Wikipedia:Reference desk/Archives/Science/2014 November 25

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November 25

Odd hummingbird aggression

Recently I saw an Allen's Hummingbird in my backyard, chasing a Lesser Goldfinch. It was clearly deliberate, since the finch would flutter from tree to tree, and the hummingbird would follow it and hover around until it left, several times until they both left the yard. The hummingbird in question is an adult male and appears to have declared my yard his territory (there's also a female of the same species in the front yard). I have never seen a hummingbird attack a goldfinch; in my experience they mostly show aggression toward other hummies, and occasionally squirrels. What could account for this unusual aggressive behavior? 75.4.21.125 (talk) 01:06, 25 November 2014 (UTC)

I'm not a hummingbird expert, but I was once a member of a bird forum where hummingbirds were a common topic of discussion. I seem to recall people saying that hummers could be quite scrappy little things, when the urge arose - even though they don't look like much. --Kurt Shaped Box (talk) 01:31, 25 November 2014 (UTC)

They sure are fierce! What seemed odd to me is that this one was attacking a creature that was neither a competitor (goldfinches, as far as I know, don't drink nectar or eat insects) nor a potential threat. And it only went after one goldfinch, ignoring all the others and the house finches, doves, jays, etc that were around75.4.21.125 (talk) 03:56, 25 November 2014 (UTC)

Birds as a clade are just territorial creatures in general and there are all manner of complex relationships between species that can lead to behaviours that at first seem counter-intuitive (and in some cases in fact are). But if you're capable of differentiating and sexing these species, you probably already know that. In this case, it's worth noting that when smaller birds, hummingbirds included, harass larger birds it often has more to do with protecting a nest or territory associated with a potential mate than general aggression prompted over feeding territory and other resources, and that seems to fit the bill (hah!) with the situation you describe, except this isn't really the season where aggression associated with mating is strongest, unless you are in a particularly warm latitude. Hummingbirds are also intensely curious creatures and have been known to follow other birds, creatures and objects around for a time, especially if they exhibit strong colors. Was the hummingbird making a racket or taking dives at the finch? Both are common when they are significantly agitated. Snow talk 05:04, 25 November 2014 (UTC)

I'm in Southern California and apparently some hummingbirds build nests in winter (I saw an Anna's Hummingbird doing so last January). And the hummingbird didn't dive (as Allen's often do when aggressive), but it did hover near the finch and seemed to have its feathers fluffed. 75.4.21.125 (talk) 14:40, 25 November 2014 (UTC)

Yes, hummingbirds whose territories extend into the tropics or otherwise warm habitats are known to mate year round, but even tropical and subtropical climates, October and November are the least likely months for nesting. On the whole, I'm inclined to assume this was just a mild territorial tiff on the part of the hummingbird. Though as to whether it has anything to do with the neighboring female, I wouldn't venture to guess in this case. My previous caveat that aggression towards larger species usually has something to do with nesting or mating not withstanding, hummingbirds are known to sometimes zealously guard a feeder, sometimes wasting a hours or even days chasing away all comers that it can get away with harassing even if it only has need to feed a handful of times itself. Conventional wisdom has it that they do with when preparing for migration, and though at first I assumed your little scraper wouldn't have much need to move much farther south (and would already be down there if he did), our article on the species says that it winters on the central coast of Mexico, so it's quite possible he's stockpiling nutrients from some source in your yard and was not going to risk any of it going to no damn finch, not when everyone knows those guys are yellow-bellied. Bwahaha! Snow talk 03:25, 26 November 2014 (UTC)

I'd agree with general territorial defensive behavior. A few other things: goldfinches don't sip much nectar but they will eat buds. So technically there could be some competition in the sense that a bud eaten by a finch will not be able to later produce nectar for the hummingbird. I'm not familiar with Allen's but the common ruby-throated is very curious, and will check out many brightly colored things. So it may have just been interested and not really attacking/defending. SemanticMantis (talk) 15:40, 25 November 2014 (UTC)

• As I have long warned, if hummingbirds had mouths like great whites', rather than beaks designed for stabbing they'd rule the world. μηδείς (talk) 17:41, 25 November 2014 (UTC)

Tip-of-the-pen phenomenon?

I know that there is this phenomenon called tip-of-the-pen, which is very similar to tip-of-the-tongue, but it occurs in cultures where the writing is not phonetic and more logogrammatic. A person knows the word and can say it, but just forgets how many brushstrokes there are in the single logogram/character and how to put it together meaningfully. I think "tip of the pen" is the official name for it, because I do remember a brief mention about it in a textbook. The brief mention was that the relatively new phenomenon is not well studied, but that may mean there are some insights into it, right? How many studies have been done on tip-of-the-pen up to this date, and are there any in English? 71.79.234.132 (talk) 02:14, 25 November 2014 (UTC)

It's unlikely to be a phenomenon in English because you can always rite yor wurds fonetikly. People make spelling mistakes in the process - I find that I sometimes get stuck on the correct spelling of a word - but never that same complete inability to write the word at all.

