Nat Simons, along with his wife Laura Baxter-Simons, co-founded Sea Change Foundation, a private family foundation currently dedicated to addressing global climate change. Established in 2006, Sea Change works to support private and public policies and foster investments and practices that will reduce the most substantial sources of greenhouse gas emissions. Nat and Laura are signatories of the Giving Pledge.

In 2009, Nat and Laura started Prelude Ventures, an early-stage climate tech investment group which focuses on emerging companies poised to speed the transition to a low-carbon economy. Prelude works closely with other venture funds and family offices active in climate tech, and is a member of the Breakthrough Energy Coalition. Nat also manages Meritage Group, a US-based investment management firm spun out of Renaissance Technologies, where he remains a board member.

Nat holds a BA in Economics and an MA in Mathematics from UC Berkeley.