The eruption of Mt. Tambora in Indonesia in 1815 pumped so much sulfur dioxide into the stratosphere that New England farmers found their fields frosted over in July. Climate change, it seems, can be quick and overwhelming, at least on short scales. The eruption of the Mt. Pinatubo in the Philippines in 1991 cooled global temperatures for several years by about half a degree Celsius. Sulfur dioxide works.

So how about this: We send a fleet of airships high into the stratosphere, attached to hoses on the ground that pump 10 kilos of sulfur dioxide every second. The airships then spew this mix into the upper atmosphere, a aerosolized pollutant that, turning the skies Blade Runner red, shields the planet from the Sun’s heat. Call it geo-engineering, an extreme form of human climate manipulation that is the subject of a recent story in The Atlantic.

Into the Anthropocene

Writer Graeme Wood notes that our activities have been transforming the planet for centuries now, leading some to dub our era the ‘anthropocene’ period. Says Wood:

…humans have reshaped about half of the Earth’s surface. We have dictated what plants grow and where. We’ve pocked and deformed the Earth’s crust with mines and wells, and we’ve commandeered a huge fraction of its freshwater supply for our own purposes. What is new is the idea that we might want to deform the Earth intentionally, as a way to engineer the planet either back into its pre-industrial state, or into some improved third state. Large-scale projects that aim to accomplish this… constitute some of the most innovative and dangerous ideas being considered today to combat climate change.

For it turns out that the sulfur dioxide idea is just one among many. Scottish engineer Stephen Salter discusses a strategy to use a fleet of 1500 ships to churn seawater, spraying it high into the clouds to add moisture and make the clouds more reflective. Roger Angel (University of Arizona) proposes a series of huge electromagnetic guns in the upper atmosphere that would launch a Sun-shield made up of millions of Frisbee-sized disks to the L1 Lagrangian point, effectively scattering sunlight.

Freelancing Global Climate Change

The danger here, beside the unintended consequences that could so quickly attend such schemes, is that international cooperation on climate change could quickly be rendered irrelevant. Solutions like sulfur dioxide are cheap enough — $100 billion would be enough, Wood says, to reverse anthropogenic climate change entirely, and it might cost far less — that a single country could take on the challenge itself.

Wood turns to geophysicist Raymond Pierrehumbert (University of Chicago) for thoughts on possible unintended consequences of the sulfur dioxide strategy. The geophysicist reminds him of the Greek legend of Dionysius II, who to make a philosophical point suspended a sword over Damocles’ head from a single hair:

According to Pierrehumbert, sulfur aerosols would cool the planet, but we’d risk calamity the moment we stopped pumping: the aerosols would rain down and years’ worth of accumulated carbon would make temperatures surge. Everything would be fine, in other words, until the hair snapped, and then the world would experience the full force of postponed warming in just a couple of catastrophic years. Pierrehumbert imagines another possibility in which sun-blocking technology works but has unforeseen consequences, such as rapid ozone destruction. If a future generation discovered that a geo-engineering program had such a disastrous side effect, it couldn’t easily shut things down. He notes that sulfur-aerosol injection, like many geo-engineering ideas, would be easy to implement. But if it failed, he says, it would fail horribly. “It’s scary because it actually could be done,” he says. “And it’s like taking aspirin for cancer.”

A Carbon-Cutting Alternative

Cutting carbon emissions seems like a far preferable solution, and it’s one that Freeman Dyson suggested in a geo-engineering strategy he designed as far back as 1977, one that would create forests of trees engineered to be more effective at drawing carbon from the air, trapping the carbon in the topsoil. Other carbon-withdrawing schemes call for creating large towers whose grids would be coated with a chemical solution that could bind carbon-dioxide molecules. That one, by David Keith (University of Calgary), stashes captured carbon deep underground.

Ponder the implications when any one of the 38 people on the planet who have $10 billion or more in private assets could try to reverse climate change single-handedly. There’s one more Fermi solution — technological civilizations run afoul of their own technology as the cost of tackling massive projects drops to the point where individuals or small groups can destroy an ecosystem while attempting to fix it. Is a game-changing technology to fix climate change worse than the problem? Perhaps a more judicious view is that a technological big fix is what Wood calls “…the biggest and most terrifying insurance policy humanity might buy — one that pays out so meagerly, and in such foul currency, that we’d better ensure we never need it.”