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Talk:Carrying capacity

Definition
"The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely". This definition is consistent among dictionaries and it is excellent. It is very useful and we need to comprehend what it actually means. "indefinitely" means "unlimited or unspecified period of time". This means that when the species is consuming resources (that enable more to live at one time) faster than they renew, the species is over the carrying capacity. This is a time independent concept that is dead useful. It tells us about the potential for premature death. It tells us nothing about the premature death that might or might not be happening right now. If we use accounting as an analogy, exceeding the carrying capacity is like having a debt. It does not tell us whether the bills are being paid today. It tells us that a bill is due sometime in the future. Notice what happens when we properly comprehend this. In order to avoid those future premature deaths, we have to ensure that we either 1) discover methods of providing for our numbers without relying on resources that will become scarce, or 2) average less than 2 babies until we no longer require the use of resources faster than they renew. Obviously the first solution is speculative (don't waste time explaining your favorite future technology that will save the world). As others on this talk have pointed out, humans are the only species that can really contemplate executing either of these choices. Other species always suffer the killing back down to the level that the renewable resources can sustain. Also note that this means it is rare that we observe any species above the carrying capacity. This includes humans. The past several hundred years of human existence is that rare situation. We have discovered a stockpile of resources (fossil fuels for example) and how to burn them to increase food production.

The problem with the current article is that it confuses this simple and useful concept described in the previous paragraph with another concept. That other concept is the premature death that is happening today. This would be like an accountant failing to differentiate between the profit/loss and the debt. In this case the profit/loss is the ability to keep our numbers alive today. Let me clarify what I mean by premature death. When discussing reproduction in a finite environment, we must recognize that environmental destruction and reduced quality of life are secondary issues. All the other factors, except child mortality, mentioned in the "overpopulation" and "carrying capacity" articles are simply optional. Children must die at the rate of (x-2)/x where x is how many babies the adults average. If we average 3 babies, then 1/3rd of the children must die. Notice that we don't mention this brutally simple and obvious math formula. Population scientists always discuss some arbitrarily short time span where one of the 4 following factors are changing allowing more (or less) children to live during that finite time span. The factors are 1) increasing food supply, 2) increasing age that the babies are created, 3) reducing adult life expectancy, and 4) reducing income differential. Notice that these factors must be changing in order for more (or less) children to survive than the formula dictates and obviously none of these factors can be changing for long. They are all bounded. The bottom line is that the other concept that is being confused into "carry capacity" is the side effects of attempting to avoid the child mortality caused by averaging too many babies. The child mortality happens when the population is at the limit of what can be kept alive right now. If we properly separate these 2 concepts, carrying capacity and the limit, these articles become short and simple and dead useful.

We are at the limit right now and have always been at the limit. Averaging too many babies creates the groups of people that suffer starvation related child mortality. These groups of people have always existed. The fact that the population is increasing just tells us that the limit is increasing and therefore we don't expect to see (x-2)/x deaths right now. Most people will argue that we can easily keep the ones that died alive if we improve sustenance distribution. This logic fails the most basic sniff test. It is saying that we are not at the limit now because we can behave differently in the future. Furthermore that argument is using the existence of other people, which is fundamentally bogus. This can be seen when I rephrase the statement. "we are not at the limit because the other people that had the subsistence could have shared it properly". If those other people did not exist, then what stops the victims from simply picking the food up off the ground? The existence of 7.3b people forces us to have distribution systems. "other people" is exactly what is created when we average too many babies.

Several years ago I changed the "carrying capacity" and/or the "overpopulation" article to state these simple concepts. My changes were immediately removed because I cited no scientific sources. I then reviewed the rules for Wiki and concluded that the removal was correct. The goal of Wikipedia is to state the current conventional wisdom. These 2 articles are properly stating the current conventional wisdom. That wisdom is confused and these articles are confusing. For example: "the use of fossil fuels has been alleged to artificially increase the carrying capacity of the world by the use of stored sunlight". "alleged"? Are we really confused about the fact that fossil fuels enable the production and distribution of more food? "artificially"? What is artificial about that increase? It is very real. What's really going on with this sentence is the confusion of what "carrying capacity" really means. That confusion is very real in the scientific community and this article is properly reflecting that confusion.

How do we convince population scientists to understand these 2 concepts I have stated? How do we clear up this confusion?

@Avram Primack, see above. Yes, carrying capacity is not a constant. We don't need to attempt to discover that number for any particular time period. Knowing that number is not useful. We just need to know whether we are, or are not, consuming resources faster than they renew. That tells us whether we have a premature death debt. Furthermore attempting to put a time frame on carrying capacity is a mistake. It will add confusion and disagreement and solve nothing.

@Esker7, yes, your second definition is essentially what the definition of carrying capacity is already stating.

Johntaves (talk) 18:25, 1 November 2016 (UTC)

 * A couple of points. First, it is usual to post comments at the bottom of the page, or at least in an appropriate context where other readers are likely to notice them. Second, you, like some other people on this talk page, entirely misunderstand what Wikipedia is about. It is not a platform dedicated to "the truth" and your own private original research. It is an encyclopedia which attempts to accurately summarise the state of current thinking as reflected in reliable sources, such as articles in peer reviewed academic publications. For this reason, Wikipedia articles should contain only statements that can be verified by citing reliable sources. If you want to continue making comments for the edification of Wikipedia editors then please first read the relevant guidelines. You will find them by clicking on the links embedded in this reply. If you lack reliable sources for your views, then they have no place on Wikipedia. --Epipelagic (talk) 20:27, 2 November 2016 (UTC)

First, environmental carrying capacity is not a number. It can only be a number in theory, and then only represented by a variable, K. In the real world, carrying capacity is a complex interaction of environmental factors that vary from year to year, so I suppose that we could next discuss the correct and relevant time scale for determining the number. In any case, carrying capacity is not a constant, and varies from time to time and place to place. Second, taking this into account, it is not necessary to have birth or death rates increase or decline in order to reach it. This may happen in extremely controlled experiments such as are reported in introductory ecology text books, but not in real life. Third, any species that has the ability to lower its carrying capacity in nature either has done so to the point where they no longer exist, or only exists by escaping into uncolonized patches of habitat. Certainly humans are not the only species capable of changing their own carrying capacity, either up or down. To assert this is to claim more place for humans than is our due. I could go on... Avram Primack

This page should link to http://en.wikipedia.org/wiki/Sexual_selection, which provides additional information on r-Selection and K-selection. -- Nick Gall (nick.gall@metagroup.com)

"Humans are the only species known to possess the ability to increase their carrying capacity." This isn't really true, as the Gaia Hypothesis states that all life tends to improve the chances for continuation of life (thus increasing carrying capacity... right?) -booyabazooka

 * As I understand it, if carrying capacity is the ability of an evironment to support a population, then humans have demonstrated a unique ability to dramatically increase the carrying capacity of their environment by:

 * a: the development of agriculture
 * b: the domestication of other species and elimination\control of natural predators
 * c: most recently through the massive appliction of so-called 'fossil fuel' energy sources that had been sequestered as hydrocarbon deposits, which would have been otherwise unavailable without the application of human tools.

 * Should this be confused with the Darwinian concept of natural selection where one species gains an advantage over another species in the competition for resources? That's a debate that's probably best left for another page...
 * -jerry mcmanus

 * Humans increase carrying capacity primarily by (1) applying technology to food production (at the simplest level, putting manure in the field to fertilize the crops) so that the productivity of a given piece of land increases and (2) transporting food over distances so that people can live in places where food is not produced or not produced in adequate amounts to support the population living there (e.g., Manhattan). I assume when you refer to fossil fuels you're referring to part (2).

 * I came to this page to say that I'm deleting the comment about white tailed deer and eugenics since it is not NPOV. Perhaps it would be better suited to a page (or a whole other website) about (or for) proponents of eugenics, i.e., Nazis. Vcrs 21:28, 7 August 2006 (UTC)

 * Okay, I've calmed down now and while I did remove the comment, I changed what I had written to make it more NPOV, since admittedly my original formulation was anti-eugenics and therefore not NPOV either. I tried to make it more general and lay out some different reasons (including those I don't agree with) why people might prefer to frame sustainability discussionsin other ways than population.
 * Vcrs 22:25, 7 August 2006 (UTC)
 * Don'ts beavers also increase the carrying capacity? Then there are those ants that raise aphids.  So humans arn't alone in raising carrying capacity.

The first two paragraphs of this article give two distinct definitions of Carrying Capacity, namely:

 * 1. "kohg

and

 * 2. "Thus, the carrying capacity is the number of individuals an environment can support without significant negative impacts to the given organism and its environment."

The first definition allows the population (say of humans) to sink into poverty, a condition that must be considered to have a significant negative impact on the organism! The second definition rules that out. Frankly, I like the second definition better, but it is probably not consistent with the original intent of the person who first applied the term to biological populations, and thus should be removed.Esker7 (talk) 14:37, 2 August 2009 (UTC)

Human Differences
Humans are the only animals that kill their competiors. That takes us outside the realm of natural selection. That begins artifical selection. What is left out of the human ability to increase carrying capacity for our own species, is our near total  lack of concern for the animals whose habitat we destroy.

So it could be argued that we don't increase the actual carrying capacity at all, we just shift it to the crops we enjoy. If the deer that were in the area before the farm came along, happen to like our corn crop, we simply shot them as well. Hence increasing the monoculture, and make it more possible for locust (for example) to alter the carrying capacity to their benefit. Sounds like Human carrying capacity should be added to the article.

