Over the past two centuries, experts have warned of the consequences of unchecked population growth, citing potential resource shortages and environmental instability. However, many countries today face the opposite challenge: declining populations and aging demographics, leading to economic instability. These dual crises — surging population growth in some regions and significant declines in others — are reshaping the global landscape, affecting economies, the environment, and technological development.
Historically, concerns about population growth were raised by Thomas Malthus in the 18th century and later revived by Paul Ehrlich in the 1960s. Both predicted that a population explosion would outstrip agricultural productivity and cause resource scarcity. Critics countered that human innovation — itself a product of growing populations — could mitigate these impacts. Advances in agricultural efficiency, for instance, have supported larger populations, even as the current growth rate has slowed since the 1960s.
Unified growth theory explains how economic progress evolves from slow technological development and high population growth to more modern phases characterized by improved income and declining population rates. When technological advancement coincides with declining population growth, it can reduce national environmental footprints and support both economic and environmental sustainability. However, this transition often requires upfront investment in green technologies, which can strain public and private finances in the short term.
At the other end of the spectrum, population decline presents its own economic challenges. Many affluent nations now face inverted age pyramids, with a growing elderly population and shrinking working-age base. This shift hampers technological progress, strains social support systems, and contradicts the trajectory outlined in unified growth theory. Currently, 63 countries have peaked in population, and dozens more are expected to do so within three decades. Some projections even suggest global population may plateau between 2060 and 2100, reaching approximately 10.2 billion.
The book Empty Planet argues that once fertility drops below replacement levels, it’s difficult to reverse due to social changes like urbanization, rising child-rearing costs, and increased individual choice. This results in tangible economic impacts, particularly in wealthy countries where per capita GDP declines as populations age. Compounding this issue is a reluctance among these nations to support immigration, a vital buffer against low birth rates. In the U.S., anti-immigration policies are exacerbating population decline and undermining the country’s previous leadership in green technology development.
Canada, too, is facing similar pressures, reducing immigration targets and relaxing its environmental commitments. This undermines efforts to transition away from fossil fuels, as economic concerns increasingly overshadow environmental policy discussions.
If nations fail to account for how population dynamics influence economic and environmental outcomes, they risk pursuing short-term solutions that ignore deeper structural issues. Achieving sustainable development requires a holistic approach that integrates technology sharing, responsible economic planning, and open immigration policies.
The United Nations Sustainable Development Goals offer a global framework, but their success hinges on recognizing and addressing the interconnected roles of population growth, economic stability, environmental protection, and international cooperation. Without public pressure to prioritize these connections, the current momentum toward sustainability could stall.