Another interesting (and perhaps related) phenomenon in English is almost the opposite. My wife will ask me to spell a word that she doesn't know - and the only way I can spell it for her is to first write it down and then read back what I wrote.

SteveBaker (talk) 03:12, 25 November 2014 (UTC)

Ack, I meant RESEARCH PAPERS in English. 71.79.234.132 (talk) 05:13, 25 November 2014 (UTC)

As Steve notes, it is highly unlikely for the phenomena to manifest in English as produced by a developmentally mature and fully literate person, owing to the fact that the entire writing system is comprised of a 26-character alphabet and couple dozen forms of punctuation. The tip-of-the-tongue phenomena is in large part owed to the vast (and increasingly large with each successive modern generation) stock of words a person learns over the course of their life, many of which may not be used regularly, leading to that typically rare, but vexing phenomena where you've half formed the linguistic representation of a concept and know basically the meaning of the word you are trying to conjure (note that we all almost always respond to this frustrating event with vague invocations of the definition: "It's almost synonymous with term X, but you only use it context Y and it's less absolute-sounding than word Z!") but are stuck as the language centers of your brain try to apply fuzzy logic to all the various phonetic, syntactic and semantic associations that might lead you to the proper form. The small sample of letters are used routinely and besides which are largely processed by different regions of the language centers of your brain. Tip-of-the-pen is similar in that there are large number of similar phenomena (logograms or pictograms) which may need to be recalled, though they too use still different, if somewhat overlapping, brain regions from those employed with an alphabet or syllabary.

That being said, there are extreme cases where English speakers and other practitioners of written languages that employ phonetic (rather than logographic) characters may have difficulty recalling or producing the appropriate characters, such as with the conditions agraphia, alexia, apraxia, and, depending on your definition, some forms of aphasia. These sometimes debilitating conditions usually occur as the result of stroke, head trauma or other neurological damage and, combined with modern imaging have actually been immensely helpful in helping to chart which parts of the language centers of the brain regulate which parts of language perception, conceptualization, and production, so in that sense there are actually is a significant body of work which treats the phenomena of the inability to produce usually easily recalled and produced characters in English (and a significant number of other languages). If you have access to JSTOR or another major academic database, I recommend plugging the above terms into it. Failing that, Google scholar will probably give you no shortage of hits, some of them open-content. If neither points you towards the information you need, however, or if you are having difficulty parsing what will largely be highly technical linguistic and neurological terminology, post a follow up comment and I'll see if I can't isolate some more germane and readily-accessible works. Snow talk 04:37, 25 November 2014 (UTC)

I think there is a complete misunderstanding of my request. When I said "English", I was referring to research papers written in English about the tip-of-the-pen phenomenon. But now that two people have misunderstood it, I think my original statement was written in a non-intentionally misleading way. 71.79.234.132 (talk) 05:18, 25 November 2014 (UTC)

I also have a neuroscience background (BS) in RL, so I at least have college-level knowledge of terms and anatomy. So, the real barrier is language. I can only read articles in English. 71.79.234.132 (talk) 05:20, 25 November 2014 (UTC)

Ah, ok, I see. Well, unfortunately I have less guidance to give in finding articles about the phenomena in neurologically healthy individuals speaking languages that employ a logographic writing system. :( A Google scholar search turns up these abstracts: 1, 2, 3, none of which I have access to just at the moment, but which all contain reference to "tip-of-the-pen" or "tip-of-the-brush", but which might be using them in a more literal sense than the figurative use you are seeking. In any event they seem more concerned with second-language acquisition than language cognition. This paper does treat the exact phenomena you are looking into, but not in significant detail. Unfortunately, I think you're going to find that this particular subject will not have much treatment in English, as it is a foreign concept to most English speakers. Sorry I couldn't be of more help with regard to the exact concept. If however you are looking at the phenomena under the lens of cognitive-/neuro-science, I still think looking at the above-mentioned conditions will give you a great deal of insight in the way the brain processes symbolism associated with linguistic processes. Best of luck! My formal background is also largely in cognitive science, and my first degree was in linguistics and thus the intersection of the two is always of fascination to me, so if this line of inquiry leads to other questions, don't hesitate to return here or contact me on my talk page. :) Snow talk 06:17, 25 November 2014 (UTC)

FWIW, this was recently (within the last month) discussed at the Language Log blog in the context of Chinese, where it was referred to as "character amnesia". {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 13:49, 25 November 2014 (UTC)

In logographic writing systems, it's completely normal to know exactly how to pronounce a character and what it means, but have no idea how to write it. There's nothing surprising or psychologically interesting about that--if words in English consisted of random letters arranged in a random order, with no relation whatsoever to their pronunciation, you'd often forget how to spell a word. --Bowlhover (talk) 17:02, 25 November 2014 (UTC)

