In November, Stephen Hawking warned that humans needed to colonize another planet within 1,000 years. Now, six months later, he’s saying we have to do it within 100 years in order to avoid extinction. There’s a problem with this plan: under almost no circumstances does is colonizing another planet the best way to adapt to a problem on earth.
Let’s start with Mars, which is a favorite planet for colonization scenarios, including for Elon Musk who thinks we should colonize Mars because earth will eventually face a “doomsday scenario”. The problem with this is that there is almost nothing that could happen to earth that would make it less hospitable than Mars. Whether it’s nuclear war or massive global warming, post disaster earth would be way more habitable than Mars.
For example, we worry that the oceans on earth will get too polluted, or too acidified, or rise up too high. It’s true that could make life on earth very hard. But on Mars the only surface water is frozen in the polar ice caps. We would be hard pressed to ruin the water on earth so badly that it’s worse than what’s available on Mars.
We also worry about the level of carbon dioxide we humans are creating. But there’s nothing we could do to earth’s atmosphere to make it as bad as Mars, which is both extremely thin and also 96% carbon dioxide. Not to mention a significantly lower level of gravity. Whatever we’d have to do on Mars to make the atmosphere habitable would be more easily done on a very very ruined earth.
Even if an asteroid were to strike earth it would remain more habitable than mars. For example, consider the asteroid that struck the earth 66 million years ago creating the Chicxulub crater and wiping out 75% of plant and animal species on earth, including the dinosaurs. Well that disaster still left 25% of species that survived, all of whom would die instantly on the surface of Mars.
If an asteroid like this was heading for the earth here’s what we would do instead of abandoning the planet. First, we’d try to deflect it. If we didn’t know how to do that, everyone who lived on the part of the planet where it was going to land would move to safer parts of the planet. If need be we’d create biodomes and move into them, maybe even at the bottom of the ocean. “Impossible!” you say? “Technology and human behavior would never allow this!” you insist? It’s true it would be extremely hard and today’s technology wouldn’t allow it. And yet it would still be way, way easier than colonizing another planet. If you think getting humans to abandon a continent peacefully is hard, try getting them to abandon the planet.
Perhaps we could focus on colonizing another planet then. One with an atmosphere closer to ours than Mars. This may be possible, but the technology required to do this is a far smaller life than the technology required to build habitable ecosystems on the bottom of the ocean, deflect asteroids, reverse global warming, or cure pandemics. The closest star system to us is Alpha Centauri, which is 4.3 light years away. At a max speed of around 17,000 mph would take existing space shuttles 165,000 years to reach this. Even the faster New Horizon probe, the first to visit Pluto, would take 78,000 years.
The technology required to travel fast enough to get to other planets makes geoengineering to reverse climate change seem quaint.
It is hard to come up with a scenario where evacuating the earth makes the most sense. So why do so many smart people obsess about it? I think the issue is that nerds find space travel and colonizing other planets extremely appealing because they love science fiction and space exploration exciting. That’s fine, and if some billionaires want to colonize Mars for fun I say go for it. But unfortunately, their nerd desires are biasing their assessment of how humanity should prepare for doomsday threats. Sorry nerds, we won’t be evacuating earth. If we are underestimating the risks of doomsday threats, lets instead invest in the technologies that will help protect earth from them. Even though I am not an expert on space, physical sciences, or basically any relevant field, I can tell that this is obviously true. Maybe just it takes an economist to see through the nerd fantasies.
ADDENDUM: The goal of colonizing to preserve the species rather than evacuate doesn’t make sense either. If there are habitable planets within reach, then there must be many, many habitable planets that aren’t within reach. In this case the Drake Equation implies humans are not alone in the universe, and therefore our existence is far less special, lowering the benefit of preserving humanity. In a world of other habitable planets, saving the actual life on earth grows in importance compared to preserving the species somewhere in the universe.