1. Life strives to survive, grow and procreate. This is self-evident.

2. As a result of (1), life expands to fill the space available. This is demonstrably true throughout the 4.5 billion years of the history of the Earth.

3. Life on Earth is not sustainable; the Sun will expand and fry the Earth in 5-10 billion years time.

Be it accepted that (3) is true and that (1) and (2) are primal life imperatives, The Life Imperatives, then clearly humankind is the only life force able to achieve the continuance of life. Therefore, any cost we impose on “the planet”, or “the universe” is worth it for the further continuance of life.

Or do these people hate life itself??

By whom?

“there is logically a limit to human population based on available land, technology, energy resources, water resources and ecosystem service output”

There is only a ‘limit’ in the sense that, at one instance, you might be able to speculate what the maximum population the other entities are capable of producing/supporting. But as soon as you move forward in time, that relationship will cease to hold. Not least because just as you observed it in the instant, the population will see for themselves as they approach problems and develop accordingly, to increase available water, maybe to expand the productivity of ecosystems, focussing development efforts, to reclaim land, or to build upwards, downwards, or outwards. This limit is therefore neither empirical, nor logical. It doesn’t ‘exist’. It’s not a ‘fact’ waiting to be discovered.

“you can’t escape the fact that the Earth has a finite human population limit.”

You really need to read what we’ve written more closely… We said to SJones, ‘Well, we might need to stop if we were standing shoulder-to-shoulder.’

There may well be a ‘finite’ limit. But speculation as to what that limit is is just that… speculation. You can’t do it empirically. And you can’t find the ‘right’ answer theoretically, nor test it. And as we have shown, the ‘limit’ has changed, and (OPT’s efforts notwithstanding) will change. What remains is a very silly concept that reduces to ‘you can’t have an infinite population on a finite planet”.

However hard we try, we will never have an infinite population.

“Whilst I agree that technology is the key to solving the energy crisis and global warming I don’t think it’s limits are boundless.”

What are the bounds of technology? When will it stop? Are we half way there yet? Or three-quarters?

“The statement is first too broad and too general.”

That is our point about the terms you used to identify ‘health of the biosphere’. But…

” there is already an ample quantity of quality empirical research linking species diversity to ecosystem productivity and in turn ecosystem services”

Even if that were true – and we don’t believe that it is – what may be true of our ability to measure the ‘health’ of an ecosystem, that does not say much about our ability to measure the health of all ecosystems, the biosphere. the world is still substantially larger than what we are capable of measuring.

“we don’t know when these systems will collapse and stop working”

Equally we don’t know if they will collapse and stop working, or whether they will stutter and reorganise themselves. History would suggest the latter. There is a difference between change and destruction, after all. Just ask an ecologist. Conservation is, however, a ‘normative science’, even according to many conservation biologists and ecologists.

But as has already been stated, there is logically a limit to human population based on available land, technology, energy resources, water resources and ecosystem service output. Of course that limit can change and considering and accepting that number’s potential to change lends this area of study objectiveness. Without assuming that one day we will evolve into godlike beings with no need for nourishment you can’t escape the fact that the Earth has a finite human population limit. Therefore, beating up folks for pointing out the obvious is a bit harsh.

“No, we said the opposite. We said “It looks like we’re saying that ‘technology will solve all our problems. But that’s not quite what we’re saying. What drives technological progress is the political process.”

I’m not disagreeing with this. My language later could have been clearer. I included the political will part in the equation to reference your point here. Later when I say that you assume technology trumps all I should have been clearer. Your point is that politics is the road block to proper development and increased population (reduced degradation of the biosphere) and without that technology would greatly assist us to increase population and decrease environmental degradation. Whilst I agree that technology is the key to solving the energy crisis and global warming I don’t think it’s limits are boundless.

“You mention species, biomass and diversity, but the state of knowledge of all of these is highly rudimentary.”

I’m not sure I agree with this. The statement is first too broad and too general. Second, there is already an ample quantity of quality empirical research linking species diversity to ecosystem productivity and in turn ecosystem services (indeed my point). Third, it’s not really a contentious point to state that ecosystems containing diverse ranges of species tend to be healthier (i.e. more robust to external influence) ecosystems. Degraded and simplified food webs equate to more fragile and less productive ecosystems (both in terms of biomass throughput and service output).

“Similarly, the study of ecosystem services (to which you seem to be alluding) is a very new field (and a highly politically charged one). No doubt our understanding of such processes will increase.”

Our understanding will increase, but it’s not true to state that it’s a new field. The idea of ecosystem services has been with us for 150 years or so. Also, what doesn’t need any more research to prove is that human civilisation is built on and is entirely reliant upon the free ecosystem services which nature provides us with. Or, that through our current actions we have been degrading these systems. Indeed, we don’t know when these systems will collapse and stop working, but pointing out the uncertainty in the likelihood of a future event doesn’t mean we shouldn’t consider how to prevent it from happening. Additionally, playing down the likelihood of such events and exaggerating the uncertainties with vague statements (i.e. “if at all”) does not change the fact that we know systems can collapse, they collapse when we simplify them and we don’t know how simplified they need to be before they collapse – that’s the only fair assesment of th field at the moment.