Ehh, no real need to talk down to the OP or dismiss his interest in this subject. Everyone who's participated in this thread thus far seems perfectly aware of the nature of the phenomena and is unsurprised that it occurs. Tip-of-the-tongue is a perfectly familiar and not altogether surprising phenomena as well and yet has been found to be immensely "psychologically interesting" to academics in neuro- and psycholinguistics who feel it provides a lot of insight into how the brain organizes conceptual phenomena, matches them to representative morphemes and handles associations between related semantic and phonemic classes, to just begin to list its implication. Suffice to say, whatever the nature of the interest, the OP is intrigued by this similar phenomenon and is looking for research upon it and our job here is to detail such resources, or at least point him towards them -- not condescendingly tell him what he clearly already knows and imply that there is no intellectual merit to his interest beyond that simple overview. Especially when there is in fact immense merit; there's no surprise as to why children make syntactic and morphological errors when learning language either, but studying the nature of those errors and the particulars of how they occur led to arguably the single greatest development in the history of linguistics with massive implications that reshaped the cognitive sciences and our understanding of how the human mind operates and generates some of the qualities that are most unique to our species. Snow talk 20:57, 25 November 2014 (UTC)

I wasn't trying to be condescending at all. I'm sorry if I appeared that way. I just thought that the OP might not know how normal it is to forget a character in logographic systems. It's more similar to forgetting a phone number than tip-of-the-tongue, because the characters often have no relation to how they're pronounced or what they mean.

Also, I'm a native Chinese speaker, so I have no idea how much a typical English speakers knows about logographic writing systems. I wasn't assuming the OP is stupid, since I don't think everyone should be expected to know about all the different types of languages in the world. --Bowlhover (talk) 21:31, 25 November 2014 (UTC)

Fair enough! It just seemed a little pointy, is all, and suggestive that the inquiry was about a superficial and uninteresting topic. But certainly I take you at your word that it was not nearly your intent; hopefully you'll take me at mine when I say my own response was meant only to defend against a perceived judgement of the value of the topic and the OP's interest and that the kindly tone you used to clarify the matter is well appreciated. :) Snow talk 22:21, 25 November 2014 (UTC)

Some native Chinese speakers grow up in China and are given a formal education in the Chinese language. Some Chinese speakers grow up overseas, usually in places where Mandarin is not the dominant language. The latter may be able to speak Chinese, but may not be able to read/write it unless given a formal education in Chinese writing. I am part of the latter population. I was raised mostly in the United States, and there was one year in my childhood where I got the opportunity to take a Chinese class and a piano class before I moved to a different state where the Chinese population seemed even smaller. Suffice it to say, I usually use Yabla Chinese and my knowledge of pinyin to decode my parents' speech and use of idioms. It's not a perfect method, because my parents speak Mandarin with a regional accent, but my pinyin approximations usually get me the right Chinese word most of the time. I can't speak for the normalcy of not being able to read/write Chinese characters. TBH, my dad uses a program to input pinyin and output the correct character, while my mom does not use pinyin at all. (They never learned pinyin in their childhood.) Luckily for her, there is a search engine that allows her to scribble brushstrokes onto the computer screen and find the right Chinese logogram. The time when they actually ask each other for help on a specific character is extremely rare. 71.79.234.132 (talk) 02:37, 26 November 2014 (UTC)

Interesting - so, is your interest on the phenomena of tip-of-the-pen purely a matter of curiosity about the occurrence itself or are you looking for learning/work around strategies for more practical purposes? Because I actually came across a number of sources on the latter topic when first responding, which I dismissed at the time as not germane to what you were looking for. Snow talk 03:02, 26 November 2014 (UTC)

Out of curiosity about the occurrence. As previously stated, I am just curious, because it's briefly mentioned in a now-sold textbook. The brief mention was really a caption to a picture on the side of the main text, and it basically said that the tip-of-the-pen phenomenon is one that is not well studied. But its nature is very similar to tip-of-the-tongue. So, what are the sources you found? 71.79.234.132 (talk) 05:34, 26 November 2014 (UTC)

Inserts in injection molding process

When Injection molding products made of liquid silicone rubber is it possible to have a set of inserts prepositioned inside the mold so that once silicone is injected they would be secured in it? Its just that I cant see any other way to secure metal parts within silicone body due to the inertness of silicone rubber. If it is possible, is it a common practise for the industrial scale production? Also how would you position such an insert in a way that is entirely covered with rubber from all the sides? Because in this case the insert can not have any connection points with the mould for it's prepositioning.195.94.247.199 (talk) 11:17, 25 November 2014 (UTC)

The easy way to do this is to create the moulding in two halves (or more layers), with the inserts placed at the edge of the first moulding, then sealed by the second moulding. The trick of using fine rigid wires is probably too fiddly for mass-production. Both methods leave a trace. Dbfirs 21:14, 25 November 2014 (UTC)

You can always fabricate difficult products in one step if if you allow a high percentage of waste/failed results but reliable results are usually only achived by splitting up the process into multiple steps. --Kharon (talk) 02:23, 26 November 2014 (UTC)

I suppose the positioning wires could be made out of something that will slowly dissolve, perhaps using a bit of solvent mixed in with the silicone. StuRat (talk) 15:58, 26 November 2014 (UTC)

Dry juice

Is it possible to dry juice or other drink in a powder ??

