Should we build a nature reserve on Mars?

There are 8 billion of us now. The UN says when the population peaks around the year 2100, there'll be 11 billion human souls. Our population growth is colliding with the natural world on a greater scale than ever, and we're ...

Planet Earth: 8 billion humans and dwindling resources

Are eight billion humans too many for planet Earth? As we reach this milestone on November 15, most experts say the bigger problem is the overconsumption of resources by the wealthiest residents.

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