The implicit population hypothesis hidden within EU Green party platforms

By Phil Cafaro

In the run up to elections to the European Parliament in May, 2019, the coalition of European Green parties has put forth a statement of principles and political goals: “Priorities for 2019: What European Greens Fight For.” Organized around twelve key goals, all in line with “core Green values that we pursue in the quest for popular democracy,” it articulates a strong and progressive environmental vision. Its environmental goals start with fighting climate change—“the defining challenge of our times”—by phasing out all coal use by 2030, promoting energy efficiency, and moving quickly to 100% renewable energy sources. It continues with commitments to boost trains at the expense of (more polluting) air travel, reducing air and water pollution within the EU, and eliminating non-recyclable plastics. “To preserve our valuable nature,” Greens advocate that nations “expand protected natural areas significantly so that they cover key ecosystems.” They also seek to reorient EU agricultural policy, by “producing good local, GMO and pesticide-free food” and “farming without cruelty to animals.”

Curbing population growth, however, is not one of these key environmental goals, or even a subsidiary one—despite the fact that many EU nations are currently on track for substantial population growth in the coming decades, which could undermine environmental protection efforts. Neither in “Priorities for 2019,” nor in the related “Manifesto 2019: Time to renew the promise of Europe,” nor in a more elaborated list of policy positions on its website, does the EU Green coalition affirm the need to limit, end, or reverse population growth—either as a stand-alone policy goal, or as necessary to any of the environmental goals it does endorse. In discussing the means to decrease carbon emissions, increase protected areas, or achieve any other environmental goals, limiting European numbers is not mentioned.

Immigration policy is discussed in these documents—not for any potential role in impacting future population numbers, but as part of affirming immigrants’ rights and combatting xenophobia and racism. A core Green goal in “Priorities for 2019” is to “defend the right to asylum and establish legal and safe channels for migration,” as a matter of “solidarity” and “humanity,” with the strong implication that attempts to limit immigration manifest a lack of humanity. A related statement on “Human Rights and Migration” advocates “a more ambitious resettlement and relocation scheme,” with the clear goal of increasing immigrant numbers. “We Greens are uncompromising on defending the rights of asylum seekers and migrants,” it states—while remaining silent regarding any rights that EU citizens might have to limit immigration, or set immigration levels for the common good.

Having reviewed recent policy manifestos from several national Green parties, these coalition statements appear to accurately represent the national parties’ own positions on population matters (see for example statements from the UK Green Party on population and migration). Based on these documents, the EU’s Green parties appear to hold the following implicit hypothesis: Population size has no important role to play in the efforts of EU nations or the EU as a whole to meet their environmental challenges and create ecologically sustainable societies.

To be clear, the Green coalition does not affirm such a position explicitly, nor do any of the national Green parties (so far as I know). However, they act as if this hypothesis was true: ignoring current European overpopulation and proposing immigration policies that could greatly increase future EU population sizes, while simultaneously pushing for a number of very ambitious environmental goals. None of these parties have embraced lower fertility or other European demographic trends that could lead to smaller populations, which suggests that they see no environmental value in them. Some, such as Norway’s and Austria’s Green parties, argue for more immigration for conventional economic reasons, which implies that they see little environmental disvalue in higher populations. All this indicates that European Greens believe the implicit hypothesis—which is why it needs to be made explicit and tested against reality.


If immigration into the EU was a minor factor influencing future population numbers, Europeans might set immigration policy without worrying about its environmental impacts. But that is not the case. Consider population projections out to 2100 for Germany, the EU’s most populous country, under five different potential immigration scenarios, from zero net migration through a continuation of recent immigration levels up through 4X the status quo net migration level (all projections below are from Cafaro and Dérer, New Policy Based Population Projections for the European Union with a Consideration of their Environmental Implications): 

Status quo migration is the continuation of the past 20 years average annual net migration level (259,316). Migration scenarios use total fertility rates varying between 1.65 and 1.90, with higher immigration levels projected to drive higher TFRs. Source: Cafaro and Dérer, 2018.