Why not? Ruslik_Zero

Yes, for various methods please see Drying (food).--Shantavira|^{feed me} 13:05, 25 November 2014 (UTC)

Milk and eggs are available dried. For fruit juice, it is normally concentrated, and then the water is re-added either by the consumer, or the packager. The latter is normally done for juices that are transported large distances by sea. CS Miller (talk) 13:23, 25 November 2014 (UTC)

I dunno, but I suspect that fruit juices contain live plant cells and drying them would kill the calls, at which point rehydration would produce something, but probably not what you would call juice. Which is why juices are typically concentrated, not dried. 50.126.104.156 (talk) 15:41, 25 November 2014 (UTC)

I have seen dried orange and lemon juices before, if that helps. --Kurt Shaped Box (talk) 18:26, 25 November 2014 (UTC)

See Drink mix for our (fairly limited) article on the subject, although I'm not sure something made from powder could be legally described as "juice" (rather than "fruit flavoured juice drink" or similar). Powdered fruit juice is a common component of field rations, and was part of the Apollo astronauts' daily diet. Tevildo (talk) 19:13, 25 November 2014 (UTC)

For example, if you tried to dry grape juice and reconstitute it, I suspect you'd get something raisin juice, instead. StuRat (talk) 16:01, 26 November 2014 (UTC)

Climate Change Explanation

I've been hearing about Climate Change for years, but I've never come across a good, solid explanation of the phenomena. I just saw a story in IEEE Spectrum that "Climate scientists have definitively shown that the buildup of carbon dioxide in the atmosphere poses a looming danger.", but when I follow the link I only find more of the same kind of stuff I have been seeing.

What I would like to see would include, at the minimum,

- an explanation of how much radiation is reflected/absorbed depending on the level of CO2 in the atmosphere,

- a historical record of global temperatures going back 100,000 years along with an estimate of how accurate those temperatures are, and

- a summary of CO2 sources and sinks and their relative size.

Oh, and without all the political claptrap that seems to the largest part of any story about climate change. Is that too much to ask? 50.126.104.156 (talk) 15:37, 25 November 2014 (UTC)

No, it's too little. The politics is crucial, since that determines whether we are going to see major cities worldwide abandoned to flooding in our own lifetimes, and mass migration due to crop failure. AlexTiefling (talk) 17:04, 25 November 2014 (UTC)

One problem is that everything you are asking for involves multiple layers of assumptions, models, indirect measurements, proxies, extrapolation and averaging. Even the historical temperature record is derived from indirect measurements once you go back beyond human record keeping. And, inevitably, the selection of relevant data, analysis methods and models involves a degree of subjectivity. Gandalf61 (talk) 17:32, 25 November 2014 (UTC)

The points above are apt, but to actually provide a good data source -- The place to go is the IPCC - they are an international body of scientists who have been examining the causes and impacts of climate change for quite a while now. Here is their front page [1]. They issue lots of separate reports, on things like impacts on water or forest systems. Here is their synthesis report, which ties together all of the reports made for the 5th assesment report (AR5) [2] It has all kinds of data, including a nice summary graphic on p.37 that goes back to 1850. There are many other IPCC documents that will go into more detail on the reconstructions we have for climate ~10k years ago, and others that will go into sources and sinks. There are still other sections/reports covering models and assumptions, as well as analysis of political actions and mitigation. But I think the synthesis summary is a good place to start for scientific consensus and apolitical reporting.

In my experience, anyone who claims the IPCC is politically biased or unreliable can be safely disregarded as a crackpot. They are the preeminent world body of experts and they will provide you with exactly what you ask for, if you are willing to look around a bit and read long documents. SemanticMantis (talk)

I think it is disingenuous to put forth the IPCC as the metaphorical spokesman for scientific consensus. The IPCC is one organization, and it happens to be a highly politicized organization; and while they do try to provide a survey of the state of knowledge, they are not the official headquarters-division to whom all of climate-scientists report!

I have read several of IPCC's reports in entirety; and I have read several more in brief. I recommend that anybody who wants to inform their opinion also read the IPCC reports. You can find them online at no cost.

You can read about the different types of report produced by the IPCC. I have found the Assessment Reports to be rather unpleasant; they are not laid out as well as a good textbook, but they are not as brief or to the point as a journal publication. When summarized into a sound-bite for the popular press, the important details (like which parts of a report are novel, and which parts are uncertain) are glossed over. However, that's not really so much the fault of the IPCC as it is the fault of an incompetent journalist!

