Jacinda Ardern, former Prime Minister of New Zealand, is prioritizing optimism in the movement to combat the climate crisis—as well as expectation for leaders to do their jobs. If we resign ourselves to destruction, she says, politicians will never act to prioritize sustainability and reversing the effects of climate change. “I have an expectation bias,” the 44-year-old said during a panel, moderated by TIME Editor in Chief Sam Jacobs, at the inaugural Climate Leadership Forum in New York City on Monday.