to reconstruct past climates--each having it's own characteristics such as accuracy, time-resolution, locations etc.
All she wrote was that the models didn't match the real world data for the last 10 years (paraphrased). I listed which kinds of data I wanted to see - another poster has provided more satisfying response so never mind. I do disagree that short timelines or only/mostly CO2/glacial ice sheet area data clinch the theory though. thanks all for your help clarifying the real situation - imma happier now that the climate science theory has a solid footing.
So do you get it yet? Do you see why the slashdot article focusing on < 10 years was disingenuous when discussing climate?
Goodo. So now we're down to time scales.
Meteorologists have conventionally used 30 years as the definition for distinguishing weather from climate. They'll probably continue to do so. However, there's now some backing for being able to detect changing climate in fewer years than that.
http://muenchow.cms.udel.edu/classes...Santer2011.pdf
The takeaway from the abstract is this bit.
Because of the pronounced effectof interannual noise on decadal trends, a multi-model ensemble ofanthropogenically-forced simulations displays many 10-year periods withlittle warming. A single decade of observational TLT data is therefore inadequatefor identifying a slowly evolving anthropogenic warming signal.
Our results show that temperature records of at least 17 years in lengthKeep this one close handy, so whenever you see an argument about any climate matter based on a short period you'll have your little reminder to recheck the data for at least 17 years or maybe 30+ years and see if it affects the proposition being advanced.are required for identifying human effects on global-mean tropospheric
temperature.
(Sorry about the formatting on the quote. It's very uncooperative.)
Last edited by adelady; February 11th, 2012 at 01:13 AM. Reason: format, spelling
This is not an issue of 'getting it'. Climate science is not a revealed holy truth that I must pull away the veil of ignorance from my eyes to see.So do you get it yet? Do you see why the slashdot article focusing on < 10 years was disingenuous when discussing climate?
It is a theory that I believed had substantial lines of evidence supporting it.
Slashdot is known for it's partisanship and politics but the woman who wrote that wrote as if one single model dominated the theory and it failed to predict accurately.
This troubled me because true hard science is signified in part by a theory that can not only explain past or present events completely but can predict the future events and can be examined by the scientific method and reductionism.
The strength of climate science is NOT in the models and their predictions - it is in the accumulated evidence across centuries and millennia which shows we are departing significantly from past climate patterns.
Now, do YOU get it?!
There are (as you can see) dozens of models, all approaching the intractable problem that the model must take less time to run than reality from different directions. While they disagree in details, the overall result is undeniable, and even lowest outliers predict continued warming long after our lifetimes.... even if we stop adding more CO2 now, which as we know, ain't gonna happen.
There are many garbage websites, and many women as well as men saying foolish things.
The question is why you would go making an issue out of one of them, in particular giving credence to someone who is obviously out to lunch in the matter.
But much of the value of it is there - our comprehension of the present and awareness of possibility is much improved by them.
Those genuinely interested in how well models compare to recent data might find it worth a look at Gavin Schmidt's recent post "2011 Updates to model-data comparisons" at RealClimate.
Ballyhoo, the strength of climate science is reflected in the models. They are built around understanding of climate processes. Without them the task of making predictions - and that is a crucial element of the tasks climate scientists have been asked to perform on our behalf - would be made far more difficult. Waiting on the real world to deliver results will put them (in the long run) beyond dispute, but I'd prefer to encourage methods that deliver them sooner. Other methods besides modeling will be just as subject to deliberate efforts by opponents of action on climate to bring them into disrepute. I think your concerns about climate models are unfounded.
Not so, the evidentiary history show we are departing from normal climate cycles, don't the models rely on past and present data to initialize their models? They might confirm the theory but they don't prove it. Also, exactly how far into the future do these models predict?
No. Weather models rely on initial conditions, climate models don't.don't the models rely on past and present data to initialize their models?
Climate models are simply set up with physics equations, geographical information and similar general principles (like expected frequency of volcanic eruptions for instance). And the details here are waaaaay beyond my pay grade. They 'spin the model up' from an absolutely neutral state. And watch what happens.
They know the models are pretty good because they come up with things like the ENSO cycle all by themselves.
They can run a 'forever' scenario if they've got computing time to spare. The big issue is what information do you feed in for the future.Also, exactly how far into the future do these models predict?
Greenhouse gas emissions for example. You have to put in something about forcings. We know about Milankovitch cycles and TSI and sunspots and they're more or less known for a reasonable length of time, so they're OK. But emissions scenarios? They already have half a dozen in the IPCC reports. They can run them for a couple of centuries. But you have to balance the time and expense against the value of the results. When you absolutely know that only one of these values will apply (or be anywhere in the ballpark), and you have to run hundreds of simulations for every option, you have to draw the line somewhere.
