It sounds like something out of a Marvel movie, but scientists have said halving the human population over a span of about two centuries could make the planet much more sustainable by reducing excess consumption.

In the 2018 Hollywood blockbuster Avengers: Infinity War, the “Mad Titan” Thanos played by Josh Brolin halves the population of the universe instantly using the mystical “Infinity Gauntlet” to stop the suffering caused by overpopulation.

Now, researchers estimate that halving the Earth’s human population, more gradually over 200 years and not like the instant decimation of life brought about by Thanos, could ease our negative impacts such as decreased wildlife populations and increased carbon emissions.

Scientists argue that the indiscriminate use of Earth’s resources by humans has led to environmental effects, ranging from biodiversity loss to climate change.

Biodiversity loss, resource consumption rates, and pollution levels are strongly linked to human population size, they observe in the study published in the journal Sustainable Development.

Over the past few hundred years, there has been a dramatic increase in human lifespan, quality of life, lowered child mortality and poverty, as well as expanding access to education and human rights.

These have led to a profound growth in global population, reaching about two billion in the 1920s to the current 8.3 billion.

“Our collective impact upon the planet's ecosystems has become overwhelming and unsustainable,” scientists write.

Estimates suggest the population growth is currently about 0.85 per cent per year.

People in high-income nations also tend to consume about 13 times more energy per capita than low-income nations, researchers find.

Scientists warn that the ever-increasing levels of population and resource consumption are not in the interests of future generations.

“Global environmental problems are caused by people, nothing else,” they wrote, adding that “gently reversing population growth is the better course”.

“Helping population growth end and gently and justly reverse, while also moderating per capita impacts, is our best hope to secure a sustainable, desirable future worldwide,” scientists concluded.

The progression to lower populations will also improve the economic well-being of nations, they say, observing that many countries with declining populations have seen increases in per capita GDP, work participation, and real wages.

Citing an example, they say the Indian state of Kerala limiting its population growth three decades ago via higher education, female empowerment, delayed marriage, and extensive access to voluntary family planning, has led to its rise from “one of the poorest to one of the most prosperous Indian states”.

Researchers show that slowing and gradually reducing the human population to about 4 billion or less from its current 8 billion by 2200 can lead to a much more sustainable planet.

“Among the benefits are habitat recovery and conservation of wild species, reduced greenhouse gas emissions and other pollutants, reduced conflict over resources, and the reduction of global poverty,” scientists write.

“A more modest population – gently easing population to 4 billion by 2200 – would protect Earth's natural heritage, including its wild habitats, wild species, and its climate. Such a world is within our grasp,” they concluded.