Population growth is a key contributor to the pressures pushing at our planetary boundaries. In Rio+20 discussions, implications of population growth have become shrouded in platitudes. It is important that discussions on planetary limits clearly lay out possible strategies that can alleviate these pressures.

As the world population grows toward 10 billion, consumption of water, food and energy is expanding at a rate that cannot be maintained without depleting the planet’s resources. If we fail to address these two issues together, we face a grim future of economic, social and environmental ills, warns a new report prepared by a group of scientists and other experts for the Royal Society.

“Thank you for coming on this gorgeous day, to sit in an airless, lightless room and discuss how to save the world,” said John Mutter, director of Columbia’s PhD in Sustainable Development and a member of the Earth Institute faculty, in welcoming the audience of the Sustainable Development Seminar, “The Population Bomb: Defused or Still Ticking?” The seminar brought together a panel of demography and population experts, who, Mutter calculated, shared a total of 121 years’ experience in the field. It became apparent, upon the beginning of the discussion, that the population bomb was not so much ticking, as exploding. The current world population, which is estimated to be 7 billion, is projected to reach 10.2 billion by 2100.

Can we manage the needs of 9 billion people for water, food and energy without depleting our resources and ruining the environment? “The solutions,” says Tim Fox, “are all within the capability of existing technology.”

Earth’s population has more than doubled in the last 50 years to 7 billion. The numbers represent big challenges—feeding and providing for additional people on a planet already stressed by environmental damage and climate change. What can ordinary individuals do?