 Annual net migration into Germany has averaged about 260,000 over the past twenty years. Continuing at this level for the rest of the century would lead to a relatively stable German population, according to our calculations, while increasing or decreasing annual immigration levels would lead to populations that were tens of millions higher or lower by 2100, with all that implies environmentally. Setting net migration at 4X this status quo level roughly models sustaining the immigration levels reached during the mass influx of 2015-16. This would lead to a 123% population increase: from 82 million Germans today to 184 million by 2100.

How would more than doubling Germany’s population impact efforts to cut back on the use of coal, while keeping nuclear power plants shuttered? How much would it constrain efforts to provide better living conditions for farm animals, or to leave more land fallow in the Elbe River delta for wildfowl? How many more houses would need to be built and how much more concrete and asphalt would need to be poured to accommodate over 100 million more Germans? No one is asking these questions—certainly not the politicians writing Die Grünen’s political platform. But they should be, because young, rapidly growing populations in Africa and the Middle East mean that many more people may want to reach Europe in coming decades.

Across the EU, changes in immigration policy have the potential to increase or decrease populations substantially. Here are our projections out to 2100 for the United Kingdom, again under five plausible immigration scenarios ranging from zero net migration through a continuation of recent immigration levels (averaging about 230,000 annually) up through 4X the status quo net migration level: 

United Kingdom_migr
Status quo migration is the continuation of the past 20 years average annual net migration level (230,107). Migration scenarios use total fertility rates varying between 1.74 and 1.99, with higher immigration levels projected to drive higher TFRs. Source: Cafaro and Dérer, 2018.

 According to the official migration policy statement of the UK’s Green Party: “richer regions and communities do not have the right to use migration controls to protect their privileges from others.” “Communities and regions should have the right to restrict inward migration,” they continue, but only when “prospective migrants have, on average, equal or greater economic power than the residents of the recipient area”—a caveat that today and for the foreseeable future would commit the UK to an “open borders” immigration policy. If we take the 4X status quo immigration projection as a (very conservative) proxy for open borders, we find that it would lead to a 169% increase in the UK population over the course of this century, from 65 million today to 175 million by 2100. The environmental implications of such an increase are staggering for such a small and already overcrowded island. They are also largely ignored by the UK’s Green Party, with some noble exceptions (see for example good discussions by Jonathon Porritt and Rupert Read).

These projections illustrate a crucial lesson: that relatively small changes in annual immigration levels can lead to enormous differences in future population numbers. Most European Greens seem oblivious to the power of exponential growth. We encourage readers interested in the potential demographic impacts of immigration policy on particular EU countries, or the EU as a whole, to read TOP’s recent working paper from which these projections are taken. There we provide full population projections out to 2100 under a variety of plausible immigration and fertility policy regimes for all the nations of the EU, in appendix I.


Population size has no important role to play in the efforts of EU nations or the EU as a whole to meet their environmental challenges and create ecologically sustainable societies. Stated explicitly, this hypothesis may seem absurd. How could human numbers not make a difference in our environmental impacts, in whether we can find solutions to our environmental problems or create genuinely sustainable societies? Yes, but in recent years, many environmentalists have stopped talking about population matters and now have little sense of just how consequential they are. Another look at those environmental policy goals from the Green Parties coalition may snap us back to reality.

In theory, the EU might phase out fossil fuels and phase in renewable energy sources very quickly. In practice, increased demands will make it harder to take viable and economical energy sources off the table. In theory, we can limit air and water pollution, or plastics use, to almost any degree we choose. But in practice, every person generates some amount of resource use and trash, so declines in per capita pollution may be offset by increases in the number of “capitas.” In theory, we can increase our numbers while also improving our agricultural practices. But in reality, more benign agricultural practices have costs, both in money and in terms of lost productivity, and it is harder to forego higher agricultural productivity when the demand for agricultural products is increasing due to more people.

“To preserve our valuable nature, we want to expand protected areas significantly, ensure they cover key ecosystems, and guarantee that the protection really works,” the Green coalition writes in “Manifesto 2019.” “We want to increase marine protected areas to 20% of our seas.” Sounds great. And in theory, Europeans could both add a lot more people and devote more land and more marine areas to wildlife preservation. But in practice, population growth tends to sacrifice natural lands to human interests, whether for housing, agriculture, energy production, or any of the thousand and one other uses clever people can find to further our own well-being. It is population decrease that opens up more lands for “rewilding,” cuts human pollution, and in many other ways decreases the relentless human pressures that drive biodiversity losses.