I much prefer to read factual scientific information in peer-reviewed scientific journals. For example: Journal of Geophysical Research and Geophysical Research Letters are two excellent sources of information on geophysics, including planetary-scale climate. For summary reports, Eos is an excellent magazine-format that is very accessible to less-technical readers. You might also enjoy the oft-feisty "AGU Blogosphere" blog.

But, the IPCC is widely-cited, and is, at its core, a literature review of other peer-reviewed research. So, to directly address the original questions: Grab the 2007 IPCC Assessment Report (2007 is the most current complete report, though a new report Climate Change AR5 will be forthcoming in the next few weeks). Among many thousands of pages of background material, it contains, in direct answer to the OP's specific asks:

• "a historical record of global temperatures going back 100,000 years along with an estimate of how accurate those temperatures are":
  • Chapter 05: Information from Paleoclimate Archives
  • Figure 5.3, Orbital parameters and proxy records over the past 800 kyr (including a sea surface temperature model)
• "an explanation of how much radiation is reflected/absorbed depending on the level of CO2 in the atmosphere":
  • Box 1, Figure 5.1, schematic illustration of multiple interactions between ice sheets, solid earth and the climate system which can drive internal variability and affect the coupled ice sheet–climate response to external forcings on time scales of months to millions of years
  • Chapter 07: Clouds and Aerosols.
  • Chapter 08: Anthropogenic and Natural Radiative Forcing.
  • Figure 8.1, Calculation Methodology cartoon; and in fact, this entire chapter.
• "a summary of CO2 sources and sinks and their relative size.":
  • Chapter 8.2.1, "Introduction" to atmospheric chemistry. Anthropogenic and natural inputs are considered.

Do we want to nitpick at any of these findings? Of course. Some of us are formally-trained geophysicists! But before we can nitpick, we have to first educate and inform ourselves.

I am inclined to believe that the role of atmospheric carbon dioxide - specifically, anthropogenic carbon dioxide - is greatly overstated by the popular press. But, that's not really the fault of the IPCC, or any of the other hard-working scientists who are seeking to elevate the discussion about climate-policy using factual evidence. Heck, the IPCC publishes a thousand-page scientific textbook that pretty much explains everything that we know - except that it's written at a level that is accessible only to physicists and chemists and climate scientists! Most people aren't quite autistic enough to spend a few days reading about the real science; for most people, it's much more fun to brand ones-self an "activist" and form an angry protest mob, because physics and chemistry are difficult!

If you're really new to the field of climate and meteorology, and you are looking for a very introductory textbook to meteorology, I can think of no better book than Aviation Weather. This entire textbook is available at no cost online as FAA Advisory Circular 00-6A. It has an excellent introduction to the Earth's atmosphere, its structure, and its dynamic processes, and it's written at the level of a very introductory university course.

Nimur (talk) 19:59, 25 November 2014 (UTC)

You say the IPCC reports are too long and hard for most people to read, but then you say you prefer primary literature? Certainly most non-scientists/can't won't read the primary literature, and I think the executive summaries from the IPCC are fairly accessible to an educated lay person. You can't really have it both ways- primary literature is too technical and popular press is low on content and high on politics. IPCC is certainly closer to the former than the latter, but it depends on the document in question. As for being a metaphorical spokesperson - there really isn't one as you know, but I was absolutely no being disingenuous -- the IPCC's broad conclusions are largely the scientific consensus. Virtually all the top names for each subfield are tapped to review and criticize IPCC reports. Each chapter had dozens of named reviewers, who had hundreds of helpers, and there was also an open comment period. There is no general finding reported by the IPCC that does not report the consensus of most of the top experts in each subfield. Of course experts will debate smaller details (model assumptions, exact year of a bad benchmark being hit, etc.), but IPCC is the closest thing we have to an official consensus on causes and effects of climate change. (Disclosure: I helped review a chapter of AR5). Surely it is better to offer the publications of a consortium of international experts than to tell the average joe to go read the primary literature. SemanticMantis (talk) 20:50, 25 November 2014 (UTC)

1) Carbon dioxide (CO2) enhances the greenhouse effect, causing more radiative energy to be trapped near the surface of the earth. Ultimately, nearly all energy in the atmosphere derives from the sun, and the sun's input isn't changing significantly, but the CO2 holds that energy closer to the surface. The analogy that is often used is something like putting on a winter coat. The coat itself doesn't generate any heat, but it holds in the heat allowing the person inside to stay warmer. For convenience, scientists often use a simplified description of CO2 impacts on radiation, wherein they equate the radiative impact of CO2 changes with an equivalent amount of excess sunlight at the top of the atmosphere. That is to say, if the sun increased by X then that's about the same as CO2 increasing by Y. This is an over simplification for a number of reasons, but it is a convenient framework for thinking about the problem of greenhouse gases, so it is widely used. For CO2, the equivalent top of atmosphere radiative forcing is

