Researchers at Flinders University in Australia, led by Corey Bradshaw, analysed more than two centuries of population data and found that humans are living well beyond the planet’s long-term carrying capacity.

Carrying capacity is the estimated number of individuals an environment can sustain based on available resources and their regeneration rate.

The study estimates Earth’s maximum human capacity at around 12 billion, while the optimal sustainable population, given current consumption patterns, is only 2.5 billion.

Today’s population stands at roughly 8.3 billion, far exceeding sustainable limits.

Bradshaw’s team noted that the global population is likely to peak between 11.7 and 12.4 billion by the late 2060s or 2070s if current trends continue.

Even with slowing growth rates, humanity is already surpassing what the planet can sustainably support, contributing to overconsumption, biodiversity loss, and environmental strain.

The researchers warn that fossil fuel use has temporarily masked natural limits, but this has come at the cost of climate change, ecosystem disruption, and declining resources such as water.

They stress that without significant changes to energy, land, and food usage, billions could face instability in the near future.

“The Earth cannot sustain the future human population, or even today’s, without a major overhaul of socio-cultural practices,” Bradshaw said.

“Smaller populations with lower consumption create better outcomes for both people and the planet. The window to act is narrowing, but meaningful change is still achievable if nations work together.”