Ballyhoo, successive independent committees of the US National Academy of Sciences - drawing on the cream of US scientists - don't seem to see the problems with computer models that you do. The Royal Society doesn't either. Why the distrust of them? Surely not because an article at Slashdot.
Because I don't anyone's word for anything. A model in and of itself is not a proven theory. Experimental data is what makes or breaks a theory. I prefer relying on historical evidence, not mathematical projections which can be skewed by some unforeseen chaotic variable. If some single model is found that could match reality well for a few decades then fine. But a bunch of models that agree is not enough for a decade or two or even three is not enough.
The current generation of CPDN (BOINC Distributed computing) models are back verified for at least 60 years to prove the parameter settings are realistic.. The models that get to run on supercomputers (faster, but less ability to tweak the parametrs due to time contraints) do the same thing.Because I don't anyone's word for anything. A model in and of itself is not a proven theory. Experimental data is what makes or breaks a theory. I prefer relying on historical evidence, not mathematical projections which can be skewed by some unforeseen chaotic variable. If some single model is found that could match reality well for a few decades then fine. But a bunch of models that agree is not enough for a decade or two or even three is not enough.
It appears you don't understand how real world climate modeling works at all.
And a variety of slightly different models gives a much more useful view of the model sensitivity to various settings.
I said as much about 50 posts ago... and 20...
I'm pretty sure I never claimed to understand the models, which is why I posted my question here. Also, back-verifying a model is called tweaking your model to fit past data. I am extremely skeptical that models do not include historical data to model the present and future. If you care to post excerpts and cite articles together to prove it then feel free. You can't know how to setup your equations and what variables to include in what relationships without real world data so whoever it was that wrote that the equations alone sufficed to make the model accurate is wrong in my view. But again feel free to post the excerpt from a journal.The current generation of CPDN (BOINC Distributed computing) models are back verified for at least 60 years to prove the parameter settings are realistic.. The models that get to run on supercomputers (faster, but less ability to tweak the parametrs due to time contraints) do the same thing. It appears you don't understand how real world climate modeling works at all. And a variety of slightly different models gives a much more useful view of the model sensitivity to various settings. I said as much about 50 posts ago... and 20...Because I don't anyone's word for anything. A model in and of itself is not a proven theory. Experimental data is what makes or breaks a theory. I prefer relying on historical evidence, not mathematical projections which can be skewed by some unforeseen chaotic variable. If some single model is found that could match reality well for a few decades then fine. But a bunch of models that agree is not enough for a decade or two or even three is not enough.
Anyone? Anything?Because I don't anyone's word for anything.
You can't have any interest in science then. It is simply not possible for anyone, including the brain-the-size-of-a-planet, rocket-science physicist types to know every relevant thing about climate. Being the best person in the world on radiative physics of gases (as an example) won't help you, let alone leave you enough time, to be similarly expert on forestry or glaciology or coral reefs or paleoclimatology or oceanography or agriculture or bird migration or the dozens of other related disciplines.
It's about two things.
Firstly, it's about who do you trust. Or whose collected wisdom do you accept. If an organisation of thousands of physicists with 10s of thousands of years experience in a variety of specialties tells you that they collectively agree with the conclusions of a particular specialty with 50+ years of successful work behind it, why would you doubt them? And the same thing happens with chemistry, geology, biology, every other area of expertise, you'll doubt them too?
Secondly, and more importantly. There's a world of difference between accepting scientific results with the proviso that you'll happily change your mind if better data, analysis, theory comes along to describe or explain things differently - and constantly doubting that anything you're told is valuable at all. There's nothing wrong with finding out you were wrong. Scientists have to live with this uncomfortable truth day in, day out. Remember, we on the outside only see the publicly released results. We don't see the failures unless they happen after a theory or conclusion has gone into the public arena.
Personally speaking, I'm reasonably happy to accept that the conclusions and the models are pretty good. However. A big however. The abject failure to show anything remotely like the plummeting Arctic sea ice shows that there's something amiss somewhere. I suspect the issues with modelling heat transfer into the deep ocean and how that might translate into melting sea ice from below have seriously impacted capacity to make good projections here. (Whereas the projections for Antarctic sea ice extent have been pretty well spot on. Maybe it's just a coincidence that the Antartic sea ice is isolated from warming ocean currents by the circumpolar current. Antarctic Circumpolar Current - Wikipedia, the free encyclopedia Maybe not. )
Another however. The projections about the likelihood of severe weather events are a bit out. AFAICS they're running 20+ years ahead of the anticipated timeline. But we'll have to wait for the next IPCC report to see if the view on this has changed.