Restated from the book Ishmael by Daniel Quinn

--Lee Wells 03:34, 18 June 2006 (UTC)
 * That argues that human population dynamics are best modeled by some set of Lotka-Volterra-like equations. Kim Bruning 09:17, 20 July 2006 (UTC)
 * see also (Lotka-Volterra_equation) for more clarity, before taking things N-dimensional. ;-) Kim Bruning 09:19, 20 July 2006 (UTC)

 * If you already come up with this great book by Daniel Quinn, then at least make it correct! Daniel Quinn doesn't say it's "humans", who "are the only animals that kill their competitors", but it's what he takes into calling the "Takers" (commonly known as "civilized"). For good reason, he singles out those he calls "Leavers" (people living in tribes, so called "primitives"). -- termi 23:10, 28. Dez. 2006 (CEST)

 * Given that this is a myth, does it really matter? Other species are known to attack & kill competition, both internal (same species) and external (other species) competiton.  Given how long ago this was first recognized, if you must have examples...I suggest you google it. 71.76.235.161 01:07, 19 June 2007 (UTC)

 * If you want one, consider elephants. They are known to knock down whole woodlands just to create grasslands, which provide them with more food. There are very few things that are unique to humans. Richard001 01:23, 26 September 2007 (UTC)

Logistic curve
Amazingly, the logistic curve is not mentioned here at all, even though carrying capacity is actually a property of that curve. :-P This is akin to not mentioning the greenhouse effect in an article on global warming, or forgetting to mention that earth is a planet. ;-) Kim Bruning 09:15, 20 July 2006 (UTC) (And lotka-volterra can also have a carrying capacity for each participant, of course, I last did this stuff years ago. ) Kim Bruning 09:27, 20 July 2006 (UTC)

Maybe that's because the current state of Wikipedia contributions is so overburdened with the fear of copyright infringement that everyone is afraid of trying to upload the graph. [I know I am]

I tried to start a Human Carrying Capacity article and managed to upload the wonderful table put up by a university from Joel Cohen's book 'how many people can the earth support' it was 'found' illegal in less than a day. Since I was dumb enough to include the reference of where it came from it was found to be 'copyrighted' and therefore unusable -- even though i gave the copyright reference. yes it is a grave injustice not to include the curve in the article, i even know of a couple of websites that include the article, but why put it in if some yo-yo is going to pull it for fear of 'copyright infringement' then you get accused of trying to 'piss someone off' if you put it back.

welcome to the world of NPOV. Sucks doesn't it? -Lee Wells 13:43, 30 July 2006 (UTC) P.S. you are more than welcome to try and upload the graph if you are succussfully, maybe you can tell me how i can reupload the table I spoke of.

"Amazingly, the logistic curve is not mentioned here at all, even though carrying capacity is actually a property of that curve." -- I don't agree at all. The logistic curve might apply in the situation where the population limit (the max that can be kept alive in the environment) is a fixed number and the species was introduced into that environment such that its numbers are below the limit. In that very rare situation the population might follow a logistic curve. Regarding the human situation, this is useless on both counts. 1) Humans have existed in the environment for plenty of time for our numbers to have hit the limit. Indeed the bulk of human history is characterized by no growth in the population and therefore the population must have been at the limit (unless you are going to invent some magical fertility rate regulator that prevents us from cramming too many humans into the environment and thus causing death). And 2) we obviously have managed to discover plenty of ways of increasing the limit. Farming, and refrigeration are a tiny fraction of the discoveries that have increased the limit. Notice that this is why Joel Cohen failed to fit any simple math curve to human population numbers. He's trying to fit a math curve to resulting population changes from immeasurable technology discoveries. Johntaves (talk) 21:59, 1 November 2016 (UTC)

Major Edit coming up
Critiques of application to humans will be folded into humans for the VERY simple reason that carrying capacity is (as i understand it anyway) a NUMBER -- NOT A POLICY the 'forced sterilization' argument may have usefulness under Population control, (oh wait surprise it's already there!) but in any case references need to be included. This is supposed to be a reference tool, people can't find what they need if it's mislabeled. If anyone has any problems with this please discuss here. [a google search only turned up forced sterilization and carrying capacity in Wikipedia] that should tell you something. Lee Wells 23:40, 24 August 2006 (UTC) Completed. Rereading for about the fouth time it seems a little uneven, but I tried to group statements about the same idea in the same place. Statements that seemed obviously in error I tried to correct (like ecological footprint says nothing about population size), Lee Wells 18:56, 4 September 2006 (UTC)

 * Seems like it's still full of opinions, or even more full of opinions than before. I was trying to incorporate various scholarly points of view; it seems like it's back to having just one point of view. This isn't appropriate for an encyclopedia. Make your own website if you want to just hammer home your point of view.

 * Some examples: "Abandoning the entire concept because... would be like..." is clearly an argument, not a reporting of fact--it belongs on this page, not in the entry. The comments about money certainly do not reflect any kind of scholarly consensus, and again, they are an argument--you even admit that you're over-simplifying. "This is not what carrying capacity is about," is your opinion. "Their inability to see the problem, blinds them to the ability to solve it," is just poetry.

 * In response to your comments above, there's no such thing as an apolitical number. What you count determines what you think is important, and vice versa. If I say I'm going to study poverty, I will get a very different conclusion if I study the number of dollars going into schools in poor neighborhoods, versus if I study the number of teen pregnancies in poor neighborhoods. Those are both "numbers" but they are also implicitly policies. You have to be careful and aware of all the implications of any number you use.

 * And, I didn't say carrying capacity would lead to forced sterilization--I used very careful language there.

 * It also now has grammar problems (sentences started with a lower-case letter, fragments, etc.)

 * I can't work on this right now and it seems like you're really determined to have it your way, so there's no point. Oh well. Have fun.

 * Vcrs 04:22, 5 September 2006 (UTC)

Extraneous sentence
i have moved the following sentence not connected to any thought pattern to this talk page until someone can sort out its role (if any) in the subject article:

"Used in accordance with Fair use . "

Anlace 18:21, 10 September 2006 (UTC)

Article request/guidelines
Hi - I've been resolving a dispute over this article over the past few weeks, and would like to present my recommendations for the article (or at elast those which are relevant) here. Note that they are only suggestions, but I'd hope that in time they'd serve to improve the article as a whole.
 * Source all/as many as possible additions per WP:CITE and WP:V
 * Most importantly, keep a Neutral Point of View
 * Avoid weasel words
 * Discuss major changes on article talk page
 * Break "Critiques of Applications to humans" off into a sub section
 * Clean up article as a whole, removing POV, SPAG errors and weasel words
 * Perhaps add a "response to critiques" section, into which the counter arguements (fully sourced) against the critiques can go
 * Discuss all major cahnges on this, the talk page
 * It may also help to try out major changes in the article sandbox - Carrying capacity/temp

I hope this can help to bring this article forward, and make it a better resource for thouse who look for it. Please direct any repsonses to my comments here (or to my talk page). I will try to help out with these changes when I get time. Thanks M  a  rtinp23  19:45, 17 September 2006 (UTC)

 * This needs a NPOV tag added to it. Will go do that now... 71.76.235.161 01:07, 19 June 2007 (UTC)

Carrying capacity
the graph for carrying capacity can be found nowhere on earth. WHo has taken this jewel from among us??

it was a jew. a black one

 * Here is what Derrick Jensen, a great writer and philosophy says about carrying capacity in his talks: it's the number of a type of population that can be supported on one place. He comes up with all this mostly, because so many people say there are too many people on the planet. It's not only the number of people that's problematic here. As he says: you can have a billion dear on one small island and it won't be any problem as long as they don't eat or shit, but just stand. So the problem with any population is the amount of damage they do to the place they are living (humans, animals, plants and the landbase in general). Maybe, just as a suggestion, we could add this to the main page. I mean, at least Derrick's sort of "definition". I think it's short and makes it all clear in a simple way. As I say: just as a suggestion. -- termi 23:19, 28. Dez. 2006 (CEST)

Perhaps carrying capacity should be broken into GENERAL i.e. bandwith (even telephone wires have a 'carrying capacity') & BIOLOGICAL. Then again both are so similar, the GENERAL term sim & BIOLOGICAL serve to explain each other.

 * oppose the unsigned post above. this article should not be deleted with trivial uses in other applications. if you want to discuss bandwidth, go to that article. Anlace 04:02, 15 January 2007 (UTC)

Problems with Critiques
Unfortunately THE EARTH IS FINITE and the author of this section fails to understand this SIMPLE point. Human migrations aren't possible across national boundaries anymore. Unfortunately the Earth is one large 'bounded space' which includes arable land which by ALL accounts is shrinking. Saying that carrying capacity doesn't apply to humans implys humans aren't animals thus they are immune from the law of evolution, and natural selection. [Thus this article discredits evolution, another term that is having enough problems in American public schools, without this 'Critique']

If Wikipedia editors feel that Critiques should be a seperate section, then I feel a 'response to critiques' is necessary. However I feel this solution would make the article less readable, so I'm asking for other ideas. Lee Wells 21:57, 14 January 2007 (UTC)

 * whoever authored this section has a strong POV that flies in the face of facts. the mis-spellings are also a tip off to the intellectual origin.  the whole section can be deleted until someone comes up with a better section. Anlace 04:06, 15 January 2007 (UTC)

Well I don't know if I fixed it to everyone's satisfaction or not but then again that's why Wikipedia has those [edit] links. Lee Wells 15:46, 28 January 2007 (UTC)

I got rid of the point/counterpoint format, and removed the unsubstantiated claims of the original editor. I also deleted the last several points completely, as they were purely argumentative, and in some cases, even the responses were misguided. (1) It's a misapplication of Occam's razor to say a simplistic argument is superior. (2) It's a gross oversimplification to suggest Rwanda was caused by population pressure. (3)Carrying capacity is not the basis of evolution, but one of many selective pressures. People would be subject to carrying capacity even if they hadn't evolved, as long as they have to compete for finite resources. (After all, Malthus came before Darwin.) At any rate, the points to which these errors responded were purely philosophical and unsubstantiated, so I deleted both point and counterpoint in these instances. JoeFink (talk) 17:20, 30 January 2008 (UTC)

This part of the article is wrong
The article states: "If the average American today owned 40 acres of arable land, there would be about 11.3 million Americans, instead of over 300 million, conversely our living standard would be higher. Most Americans would probably be farmers"

That statement is false for two reasons.

