Scientists urge population rethink ahead of Rio+20

By Tierney Smith

The world must drastically curb population growth to be in with a chance of holding back an irreversible global ‘tipping point’ warn scientists on the eve of the Rio+20 Earth Summit.

The global population hit seven billion in late 2011 and current predictions put it hitting nine billion by the middle of the century.

The report, published in Nature, warns that an accelerating loss of biodiversity and destruction of ecosystems, rapid population growth and resource use and climate change could be driving the Earth towards an irreversible, planet-wide tipping point that would have destructive consequences.

The researchers warn we are on the path to an irreversible tipping point for the planet (© NASA)

The authors predict this tipping point could be reached within the century, and warn that once reached it could mean the collapse of the planet’s ecosystems as we know them in the blink of an eye.

They use examples of previous shifts, for example the end of the last ice age 12,000 years ago when the world went from being glaciers to its current state within just 1,000 years.

“That’s like going from a baby to an adult state in less than a year,” said Arne Mooers, one of the report authors. “Importantly, the planet is changing even faster now.”

Unsustainable Pathway

The researchers concerns are echoed by the UN Environment Programme whose latest report warns that the world “continues to speed down” an unsustainable path.

The fifth edition of the Global Environment Outlook (GEO-5) launched ahead of Rio+20 found that in spite of a number of international agreements to protect the planet only four out of 90 of the most important environmental goals had seen significant progress.

UNEP have urged for drastic action and big-scale measures to be adopted to reverse this pattern.

“If current trends continue, if current patterns of production and consumption of natural resources prevail and cannot be reversed and ‘decoupled,’ then governments will preside over unprecedented levels of damage and degradation,” said Achim Steiner, Executive Director of the UNEP.

7% from destruction

The authors of the Nature report examined studies of small scale ecosystems to show that once 50-90% of an area has been altered the entire ecosystem tips into a state far different from the original.

While they say no one knows how close the Earth is to a global tipping point, many of the warning signs are there, and they conclude that the world should keep as far away from the 50% mark of transformation of the Earth’s surface to avoid collapse.

With the conversion of landscapes to agriculture and urban usage, we’ve already reached the 43% mark on surface transformation.

The report warns that with the quadrupling of the human population in a century and with more pressure placed on fossil fuels we are already seeing changes such as species extinctions and dead zones in our oceans.

The report concludes that the world must drastically lower population growth and resource use (© James Cridland/Creative Commons)

“In a nutshell, humans have not done anything really important to stave off the worst because the social structures for doing something just aren’t there,” says Mooers. “My colleagues who study climate-induced changes through the earth’s history are more than pretty worried. In fact, some are terrified.”


On the eve of the Rio+20 Earth Summit the report authors set out five clear actions which must be taken immediately to delay or minimise the planetary shift.

Urgent action should be taken to reduce the world population and to reduce per-capita resource use, according to the reports conclusions. Fossil Fuels should be replaced by sustainable sources and a more efficient food production and distribution system should be developed which does not take over any more land.

Finally the authors urge for areas of the Earth which has not already been taken over by human populations to be better managed – both on land and at sea – and protected as reservoirs for biodiversity and ecosystems.

“My view is that humanity is at a crossroads now, where we have to make an active choice,” said report co-author Anthony Barnosky. “One choice is to acknowledge these issues and potential consequences and try to guide the future. The other choice is just to throw up our hands and say, ‘Let’s just go on as usual and see what happens.’

“My guess is, if we take that latter choice, yes, humanity is going to survive, but we are doing to see some affects that will seriously degrade the quality of life for our children and our grandchildren.”

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