Mac began his career in environmental law. He has worked for a U.S. Representative, two U.S. Senators, and two federal judges. Mac has also worked in the U.S. Department of Energy Office of General Counsel, the U.S. Department of Justice Environment and Natural Resources Division, and the U.S. Environmental Protection Agency Office of Enforcement and Compliance Assurance. He started another carbon removal startup company, which won the UCLA School of Law Lowell Milken Institute-Sandler Prize for New Entrepreneurs. Mac founded Mote in 2020 when his friend and now co-founder and CTO Josh Stolaroff published the rationale for the business in a Lawrence Livermore National Laboratory report entitled Getting to Neutral.