First, farming productivity in the U.S. is high enough today so that only 2% of the population needs to be farmers. This is true, regardless of whether the U.S. has 11 million people, or 300 million people.

Secondly, a long time ago, when almost everyone worked on farms, the standard of living was lower, not higher. If everyone is working on a farm, then there would be no one to build washing machines, refrigerators, telephones, or light bulbs. Without these things, our standard of living would be lower, not higher. Grundle2600 19:15, 14 May 2007 (UTC)

 * I've removed this section; it seems to be off-topic and seems to abuse the numbers it cites in making its dubious claims. -- Beland 00:25, 26 July 2007 (UTC)

No it is not
This part of the article is what makes it correct: One can also argue that if the United States of America have lost World War II if its population been that small compared to the rest of the world, so living sustainably when the rest of the world does not would have its drawbacks.

Notice the word SUSTAINABLY the reason that 2% of the American population is all that it takes to feed the rest of the United States is that it is done UNSUSTAINABLY the entire article is on CARRYING CAPACITY which by definition is what you mean by SUSTAINABILITY.

the only thing that is wrong with the statement is that it only implied sustainability a problem i will fix right now. Lee Wells 02:26, 20 May 2007 (UTC)

All that really is wrong is it uses the term living standard rather than quality of life which would hold true.

Modelling and Ecological Applications of carrying capacity
Does anyone else here think it might be a good idea to inclue a bit of information of the use of carrying capacity in modelling? For one the theory of carrying capacity is applied widely in Applied Ecology and conservation though the use of population viability analysis etc. Surely this article is a little too centered on humans? --Philthemancunian 23:30, 5 October 2007 (UTC)

Under the mathematics/modelling section, a simple program I found to show carrying capacity is the WATOR: Predator-Prey Simulation game. I did not know where to put this information in the article but I believe it to be a worthwhile inclusion.Septagram (talk) 16:33, 9 July 2009 (UTC)

5.3 Humans are exceeding
I don't understand what citations are required in this section. It certainly could be written better, but the point seems so simple that there is nothing to cite. I'll try some other ways of explaining it.

If an organism consumes the resources that it requires to sustain its current population faster than those resources can renew, then its population is by definition above the carrying capacity. I don't see how anyone can disagree with this. I didn't figure out how to state this concept in the definition of carrying capacity. It seems to be a natural conclusion from the definition.

Coal and oil are renewable resources, yet humans are clearly burning them faster than they can renew. Maybe we should cite that coal and oil took hundreds of millions of years to create. Coal and oil are not necessary for human life, but one must agree that humans require those resources to feed the current 6.7 billion population. In other words, coal and oil are necessary to support the population. I don't see a need to cite anything for this observation.

You can make an argument that it is possible to feed 6.7b humans without coal and oil, but that position would certainly be built on a lot of speculation and simulation. That position would need citations. That would be theory - a situation that does not exist, so it can't be used to say humans are not past the carrying capacity. It could be used to say that the carrying capacity will rise to meet and exceed the population, but still we are left with the fact that right now we are above the carrying capacity.

You can argue that oil and coal will last a long time and therefore "temporary" is "a long time", but so what? Carrying capacity is not about "long time" or "short time" it is indefinite. In other words as long as the conditions remain the same, it will go on forever. Clearly coal and oil will not go on forever so unless something else is invented (which could be as complex as a completely solar based energy system serving everyone) to allow us to produce the required food without using resources faster than they renew, the population must shrink.

We are discussing this "carrying capacity" concept to understand the current state and what we must do to deal with the future. If we somehow let ourselves be fooled into thinking that we are not way above the carrying capacity, then we are allowing ourselves to conclude that we don't need to do anything differently. We don't need to invent some new stuff that will give us the energy to feed 6.7b without consuming resources faster than they can renew. Do we need to cite something to comprehend this?

You might point out that the sun will burn out in 5b years, and therefore all species are over populated. This is true, and therefore over the next several tens or hundreds of millions of years we must reduce the human population so that we can live comfortably within the diminishing area that is still hospitable on the planet. Clearly this does not require immediate understanding and action. Oil and coal on the other hand will run out within a time span that is similar to a human life time (I agree that a citation is needed for this sentence, because it is not common knowledge when oil will run out). If nothing is invented or changed to raise the carrying capacity, then the population will drop as oil and coal become scarce. Johntaves (talk) 05:58, 19 September 2009 (UTC)

Clarification needed
"The World3 model of Donella Meadows deals with carrying capacity at its core." What does this statement mean? Can someone put it in clearer language please? SweetNightmares (talk) 01:16, 25 February 2010 (UTC)

 * Done. Mikael Häggström (talk) 10:23, 3 January 2011 (UTC)

"Agricultural capability on Earth expanded in the last quarter of the 20th century. But now there are many projections of a continuation of the decline in world agricultural capability (and hence carrying capacity) which began in the 1990s." What is agricultural capability? Is the term synonymous with agricultural productivity? Is agricultural capability a measure of the biophysical capacity for cultivating crops? Whereas agricultural productivity simply measures the efficiency of crop production without considering the capability of lands to withstand said mode of production? I think a distinction should be made. Also, a citation should be added for the "decline in capability" statistic. --Daliposc (talk) 02:01, 31 January 2017 (UTC)

The last line of Ecological footprint section, "The authors overlook the fact that burning fossil fuels helps to create sustenance that keeps many more people alive than otherwise.", seems more like an opinion then a fact. It would be an interesting section to expand on but currently is completely unsubstantiated. Brennand97 (talk) 21:13, 11 February 2017 (UTC)

Global Footprint Network
The section on ecological footprint was greatly expanded, using material from the Global Footprint Network, (http:///www.footprintnetwork.org) if at all. I don't think that's a reliable source. I haven't checked whether the material really was taken from that web site, as the reference tags are vague as to where on the site they were referring to. — Arthur Rubin (talk) 07:31, 1 March 2010 (UTC)

Merge from Optimum population
I think the scope of Optimum population is too similar to this one to justify separate articles. Optimum population could very well be a separate section within the Humans section in the Carrying capacity article, and any major differences between the two parameters explained there. Mikael Häggström (talk) 10:23, 3 January 2011 (UTC)
 * Oppose – It is true that the current version of the article makes it look like optimum population is just a direct consequence of carrying capacity. However, the concept of optimum population can be far more complex than that, as a casual perusal of Google scholar clarifies. The population needn't be confined to human populations, and what is the optimum population can change as the outcomes that are sought change. What for example, might be meant by optimum populations when you are looking at species interactions? Better than merging would be to expand optimum population as a concept in its own right. --Epipelagic (talk) 19:10, 14 January 2011 (UTC)
 * Very well, it seems optimum is rather distinct. I'll remove the merge-tags. Mikael Häggström (talk) 13:06, 19 February 2011 (UTC)

Still very incomplete and focused on human populations
The first paragraph should define the concept and put it in context. Carrying capacity is a theoretical ecological concept. It involves a one dimensional model that includes no environmental or species factors. It has no operational definition that can be used to evaluate any real world situation.

The first sentence is.... "The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment. " Better as....

Carrying capacity is a theoretical ecological concept that describes how a population responds to limits an otherwise stable environment in which resources and competitors are constant. It is formally defined as the maximal number of a species that can be supported by an environment. Mathematically it is the value of K in the logistic equation which is used to describe population growth in limited environments. In the real world resources and the population of competitors and food items are always changing, so it is difficult identify whether or not any species has reached or exceeded its carrying capacity. Still, the concept is useful in fisheries management in trying to identify maximum yield, and in ....

The next sentence is nonsensical and repetitive....what is the concept of population equilibrium and how is it different? Environmental maximal load is jargon for carrying capacity, and you cant use a word to define itself.

"In population biology, carrying capacity is defined as the environment's maximal load,[1] which is different from the concept of population equilibrium."

The next paragraph immediately jumps to humans without giving any discussion of whether or not there are any animal or plant examples of carrying capacity.

"For the human population, more complex variables such as sanitation and medical care are sometimes considered as part of the necessary establishment. As population density increases, birth rate often decreases and death rate typically increases."

