As Canada’s environment minister in 2015, Catherine McKenna emerged as a leading voice in the climate debate. She also faced some of the unprecedented and disturbing abuse that was aimed at public officials, and became an advocate for the voice of women in politics. McKenna is still a force at the centre of Canada's climate discussion and the global one. She talks to Wonk host Amanda Lang about the urgent economics of climate change, her new memoir and why Canada needs to deal with rising polarization.