Fortunately, according to the most recent UN population projections, Europe is the first continent to have broken the back of the population explosion that has defined humanity’s demographic trajectory over the past two centuries. Much of Europe is very densely populated, but thanks to sustained below-replacement fertility levels for the past two generations, population decline in Europe is now a possibility. If current fertility and migration trends continue, the EU’s population is on track to decrease 10% by 2100: slowly, gradually and manageably. This is a very hopeful development, which European environmentalists should support and build upon. Instead, Europe’s Green parties have been among the continent’s strongest advocates for continued population increase. Perhaps if “the implicit hypothesis” was made explicit—and rejected, as it should be—that might change. At a minimum, debating the implicit hypothesis would help Greens formulate more honest and consistent policies, through a better understanding of the trade-offs that any immigration policy necessarily will involve.

European Union_migr
Status quo migration is the continuation of the past 20 years average annual net migration level (1,188,235). Migration scenarios use total fertility rates varying between 1.65 and 1.90, with higher immigration levels projected to drive higher TFRs. Source: Cafaro and Dérer, 2018


Do you want to learn more about the solutions for overpopulation and actions towards sustainability? What actions we need to take on individual, community, national and global level? Check out the Overpopulation Project’s list of solutions!

Print Friendly, PDF & Email

9 thoughts on “The implicit population hypothesis hidden within EU Green party platforms

  1. Excellent, excellent report. Should receive widest possible distribution. I think Einstein wrote, “In theory, practice and theory are alike. In practice they are not.”

  2. Somewhere along the way the “Greens” went from being interesting and somewhat principled to just plain silly. A sad story….I left them after 20 years as a result of their collective ridiculousness regarding their inability (unwillingness) to see the obvious connection between population and environmental degradation.

  3. I always used to support the Greens, but abandoned them when they replaced a cogent commitment to population reduction with politically correct nostrums and feel good hand waving.
    Some of their more vociferous supporters have even taken to shouting down population campaigners.
    Their obstinate and misguided attempts to square the environmental circle are not being challenged as they should be.
    Recently a well meaning friend, moved to reduce her reliance on plastics having watched a recent Attenborough programme, asked me in all seriousness, why human population growth should have any connection with rapidly declining numbers of wild birds.
    Taboo and short sightedness have resulted in a worrying lack of logical joined up thinking.

  4. Based on data of the Global Footprint Network, a sustainable population of the EU would amount to 244 million inhabitants, that of Germany to 25 million and the UK to 17 million. This would imply that zero net migration is not sufficient to create sustainable societies and that a strong reduction of fertility rates is inevitable. These numbers do not take the outphasing of fossil fuels (for agricultural machinery, fertilizers, transport, processing and distribution) into account; in this case sustainable population numbers will be much lower.
    Three questions: #1: Do you think that information on sustainable population sizes is relevant? #2: Do you believe that Global Footprint Network date are reliable enough? #3: If so, don’t you think that TOP should report data on sustainable population sizes?

    1. Dear Jan,
      The global footprint network and their reports are not focusing at all on sustainable populations. We can calculate the populations when the total footprint equals the biocapacity – it maximizes the population being supported by the land, using up ALL its renewable resources and all its capacity to absorb their waste and pollution. If we calculate this population sizes based on EF’s most recent data (2016), we find Germany should reduce to 27,3 and the UK to 16,4 million people (close to the values you referred to). We can also see that 132 countries need to decrease to meet biocapacity on present per capita footprint, China and India the most. 49 countries’ population is below the “sustainable” (total=181 countries or territories). The countries that are not in overshoot of the biocapacity on their present per capita footprint and populations include Sweden, Norway, Brazil (with the largest biocapacity). I think the relevance of these “sustainable population” numbers are limited, as they assume the total exploitation of biocapacity with today’s technology and efficiency that might also differ under different population sizes. In addition, the whole approach is very anthropocentric, the Global Footprint data on biocapacity and footprint are maybe reliable but they are not really made for calculating sustainable populations. Still, it is certainly an interesting excercise to see the populations meeting biocapacity under today’s per capita footprints to have a sense how much our populations are in overshoot.