The next paragraph is full of woulds...a signal that means that we are not really sure. To make it definite it should be couched in will... Avram Primack (talk) 19:04, 8 December 2011 (UTC)

 * Rather than struggling to articulate my concerns about this article, I think I'll just say that I am largely in agreement with Avram Primack's remarks. How disheartening to see that the situation hasn't gotten any better in the last 3 years! Sigh... :( Cgingold (talk) 21:08, 2 March 2015 (UTC)

 * Exactly! I came here to learn about ecology and population dynamics, not read some whiny polemic diatribe cited to extremist fringe sources. This article is highly skewed from the conventional concept. I'm going to heavily trim the sections -everything but the intro. Leo Breman (talk) 20:42, 7 May 2020 (UTC)

Human Carrying Capacity of Planet Earth is Complete Garbage
An actual, verifiable scientific attempt at determining human carrying capacity of Earth requires you to set upper limits on innovation (which happens to affect resource discovery & utilization), information storage & sharing, and cooperation. Anyone who makes such claims has historically & inevitably always ended up looking like a fool. -Reticuli 71.72.161.102 (talk) 20:40, 6 August 2016 (UTC)
 * Can you produce arguments? 136.153.22.8 (talk) 03:07, 18 October 2016 (UTC).
 * It's certainly up for debate, see: Malthusian trap --Daliposc (talk) 02:21, 31 January 2017 (UTC)

Article Critique
This article could be expanded to cover more information. I feel as though it has a shallow exploration of carrying capacity and could have more topics covered rather than just the factors that govern carrying capacity and the ecological footprint. Pipertownsend (talk) 06:04, 19 May 2017 (UTC)

Where is the contradiction?
Although you added a cleanup tag to this article, I still don't know which part of the article contradicts the Human overpopulation article. Can you explain the reason for this cleanup tag? Jarble (talk) 20:11, 7 August 2017 (UTC)
 * Human_overpopulation says estimates of carrying capacity range from 0.65 to 98 billion with a best guess of 7.7 billion, but also cites single studies giving 200 billion and "1.5 Earths of biocapacity to meet humanity's current levels of consumption" which implies less than 5 billion. Carrying_capacity gives a range of 4 billion to 16 billion and a best guess of 10 billion but "More recent estimates are much lower".  The parameters and sources are different, but this raises questions.  Is one of these sources more reliable than the other?  If they are both just as reliable, shouldn't they both be presented?  Are these merely two different slices of what is essentially the same data?  Would it be better to plot a graph showing all of the studies included in these meta-studies, maybe color-coded by date?  It seems like we shouldn't necessarily call out single studies given how many different estimates there are. There's also the question - unaddressed by either article - whether estimates lower than the current world population can be correct. -- Beland (talk) 12:44, 8 August 2017 (UTC)
 * Paul and Anne Ehrlich discuss this in several of their peer-reviewed papers and books. For example, from their 2004 book One with Nineveh, pp. 182: "Carrying capacities are difficult to calculate for any organism, but ... it is often quite easy to tell when a carrying capacity has been exceeded - that is, when support of a population is degrading the capacity of the environment to support future generations."
 * And the same source also appears to be saying that estimates lower than the current world population can be correct, e.g. on pp. 182: "There is no question that, for earth as a whole (including those parts of it we call Australia and the United States), human beings are far above carrying capacity today." Ijon Tichy (talk) 12:05, 29 September 2017 (UTC)

RBlew (talk) 16:29, 3 February 2018 (UTC) Carrying Capacity is a multivocalic concept [] – which itself has a carrying capacity of how many different meaning a word can have. Depending on context carrying capacity can be in a closed system where a number can be applied as in engineering with the load bearing capacity of a bridge, the time till structural failure under given conditions, the operating envelope of a device. In some cases a number is applied when in reality this is more a mean of a variance in statistical distribution (z score). A recommended dose of a medicine, or what is a lethal dose of a toxin, depend on the status of the patient at the time. In open systems carrying capacity is subject to a wide range of factors, where a biome can have a higher carrying capacity than living organisms present, and then can be vastly exceeded by a rapid environmental change (hurricane, flood, fire, deforestation, oil spill), where a given population. Human carrying capacity is even more of a moving target and even reverses rules related to growth curves, for example a more affluent county may have a slower birth rate as more children survive to adulthood, and gathering wealth become more important that assure progeny. The human technology and cultural ability to exploit a wide range of environments, find new resources, create more energy, endure in less that optimum conditions, can push carrying capacity beyond apparent limits of finite resources. From looking over the article the current version is accurate and the dispute tag can be removed. Someone may want to the terms has a wide variety of meaning, though the See Also section convey with wide number of ways the term is used, though recommend Malthusianism [] and Malththusian Catastrophe, Criticisms [] be added to the article.

The human overpopulation article's uncited estimate of the maximum possible population that will ever exist on earth at 4 billion is clearly wrong, as evidenced by reality. The UN reference with a summary of estimates averaging at 10 billion used here is good. The editors of that article seem to be confusing terminology and using 'carrying capacity' incorrectly. I think what they mean is the K of a earth in which humans were completely sustainable, something which is not implicitly implied. Leo Breman (talk) 14:32, 8 May 2020 (UTC)

planetary boundaries
this assessment has recently been updated - see katherine richardsons report from last month 123.208.37.87 (talk) 03:41, 16 October 2023 (UTC)

title: Talk:Carrying capacity


text:
Handa Island

Handa Island (Eilean Shannda) or usually Handa, is an island in Eddrachillis Bay off the west coast of Sutherland, Scotland. It is 309 ha and 123 m at its highest point.

The island is of national importance for its birdlife and maritime vegetation, and is a Scottish Wildlife Trust nature reserve, a Site of Special Scientific Interest (SSSI), and a Special Protection Area (SPA). Handa also forms part of the North-West Sutherland national scenic area, one of 40 such areas in Scotland.

A small ferry sails to Handa from Tarbet on the mainland and boat trips operate to it from Fanagmore. The island receives five thousand visitors per annum.

Etymology
The island's name is of mixed Gaelic and Norse origin. The Norse name was Sandey meaning "sand isle" from sandr. It was recorded in Joan Blaeu's 1654 Atlas of Scotland as "Ellan-Handey" with the addition of the Gaelic Eilean (meaing simply "island") and the Norse form having become Handey and ultimately "Handa" due to due to aspiration in Gaelic. MacBain and Haswell-Smith support the derivation of "sand isle", although Mac an Tàilleir translates the modern Gaelic of Eilean Shannda as "island at the sandy river".

Geography and geology
Handa is composed of Torridonian red sandstone and surrounded by cliffs covered with birds. In the north is a hill with two peaks, with the south and east being lower lying. The north and west have 100 m cliffs, and there are beaches in the south and east. The Sound of Handa separates it from the mainland and smaller islands around Handa include Glas-Leac to the south, Eilean an Aigeach to the north east and Stac an t-Sealbhaig to the north.

The Great Stac of Handa was first climbed in 1876 by Donald McDonald, a native of St Kilda, who crosssed the 24m gap between the stack and Handa "swinging hand-over hand from a rope". It was first climbed from the sea in August 1969 by Graeme Hunter, Hamish MacInnes and Douglas Lang. The height of the stack, which is one of the tallest in Scotland, is variously recorded as 72 m, "about 107m" and 115m. The nearby Stacan Geodh Bhrisidh is 40 m high and was also first climbed by that trio in the same year.

Flora and fauna
Handa is noted for its birdlife, which includes puffins, razorbills and guillemots. The SPA designation lists six priority species: fulmar, great skua, guillemot, kittiwake, and razorbill. The breeding colonies of razorbills and guillemots on Handa are the largest in the UK, representing 11% and 9% of the total British population respectively. The arctic skua and kittiwake populations are also of national importance, representing >1% and 2% of the British population respectively. Other birds at Handa include eider ducks and oystercatchers, and seals and otters can often be seen at Boulder Bay on the island's southern coast. Dolphins, basking sharks and several species of whale regularly visit the seas surrounding Handa.

Handa is also of national importance for its maritime vegetation. The exposed cliff tops are home to maritime grassland species that can tolerate salt, such as thrift, sea plantain and Festuca rubra. In less exposed areas can be found herb-rich grasslands which support species such as Yorkshire fog, bluebell and Scots lovage. Heather and crowberry are also widespread across the island.

History
In the past the island was used as a burial place, and there are still the remains of a chapel in the south east, commemorated in the name Tràigh an Teampaill (Beach of the Temple). The use of Handa as burial place is thought to be due to the fact that wolves would dig up graves on the mainland so frequently that the inhabitants of Eddrachillis resorted to burying their dead on the island:

":On Ederachillis’ shore
 * The grey wolf lies in wait,—
 * Woe to the broken door,
 * Woe to the loosened gate,
 * And the groping wretch whom sleety fogs
 * On the trackless moor belate.

 * Thus every grave we dug
 * The hungry wolf uptore,
 * And every morn the sod
 * Was strewn with bones and gore:
 * Our mother-earth had denied us rest
 * On Ederchaillis’ shore"

- The Book of Highland Minstrelsy, 1846

It had a population of 65 in 1841 butfollowing the 1847 Highland Potato Famine the inhabitants emigrated to Nova Scotia. In some ways this is surprising, since it is recorded that the islanders had a fairly varied diet including oats, fish and seabirds, rather than depending heavily on a potato crop. The islanders had a parliament, similar to that of St Kilda, which met daily, and the oldest widow on the island was considered its "Queen".

The island is now part of the Scourie Estate, owned by Dr Jean Balfour (until her 2023 death) and J.C. Balfour. The Balfours leased Handa to the RSPB for 25 years, however this lease was not renewed, because the Balfours wished a Scottish-based body to run the island; as a result the Scottish Wildlife Trust (SWT) took it over. Under the SWT the island is managed by one warden and a handful of volunteers during the summer months.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Handa Island


text:
Bicycle-sharing system

A bicycle-sharing system, bike share program, public bicycle scheme, or public bike share (PBS) scheme, is a shared transport service where bicycles are available for shared use by individuals at low cost.

The programmes themselves include both docking and dockless systems, where docking systems allow users to rent a bike from a dock, i.e., a technology-enabled bicycle rack and return at another node or dock within the system – and dockless systems, which offer a node-free system relying on smart technology. In either format, systems may incorporate smartphone web mapping to locate available bikes and docks. In July 2020, Google Maps began including bike share systems in its route recommendations.

With its antecedents in grassroots mid-1960s efforts; by 2022, approximately 3,000 cities worldwide offer bike-sharing systems, e.g., Dubai, New York, Paris, Mexico City, Montreal  and Barcelona.

History
The first bike sharing projects were initiated by various sources, such as local community organizations, charitable projects intended for the disadvantaged, as way to promote bicycles as a non-polluting form of transportation – and bike-lease businesses.