$\Delta F\approx 5.35\times \ln {C \over C_{0}}~\mathrm {W} ~\mathrm {m} ^{-2}\,$

where C is the current CO2 concentration and C₀ is the preindustrial concentration (280 ppm). The logarithm comes about because the wings of the CO2 absorption band are approximately exponential. So, to give some concrete numbers. Today's CO2 level is about 400 ppm. So that is roughly the same as $\Delta F\approx 5.35\times \ln {400 \over 280}=1.9~\mathrm {W} ~\mathrm {m} ^{-2}\,$. Averaged over the whole Earth, the sunlight at the top of the atmosphere is about 340 W/m², so the impact of CO2 thus far is equivalent to about a 0.55% increase in sunlight. Now, 0.55% doesn't sound like a lot, but the average temperature of the Earth is presently about 288 Kelvin (15 Celsius / 60 Fahrenheit), and without the sun we'd be near 0 Kelvin (-273 C / -460 F). 0.55% of 288 K is still about 1.5 degrees C (2.7 degrees F) of warming. That's a very oversimplified way of looking at it, but still gets about the right magnitude of effect. A more sophisticated way is to introduce the notion of a climate sensitivity, which is just a fancy way of saying how much will the temperature change for a given amount of radiative forcing. Unfortunately, the climate sensitivity still has large uncertainties, but recent estimates suggest the equilibrium climate sensitivity is roughly 2 to 4.5 degrees C per doubled CO2 (= 0.5 to 1.2 degrees C per W/m² radiative forcing equivalent). Using the present 400 ppm of CO2, that would lead to an estimate of 1.0 to 2.3 degrees C (1.7 to 4.1 degrees F) at equilibrium, i.e. allowing that CO2 levels stayed approximately constant for long enough for the oceans to reach a steady temperature. Observed warming since 1850 is about 1.0 C (1.8 F), at the low end of the predicted range, but the oceans are still absorbing heat and even if CO2 levels stopped increasing we would have a long time to go before temperatures stabilized. Dragons flight (talk) 20:12, 25 November 2014 (UTC)

For clarity: the IPCC uses and endorses the concepts of radiative forcing and climate sensitivity that User:Dragons flight described. These equations are essentially linearized models of perturbations to the thermodynamic balance. If one is so inclined, one can find more complicated models of planetary energy balance; but it's almost tautological that if we use a more complex model, that lends itself to more complex predictions that are subsequently more difficult to validate with observational evidence. After all, the modern theory of complex systems evolved out of a famous scientist's computational climate model! Nimur (talk) 20:25, 25 November 2014 (UTC)

And if you're not willing to read long documents (I'll be honest--I'm not), here are a few links to get the OP started.

Carbon cycle has a good chart showing the major carbon sinks/sources, along with how much they release/absorb per year. It doesn't have percentages, but you can compute them yourself.

Temperature of the Earth, with multiple sources for the past 100,000 years: [3] --Bowlhover (talk) 21:21, 25 November 2014 (UTC)

3) Carbon in the Earth system can roughly be divided into four groups: atmosphere, biosphere on land (including both living and recently deceased plants/animals), oceans, and near-surface geosphere (carbon bound in rocks). Each of these pools include very large quantities of carbon and except for the geosphere fluxes between pools are also large. Environmental carbon is usually expressed as gigatons of carbon (GtC) equal to 10¹² kg of carbon, and only the carbon content is counted regardless of if it is bound to oxygen (as CO2) or some more complex organic form. Using the numbers in carbon cycle, the four pools of carbon contain roughly the following at present: atmosphere 720 GtC, biosphere on land 2,000 GtC, oceans 38,400 GtC, geosphere 75,000,000 GtC. As one can see the atmospheric piece is actually the smallest, while the geosphere pool is huge. A small fraction of the geosphere pool consists of exploitable fossil fuels, about 4000 to 6000 GtC. The fluxes between the pools are also large, except for those involving the geosphere. In addition, most of the exchanges are roughly symmetrical. For example, nearly the same amount of carbon moves from ocean to air as from air to ocean each year, about 90 GtC/yr, with an estimated net flux of only about 2 GtC/yr from atmosphere to ocean. Similarly from atmosphere to biosphere and from biosphere to atmosphere, the flux each way is about 120 GtC/yr, with a net flux towards the biosphere estimated at about 3 GtC/yr. With exchanges this large (e.g. 120 GtC/yr), the atmosphere and biosphere take only about 15 years to equilibrate, so for long-term purposes they can be imagined as a single pool. The ocean carbon pool is much larger, so it can take hundreds of years to equilibrate. The natural flux from the geosphere to the atmosphere and ocean is small, ~0.5 GtC/yr, and mostly due to a combination of weathering of rocks and volcanic activity. The net flux into the geosphere is even smaller at present, ~0.1 GtC/yr. By contrast, the carbon we are adding to the atmosphere by intentionally extracting and burning fossil fuels is about 8 GtC/yr. As we add this carbon to the atmosphere, it shifts into the biosphere and ocean. This redistribution is important to us as it presently offsets about half of what we emit. If we could magically stop burning fossil fuels tomorrow, then the atmospheric levels would decline for a long time as carbon dioxide continued to move out of the atmosphere and into the ocean and land. However, because the flux into the geosphere is so low, it will take many thousands of years, to move carbon out of the land/air/ocean system and return it to the ground.