Ballyhoo, if you expect to be able to learn enough to make your own mind up without resort to trust in any of the world's scientific institutions and publications or leading experts you are in for a long hard slog. I suggest university enrollment at your earliest opportunity rather than forums or blogs. While you are doing the decade or more of preliminary boning up on the underlying sciences to get you to PhD level and knowledgeable enough to make your mind up our window of opportunity to act to avoid extremely dangerous climate change will largely have passed.
In the meantime are you going to support or oppose regulatory legislation, pigovian taxation on high emissions energy and/or subsidised deployment of low emissions alternatives? Keep in mind that climate science tells us quite clearly that the impacts of emissions now take decades to centuries to be fully realised and are irreversible by any practical means - and that is not a conclusion that relies on GCM's.
The equations in question are physical equations - which of course are based on data from observation and experiments - a loooong time ago.You can't know how to setup your equations and what variables to include in what relationships without real world data so whoever it was that wrote that the equations alone sufficed to make the model accurate is wrong in my view.
Lapse Rate - Overview of Lapse Rate
Clausius
and dozens of others.
For insight on how they're put together, this is a nice piece from a student just getting started in this area.
How do climate models work? « ClimateSight
Some of her answers to comments relate rather well to some of your concerns as well.
And from the blokes who've been doing it for a living for ages ..... RealClimate: FAQ on climate models
And their answers to comments are also helpful. (I've only looked at the first page this time.)
I was going to make that point adelady.
The models are derived from basic phyics.
The half dozen or so weather prediction models do the same thing, but with more detail, they're called primitive equations. IOW, Stuff like F=ma and all that.
All the computers do is allow us to run experiments in faster than real time. In order to fit that into available computational availability, some of the phyics is simplified. The question is, what simplifications work to predict how climate has responded over the last 3 or 4 score years. To run thousands of years (without taking thousands of years) approaches that have worked on shorter time scales are compacted and tried to see which fit the actual data the best. Remember, climate deals with wide areas over long time scales, so day to day precision is a waste of resources.
And it's not like we even know exactly what data makes a difference yet. That's the purpose of the model experiments, to find out what works to recreate past climate, and which things don't seem to make a difference in the long run.
adelady, regarding the arctic, I suspect three possible sources of unerestimating the extreme melt. One would be a probably minor tweak in the albedo feedback. Another might be underestimating the feedback from tundra releasing CO2 and Methane. And finally, the models create ENSO fairly well in the Pacific Basin; but it's 10 times larger, twice as deep and acts as a single huge system. The Arctic Ocean on the other had is smaller, divided by the Losmonosov Ridge, and has limited inflow and outflow routes. I don't know how closely the ocean part of the models reflects all that level of detail over a much smaller area. Those are just educated guesses, based on my understanding, but they're better than WAG's
I read this a lot and not sure where it comes from. The models are mostly based on physical equations with stochastic elements to introduce realistic variation to represent weather. The number of variable is huge and not just over the one and two dimensional scale we tend to see in oversimplified average global temperate charts, but in elevation, latitude and longitude and time over temperature, humidity, wind speed, pressure, long wave radiation, short wave radiation, all the phase changes between solid ice and water vapor, evaporation and many more either handled directly or parameterized in some way. And that's just the atmosphere. These global climate models also simulate ocean changes, currents, as well as responses of surface ice and vegetation as well as add random inputs like volcanic eruptions etc. And it's not only the past sixty years that they match, but variations of Global Circulation models even being used to model paleoclimatology such as the break up of Pangaea and the results consistent with proxy climate observations from that period.Also, back-verifying a model is called tweaking your model to fit past data.
The very nature of the models make it quite literately impossible to just "tweak" to match past conditions. Are they perfect, heck no, but every increase in computing power over past 25 years have been completely tapped in less than 18 months by climate modelers who continue to increase resolution of the atmosphere, oceans, and geology, replace parameterizations with physical models of smaller and smaller features and add new aspects are discovered.
True. But it's as close as you ever get with natural science which can only match and be consistent with observations since we can't run live real world experiments.A model in and of itself is not a proven theory.
I'm afraid I find it hard to reply to this sort of comment without being offensive.
There is a place for scepticism but that is just ridiculous.
The sort people who say this presumably go off and study medicine for 5 years if they get seriously ill - "I'm not going to trust those doctors".
Something wrong with the car? Go and learn about how the internal combustion engine, the control electronics and everything else works. Oh, and learn to make new parts on a lathe because you are not going to trust those parts manufacturers when they say they make suitable components.
On another forum someone said something along the lines of, "I'm not sure about relativity because I don't know enough math to be sure it is right". Presumably he must assume that all the thousands of people who do know the math have overlooked some trivial error that this genius would spot.
Surely that sort of attitude is just backwards. A more reasonable statement might be, "I'm not sure about relativity but I don't know enough math to show it is wrong (so I will shut up now)". Hopefully, they will then go and learn the math. At which point they would have to concede that it works as described.
