A growing population is not intolerable per se but because of the increasing impact it must have on the natural environment.
Those famous electoral TV debates are getting closer - and it's intriguing to imagine the dialogue between UKIP leader Nigel Farage and the Green leader Natalie Bennett.
One big area of disagreement is of course immigration, and the Greens' immigration policy is, in their own words "liberal" - which in practice means absolutely no constraint or restriction on who enters the or stays in the UK.
Specifically, the Green Party "will progressively reduce UK immigration controls" and give non-Europeans the same free-movement rights as Europeans. That is, everyone is free to move in.
In my opinion, Bennett will struggle to defend this policy in debate with the populist Mr Farage, given the large scale immigration it would be certain to provoke if implemented any time soon. Even committed Greens will find it unrealistic - except as a very long term aspiration.
More cynically - has the Green Party given any thought to what the electoral consequences will be when their open door policy becomes widely known? As Mr Farage will surely make sure it does?
People look to the Greens for the promise of a long-term sustainable future for their descendants and the UK, as well as the Earth itself. So a policy that appears to actively negate that aspiration - by encouraging overpopulation and cultural instability - must undermine the party's credibility in many voters' eyes.
The population question
As a green (Oxford Ecology Movement) candidate in the 1979 general election I can quote our policy at the time: "The national aim is a replacement birth-rate in the short term, followed by a gradual reduction over the next 1 or 2 centuries to 20-30 million in Britain, achieved through education and popular consent."
The Green population policy today is less specific, worthy but lacking in substance - focussed more on global than UK issues, which enables the more political and controversial issue of the UK population (and the link to immigration) to be fudged.
The main thrust appears to be that we'll need to look at population at some undefined future date (PP101, 103), but in the meantime we can have as many children as we like (PP106) and let everyone in who wants to come (PP111), provided we keep half an eye on "economic and environmental pressures".
It is all very vague and woolly, and while it implies the need for an eventual limit, there is no thinking about what a sustainable population for the UK might be, thus also no means to achieve it, even if lip-service is paid to population being a proper subject of public debate (PP107).
There is a medium-term aim (PP120) "to promote debate on sustainable population levels for the UK ... to increase awareness of the issues not to set specific population targets." But to discuss a sustainable population for the UK without having any idea of what you are aiming at seems, for a Green policy, worse than pointless.
Surely the essence of the green approach to life and humanity is long-term sustainability? So difficult issues like actual numbers and how to achieve them need to be openly and clearly discussed.
The emphasis is however on world population limits. Indeed some local Greens have suggested to me that as long as the total world population is stabilised, it doesn't matter how people are distributed. So it's OK for lots of people to flood into nice rich UK as this will result in fewer poor people somewhere else.
So apparently we should ignore our own interests in order to altruistically solve those of others currently less fortunate. It's a noble wish, but surely each country needs to have policies that at least safeguard their own viability?
The debate must be allowed to take place
Fortunately the Green population debate is far from over. In recent posts on The Ecologist, Biff Vernon has argued for a population policy by stealth focussed on women's status and health in poor countries, while Simon Ross from Population Matters argued that evading the core issue is dishonest and that in any case we have issues here in the UK.
Rupert Read, the Green prosective candidate for Cambridge, has also thrown his hat in the ring, in an Ecologist article that outright opposes mass immigration: "We Greens need to be absolutely and resolutely pro-immigrant - while turning against large-scale immigration."
The Ecologist's founding editor Edward Goldsmith would probably have sided with Read and Ross. As he wrote in 1989 in 'The population explosion', "A growing population is not intolerable per se but because of the increasing impact it must have on the natural environment. This impact is greatly magnified by the increase in material consumption made possible by economic development."
But not only does the Green Party today have no coherent population policy, there is a campaign within the party to denigrate and censor the one UK organisation that does, Population Matters.
Already banned from advertising in Green World, the activist promoting this exclusion, Adam Ramsay, has also recently persuaded my local party in Oxfordshire to prevent Population Matters from having a stall at our annual Green Fair, a popular fund-raising event held in December, with stalls from all manner of ethical-ish small traders, wildlife/animal welfare groups, and various right-on campaigning groups.
Ramsay's views are online on two blogposts on Green European Journal and Bright Green Scotland with vigorous counter-argument and comments under each, taken up also by Derek Wall on Another Green World.
Ramsay's arguments at the Oxford meeting were emotive - he invoked supposed population bogeyman Thomas Malthus (see Wikipedia for a balanced view), the 19th century Irish potato famine, a Swiss population group using the term 'lebensraum' ('living space, biosphere', but used by Nazis and therefore bad).
And all that before he finally got round to two of Population Matters' policies that are said to clash with what is acceptable to the Green Party: means-tested benefit on 3+ children and "no net immigration".
Natural partners, not enemies
Apart from the two policies just mentioned, Population Matters' aims closely match those of the Green Party - resources, pollution, energy usage etc - so why not try to work together?