The earliest well-known community bicycle program was started in the summer of 1965 by Luud Schimmelpennink in association with the group Provo in Amsterdam, the Netherlands. the group Provo painted fifty bicycles white and placed them unlocked in Amsterdam for everyone to use freely. This so-called White Bicycle Plan (Wittefietsenplan) provided free bicycles that were supposed to be used for one trip and then left for someone else. Within a month, most of the bikes had been stolen and the rest were found in nearby canals. The program is still active in some parts of the Netherlands, e.g., at Hoge Veluwe National Park where bikes may be used within the park. It originally existed as one in a series of White Plans proposed in the street magazine produced by the anarchist group PROVO. Years later, Schimmelpennink admitted that "the Sixties experiment never existed in the way people believe" and that "no more than about ten bikes" had been put out on the street "as a suggestion of the bigger idea." As the police had temporarily confiscated all of the White Bicycles within a day of their release to the public, the White Bicycle experiment had actually lasted less than one month.

Ernest Callenbach's novel Ecotopia (1975) illustrated the idea. In the utopian novel of a society that does not use fossil fuels, Callenbach described a bicycle sharing system which is available to inhabitants and is an integrated part of the public transportation system.

To prevent thefts, bike sharing programs gravitated to smart card control systems.' One of the first 'smart bike' programs was the Grippa™ bike storage rack system used in Portsmouth (UK)'s Bikeabout system. The Bikeabout scheme was launched in October 1995 by the University of Portsmouth, UK as part of its Green Transport Plan in an effort to cut car travel by staff and students between campus sites. Funded in part by the EU's ENTRANCE program, the Bikeabout scheme was a "smart card" fully automated system. For a small fee, users were issued magnetic striped 'smart cards' readable at a covered 'bike store' kiosk, unlocking the bike from its storage rack. Station-located CCTV cameras limited vandalism. On arrival at the destination station, the smart card unlocked cycle rack and recorded the bike's return, registering if the bike was returned with damage or if the rental time exceeded a three-hour maximum. Implemented with an original budget of approximately £200,000, the Portsmouth Bikeabout scheme was never very successful in terms of rider usage, in part due to the limited number of bike kiosks and hours of operation. Seasonal weather restrictions and concerns over unjustified charges for bike damage also imposed barriers to usage. The Bikeabout program was discontinued by the university in 1998 in favor of expanded minibus service; the total costs of the Bikeabout program were never disclosed.

One of the first community bicycle projects in the United States was started in Portland, Oregon in 1994 by civic and environmental activists Tom O'Keefe, Joe Keating and Steve Gunther. It took the approach of simply releasing a number of bicycles to the streets for unrestricted use. While Portland's Yellow Bike Project was successful in terms of publicity, it proved unsustainable due to theft and vandalism of the bicycles. The Yellow Bike Project was eventually terminated, and replaced with the Create A Commuter (CAC) program, which provides free secondhand bicycles to certain preselected low-income and disadvantaged people who need a bicycle to get to work or attend job training courses.

In 1995, a system of 300 bicycles using coins to unlock the bicycles in the style of shopping carts was introduced in Copenhagen. It was initiated by Morten Sadolin and Ole Wessung. The idea was developed by both Copenhageners after they were victims of bicycle theft one night in 1989. Copenhagen's ByCylken program was the first large-scale urban bike share program to feature specially designed bikes with parts that could not be used on other bikes. To obtain a bicycle, riders pay a refundable deposit at one of 100 special locking bike stands, and have unlimited use of the bike within a specified 'city bike zone.' The fine for not returning a bicycle or leaving the bike sharing zone exceeds US$150, and is strictly enforced by the Copenhagen police. Originally, the program's founders hoped to completely finance the program by selling advertising space on the bicycles, which was placed on the bike's frame and its solid disc-type wheels. This funding source quickly proved to be insufficient, and the city of Copenhagen took over the administration of the program, funding most of the program costs through appropriations from city revenues along with contributions from corporate donors. Since the City Bikes program is free to the user, there is no return on the capital invested by the municipality, and a considerable amount of public funds must constantly be re-invested to keep the system in service, to enforce regulations, and to replace missing bikes.

The modern wave of electronically locked bikes took off in France. In 1998 the city of Rennes France launched Velo a la cart using a magnetic card to release bicycles, which was operated by Clear Channel. Then the French advertising company, JCDecaux begain launching larger systems in Vienna (2003), Lyon (2005), and Paris (2007), among others. The Paris system captured the attention of the world and catalyzed steep growth in bikesharing systems around Europe, Asia, South America, and North America. In North America, the BIXI project (a portmanteau of the french "bicyclette" and "taxi" or "bycyle taxi") launched by the City of Montreal in 2009. It garnered a sizable ridership and the city created the Public Bike System Company to begin selling the underlying infrastructure to several other cities, including Washington D.C.'s Capital Bikeshare (2010), New York City's Citi Bike (2013), and London's "Boris bikes (2010)". The PBSC was privatised in 2014 and was later acquired by Lyft in 2022. Separately in 2018, Lyft had acquired Motivate, an operator of many BIXI-based systems. Meanwhile, the original BIXI system has been operated directly by the City of Montreal since 2014.

In 2016, the Portland Bureau of Transportation (PBOT) launched Biketown, also known as Biketown PDX, a bicycle-sharing system in Portland, Oregon. It is operated by Motivate, with Nike, Inc. as the title sponsor. At launch, the system had 100 stations and 1,000 bicycles serving the city's central and eastside neighbourhoods, with hopes to expand outward.

Bike share technology has evolved over the course of decades, and development of programs in Asia has grown exponentially. Of the world's 15 biggest public bike share programs, 13 are in China. In 2012, the biggest are in Wuhan and Hangzhou, with around 90,000 and 60,000 bikes respectively.

As of December 2016, roughly 1,000 cities worldwide have a bike-sharing program.

Categorization
Bike-sharing systems have developed and evolved with society changes and technological improvements. The systems can be grouped into five categories or generations. Many bicycle programmes paint their bicycles in a strong solid colour, such as yellow or white. Painting the bicycles helps to advertise the programme, as well as deter theft (a painted-over bicycle frame is normally less desirable to a buyer). However, theft rates in many bike-sharing programmes remain high, as most shared-use bicycles have value only as basic transport, and may be resold to unsuspecting buyers after being cleaned and repainted. In response, some large-scale bike sharing programmes have designed their own bike using specialized frame designs and other parts to prevent disassembly and resale of stolen parts.

Staffed stations

 * Short-term checkout

Also known as bicycle rental, bike hire or zero generation. In this system a bicycle can be rented or borrowed from a location and returned to that location. These bicycle renting systems often cater to day-trippers or tourists. This system is also used by cycling schools for potential cyclists who don't have a bicycle. The locations or stations are not automated but are run by employees or volunteers.

Regional programs have been implemented where numerous renting locations are set up at railway stations and at local businesses (usually restaurants, museums and hotels) creating a network of locations where bicycles can be borrowed from and returned (e.g. ZweiRad FreiRad with at times 50 locations ). In this kind of network for example a railway station master can allocate a bicycle to a user that then returns it at a different location, for example a hotel. Some such systems require paying a fee, and some do not. Usually the user will be registered or a deposit will be left by the renting facility. The EnCicla Bike Share System in Medellín on its inception in 2011 had 6 staffed locations. It later grew to 32 automatic and 19 staffed stations making it a hybrid between a zero generation and third generation system.
 * Long-term checkout
 * Long-term checkout

Sometimes known as bike library systems, these bicycles may be lent free of charge, for a refundable deposit, or for a small fee. A bicycle is checked out to one person who will typically keep it for several months, and is encouraged or obliged to lock it between uses. A disadvantage is a lower usage frequency, around three uses per day on average as compared to 2 to 15 uses per day typically experienced with other bike-sharing schemes. Advantages of long-term use include rider familiarity with the bicycle, and constant, instant readiness.

The bicycle can be checked out like a library book, a liability waiver can be collected at check-out, and the bike can be returned any time. For each trip, a Library Bike user can choose the bike instead of a car, thus lowering car usage. The long-term rental system generally results in fewer repair costs to the scheme administrator, as riders are incentivised to obtain minor maintenance in order to keep the bike in running order during the long rental period. Most of the long-term systems implemented to date are funded solely through charitable donations of second-hand bicycles, using unpaid volunteer labour to maintain and administer the bicycle fleet. While reducing or eliminating the need for public funding, such a scheme imposes an outer limit to program expansion. The Arcata Bike Library, in California, has loaned over 4000 bicycles using this system.

White bikes
Also known as free bikes, unregulated or first generation. In this type of programme the bicycles are simply released into a city or given area for use by anyone. In some cases, such as a university campus, the bicycles are only designated for use within certain boundaries. Users are expected to leave the bike unlocked in a public area once they reach their destination. Depending on the quantity of bicycles in the system availability of such bicycles can suffer because the bikes are not required to be returned to a centralised station. Such a system can also suffer under distribution problems where many bicycles end up in a valley of a city but few are found on the hills of a city. Since parked and unlocked bikes may be taken by another user at any time, the original rider might have to find an alternative transport for the return trip. This system does away with the cost of having a person allocating a vehicle to a user and it is the system with the lowest hemmschwelle or psychological barrier for a potential user. However, bicycle sharing programs without locks, user identification, and security deposits have also historically suffered loss rates from theft and vandalism. Many initiatives have been abandoned after a few years (e.g. Portland's Yellow Bike Project was abandoned after 3 years ), while others have been successful for decades (e.g. Austin's Yellow Bike Project active since 1997 ). Most of these systems are based around volunteer work and are supported by municipalities. Bicycle repair and maintenance are done by a volunteer project or from the municipality contracted operator but also can be, and sometimes is, completed by individual users who find a defect on a free bike.

