Ryan Popple, former CEO and co-founder of electric bus company ProTerra, venture capitalist for transportation electrification, early Tesla employee, Iraq War veteran and father of three, passed away on Wednesday night at the age of 44, for reasons unknown.

I had the good fortune to meet Ryan back in 2012, when UC Berkeley and UCLA Law convened a group of experts (including Ryan) on ways that California could dramatically scale up the sale of battery electric vehicles by 2025, now just a few short years away. The resulting report, Electric Drive by ’25, presented innovative and still-relevant solutions to boosting EVs, which were then in their infancy. Ryan was a major contributor to that report.

While I’ve had the chance to work with hundreds of experts over the years in our Bank of America-supported law school convening series, Ryan immediately stood out as an all-star. At a time when many people doubted that vehicle electrification was viable, he brought clear and convincing evidence that this transition was inevitable. His thoughtfulness and insights were impressive, and I made sure to keep in touch with him afterwards (and also recommended him to friends and policy makers as a valuable resource).

I was thrilled when he helped launch ProTerra and turned that company into a major player in the electric bus space. He recently left the company to return to his venture capital roots, where he was in the midst of identifying and supporting the game-changing companies of the future.

His loss is tragic, untimely, and heart-breaking. For those who work on climate change, he leaves a big hole. Condolences to his family, friends and colleagues.

For a taste of his humor, humility, and wisdom, here’s a recording of a presentation he gave last year, which shows his astuteness at identifying broader societal and environmental trends and the companies that can address them.

Rest in peace, Ryan.