In their 2015 manifesto Population Matters specifically state that they don't want to increase poverty, hence their 3-child policy is flexible, and "no net immigration" isn't a ban on immigrants as opponents like to make out, but an attempt to limit immigration to the numbers leaving, currently over 300,000 annually!
Thus there is plenty of room to 'agree to differ' on these themes, and in any case, as already discussed, I would suggest the Green Party needs to take a long hard look at their own shortcomings in this area. Most particularly there is no defensible case for the censorship and bans that these campaigners are so keen to enforce.
The Oxfordshire party has 700 members, but the decision was taken at a business meeting attended by about 25 people, with 12 voting for the ban, 5 against and several abstentions. Should important decisions affecting potential allies be taken so cavalierly ?
Both immigration and population are widely misunderstood. Immigration, or rather calls for it to be curtailed, is all too often seen in a racial or racist context. Clearly that motivates some, but we should not all be tarred with that brush - from a sustainability perspective, it makes no difference whatever what colour, race or religion extra people are.
They are, simply, people - and with our 413 people per square kilometre, England has recently overtaken The Netherlands as the most densely populated country in Europe - excluding city states. Wales, Northern Ireland and especially Scotland are less heavily settled.
For a long-term future any country needs to be fundamentally self-sufficient in food - we shouldn't have to rely on imports, as in the long run there may not be surpluses available to buy - though exchanges are of course acceptable. Oats for bananas, anyone?
At present UK population levels this would only be possible if a lot more grain went into people's mouths rather than meat animals, or a lot more land was (re)converted to high-intensity arable, itself unsustainable long-term. Also we have a responsibility to the planet's other life, so we need wild space for both that life and for our own wellbeing.
Hence ever-increasing overcrowding is not desirable. I have heard local Greens pointing out that as there are some places more densely settled than England, then we can take more people. But that begs the question - why should we? do we want to? what good will it do us?
We can't just wait for the global 'demographic transition'
I'm not for a moment suggesting that population should elbow out the other major issues facing us all - ecosystem destruction, per capita consumption and related CO2 emissions and other pollution being obviously among the most serious, with their additive impacts on global warming and climate change.
However tackling the consumption / pollution aspects without including the population factor smacks of wilful blindness to the facts. The 'demographic transition', whereby increasing affluence reduces birth rates, has no doubt delayed the crunch point, but more importantly has lulled people into a false sense that population will somehow solve itself if we can sort out poverty across the planet.
Goldsmith was in fact trenchant on that point: "To seek to reduce population by systematically encouraging economic development is thus self-defeating since it can only increase natural consumption and thus environmental destructiveness."
And it shouldn't be forgotten that most of the last century's massive world population growth arose from medical advances reducing infant and other death rates, not from increasing birth rates. It therefore makes sense to actively encourage a balancing reduction in birth rate, something that is a cultural block in many places.
Some cultures have responded quite rapidly with a demographic transition, but others, Egypt for example, have failed to do so, producing populations dramatically unbalanced with disproportionate numbers of young people and numerous negative knock-on effects from that including unemployment and wider disaffection.
In some developed countries like Japan and Italy where birth-rates have dropped, there is panic in conventional economics about the opposite problem: a preponderance of the elderly, seen as dependent on the workforce.
Hence there is a tendency to promote pro-natalist policies, or increased immigration, to offset the numbers of pensioners. In practice this is what has been happening in the UK, as millions of immigrants have flowed in over recent decades, many from Asia or Africa bringing in addition a tendency to higher birth-rates.
Having your cake and eating it
The Green Party rightly opposes "economic order that supposes the need for an ever-growing younger population to support the retired" (PP114) yet supports unrestricted immigration and "that the number of children people have should be a matter of free choice" (PP106).
But this is having your cake and eating it. There is ample evidence that increasing population exacerbates the already severe human impacts on the environment and the planet's carrying capacity. Indeed as Jonathan Porritt points out,
"we are already using 50% more resources than the Earth can sustainably provide, and unless we change course very fast indeed, even two planet Earths will not be enough to meet our burgeoning economic demands (on a business-as-usual basis) by 2030."
Addressing consumption alone is only taking half-measures, and won't stop the crunch. There are limits to growth, both economically and in population - why are we still ignoring these when the basic issues were thrashed out ad nauseam in the 1970s, not least by Goldsmith.
We don't know exactly where these limits are, and finding out should be a priority, but with 'known unknowns' it is advisable to follow the precautionary principle, particularly when its the one and only home planet that is at issue!
And the Green Party should not be afraid to say so!
Anthony Cheke is a retired sometime professional ecologist and later bookseller. Author of 'Lost Land of the Dodo, an ecological history of Mauritius, Réunion & Rodrigues'. Green parliamentary candidate in the old Oxford constituency as a co-founder in 1979 of the Oxford Ecology Movement, formed to contest that year's general election largely as a consciousness raising exercise (and then deliberately disbanded). We were to the left of the then Ecology Party and developed the 'citizen's income' later adopted by the Green Party, and stressed the importance of reducing inequality - going further than the recent book 'The Spirit Level' by recommending a range of roughly 3:1 for highest to lowest disposable incomes.