Related to this, the ability of the ocean to take up carbon is also rather complicated. Though it contains 38,000 GtC, only about 1% of that exists as CO2. Most of the remainder is either bicarbonate (HCO3^-) or carbonate ions (CO4^-2). The balance between the ocean and the atmosphere happens when the partial pressure of dissolved CO2 in the surface water is equal to the partial pressure of CO2 in the overlying air, which sets the boundary condition; however, the transformation from CO2 to carbonate and bicarbonate is also influenced by the pH of the ocean and the abundance of cations (e.g. Ca⁺²). The influences of these factors are expressed through the Revelle factor, which expresses the change in total ocean carbon as a function of changing CO2 levels. In rough terms, a 100% increase in atmospheric CO2 equilibrates with about an 8% increase in ocean total carbon content. The consequence of this is that even though the ocean is a huge carbon pool, it can only capture about 50% of our fossil fuel emissions. The land captures another 35%, leaving ~15% of the emissions to linger in the atmosphere for thousands of years. Dragons flight (talk) 05:37, 27 November 2014 (UTC)

The fundamentals first. The laughable attempts to pass off CO2 sensitivity estimates based on the temperature record since 1850 should be regarded as stabs in the dark, as the error bounds associated with a temeperature reconstruction such as HADCRUT4 are large and ever increasing, once we go back beyond 30 odd years ago. Greglocock (talk) 21:44, 25 November 2014 (UTC)

Svante Arrhenius computed an approximate climate sensitivity from first principles around 1900. Since we are fairly far from climate equilibrium, it's indeed non-trivial to derive climate sensitivity directly from the recent temperature and CO₂ record. But then I don't think that is a major method used. --Stephan Schulz (talk) 16:16, 27 November 2014 (UTC)

it is a difficult subject. In absolute terms the changes are quite small, temperature is relative to absolute zero at -273°C so a change of 2°C is less than a single percent - and yet it means a huge change for us. It is difficult to get within a factor of 2 about the probable change, a lot of work has been done and the estimates and error bounds are the best that can be done at the moment. At the end of the day it comes down to whether you think all those scientists are actually doing their best to come up with a good estimate or whether you think they are practically all deluded or involved in a giant conspiracy. As to acting on what they say the question is rather like going to the doctor and being told you have cancer. Of course a lot of people will just deny anything is wrong with them, and sometimes nothing bad does happen as the outcome isn't definite, but is it a rational way of dealing with bad news? Dmcq (talk) 23:36, 25 November 2014 (UTC)

The effects of global warming on the human world is hard to predict, but the OP is asking for more definite information. The sizes of carbon sources/sinks and how much radiation CO2 absorbs are both measurable, the latter to a very high precision. --Bowlhover (talk) 00:24, 26 November 2014 (UTC)

I was explaining that what they were asking for was too much to ask for which is what they asked. Dmcq (talk) 08:44, 26 November 2014 (UTC)

• Read After the Ice Age by Canadian scientist E. C. Pielou who mentions the fact that the interglacial period we are enjoying (with its temperature maxima long over) has already begun it's next ice age cycle. μηδείς (talk) 03:53, 26 November 2014 (UTC)

• CO2 as a forcing is fairly easy to find in IPCC. I believe the total increase of CO2 from 1750 to present (50% increase) is equivalent to 1.5 W*m² (the total from the sun is on average around 1500 W*m²). Annual, seasonal, and daily fluctuations of CO2 are pretty large. Solar activity variation is on this order of magnitude. The larger concern isn't what's happened so far as it's not particularly significant (or even attributable to CO2), but the lifetime and accumulation of CO2 makes the 50 and 100 year projection significant. Also, it's not clear what happens to other GHG's such as water vapor so while the forcing of CO2 might be known, how it affects other forcings (i.e. how sensitive the climate is to CO2) is still being researched.
• There's nothing that will compare to the recent record. Even since 1850, natural variations have swamped the global warming signature. For example, glaciers that are in retreat since 1850 had periods of growth such as from 1950 to 1970. To see global wrming effects directly requires pulling a very small signal from data that naturally varies. It's also not understood why most of the surface warming is arctic with little tropical warming and antarctic cooling. It was only recently discovered that a lot of measured sea level rise in Greenland and even the landfall of Sandy was due to a teeter-totter effect of melting glaciers (land rises under the glacier, sinks in another place).
• Carbon cycle [4] shows some of the numbers. Human contributions are mostly fossil fuel combustion and cement. It is a relatively small contribution and some of the sinks have actually adapted (i.e. oceans have absorbed about half of all human emissions which changes the pH of the oceans, also a warming ocean will start returning CO to the atmosphere). One of the difficulties in assessing the ultimate effect of global warming is that the contributions year over year are very small. Much smaller than natural variation which is why climate change must be studied over decades. It's also why weather variations cannot be attributed to climate change. --DHeyward (talk) 07:33, 26 November 2014 (UTC)

