Over the next 40 years, the world is set to add 2.3 billion people . Millions more will join the middle class, pushing consumption upwards and further straining the world’s natural resources. Variables like climate change and political instability will exacerbate that strain and complicate efforts to bolster peaceful and stable development.correspondent Kenneth Weiss and photographer Rick Loomis examine these numerous and interconnected challenges in a five-part series on population growth and consumption dynamics