During the northern autumn, Henry Paulson Jr., the former US Treasury secretary, received a call from Paul David Hewson, better known as Bono. The musician-activist-investor had an idea and "an ask": Bono, who helped found TPG's $US5 billion ($6.7 billion) Rise funds focused on "impact investing", told Paulson the investment firm wanted to create an even bigger platform to focus exclusively on combating climate change – and he wanted Paulson to run it.