There is no "good, solid explanation" but we clearly see "good and solid" evidence that something is seriously going wrong(like rapidly melting glaciers). Additionally it is absurdly strange that every producer has to prove his products can cause no harm and that they are foolprove reliable but in the climatechange debate this seems turned around and made near impossible that way that even clear evidence is not enough to prove massive pollution is causing seriouse harm. --Kharon (talk) 16:04, 26 November 2014 (UTC)

Since we are coming out of an Ice Age wouldn't it be a bit odd if the glaciers weren't melting? Greglocock (talk) 19:39, 26 November 2014 (UTC)

The ice age cycle is approximately 100,000 years long. You would indeed not expect any noticeable changes after only 100 years, which is 0.1% of the cycle, but drastic changes have been observed in the past few decades. Look at the data and convince yourself that the ice age temperature changes are orders of magnitude too small to explain the recent warming. Also notice in that graph that we're already near the peak of the cycle, where natural warming rates are expected to slow down or reverse. --Bowlhover (talk) 20:17, 26 November 2014 (UTC)

You are assuming some sort of gradualism argument. Since the climate is chaotic there is no reason to assume that all changes should be slow. Greglocock (talk)

Unsourced Opinion
The following discussion has been closed. Please do not modify it.
(1) The IPCC is a political body, and its article is the most highly policed one at WP, as far as I am aware. Try changing, for instance, the statement that it is scientifically tasked to a bureaucratically tasked entity, and see what happens. (2) We have only been measuring glacier expansion and retreat for the last century or so. Across the globe some are retreating and some are expanding. (3) Natural sources of CO2, such as volcanoes so swamp human emissions as to make the latter negligible in overall effect. (4) It is well known that there have been higher concentrations of CO2 with lower global temperature and (5) that the warm periods of 6,000 BC, the Roman era, and the late Middle ages make our period a cold snap in comparison, and (6) that no panicked advocacy of climate change is made without the implicit political claim that economic expansion (carbon footprint) is evil, and draconian redistributive schemes are called for. (7) The coming ice age of the 70's was of course also taken as proof that economic expansion (reflective smoke) is evil, and draconian redistributive schemes are called for. (8) So, just ignore the facts, since they are claptrap, and accept that economic expansion is evil, and draconian redistributive schemes are called for. μηδείς (talk) 20:39, 26 November 2014 (UTC) Short Brigade Harvester Boris (talk) 23:46, 26 November 2014 (UTC) The real claptrap are your unreferenced and long-debunked statements that have everything to do with politics--even though the OP specifically said "without all the political claptrap"--and nothing to do with reality. In the end, it's the OP's choice whether to trust the scientific consensus given in the references, or a random stranger making unreferenced claims on the Internet. --Bowlhover (talk) 02:01, 27 November 2014 (UTC)

Here is a graph of temperature change over the last 450,000 years [5]. This is part of a series of graphs of global temperature over different time scales. Each page links to the next longer and shorter time scales. The next shorter time scale is 12,000 years, which has estimates by several different methodologies plotted on the same graph, and can give you an idea of the inherent error in the estimations. Given that glaciation cycles last about 100,000 years, I find it useful to look at the 5 million year time frame (the next longer time scale). At some point continental drift comes into play, so time scales longer than a few million years are probably not useful in separating the anthropogenic component from the natural short-term baseline. It is still instructive to look at the 65 million year plot to see how much cooler it's gotten since the dinosaurs went extinct. Ice age gives a pretty good overview of natural temperature cycles, and includes the 450,000 and 5 million year plots I've mentioned (click on them to see the bigger version). I hope you're still reading in spite of the political diatribes.--Wikimedes (talk) 07:48, 27 November 2014 (UTC)

Image blurring

Is it possible to blur a printed image by layering something on it? Placing a mate film over it will not do as in this case blur effect comes at a price of desaturation? Can some kind of polarised film or flat lens do the trick?176.14.253.145 (talk) 21:03, 25 November 2014 (UTC)

Seeing imagery through slightly wavy but otherwise clear glass seems to do this. Also, seeing imagery through clear water but with a degree of disturbance at its surface seems to do this as well. Bus stop (talk) 01:35, 26 November 2014 (UTC)

They used to smear vaseline on the lenses of camera to make a soft focus effect. Not sure if it will work, but you could put glass over the image and see how it works on the glass. 217.158.236.14 (talk) 11:32, 26 November 2014 (UTC)

There exist soft focus lenses that use spherical aberration to create a soft focus effect. Diffusion filters can also be used for soft focus; thin nylon or silk fabric is sometimes tried, or one could buy a professional filter. Motion blur is a third way to blur an image. --Mark viking (talk) 11:56, 26 November 2014 (UTC)