Coin deposit stations
Also known as Bycykel or as second generation, this system was developed by Morten Sadolin and Ole Wessung of Copenhagen after both were victims of bicycle theft one night in 1989. They envisioned a freely available bicycle sharing system that would encourage spontaneous usage and also reduce bicycle theft. The bicycles, designed for intense utilitarian use with solid rubber tires and wheels with advertising plates, have a slot into which a shopping cart return key can be pushed. A coin (in most versions a 20 DKK or 2 EUR coin) needs to be pushed into the slot to unlock the bike from the station. The bicycle can thus be borrowed free of charge and for an unlimited time and the deposit coin can be retrieved by returning the bicycle to a station again. Since the deposit is a fraction of the bike's cost, and user is not registered this can be vulnerable to theft and vandalism. However, the distinct Bycykel design, well known to the public and to the law authorities does deter misuse to a degree. Implemented systems usually have a zone or area where it is allowed to drive in. The first coin deposit (small) systems were launched in 1991 in Farsø and Grenå, Denmark, and in 1993 in Nakskov, Denmark with 26 bikes and 4 stations. In 1995 the first large-scale 800 bike strong second generation bike-sharing program was launched in Copenhagen as Bycyklen. The system was further introduced in Helsinki (2000-2010) and Vienna in (2002) and in Aarhus 2003.

Automated stations
Also known as docking stations bicycle-sharing, or membership bicycles or third generation consist of bicycles that can be borrowed or rented from an automated station or "docking stations" or "docks" and can be returned at another station belonging to the same system. The docking stations are special bike racks that lock the bike, and only release it by computer control. Individuals registered with the program identify themselves with their membership card (or by a smart card, via cell phone, or other methods) at any of the hubs to check out a bicycle for a short period of time, usually three hours or less. In many schemes the first half-hour is free. In recent years, in an effort to reduce losses from theft and vandalism, many bike-sharing schemes now require a user to provide a monetary deposit or other security, or to become a paid subscriber. The individual is responsible for any damage or loss until the bike is returned to another hub and checked in.

Some cities allow to use the same card as for bus and rail transport to unlocks the bycicles.

This system was developed as Public Velo by Hellmut Slachta and Paul Brandstätter from 1990 to 1992, and first implemented in 1996 by the University of Portsmouth and Portsmouth City Council as Bikeabout with a magnetic card used by the students and on 6 June 1998 in Rennes as LE vélo STAR, a public city network with 200 bikes, 25 stations and electronic identification of the bikes or in Oslo in 2001. The smart card contactless technology was experimented in Vienna (Citybike Wien) and implemented at a large scale in 2005 in Lyon (Vélo'v) and in 2007 in Paris (Vélib'). Since then over 1000 bicycle sharing system of this generation have been launched. The countries with the most dock based systems are Spain (132), Italy (104), and China (79). , public bike share systems were available in 50 countries on five continents, including 712 cities, operating approximately 806,200 bicycles at 37,500 stations. , the Wuhan and Hangzhou Public Bicycle bike-share systems in China were the largest in the world, with around 90,000 and 60,000 bicycles respectively. By 2013, China had a combined fleet of 650,000 public bikes.

This bicycle-sharing system saves the labour costs of staffed stations (zero generation), reduces vandalism and theft compared to first and second generation systems by registering users but requires a higher investment for infrastructure compared to fourth generation dockless bikes. Third generation systems also allow adapting docking stations as recharging stations for E-bike sharing.

Dockless bikes
Also known as Call a Bike, free floating bike or fourth generation, the dockless bike hire systems consist of a bicycle with a lock that is usually integrated onto the frame and does not require a docking station. The earliest versions of this system consisted of for-rent-bicycles that were locked with combination locks and that could be unlocked by a registered user by calling the vendor to receive the combination to unlock the bicycle. The user would then call the vendor a second time to communicate where the bicycle had been parked and locked. This system was further developed by Deutsche Bahn in 1998 to incorporate a digital authentication codes (that changes) to automatically lock and unlock bikes. Deutsche Bahn launched Call a Bike in 2000, enabling users to unlock via SMS or telephone call, and more recently with an app. Recent technological and operational improvements by telephones and GPSs have paved the way for dramatic increase of this type of private app driven "dockless" bicycle-sharing system. In particular in China, Ofo and Mobike have become the world's largest bike share operators with millions of bikes spread over 100 cities. Today dockless bike shares are designed whereby a user need not return the bike to a kiosk or station; rather, the next user can find it by GPS. Over 30 private companies have started operating in China. However, the rapid growth vastly outpaced immediate demand and overwhelmed Chinese cities, where infrastructure and regulations were not prepared to handle a sudden flood of millions of shared bicycles.

Not needing docking stations that may require city planning and building permissions, the system spread rapidly on a global scale,. At times dockless bike-sharing systems have been criticized as rogue systems instituted without respect for local authorities. In many cities entrepreneurial companies have independently introduced this system, despite a lack of adequate parking facilities. City officials lack regulation experience for this mode of transportation and social habits have not developed either. In some jurisdictions, authorities have confiscated "rogue" dockless bicycles that are improperly parked for potentially blocking pedestrian traffic on sidewalks and in other cases new laws have been introduced to regulate the shared bikes.

In some cities Deutsche Bahn's Call a Bike has Call a Bike fix system, which has fixed docking stations versus the flex dockless version, some systems are combined into a hybrid of third and fourth generation systems. Some Nextbike systems are also a 3rd and 4th generation hybrid. With the arrival of dockless bike shares, there were in 2017 over 70 private dockless bikeshares operating a combined fleet of 16 million sharebikes according to estimates of Ministry of Transport of China. Beijing alone has 2.35 million sharebikes from 15 companies.

In the United States, many major metropolitan areas are experimenting with dockless bikeshare systems, which have been popular with commuters but subject to complaints about illegal parking.

Goals
People use bike-share for various reasons. Cost and time are primary motivators for using bike-sharing programs, in particular the perceived cost of travel and time saved traveling. Some who would otherwise use their own bicycle have concerns about theft, vandalism, parking, storage, and maintenance.

Sustainable alternative for short trips
Most large-scale urban bike sharing programmes have numerous bike check-out stations, and operate much like public transit systems, catering to tourists and visitors as well as local residents. Their central concept is to provide free or affordable access to bicycles for short-distance trips in an urban area as an alternative to private vehicles, thereby reducing congestion, noise, and air pollution. According to research in 2016, the bike sharing system in Shanghai saved 8,358 tonnes of petrol and decreased carbon dioxide and NOx emissions by 25,240 and 64 tonnes, respectively. The research also stated that bike sharing system has great potential to reduce energy consumption and emissions based on its rapid development.

Last mile problem
Bicycle-sharing systems have also been cited as a way to solve the "last mile" problem of public transit networks. According to a research conducted on YouBike system in Taipei, on 2014, the bike sharing system in residential area are more popular, and as a first/last mile of transport mode to and from the station to their desired locations. However, dock systems, serving only stations, resemble public transit and have therefore been criticized as less convenient than a privately owned bicycle used door-to-door.

Operation
Bicycle-sharing systems are an economic good, and are generally classified as a private good due to their excludable and rivalrous nature. While some bicycle-sharing systems are free, most require some user fee or subscription, thus excluding the good to paying consumers. Bicycle-sharing systems also provide a discrete and limited number of bikes, whose distribution can vary throughout a city. One person's usage of the good diminishes the ability of others to use the same good. Nonetheless, the hope of many cities is to partner with bike-share companies to provide something close to a public good. Public good status may be achieved if the service is free to consumers and there are a sufficient number of bicycles such that one person's usage does not encroach upon another's use of the good.

Partnership with public transport sector
In a national-level programme that combines a typical rental system with several of the above system types, a passenger railway operator or infrastructure manager partners with a national cycling organisation and others to create a system closely connected with public transport. These programmes usually allow for a longer rental time of up to 24 or 48 hours, as well as tourists and round trips. In some German cities the national rail company offers a bike rental service called Call a Bike.

In Guangzhou, China, the privately operated Guangzhou Bus Rapid Transit system includes cycle lanes, and a public bicycle system.

In some cases, like Santander Cycles in London, the bicycle sharing system is owned by the public transport authority itself.

In other cases, like Youbike in Taipei, Taiwan, the bicycle sharing system is built by a private company partner with the public transport sector through BOT mode. To be more specific in this case, it is offered by the Taipei City Department of Transportation in a BOT collaboration with local manufacturer Giant Bicycles.

Partnership with other modes of public transport
In many cities over the world, bike sharing system is connected to other public transportation. It is usually hoped to complement the shortcomings in the greater public transport system. Sometimes, in order to encourage residents to use public transport system, local government will give discount on transferring between bike sharing system and other public transports.

Medellin
The city of Medellin is home to 3.4 million inhabitants in 173 km2 and has long faced infrastructural mobility challenges. EnCicla is a bike sharing system in the city of Medellin (Colombia, South America). The bike sharing system is connected to other modes of transportation, such as the Metro.

In 2010, three EAFIT students (Lina Marcela López, José Agusto Ocampo, and Felipe Gutiérrez) developed the idea of the EnCicla bike sharing system as part of their final project. The implementation of the system was decided in operation in August 2012, with the subsequent pilot program confirming its prospects for success. EAFIT advocated for the city to lead the system. This was implemented accordingly, resulting in the inclusion of EnCicla in the agenda of the city of Medellin and its incorporation into the transportation network. In this regard, EnCicla consists of a mixture of shared, as well as separated, bike lanes on the roadway. In the first 3 months after the official launch, 15,700 bicycle rentals took place, with usage picking up sharply in subsequent months and years. In Medellin, an attempt was made to solve the demand problem with statistical analysis using historical data. The result of this analysis was the establishment of a heterogeneous bicycle fleet, with a minimum and maximum number for each station.

In total, in Medellin there exist more than 90 stations in 7 zones, with 13 connected to other transport systems. Since inception, more than 13 million bicycles have been rented by the approximately 9,100 active members. In this context, the most frequently used stations are located in the western zone, near universities and colleges. These stations are located near train stations, which means that there is a high volume of people. To use EnCicla, citizens must register on the official website. In general, the system can be used free of charge by anyone 16 years of age or older and is available from 5:30-22:00 during the week and from 6:30- 21:00 on Saturdays. Local residents must register through Encicla's website prior to use, and tourists have the option of renting a bicycle using their passport.

