Douglas MacMartin worked as an aerospace engineer in the private sector before finding his way to academia, where he studies Sunlight Reflection Methods (SRM). The concept is based on a natural occurrence: when volcanoes erupt, they can emit sulfur dioxide gas into the stratosphere; the resulting aerosols reflect sunlight and temporarily cool the planet. MacMartin explores the logistics and uncertainties of potentially releasing aerosols in the stratosphere, including where, how much, how they would be delivered, potential weather impacts, and how much cooling could be gained. “I think of SRM kind of like seatbelts: If you are in a car and you know you’ll get into a car accident, you should take your foot off the gas (that’s like cutting CO2 emissions), hit the brakes (that’s like CO2 removal), but you still might want a seatbelt and airbags, too. That’s SRM,” he said. “Future decisions on deployment will be hard, but my hope is to ultimately support informed decisions.”