As a certain billionaire dreams of terraforming Mars to make it habitable, and governments and organisations around the world slowly turn their attention to the escalating climate crisis, I thought it might be time to examine some science-fictional ideas for terraforming the Earth.
Before I start, I want to give a quick disclaimer: I’m not a climate scientist. My job as a SF author is to ask questions (sometimes stupid questions), tell stories and provoke thought.
Earth is the only planet we currently know if that’s even slightly habitable. Mars may look good as an alternative, but if you went out on the surface unprotected, you’d die in seconds. The atmospheric pressure is a hundred times lower than it is on Earth, and what little air there is consists mostly of carbon dioxide. The average surface temperature is a lethal -62 degrees centigrade, and there’s no magnetic shield to protect the surface from deadly solar and cosmic radiation. In short, it’s a hellhole.
If we want to secure the long-term survival of the human race, our time and resources would be better employed repairing the damage to the Earth. The planet has some huge advantages over Mars, in that we can breathe the air, survive on the surface without pressure suits, and the magnetic field caused by the rotating molten core protects us from the Sun’s radiation. Add to that the abundance of water, and our world resembles a paradise compared to the alternative.
But how long will it last? If we want to see the effects of a runaway greenhouse effect, we only have to look as far as Venus, which once had oceans similar to ours. But as its surface temperature rose, more and more of its surface water evaporated to the upper atmosphere, where the molecules were broken apart by ultraviolet light, allowing the hydrogen to escape into space. With the water gone, carbon dioxide levels rose unstoppably, trapping more and more of the sun’s heat until the average surface temperature became hot enough to melt lead.
So, how do we prevent the Earth following a similar trajectory? The two most important variables seem to be the amount of solar heat reaching the planet, and the amount of carbon dioxide in the air.
We need to be scrubbing carbon and locking it up in artificial diamond blocks, which we can drop into the Mariana Trench, and genetically engineered algae in the stratosphere, absorbing the CO2 and excreting oxygen.
But how do we reduce the amount of heat we receive from the Sun? The two most obvious options are to somehow block the light or to move the Earth further out, into a cooler orbit.
Blocking the light and heat could involve painting large areas of the surface white, to reflect it back into space. Finding some way to re-freeze our poles and glaciers would also be a big help.
You want an engineering challenge? How about attaching radiator fins to the Earth? The space elevator is a well-known concept—a thread of unreasonably strong material anchored at the equator and extending up to geostationary orbit, allowing easy travel to and from the surface. But what happens if we add superconducting cables to the design, and a huge radiator fin to the top, allowing heat to be leeched from the atmosphere and dispersed into space? Vacuum is a great insulator, but there must be some way to bleed away the heat, even if we convert it into the energy to power a laser that fires it off into space. Although the idea of a powerful space laser falling into the wrong hands sounds like the plot of one of the more outlandish Bond films.
Or how about installing a huge mirror between the Earth and the Sun, like a gigantic parasol that could shade large portions of the planet from its full glare? Keeping it in place would be a challenge, as it would catch the solar wind like a sail, but it’s not beyond the realms of possibility. A cloud of reflective dust would have a similar effect, but probably be even harder to control.
Grazing comets through the upper atmosphere would deliver more water into our atmosphere, creating more cloud and further blocking the sun. But the technology to precisely deliver a comet to Earth orbit could easily be abused by a government wanting to obliterate its enemies with space rocks.
Engineering our climate will be difficult and controversial, but surely it has to be orders of magnitude easier than starting from scratch on a distant world that only a tiny percentage of us can ever hope to reach?
This article originally appeared in The Engineer.