The establishment of EnCicla in recent years has helped relieve the complex transportation system in Medelin. However, the repositioning of bicycles at stations results in increased CO2 emissions, which run counter to the environmental importance of the project. In parallel, various activities have been carried out to promote the establishment of the system. These include a program that gives people over 8 years of age the opportunity to improve their knowledge and skills in cycling.

Taipei Metropolitan Area
YouBike, a bike sharing system in Taipei–Keelung metropolitan area, Taiwan, has automated stations near all Taipei Metro stations. The integration of YouBike stations and Taipei Metro aims at solving the "last mile" problem, thus improving transit accessibility and usability. It is hoped that YouBike could complement the shortcomings in the greater public transport. Commuters can check in or check out YouBikes near the metro stations to catch connections from the station to the destination.

Transfer Discount Offered for Commuters
Starting 30 March 2021, passengers renting a YouBike from any YouBike station in the Taipei–Keelung metropolitan area receive a discount of NT$5 when using their EasyCard to transfer between YouBike and Taipei Metro, local buses (except buses that charge by distance) or Danhai LRT within one hour. Plus, the trip is only eligible for a discount when the transfer is direct. Commuters shall not utilise other means of transportation, such as Taiwan Railways, Maokong Gondola, long-distance buses, Taiwan High Speed Rail, Taoyuan Metro, or taxis.

Transfer Behavior
According to the analysis of YouBike rental and its Taipei MRT (Taipei Rapid Transit System) transfer behavior from the Department of Transportation, New Taipei City Government, YouBike has already become an important feeder mode for metro commuters: up to 55% of the subjects (the commuters who ever utilise YouBike during September, 2015) transfer by YouBike before or after taking the Metro. Adopting the YouBike and MRT transaction data of EasyCard in New Taipei City in November, 2016, almost all popular YouBike stations can be found next to the Taipei metro stations. Furthermore, transfer analysis depending on the YouBike and MRT data indicates that, the transfer ratio of loyal users (who utilise YouBike more than five times per week) is up to 60%.

Seoul Metropolitan Area
Sharing bicycles in South Korea are called 'Ddareungi' in Seoul capital area. Ddareungi is a sharing bicycle operated throughout Seoul. It is an unmanned sharing bicycle rental service that started pilot operation in 2014 and officially operated in October 2015.

The 1-hour pass for Ddareungi is KRW 1000(Approximate 1 USD), and to prevent theft, an additional charge of KRW 1000 per 30 minutes is charged for exceeding the usage time.

Transit Mileage
Transit Mileage is a benefit that can only be received by 365-day commuter pass users. If you use public transportation within 30 minutes of returning the bicycle, the mileage is accumulated. If it is difficult to travel by bus or subway, the section can be replaced with Ddareungi.

Bicycle Driving Ability Certification System Fee Benefits
Bicycle driving ability certification system requires completion of bicycle safety education, if you pass both the written and practical exams, it will receive certification and part of the Ddareungi usage fee can be reduced for two years.

QR Code Lock
From 1 March 2020, QR Code Lock was introduced as a method of renting and returning by recognizing QR codes. It is convenient because it can be rented or returned with a single scan by using a QR code-type locking device. When renting a bicycle, purchase a voucher from the bicycle app and scan the QR code on the bicycle to rent, and the lock is automatically unlocked and can be used immediately. It can return and rent a bicycle anywhere without going to a bicycle rental booth.

Sprout Ddareungyi
Existing sharing bicycles can only be used by those over the age of 15, so Sprout Ddareungyi, which can be rented from the age of 13 and older, has been launched in Seoul. The government released a policy for public bicycles with reduced size and weight compared to the existing Ddareungi bicycles so that even small-sized people, such as teenagers and the elderly, could use them conveniently.

The number of users of Seoul's public bicycle 'Ddareungi' has exceeded 3 million. It is used by about one in three Seoul citizens. General citizens have a high rate of use during commuting hours on weekdays, except on weekends, so after using public transportation such as Seoul Metropolitan Subway as well as Seoul Buses, when it is an ambiguous distance to use public transportation anymore, citizens use public bicycles near subway stations to move the most. In particular, considering that rentals and returns are made at rental stations near subway stations, citizens frequently use Ddareungi that are deployed in subway stations. To analyse, if the number of cases is classified based on the number of Ddareungi rental stations near subway stations in 2021, exit 1 of the Ttukseom Park area of Hangang Park, which is the most used in Seoul, is the first with 602 rentals, After that, Express Bus Terminal Station and Lotte World Tower's Jamsil Station Exit 2 followed. It is analysed that the most frequently used Ttukseom area, exit 1, is usually used by citizens who enjoy leisure at Hangang Park except during rush hour.

Hamburg
The bicycle sharing system "StadtRAD" of Hamburg (Germany) was launched in 2009 and now includes 3,100 bicycles and 20 cargo bikes. The infrastructure includes 250 fixed stations distributed throughout the city. With the help of the app, it is possible to rent up to two bikes. For an annual fee of €5, the first 30 minutes of each rental are free. A total of 500,000 people are registered with the app.

"StadtRAD" is an integral part of the city's mobility transition. The aim here is to reduce motorized private transport by strengthening Public transport, making it easier to switch between different modes of transport and developing the city into a bicycle city. To achieve this, the share of cyclists in total traffic should increase to 25%.

The administrative responsibility for implementing the mobility strategy is assumed by the Alliance for Cycling, which is assigned to the Authority for Transport and Mobility Change. Its task is to make the transport infrastructure bicycle-friendly by promoting the construction of bike and ride facilities, making subway stops barrier-friendly and expanding bicycle routes. In addition, it should be made easier to take bicycles on buses and trains, and traffic safety should be strengthened through traffic education in schools. Another focus is on the interconnection of the different mobility offers through the Switchh app. Citizens can switch between Carsharing, Motorized scooter or offers from the HVV by making reservations or bookings. The integration of "StadtRAD" is planned to take place in 2022.

For the practical implementation of the bicycle sharing system Stadtrad, the city has contracted "Deutsche Bahn Connect". Deutsche Bahn Connect is committed to setting up and operating a public bike sharing system with fixed rental stations within the city boundaries.

In a study conducted by the University of Hamburg, users state that they use the Stadtrad mainly for leisure (55.9%) and regularly spend time in the city center (89.9%). The frequency of use is several times a month (24.9%) and several times a half year (24.9%). In addition, the study shows that the city bike has a positive image among users, they are largely satisfied with the service and recognize environmental and health benefits. Another study by the authors shows that implementing a green public service increases both perceived social and environmental value. Perceived social and environmental values have a positive influence on the user's green attitude and intentions.

At the same time, however, the need for a reporting system for sharing systems is emphasized, which ideally should be standardized and comparable with other regions. Especially for outsourced projects, monitoring and control processes must be implemented to ensure consistent quality. This includes the use of advanced prediction models to balance the load effectively by forecasting bike-sharing activity and addressing underflow and overflow issues dynamically. In addition to the environmental benefits, financial and time constraints must also be considered in large urban planning projects. Hamburg has had increasing spending on bicycle infrastructure since 2011 and spent 15 million euros on it in 2017.

Partnership with car park operators
Some car park operators such as Vinci Park in France lend bikes to their customers who park a car.

Partnership with car-share operations
City CarShare, a San Francisco-based non-profit, received a federal grant in 2012 to integrate electric bicycles within its existing car-sharing fleet. The program is set to launch before the end of 2012 with 45 bikes.

Financing
The financing of bicycle-sharing system have been maintained by a combination of fees, volunteer, charity, advertisements, business interest groups and government subsidies. The international expansion dockless bicycles in mid 2010s has been financed by investment capital.

User fees
User rent fees may range from the equivalent of US$0.50 to 30.00 per day, rent fees for 15- or 20-minute intervals can range from a few cents to 1.00. Many bike-share systems offer subscriptions that make the first 30–45 minutes of use either free or very inexpensive, encouraging use as transportation. This allows each bike to serve several users per day but reduces revenue. Monthly or yearly membership subscriptions and initial registration fees may apply. To reduce losses from theft often users are required to commit to temporary deposit via a credit card or debit card. If the bike is not returned within the subscription period, or returned with significant damage, the bike sharing operator keeps the deposit or withdraws money from the user's credit card account. operated by private companies as is the case in most cities in China.

US

New York rental rates are among the highest in the world, as of the Citi Bike program's launch in July 2012, but this is of course subject to change. The cost of annual membership in the US varies between $100 and about $220.

Europe

Bike riders shared in Europe usually pay between €0.50 to €1 per trip, and an average of €10–12 for a full day cycling.

Volunteer work
Many first and second generation bicycle sharing programs were and are community run organisations as "Community Bike programmes", as done in IIT Bombay. Often maintenance and repair is performed by unpaid volunteers that complete this work in their own free time.

Charity sources
Charity fundraising drives and charitable organisations have and do support bicycle sharing programs, including Rotary Clubs and Lions Clubs.

Advertisement revenue
Second and third generation schemes in the 90s already prominently included advertising opportunities on the individual bikes in form of advertisement areas on the wheels or frame. Other schemes are completely branded according to a sponsor, notable example London's bike share which was originally branded and sponsored by Barclays Bank and subsequently by Santander UK Several European cities, including the French cities of Lyon and Paris as well as London, Barcelona, Stockholm and Oslo, have signed contracts with private advertising agencies (JCDecaux in Brussels, Lyon, Paris, Seville, Dublin and Oslo; Clear Channel in Stockholm, Barcelona, Antwerp, Perpignan and Zaragoza) which supply the city with thousands of bicycles free of charge (or for a minor fee). In return, the agencies are allowed to advertise both on the bikes themselves and in other select locations in the city. typically in the form of advertising on stations or the bicycles themselves.

