An international study led by Corey J. Bradshaw from Flinders University, with the participation of renowned biologist Paul R. Ehrlich, warns that the Earth could sustainably support only about 2.5 billion people, compared to the more than 8.3 billion that make up the current population.
The work, published under the title Global human population has surpassed Earth’s sustainable carrying capacity, combines more than two centuries of demographic data with advanced ecological models to analyze how human growth relates to resource use, emissions, and the planet’s physical limits.
The hidden cost of growth
For more than two centuries, the Earth’s population grew driven by technological advances, health improvements, and unprecedented energy availability. However, this expansion had a hidden cost: the accelerated use of natural resources that do not regenerate at the same pace.
The analysis reveals a key change in the mid-20th century. Until the 1950s, population growth seemed like a virtuous circle: more population generated more innovation and production. But since the 1960s, the growth rate began to fall, marking a negative demographic phase.
Projections point to a population peak of between 11.7 and 12.4 billion people towards the end of the 21st century, a figure that on paper might seem manageable, but in practice is unsustainable.
Beyond the numbers: the consumption model
The real problem is not just how many we are, but how we live. The current model is sustained by intensive resource exploitation, especially fossil energy, which has allowed the multiplication of food, goods, and services production. This “energy push” has hidden an uncomfortable reality for decades: the planet cannot regenerate what we consume at the current pace.
Estimates indicate that a truly sustainable global population, with decent living standards and within ecological limits, should be around 2.5 billion people. The difference with the current population reflects a model of globalized overconsumption, where part of the world consumes far above what the system can support.
Visible and cumulative impacts
The mismatch between population, consumption, and the planet’s capacity is already translating into concrete effects:
- Pressure on ecosystems: forests turned into agricultural lands, overexploited oceans, and aquifers at their limit.
- Intensified climate change: more population implies greater energy demand, still linked to fossil fuels.
- Loss of biodiversity: degradation of entire systems that regulate the climate, purify water, and maintain soil fertility.
- Lower resilience: degraded ecosystems respond worse to droughts, fires, or floods, increasing societies’ vulnerability.
Inequalities and vulnerability
The study also highlights the increase in inequalities. While some regions face food insecurity, others maintain consumption levels difficult to justify from an ecological standpoint. This gap increases the vulnerability of millions of people and exposes the fragility of the global system.
A warning, not an inevitable destiny
The researchers clarify that the study does not present an inevitable scenario, but an urgent warning. The decisions made in the coming decades will be key: how resources are managed, how energy is produced and consumed, and how cities are redesigned to be more efficient and resilient.
The Earth has already exceeded its sustainable carrying capacity. The challenge is not only demographic but also about the consumption model and resource management. The warning of this study invites us to rethink the relationship between humanity and the planet, reminding us that sustainability does not depend solely on how many we are, but on how we live.
