Expanding cities around the globe, especially in fast-growing countries like China, India and Brazil, are putting the world under increasing environmental stress, according to experts at a climate conference, Planet Under Pressure, in London, reports Reuters. The additional 1.5 million square kilometers of space they expect to be occupied by 2030 will mean growing greenhouse gas emissions and resource demand. The United Nations foresees global population rising from 7 billion to 9 billion people by 2050, adding roughly a million people each week.

Farsighted urban planners want to improve how cities are planned, developed and run. “Everything being brought into the city from outside—food, water, products and energy—needs to be sourced sustainably,” observes Sybil Seitzinger, executive director of the International Geosphere-Biosphere Program at the Royal Swedish Academy of Sciences.

Utility meters and sensors that monitor power generation network capacities and electricity supply and demand can help conserve energy. Builders can also target more efficient land use, better building standards and policies to promote public transportation instead of vehicle use. More urban areas need to follow the example of cities like Vancouver, in Canada, which obtains 90 percent of its energy from renewable sources such as wind, solar and tidal energies, and has developed a 100-year sustainability plan.