Or in this case: I don't know anything about how these models work but I am going to assume all sorts of things that would make them unreliable.
I hope what you're saying here is that a computer model to be hard climate science must not only generate results which match past real world data but must accurately describe future events for several decades. I think we reached the point where I have all I need to satisfy myself that Climate Science is mostly correct about manmade global warming. But I'll say it again. Any scientist that cites only a majority of climate models as proving Climate Change Global Warming is currently being ManMade is not using the greatest strength of the theory which is the historical data multiple lines of evidence. Those that say models are good enough with giving more weight to historical data are wrong and doing the science a disservice and giving ammunition to opponents of the theory.True. But it's as close as you ever get with natural science which can only match and be consistent with observations since we can't run live real world experiments.
Not sure what your are saying. Observation, the intricacies of climate theory, it's connection to dozens of other disciplines, as express through simulation, and the consistency between the two are one and the same and inseparable from each other.Those that say models are good enough with giving more weight to historical data are wrong and doing the science a disservice and giving ammunition to opponents of the theory.
Simulation alone means nothing if the mathematical foundation of the model is not based in real world data such as the historical data. A model based on equations alone without reference to historical data is worthless. Many theories have been proven wrong in history by the real world evidence. It's the historical data that makes the case for Climate Science - not simulations.
The majority of the equations in the models are based on well established physical laws from over a century ago. Very little in them that isn't based in observation--the singular exception being things which are required to minimize and dampen artificial features common to all numerical simulations such as reflections off numerical boundaries.
1) Models in general, the applications of theory which recognize and organize patterns in the evidence, provide the meaning for us - the heaps of evidence would not be "lines" without them.
"Climate Change Global Warming" is not a theory in the scientific sense - it's not one of the theories used to build models, and not one of the models built. It's a description of a category of physical possibilities - increasingly, likelihoods.
2) No scientist is citing "only a majority of climate change models" as "proof" of anything - your original source was not a scientist or critic of science, but an item of calculated disinformation from the intellectual operations of a US political faction;
and recognizable as such immediately in the assumptions necessary to give it credence, and the consequences of giving it credence.
If you are criticizing the persuasion tactics of the political factions currently identified with recognition of CO2 accumulation as a hazard and its effects as "inconvenient truth", note that they are not in control of the presentation or framing of these issues. They can't prevent you and thousands like you from giving credence to such questions as the OP, for example.
It is your responsibility to know what you are reading when you read slashdot, and make the necessary allowances.
Last edited by iceaura; February 13th, 2012 at 10:29 AM.
I think you may be being misled by the varieties of the word 'model'. Climate models are not like statistical models that might be used in economics. They're much more like architects' or engineers' models.A model based on equations alone without reference to historical data is worthless.
Just as you can't build a full-scale skyscraper or bridge to test its physical characteristics under stress from storms or earthquakes, you can't 'build' a full-scale earth to test its climate under different influences. So you simulate it on a computer, a very big, very powerful computer.
As for historical 'data'. With a model like this you can do things that can't happen physically, like shifting all the continents back to their Pangaea positions and running it to see whether the climate outcomes are consistent with the paleo record. And they are. For things that can happen physically, like major volcanic eruptions, you can set the frequency of such events according to the data of the last few centuries and see if you get the known climate outcomes. And you do.
Unsurprisingly, that's what the climate scientists say. If you want evidence of what happens when you have a lot of volcanic eruptions in a short period or if greenhouse gases are 'suddenly' withdrawn or introduced in the atmosphere, look to the paleo record. And that's the cause for concern.It's the historical data that makes the case for Climate Science - not simulations.
The leading climate scientists regard the paleoclimate record as the real cause for concern. The models just use the physical properties of the planet to show how things work in the current climate configuration.
I've cited this before but it's worth repeating.
I disagree with the last bit. We don't know 'what that's like'.Climate scientists don't often talk about such grim long-term forecasts, Huber says, in part because skeptics, exaggerating scientific uncertainties, are always accusing them of alarmism. "We've basically been trying to edit ourselves," Huber says. "Whenever we see something really bad, we tend to hold off. The middle ground is actually much worse than people think.
"If we continue down this road, there really is no uncertainty. We're headed for the Eocene. And we know what that's like."
The full article is here. And it is worth reading. http://ngm.nationalgeographic.com/20.../kunzig-text/2
Last edited by adelady; February 13th, 2012 at 03:07 PM.
Speaking of historical data. Pollen data. The paper itself is behind the usual paywall, so the overview is here 2000 Years of Climate Reconstructed from Pollen
Yet another set of evidence for historical comparisons. This time over a couple of millennia and on one particular continent.
Has anyone heard about the recent data recovered from the 1800's suggesting the oceans have been warming now for 135 years or more? This should certainly cause some models to become more accurate I would think?
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