Current Research

Our key research questions in 2019 include the following:

* Study successful nations with respect to population growth/decline, and fertility rates

Is it possible to identify societies that have successfully embraced an end to population growth? If so, what public policies characterize such countries? Which policies have been particularly effective at enabling these societies to maximize the environmental benefits of stable or declining populations, or cushioning them from any associated social or economic burdens?

* Study biodiversity and population

How do different demographic scenarios affect Europe’s environment, especially access to nature and biodiversity preservation? How do they affect Europe’s international ecological footprint, in the short and long term?

How do scenarios for population development affect Europe’s biodiversity, with particular attention to how growing or decreasing populations change opportunities for “rewilding” in various European countries? All else being equal, more people means less habitat and essential resources available for wildlife. Quantifying this would be a major contribution to planning for a sustainable future in the EU.


Key project initiatives in 2018 included the following:

* Study the environmental and economic benefits of population aging

Often presented as a problem, recent research suggests that aging populations can be part of societies’ successful transition to environmental sustainability, and that the economic challenges they incur are manageable. We build on this research with a comparative study focused on nations that seem to be transitioning successfully toward older, smaller populations. Read our article in the journal Trends in Ecology & Evolution (TREE): “Aging Human Populations: Good for Us, Good for the Earth”

* Develop new population projections under different immigration and fertility scenarios for the European Union

Immigration policy is currently a key political issue throughout Europe, while many states pursue a range of pro-natalist fertility policies. Yet most countries have not developed population projections under different immigration and fertility scenarios that illuminate the long-term demographic implications of these policies. We seek to remedy this by developing new population projections to 2100 for EU nations under varied immigration and fertility scenarios corresponding to actual policy choices.

TOP provides population projections under nine different fertility and migration scenarios and some of their combinations for every country in the EU out to 2100, in order to illuminate policy choices and their demographic consequences.

Read our published paper “Policy-based Population Projections for the European Union: A Complementary Approach,” in the journal Comparative Population Studies.

Read more about the population projections developed by TOP for all the EU countries in Appendix I, and click on the country you are interested in:


Czech Republic
The Netherlands

United Kingdom
European Union

See all the countries

See all the projection parameters used under all the scenarios and countries: Appendix II

Key projects in 2018, 2019 and in the future also include the following:

* Quantify the role population stabilization can play in mitigating and adapting to global climate change

It is well known that population growth is one of the two main drivers of continued increases in global greenhouse gas emissions (the other is growth in GDP per capita). Studies have shown that reducing future population growth could contribute substantially to efforts to limit global climate change, and to helping vulnerable societies adapt to the climate change that is inevitably coming. We are currently completing a study assessing the roles population stabilization or reduction could play in reducing greenhouse gas emissions and in increasing adaptability to likely climate change.

* Develop an ethical framework for addressing population issues

One reason for the lack of honest discussion of population matters is the fear that addressing population will lead to unethical policies or behaviors; hence the need to explore the ethics of population policy. This study will develop a framework for balancing interests and assessing policies grounded in the basic value of flourishing (both human and non-human). The goal is a framework that will provide guidance for population policy decisions that will help us create just and sustainable societies. Team efforts along these lines in 2018 included Addison Phillips’ masters thesis on immigration ethics  and discussions on “family planning as a human right” and “optimal human population size“.

We are continuing this work in 2019 and we could use your suggestions and advice! To contact us, click here, send your email addres to get on our mailing list for regular project updates.

To link to the best scientific resources on population matters, click here!