The New Climate Tech

Infusing clouds with sulfur dioxide to block the sun. Vacuuming carbon dioxide out of thin air. Adding iron to the ocean to draw greenhouse gases down to the sea floor. As recently as a few years ago, technologies designed to change Earth’s atmosphere — what is broadly known as geoengineering — were considered too impractical, too expensive and too outlandish to be taken seriously.But, as I write in a new…