Julia Marton-Lefèvre, environmentalist and academic, delivers the final lecture in the 2015 Our Changing World series. This lecture is also part of our Enlightenment Lecture series. In this lecture Julia Marton-Lefèvre will compare the profound changes that took place in the 18th century European Enlightenment, emphasizing reason rather than tradition, with the need for a new enlightenment to face the stark challenges posed by an unprecedented loss of biodiversity, a rapidly changing climate and increasing inequality among nations and individuals. Recorded on 24 November 2015 at the University of Edinburgh's George Square Lecture Theatre.