We Need Three Planets to Keep the Human Race Alive, NASA Scientist Says

Humans are using Earth's resources in a completely unsustainable way.

It's no secret that uncurbed climate change and population growth are going to (and already have) put stress on the planet. But the situation is getting so bad that one prominent NASA scientist says we have to start thinking about terraforming Mars and that, in order for the human race to survive at current levels, we will eventually "need at least three planets."

"The entire ecosystem is crashing," Dennis Bushnell, chief scientist of NASA's Langley Research Center said Thursday. "Essentially, there's too many of us. We've been far too successful as the human animal. People allege we're short 40-50 percent of a planet now. As the Asians and their billions come up to our living systems, we're going to need three more planets."

Bushnell was discussing the release of The Millennium Project's "State of the Future," an annual report that looks at global challenges and how they might be solved. He said that Mars is a good start, but we'd soon need even more space to live.

"If NASA terraforms Mars, that'll take about 120 years, and that's only one planet," he said. "We'd need more shortly."

It's not the first time someone has floated the need for humans to colonize other planets, but usually such ideas are proposed as a way for the human race to survive in the event of a cataclysmic asteroid collision or nuclear war. In 2012, the World Wildlife Fund also suggested the three-planet idea, stating that we're using about 50 percent more resources than the Earth can support, and that by 2050 we'd need three planets to sustain that rate.

Bushnell didn't say when he thought we might need three planets or what planets those might be—Mars is a good start, but beyond that, the Solar System is looking pretty barren as far as terraform-able planets go.

This is how seawater irrigation would work. Image: Seawater Greenhouse

"The point isn't to be alarmist or cynical, says Jerome Glenn, CEO of the Millennium Project. It's about identifying the challenges Earth faces and finding a way to rise above them. "We have no right to be pessimistic. We have to find out what's intelligent to do to make this species survive," he told me. "If you think the problems aren't going to get better, then why try. And if you think there aren't problems, then why change anything?"

In any case, Bushnell wasn't suggesting that we absolutely need to leave the Earth—he was saying that we need to stop consuming like we are. He's got one solution in mind: Salt water farming.

Halophytes, a class of plant that grows well in salt water, could potentially be used to create biofuel by growing plants in the middle of the oceans (or at least using salt water to irrigate plants we do have in agriculturally-unproductive parts of the world). Scientists are working on the possibility, and an MIT project suggested that some pilot programs started in India, Pakistan, Laos, Algeria, and other poor countries should be started sometime this year, but so far, not much progress has been made. Bushnell says it'd solve most of our problems.

"If you grew halophytes on wastelands using seawater, in 10-15 years you'd have fuel that cost $50 a barrel. That's half of what petroleum costs today," he said. "With that, you could solve land, food, water, energy, and climate. All of that comes together."

If we can't do that, it just may be time to start buying land on Mars.