Germany aims to be a pioneer in green energy and to fight climate change. Yet recent data suggest that the country has failed to meet its own climate goals. Following the United Nations Sustainable Development Goals, Germany’s “National Sustainable Development Strategy” aimed at a 40 percent reduction in carbon dioxide (CO₂) emissions between 1990 and 2020. But emissions will not reach the target, having stalled at 73 percent of the 1990 level since around 2010 and even increased in many regions. The government’s latest progress report states that the 2020 goal is not reachable.

Germany is also falling short on other environmental goals. Instead of reducing urban sprawl (land conversion of agricultural areas or forests into settlements and roads) to 30 hectares a day, cities are growing by 63 hectares a day. Similarly, efforts to conserve local flora and fauna are failing. The official report’s indicator of species diversity and landscape quality recently declined to 69 percent of the historical value from 1975 which was also the 2020 target value.

What happened?

Clearly, many forces are responsible for the failure of Germany’s climate policy. One important factor is demography. For many decades, experts had predicted that Germany’s population would drastically decline from 80 million to 60 million, or even 50 million, by 2050. Recent developments instead suggest that no reduction in population will occur until at least 2050.

As Figure 1 shows, population growth is unevenly distributed across Europe. Between 2014 and 2017, the population grew at a substantial rate in Scandinavia, Switzerland, the Benelux countries, Ireland, many parts of the United Kingdom, Austria, and Germany. Population decline in Europe mostly affects rural regions of Southern and Eastern Europe. In fact, the United Nations’ 2017 Revision of World Population Prospects predicts an increase in the population size of Northern and Western Europe by 20 million until 2050 according to the median forecast rather than stability or a decrease.

In Germany, only a minority of regions are experiencing population decline, and most of these are located in the former communist East. Few immigrants settle in these regions. Most immigrants target urban areas in the West that are already experiencing population growth. Most regions, both urban as well as rural areas, have growing populations and are struggling with an overcrowded housing market, shortages of schools and kindergartens, and jammed commuter trains and highways.

A few years ago, this picture looked dramatically different. Between 2005 and 2010, the population was declining in most German regions, even those with economically vibrant urban areas. Between 2012 and 2016, however, a net immigration of 3 million people (or the population of Berlin) more than offset the natural decline in the German population, which accounted for 1 million more deaths than births during the period. Even if immigration were to drop to 300,000 per year, Germany’s population in 2050 would be higher than today’s. Moreover, after more than four decades of “lowest-low” fertility rates below 1.5 children per woman, Germany recently witnessed a surprising “baby boom” as the number of births increased by a stunning 20 percent between 2011 and 2016.

Most politicians applauded the recent development, welcoming population growth as a means to combat demographic aging and an assumed shortage of labor. But demographic research has long shown that higher fertility and immigration only weakly affect population aging. However, the adverse consequences of population growth for the environment are clear and substantial.

The following graph compares two groups of German cities: The first group consists of 68 cities where the population grew by 4 percent or more between 2000 and 2008 (for example, Munich, Dresden, Freiburg or Ingolstadt). The second group is made up of 68 cities that had stable or even slightly declining populations (for example, Kassel, Wolfsburg, Bayreuth or Magdeburg). Both groups are similar in all other regards. For example, they both saw on average 30,000€ per capita GDP and 3.5 percent GDP growth per capita during the observed period.

Despite similar economic performances, the two groups’ environmental footprints are remarkably different. While the group of cities with stable populations was able to reduce CO₂ emissions by 6.6 percent, the growing cities only achieved a 3.1 percent reduction or less than half the rate of their otherwise similar counterparts. And this was during a period of generally low population growth and substantial reduction in emissions. Both trends have since reversed.

In an article published in the European Journal of Population, Jennifer Sciubba and I explore these links in greater detail with a total of 1,062 cities and regions in 22 European countries. The results suggest that in the Eastern European countries where populations are mostly declining, demography is less important compared with other factors that influence the environment.

In the West, however, population growth is clearly a key factor that explains why cities and regions are struggling to meet their environmental goals. The demographically growing cities converted much more undeveloped land into urban areas than the stable or slightly declining cities. Likewise, the more the population grew, the higher the rate of CO₂ emissions from fossil fuel combustion rose.

There is no easy fix for this dilemma. One required change would involve better managing the transition to greener energy and promoting technological innovations. While halting population growth would not be enough to save the environment, a stable or slightly declining population would greatly increase the chances that Germany and other countries will be able to achieve their climate goals by 2030, if not by 2020. Less urban growth and greener cities could be compatible with affordable housing: A stable rather than increasing demand for housing would ensure stable housing prices even without further urban sprawl. Likewise, if the population is stable, the number of households and cars would increase less, which means that emissions from ground transport and private households could be notably reduced through a greater share of electric cars or more homes’ using efficient heat insulation. If the population continues to grow, on the other hand, technological gains in efficiency are likely to be offset by higher consumption levels.

To reach the German climate goals by 2030, if not by 2020, a good first step would be to acknowledge the trade-off between growth and sustainability. The current practice of pretending the goals do not conflict is misleading. Raising awareness of this trade-off in public discourse might prompt politicians to state where their priorities lie. Voters would then face a clear choice to shape Germany’s future.