The productivity of the processes supporting these services is a limiting factor on the ultimate peak population of the human race. Likewise, our ability to degrade these services, by eroding the species diversity in the systems which support them, decreases the population which can in turn rely upon them. Given that at the moment we do not possess either the technology, the theoretical understanding or the energy resources to replace any of these free services it would be unwise to degrade them hoping that in the future that matters will improve in this regard, they may, but it spells trouble if we don’t find solutions. Let me emphasise we do not yet possess even the theoretical understanding of how we might replace these services. Therefore, given the inescapable fact that we have no way of disconnecting human survival from the well-being of the environment and that currently human population is the bulk predictor of human induced environmental degradation it is wise to at least consider ways in which to lower human population through the current mechanisms that exist for the discussion and implementation of practical ideas i.e. free speech and democracy. It’s fine and good to say we should maintain hope for future technology to find solutions to these problems, but at the moment we don’t even have the understanding of how we could go about replicating ecosystem services.

It is a comforting fact then, that water covers 70% of Earth’s surface.

“people fleeing the grinding poverty of subsistence farming in the countryside simply exchange this kind poverty for another”

Even if they are moving from rural Berkshire to London, to give up work as a farmer to be a website designer? (Actually, it’s quite likely a website designer might make the move to rural Berkshire, to ‘telecommute’, demonstrating the changing character of rural life thanks to industrialisation).

‘If … the earth´s capacity is principally defined by our intellectual capacity, how do we ensure adequate food production for a population that lives mainly in cities?’

Back of the envelope calculations again… Figures are from ONS & DEFRA. Mechanisation of agriculture allows one man to do the job of many subsistence farmers. The UK is 60% self-sufficient in food terms, and has 250,000 agricultural workers. That’s roughly one agricultural worker for every 150 people. 40 million agricultural workers could feed the world on that basis. That’s 5 and a bit times the population of London, feeding the entire world.

If we were to assume (modestly, we believe) that by 2100 agricultural, bio-tech and resource management technologies have developed to make it possible to see a four-fold increase of agricultural production, with the same physical footprint, and energy and labour input… That would mean just 10 million people could feed the world’s 6 billion. There is no reason to believe that any natural limits present a challenge to anybody’s ‘quality of life’ in the future.

We might also notice that the West’s agricultural productivity has been a problem for development in the South. It cannot compete on price or quality. Many developing countries import food from the West.

The problem is not lack of space. The problem is not lack of resources. The problem for the world is lack of development. That is a question of politics. Development is off the agenda, thanks to the influence of environmentalists, and neo-Malthusians such as the OPT. The only consequence this can have is to reduce people’s quality of life, and likely the length of their life. People like the OPT want to stop the process of making the world as productive as the UK.

“Planet of Slums by Mike Davies.”

You’re kidding, right? We haven’t read it. It looks terrible.

Slums are uglier than pictures of rural subsistence. But it’s not necessarily the case that they are the worst places to live. People move there, after all. And development always has had an ugly side, which is much easier to depict than rural poverty. Both are injustice. But largely, cities create opportunities. The aim ought to be a way of making more of them, for more people.

“we must address the question of how to maintain a burgeoning population in a manner that allows humanity to live free from poverty.”

How about we start by making development the aim of politics, here in the UK, and internationally?

“Given that we cannot do this with six billion of us…”

Who says we can’t? Malthus?

“is built on series of simplifying assumptions that may not be totally robust. ”

That is why we introduced it with the caveat ‘hastily constructed’. It was intended to be illustrative.

If you look at the discussion in context, you will see that we were questioning the necessity of the claim that ‘more people = greater footprint’, not making a claim for the necessity that more people = less footprint. In fact, we were making the point that the Neo-malthusian claim ‘is built on series of simplifying assumptions that may not be totally robust’, and that a lot of the speculation that exists about ‘limits’ is highly irrational.

“The central assumption of the first equation you posited assumes that technology can beat all.”

No, we said the opposite. We said “It looks like we’re saying that ‘technology will solve all our problems. But that’s not quite what we’re saying. What drives technological progress is the political process.

The point is not to make a mathematical identity out of our relationship with nature. The point is to show that prematurely doing so necessarily carries the consequence of limiting what self-evidently expands the ‘capacity’ of the world, making malthusianism self-fulfilling. Setting limits necessarily precludes the possibility of overcoming them. That is to say that we want to demonstrate the prior-ness of politics in the Malthusian calculus, which pretends to be objective. It isn’t. It is loaded with prejudice.

“So, do you think there are any other limiting factors to be included?”

Not sure about limiting factors, but yes, lots of factors – many of them biological and ecological. In fact, we think we’ve got that covered – under ‘tech’. You mention species, biomass and diversity, but the state of knowledge of all of these is highly rudimentary. There exists no agreement on how many species exist in total (sensible estimates range from about 6-100 million), or even what constitutes a species. Similarly, the study of ecosystem services (to which you seem to be alluding) is a very new field (and a highly politically charged one). No doubt our understanding of such processes will increase. But it’s a leap of faith to assume that they impose limiting factors on human population in any practical sense – although we think we could probably agree that having no species anywhere would make things tricky. And that very understanding of ecosystem services will enable us to use them too to our advantage to allow us to support a larger population more comfortably.

