Human population reduction is not a quick fix for environmental problems

Corey Bradshaw, Barry Brook

    Research output: Contribution to journalArticle

    72 Citations (Scopus)

    Abstract

    The inexorable demographic momentum of the global human population is rapidly eroding Earth's life-support system. There are consequently more frequent calls to address environmental problems by advocating further reductions in human fertility. To examine how quickly this could lead to a smaller human population, we used scenario-based matrix modeling to project the global population to the year 2100. Assuming a continuation of current trends in mortality reduction, even a rapid transition to a worldwide onechild policy leads to a population similar to today's by 2100. Even a catastrophic mass mortality event of 2 billion deaths over a hypothetical 5-y window in the mid-21st century would still yield around 8.5 billion people by 2100. In the absence of catastrophe or large fertility reductions (to fewer than two children per female worldwide), the greatest threats to ecosystems-as measured by regional projections within the 35 global Biodiversity Hotspots-indicate that Africa and South Asia will experience the greatest human pressures on future ecosystems. Humanity's large demographic momentum means that there are no easy policy levers to change the size of the human population substantially over coming decades, short of extreme and rapid reductions in female fertility; it will take centuries, and the long-term target remains unclear. However, some reduction could be achieved by midcentury and lead to hundreds of millions fewer people to feed. More immediate results for sustainability would emerge from policies and technologies that reverse rising consumption of natural resources.

    Original languageEnglish
    Pages (from-to)16610-16615
    Number of pages6
    JournalProceedings of the National Academy of Sciences of the United States of America
    Volume111
    Issue number46
    DOIs
    Publication statusPublished - 2014

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