Billionaire hedge fund executive and environmental activist Tom Steyer is officially making a run for the White House — and putting an aggressive climate action plan at the center of his campaign. In this episode of Political Climate, we speak with the newest contender in the 2020 Democratic primary about why he entered the crowded race, and how he plans to use "emergency powers" to combat climate change. Steyer retired from hedge fund investing in 2012 to focus his efforts on political action and issue advocacy.