Government subsidies
Municipalities have operated and do operate bicycle share systems as a public service, paying for the initial investment, maintenance and operations if it is not covered by other revenue sources. Governments can also support bicycle share programs in forms of one time grants (often to buy a set of bicycles), yearly of monthly subsidies, or by paying part of the employee wages (example in repair workshops that employee long-term unemployed persons). Many of the membership-based systems are operated through public-private partnerships. Some schemes may be financed as a part of the public transportation system (for example Smoove). In Melbourne the government subsidises the sale of bicycle helmets to enable spontaneous cyclists comply with the mandatory helmet laws.

Harvesting of user-data
GPS traceable vehicle commute patterns and usage habits present valuable data for government agencies, marketing companies or researchers. Strong commuter patterns can be filtered out and potential transportation services (e.g. commuter bus) can be tailored to existing demand. Potential audiences can be better assessed and understood.

Usage patterns

Most bike-sharing systems allow the bicycles to be returned to any station in the system, which facilitates one-way trips because the users do not need to return the bicycles to the origin. Thus, one bike may take 10–15 rides a day with different users and can be ridden up to 10000 km a year (as in Vélo'v in Lyon, France). Each bike has at least one rides with one unique user per day which indicates that in 2014 there were a minimum of at least 294 million unique bike share cyclists worldwide (806,200 bicycles × 365) although some estimates are much.

It was found—in cities like Paris and Copenhagen—that to have a major impact there had to be a high density of available bikes. Copenhagen has 2500 bikes which cannot be used outside the 9 km2 zone of the city centre (a fine of DKK 1000 applies to any user taking bikes across the canal bridges around the periphery). Since Paris's Vélib' programme operates with an increasing fee past the free first half-hour, users have a strong disincentive to take the bicycles out of the city centre. The distance between stations is only 300 - 400 m in inner city areas. in US, male users of bike sharing made up for more than 80% of total trips made in 2017.

A study published in 2015 in the journal Transportation concludes that bike sharing systems can be grouped into behaviourally similar categories based upon their size. Cluster analysis shows that larger systems have different usage patterns in different stations, whilst in smaller systems the different stations have similar daily utilization patterns.

Economic impact
Bike-share programs generate a number of economic externalities, both positive and negative. The positive externalities include reduction of traffic congestion and pollution, while the negative externalities can include degradation of urban aesthetic environment and reduction of parking. Furthermore, bike-share programs have pecuniary effects. Some of these economic externalities (e.g. reduced congestion) can be systematically evaluated using empirical data, and therefore may be internalized through government subsidy. On the other hand, "nuisance" externalities (e.g. street and sidewalk clutter) are more subjective and harder to quantify, and may not be able to be internalized.

Less traffic congestion
A primary goal of bicycle-sharing systems has been to reduce traffic congestion, particularly in large urban areas. Some empirical evidence indicates that this goal has been achieved to varying degrees in different cities. A 2015 article in Transport Reviews examined bike-share systems in five cities, including Washington, D.C., and Minneapolis. The article found that in D.C., individuals substituted bike-share rides for automobile trips 8 percent of the time, and almost 20 percent of the time in Minneapolis. A separate study on Washington, D.C.'s Capital Bikeshare found that the bike-share program contributed a 2 to 3 percent reduction in traffic congestion within the evaluated neighborhood. 2017 studies in Beijing and Shanghai have linked the massive increase of dockless bike shares to the decrease in the number of private automobile trips that are less than five kilometres. In Guangzhou, the arrival of dockless bike shares had a positive impact in the growth of cycling modeshare.

Less pollution
Not only do bike-share systems intend to reduce traffic congestion, they also aim to reduce air pollution through decreased automobile usage, and indirectly through the reduction of congestion. The study on D.C.'s Capital Bikeshare estimated that the reduction in traffic congestion would be equivalent to roughly $1.28 million in annual benefits, accrued through the reduction in congestion-induced CO2 emissions. A separate study of transportation in Australia estimated that 1.5 kilograms of CO2 equivalent emissions are avoided by an urban resident who travels 5 kilometers by cycling rather than by car during rush hour periods.

Healthy transport

Bicycle-sharing systems have been shown to have a strong net positive health effect. Cycling is a good way for exercise and stress relief. It can increase recreation and improve sociability of a city, which make people live more happy and relaxed. The report from Centers for Disease Control and Prevention (CDC) point out that cycling also help preventing disease like obesity, heart disease (can reduce up to 82%) and diabetes (can reduce up to 58%). Therefore, bicycle-sharing systems has a positive effect on mental and physical health, which attract more people to use. (Demand increase)

Reduced car parking
Bike-share programs, especially the earlier services that required docking areas along urban streets, may encroach upon the space available for on-street car parking and other auto-centric uses. While some argue that this is a negative, it is generally considered a positive side effect, since it helps further the transition away from car-dependency.

Urban clutter
In some cities, the many dockless bike-share bicycles have cluttered streets and sidewalks, degrading the urban aesthetic environment and blocking pedestrian traffic. In particular, cycles on Chinese city streets have created sections of clogged sidewalks no longer walkable, and piles of illegally parked bicycles. Due to the vehicles being left in the public right of way, or abandoned obstructing pedestrians, the dockless vehicles have been called "litter bikes".

Dockless cycles left randomly on public footpaths may impede access for wheelchair users and others who use mobility aids, and may be dangerous to people with visual impairments.

Pecuniary effects
As bicycle-sharing systems continue to grow and provide an affordable alternative for commuters, the relatively low price of these services may induce competitors to offer lower prices. For instance, municipal public transit organizations may lower prices for buses or subways to continue to compete with bike-share systems. Pecuniary effects may even extend to bicycle manufacturers and retailers, where these producers might reduce prices of bicycles and other complementary goods (e.g. helmets, lights). However, empirical research is needed to test these hypotheses.

Public-private partnerships
In public economics, there is a role for government intervention in a market if market failures exist, or in the case of redistribution. As several studies have found, bike-share programs appear to produce net positive externalities in reduced traffic congestion and pollution, for example. The bike-sharing market does not produce at the social optimum, justifying the need for government intervention in the form of a subsidy for the provision of this good in order to internalize the positive externality. Many cities have adopted public-private partnerships to provide bike-shares, such as in Washington, D.C., with Capital Bikeshares. These partially government-funded programs may serve to better provide the good of bike-shares.

Dangers of over-supply
Many bike-share companies and public-private partnerships aim to supply shared bicycles as a public good. In order for bike-shares to be a public good, they must be both non-excludable and non-rival. Numerous bike-share programs already offer their services partly for free or at least at very low prices, therefore nearing the non-excludable requirement. However, in order to achieve the non-rival requirement, shared bicycles must be supplied at a certain density within an urban area. There are numerous challenges with attaining non-rivalry, for instance, redistribution of bicycles from low-demand regions to regions with high-demand. Mobike, a China-based company, has addressed this problem by paying their users to ride their bikes from low-demand areas to high-demand areas. Citi Bike in New York City has a similar "Bike Angel" program to give discounts and prizes to balancers.

Other companies such as oBike have introduced a points system to penalize negative behavior, namely, illegal parking of shared bicycles. Economists speculate that a combination of efficient pricing with well-designed regulatory policies could significantly mitigate problems of over-supply and clutter.

The Chinese bicycle-sharing market demonstrated the danger of oversupply in 2018. Companies took advantage of unclear regulations in the preceding years to introduce millions of shared bikes to the country's cities. Users were not educated in how to use the systems properly and in many cases treated them as disposable, parking them anywhere. City governments were forced to impound the abandoned bikes when they blocked public thoroughfares, and millions of bikes went directly to junkyards after the companies that owned them went bankrupt.

Health impacts
A study published in the American Journal of Public Health reports observing an increase in cycling and health benefits where bicycle sharing systems are run. In the United States, bikesharing programs have proliferated in recent years, but collision and injury rates for bikesharing are lower than previously computed rates for personal bicycling; at least two people have been killed while using a bike share scheme.

There is also considerable evidence that bike-share programs must be adopted in tandem with city infrastructure, namely, the creation of bike lanes. A 2012 study published in the American Journal of Public Health found that Toronto's cyclists were 30–50% more likely to be involved in an accident on major roads without cycle lanes than on those with.

Criticism
Despite their theoretical and observed benefits, bike-share programs have come under attack as their presence has grown throughout the world. Much of this criticism has focused on the use of public funding – concerned critics posit that the use of tax money for bike-share programs should instead be diverted towards other services that more residents use on a daily basis. However, this argument relies on a faulty assumption that taxpayer money is a significant source of bike-share funding. An analysis by People for Bikes, an organization that advocates for new and safe bike infrastructure, found that public investment in Salt Lake City's Greenbike and Denver's B-Cycle programs was significantly less than traditional public transit (e.g. bus or rail) in those same cities, on a per-trip basis. Both Greenbike and B-Cycle's publicly funded subsidies amount to 10 percent or less of the total cost of one trip. In contrast, Salt Lake City's bus and rail system (UTA) relies on 80 percent public funding for a single trip.

Other critics claim that bike-share programs fail to reach more low-income communities. Some efforts have attempted to address this issue, such as New York City's Citi Bike's discounted membership program, which is aimed at increasing ridership among low-income residents. However, around 80 percent of study respondents reported that they had no knowledge of the program's discount.

A further criticism describes increasing discriminatory technical and organizational hurdles. In addition to registration and/or security deposits of addresses, money or bank card data, many systems require smartphones with certain operating systems and user accounts, usually by Apple or Google, or even a permanent or temporary mobile data connection for unlocking and returning the bicycles. Others offer the same functions via SMS, telephone, or a previously purchased chip card.

title: Bicycle-sharing system