How Many People Can Our World Support?

No species has altered the Earth’s natural landscape the way humans have. Our impact is so extensive that we are crossing into a new geologic epoch – the Anthropocene – propelled by human behavior. Global climate change, mass extinction, and overexploitation of our global commons are all examples of the ways in which humans have altered the natural landscape. Our growing population, coupled with rising affluence and per capita impact, is driving our planet closer to its tipping point. With population expected to reach 9.5 billion by 2050, many wonder if our natural resources can keep up with our growing demands.

The World Population Map can be viewed with the data overlay, “Anthropogenic Transformation,” created by ecologist Erle Ellis. Instead of dividing the world into classical biomes (savanna, rainforest, woodlands, tundra, etc.), Ellis conceived of depicting a map of “anthromes” to describe the way human have reshaped the earth’s ecological patterns. The Anthrome map shows croplands, rangelands, urban areas and other human settlements.


Understanding Carrying Capacity

Human population, now over 7 billion, cannot continue to grow indefinitely. There are limits to the life-sustaining resources earth can provide us. In other words, there is a carrying capacity for human life on our planet. Carrying capacity is the maximum number of a species an environment can support indefinitely. Every species has a carrying capacity, even humans. However, it is very difficult for ecologists to calculate human carrying capacity. Humans are a complex species. We do not reproduce, consume resources, and interact with our living environment uniformly. Carrying capacity estimates involve making predictions about future trends in demography, resource availability, technological advances and economic development.


Our Ecological Footprint

One way to address the challenges associated with making future projections is to look at current human impact on the planet. The ecological footprint is a measurement of the anthropogenic impact on earth. It tracks how much biocapacity (biological capacity) there is and how much biocapacity people use by comparing the rate at which we consume natural resources and generate waste to the planet’s ability to replenish those resources and absorb waste. Today, our global footprint is in overshoot. It would take 1.5 Earths to sustain our current population. If current trends continue, we will reach 3 Earths by the year 2050.


Where Do We Grow From Here?

Our planet does not have the biocapacity to sustain our current levels of growth and resource consumption. So, what can be done to minimize our collective impact on the environment? In his book, How Many People Can the Earth Support?, mathematical biologist Joel Cohen classifies current solutions into three paradigms: those looking for a “bigger pie” (improving technology), those advocating for “fewer forks” (slowing population growth), and those looking to rationalize and improve decision-making though “better manners” (changing global culture). Cohen argues that, standing along, each paradigm is necessary in solving our environmental crisis, but not sufficient. Change must come from a combination of all three. “Promoting access to contraceptives, developing economies, saving children, empowering women, educating men, and doing it all at once,” he writes, is a way to both lower our impact on the planet and improve the quality of life for all. Perhaps Oxford economist Robert Cassen said it best, “Virtually everything that needs doing from a population perspective needs doing anyway”. Adopting human-centered initiatives targeted at addressing both population growth and consumption habits, ranging from the individual to trans-national level, are our best hope for achieving a sustainable future.


Human Population 1 CE – 2050 CE