Throughout history and pre-history, human activities have already changed the biosphere drastically – we’ve deforested vast swathes, developed others for agriculture, removed entire guilds of large mammals from entire continents etc – and yet the human population has continued to grow, to a large extent, no doubt, because we have changed the biosphere drastically. And yet, it’s funny to think that had prehistoric man had a little knowledge of ecological systems and an overriding culture of doom, the few of us that survived today (assuming we had survived at all) would still be eating berries for breakfast, dinner and tea, and dying of malaria and tooth decay.

So until we have some sort of understanding of how the biosphere exerts limiting factors, and when they might kick in, if at all, we suggest it’s a tad early to be limiting population size to ’save’ the environment.

What we do know for sure is that as things stand now, the limiting factors of human development and progress are social and political. The influence of neo-malthusianism is likely to have a more devastating consequence for both people and environment than any technological development.

“should we consider the productivity of agricultural regions due to the effects of climate”

When we said “It is possible … independence from natural processes …would lower humanity’s physical (and environmental) ‘footprint’”, we were discussing the possibility of isolating agricultural production from natural processes. So no, the point of isolating production from natural processes would be to exclude the possibility of sensitivity to climate effects. Currently, of course, it would be a bit silly to grow stuff indoors. The sun and the weather mostly provide better and cheaper conditions for agricultural production. But it does not require a huge leap to imagine that this may not be the best possible way of providing food. It might be more productive and ultimately cheaper to grow things inside, vertically, and optimally, rather than depending on (and ‘disturbing’) natural processes. Such a system would necessarily be predicated on many new forms of technology. Not least, energy.

So we might want to include energy in your new formula, along the lines ‘x (energy tech x energy resources)’. Do what you like with it. Our point was that ‘energy resources’ varies as ‘energy tech’. The more tech we have, necessarily the more resources we have.

The mathematical identity you construct

Capacity = (Tech x Political Will) x Land

is built on series of simplifying assumptions that may not be totally robust. Where in this case political will is a factor ranging between 0 and 1 (1= perfect political will and policy implementation). SJones and Ben D. have already eluded to the supply of fresh water and water for irrigation as being important. I guess you could argue irrigation would fit under Tech though. That still leaves out the supply of fresh water to the capacity population. So, maybe it would need modifying to this:

Capacity = ((Tech x Political Will) x Land) x ((water tech x water resources)/water resoures)

I guess this leads me to my questions. The central assumption of the first equation you posited assumes that technology can beat all. Even in my updated equation technology plays a key role. So, do you think there are any other limiting factors to be included? For instance, should there be something included to consider the health of the biosphere, or are we independent of that? Can technology yield independence from the health of the biosphere? By health of the biosphere I mean ecosystem productivity i.e. the production and diversity of biomass across many species.

Also, should we consider the productivity of agricultural regions due to the effects of climate (i.e. precipitation, soil moisture, days of sunlight and temperature), or can technology yield independence from these external influences also?

It’s my belief that these factors should be considered. I know it’s getting off topic and your reply could be long, but if you disagree could explain why and provide some support for your beliefs?

The problem that bothers me isn´t a growing population per se ( I am bothered by the nightmare scenario of state population control such as you mentioned) but rather the quality of life that a huge population would imply. I have just finished reading Planet of Slums by Mike Davies. The book descibes how people fleeing the grinding poverty of subsistence farming in the countryside simply exchange this kind poverty for another in the cities. If, as the editors have pointed out, the earth´s capacity is principally defined by our intellectual capacity, how do we ensure adequate food production for a population that lives mainly in cities?

This may seem to be straying from the initial point, but if we reject state control of population, which I most vehemently do, and if we reject even the idea of voluntary control of our population, as proposed by the OPT, then we must address the question of how to maintain a burgeoning population in a manner that allows humanity to live free from poverty.
Given that we cannot do this with six billion of us, it will stretch our intellectual capacity to the utmost to ensure quality of life for an increased population.

More food = higher maximum population on a smaller environmental footprint.

The reason why the poor have more children is so that the children can help. A sustainance farmer with three sons and an ox prospers because there is enough help to go around, but a farmer with only an ox will barely be able to scratch a living. Read your history people!I find it amusing that the green’s attempts to reduce everyone to substistence farmers is the best way to ensure a huge population boom.

Very interesting indeed. Had never thought that way. But I think that these backwardists have always existed. In my own country we have a codeword for those people (velho do restelo, the old man from restelo) that constantly tells us we are doomed to failure in our dreams, that we cannot possibly manage to get things through, etc. This persona was invented in the 15th century in theatre.

So I’d say, yes, punch them in the nose and cry out to people, denounce this idiocy around us, but don’t worry too much. It’s as common and as eternal as corruption.