22 January 2023 |

What geoengineering is good?


Late last year, a startup called Make Sunsets intentionally emitted sulfur dioxide into the atmosphere above Baja California. It was an experiment, one for which they caught a lot of flak and from which they didn’t gather much data.

Perhaps they were trying to see if they could get away with it before implementing more ambitious tests. If that was their goal, it could have gone better; Mexico, where the first test happened, banned further such experimentation this week.

Why pump sulfur dioxide into the atmosphere? While it can make for prettier sunsets, it’s also one way of blocking solar radiation, cooling the planet.

People got turned on to this idea by studying and understanding what happens in the wake of giant volcanic eruptions. One famous case study was the eruption of Mount Pinatubo in 1991. The volcanic ash, sulfur dioxide, and other aerosols that the volcano spewed into the atmosphere cooled parts of the planet up to 1.5° C for some time.

One could theoretically create the equivalent of many mini-Mount Pinatubos at scale to slow global warming. But the potential consequences – including known unknowns and plenty of unknown unknowns – would also be far-reaching. If you thought the debates around moral hazards surrounding carbon offsets were bad, solar radiation management is a whole ‘nother ball game.

Aerosol emissions – which often accompany greenhouse gas emissions from fossil-fuel combustion – cool the planet, despite other negative impacts (photo by Marek Piwnicki)

What geoengineering is good? 

Why this setup? Make Sunsets’ business sits squarely in what’s often called ‘geoengineering,’ which broadly refers to any attempt to manipulate the environment to mitigate climate change. And while climate tech folks roundly panned Make Sunsets’ tests, we already geoengineer. All the time. 

Aerosol emissions are just one of many non-carbon and non-methane pollutants humanity pumps into the sky. They often accompany greenhouse gas emissions from fossil-fuel use, negatively impacting air quality and hurting ecosystems. That said, they actually slow global warming. To what extent the reduction in aerosol emissions alongside decarbonization will hamper progress in mitigating climate change is an active area of study for climate scientists

And beyond managing solar radiation, companies and innovators are pursuing geoengineering in many other areas. Carbon removal – which comprises numerous techniques designed to suck up excess CO2 out of the atmosphere – fits my definition of geoengineering, even if it’s a lot less controversial.

And who knows, someday it could be. If humanity gets super adept at removing carbon, you might imagine future global squabbles about the ideal concentration of CO2 in the atmosphere. 300? 275? Some levels would benefit some people and species at the expense of others. I guess that’ll be a good problem to have.

Nor are carbon removal and solar radiation management the only areas that come to mind. This week, Living Carbon raised a $21M Series A. Their pitch? Engineering trees to use and store more CO2. They actively research and edit different plant genes, manipulate their expression, and more

This work ties into carbon removal – as that’s a core piece of Living Carbon’s value proposition – but gets into editing and changing another big component of Earth’s environment, namely its flora. Considering how much controversy accompanies GMOs and stem-cell research, you can imagine a similar crowd taking a dim view of Living Carbon at some point. Which begs the bigger question: Where do we draw the line between what’s good vs. bad?

The net-net

Whether or not to geoengineer isn’t a question we can save for the future. The rate at which we’ve pumped greenhouse gasses into the atmosphere over the past three hundred years is itself a massive geoengineering experiment, one which we’re now trying to unwind and reverse.

In service of the effort to mitigate climate change, I’m not against any geoengineering approaches outlined today, save for solar radiation management. For now — I reserve the right to change my mind w/r/t to that too. 

Many other firms are pursuing work similar to Living Carbon’s, whether designing and developing more resilient crops, increasing crop yields, or applying synthetic biology to any other climate-relevant application.

As they scale, raise money, and take their innovations into the field, the lines between what’s ‘good’, ‘bad’, and what counts as ‘geoengineering’ – which carries bad connotations – will continue to blur.