Bill Gates, philanthropist and founder of Microsoft, argues that, even as we work to end the global pandemic, we can't lose sight of another existential threat: climate change. He says that we need to take aggressive action to get to net zero carbon emissions by 2050 and insists that regulation isn't enough. Businesses need to pave the way forward by investing much more heavily in climate-friendly innovation. Gates speaks with HBR editor in chief Adi Ignatius about his new book, "How to Avoid a Climate Disaster: The Solutions We Have and the Breakthroughs We Need."