In the first episode of a four-part special series on leadership, HBR Editor in Chief Adi Ignatius and Harvard Business School professor and historian Nancy Koehn analyze Shackleton’s leadership during the struggle to survive. I’m Adi Ignatius with Nancy Koehn. ADI IGNATIUS: On our next episode of “Real Leaders,” Nancy Koehn and I will be talking about the writer and environmentalist, Rachel Carson.