      1. Thank you for this reaction, Patrícia, as I presume. It is a simple sum at pre-high school level:

        “According to the 2016 data of the Global Footprint Network, The Netherlands would need 2,96 Earths to accommodate the Dutch, given their present life style. In 2016, the population size of The Netherlands amounted to 17 million people. Question: how many Dutch could one Earth have accommodated that year?”

        The GFN is a scientific institute that measures and reports, not a political organisation telling countries what to do to reduce their footprint, as CEO Laurel Hanscom told me. Nevertheless, they support individuals and communities with their footprint reduction. And they implicitly report on sustainable populations as well, as the sum above learns. This calculation can be repeated for all countries of the world, yielding numbers of inhabitants that permit everybody a fair share of the global natural resources. Of course, a number of countries could raise their biocapacity by appropriate technological measures which would allow for a greater number of inhabitants (as the Dutch did with grazing land: 6 times the yield of a global hectare); however one could ask (1) if such measures (use of fertilizers based on the use of fossil fuels, genetically modified food) are desirable, and (2) if countries are able or willing to do that.
        The GFN dataset provides us with a baseline measurement of sustainable population sizes which can vary depending on (1) a substantial reduction of consumption and pollution, (2) measures leading to a raise of biocapacity, or (3) a decrease of the population size by immigration stop or birth control.
        I understand your question: what about the other-than-humans? My hypothesis is that if we would all return to sustainable population sizes according to the GFN data, then there will be enough habitat for wildlife (no more deforestation, no more overfishing, no more excessive bush meat).

  5. James and Jane,

    We share your frustration! But these Green party immigration and population policies are not set in stone. And every national Green party includes members who agree with you on the need to limit population sizes. So we think there is hope–particularly if we continue to “connect the dots” for our fellow environmentalists, on the connection between population reduction and environmental protection.


    We certainly do think that the question of sustainable population sizes is relevant! See among other work our blog

    We find the work by the Global Footprint Network on sustainable population size valuable, but hardly the last word on the matter. In particular, their approach is fundamentally anthropocentric: focused on the question of how many people can be sustained in perpetuity, given “biocapacity.”

    For people who don’t care about other species and are thus willing to convert as much biocapacity as possible into human flesh and our support systems, GFN’s population estimates may be too low. Technological and managerial “improvements” might allow for somewhat higher populations–although not necessarily as high as we face today.

    On the other hand, those of us who believe that human beings owe it to other species to leave them significant habitat and resources for their own continuance can state unequivocally: human populations need to come down. The status quo is not morally sustainable, even if we could somehow continue to make it work for people. Human beings have no right to hog the planet’s biocapacity.

    For a succinct expression of this position, see this editorial in the journal “Biological Conservation”

    People need to decide whether we want to share the planet with other species. This is likely to make a big difference in terms of just what size populations are “sustainable,” at the local, national and global levels.

  6. Good comment, although I still harbour doubts about the likelihood of sufficient numbers of Greens adopting a sensible and long overdue commitment to population reduction.

    In my more cynical moments, of which there are plenty, I’ve come to believe that the current enthusiastic promotion of mass migration and open borders stems from an implicit acknowledgement by our dominant elites/establishments , that an avowed commitment to the pressing need for population reduction has been abandoned, for reasons of self interest and political cowardice: in other words, the increasingly distrustful and concerned public is being manipulated into accepting ‘predict and provide’.A closure of the stable door.

    This is dressed up in various guises by both left-social justice warriors- and right- expanding pool of cheap labour, growth without limits, profit opportunities.

    All attempts to raise awareness of the looming catastrophe are shut down, or dismissed and so the denial rolls on.

    I fully agree that our fellow beings, both flora and fauna, have the right to exist by and for themselves: I get increasingly exasperated by reports in the msm about new discoveries which will prove useful to humans.,with no consideration given to the fate of those organisms likely to prove profitable.

    Surely the sheer lack of space to breathe, swim, feed, reproduce, fly, walk and flourish now faced by ever more creatures and plants must be addressed: genetic diversity is under threat as humanity extends its grip on the earth’s resources.

    We hear worrying reports that some biologists are resorting to ‘triage’ and concentrating their efforts on conserving those species with a realistic chance of survival.

    An overcrowded monoculture is not a happy nor a desirable prospect.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.