Terraforming—adapting a planet to make it habitable—has become a recurring theme in science fiction, and there have been countless stories of hardy pioneers setting out to engineer a breathable atmosphere and comfortable climate on Mars and other worlds. Now, however, it seems the first world we’ll have to terraform is our own.
But how do you set out to engineer an entire planet?
The Earth is a complex system, which means re-balancing the climate won’t be achieved via a single solution. Many different approaches will need to be applied, from the widespread construction of wind and solar farms and the development of clean fusion power to programmes of massive reforestation and dietary change.
I mention dietary change, because a study published in Nature Food in 2021 shows that food production accounts for 35% of all global emissions, with meat farming by itself being responsible for 21%. The production of 1kg of wheat emits 2.5kg of greenhouse gases, whereas the production of 1kg of beef emits 70kg. But while plant-based cuisine is becoming more and more fashionable, many people don’t want to give up meat just yet. So perhaps the future of farming might involve vat-grown meat? At the moment, this technology is in its infancy, but with investment, we could soon be tucking into steaks that have been cultured from a few cells, saving an estimated 92% of the emissions produced by raising and slaughtering a cow.
In Kim Stanley Robinson’s Ministry of the Future, which Barack Obama included on his list of Books of 2020, humanity manages to slow global warming by injecting reflective particles into the upper atmosphere, reducing the amount of sunlight reaching the Earth’s surface. However, such a method might be difficult to control, and we don’t know the long-term effects of introducing so much material into the sky. A safer method of producing a similar effect might be achieved by positioning a giant sunshade in orbit. The advantage of this approach is that it could be remotely manoeuvred in order to adjust the amount of solar radiation allowed through at any one time. In addition, if coated in solar cells, the shade could also serve as a source of clean energy.
Other ideas include increasing the albedo, or reflectivity, of our planet by painting the deserts white to make up for the loss of our ice caps. In Robinson’s book, climate engineers slow the loss of Antarctic glaciers by pumping meltwater from beneath them, arresting their slide into the ocean and causing them the settle back onto the bedrock.
Despite the optimism of some billionaires, it seems highly unlikely we’d be able to terraform Mars with our current technology. However, if we were able to extract CO2 from our atmosphere and turn it into icebergs, we could fire them at the red planet, where they would gradually thicken the atmosphere and help raise the surface temperature to something bearable. Exporting our greenhouse effect to a planet desperately in need of warming up seems almost poetic.
In a previous column [Moving The Moon, Oct 2019], I suggested we might lower the moon’s orbit in order to increase the Earth’s rotation, shortening our day to 18 hours, thereby giving the East and West hemispheres of the Earth less time to warm up in the glare of the Sun. The oceans would have less time to absorb heat, and winters would become colder.
But a more extreme solution might be to move the Earth itself. Repositioning ourselves further from the sun would decrease the light and heat we receive from it—which might be bad news for some species of plants, but good news for mean global temperatures.
Obviously, moving our home planet would be dangerous, and would require huge quantities of time and energy, but it is theoretically possible. Propulsion could be achieved by converting the sun’s energy into a series of giant lasers or ion drives, deploying vast solar sails, or using near misses by large asteroids to gradually change slow the Earth’s orbital velocity, allowing it to drift outwards. Unfortunately, all those methods would take thousands, and perhaps millions, of years to work. So, if I had to write a science fiction story about moving the Earth, I’d have to employ a more exotic means of transport, such as a gravity drive or wormhole, to shunt the planet from its current orbit to a cooler one. And let’s hope we eventually develop one of those technologies. At the end of its life, the sun will expand, swallowing the inner worlds as it mushrooms into a red giant. If we survive our current crisis, we’ll need to think about moving outwards in a few million years.
This article first appeared in The Engineer magazine.