Will Steffen (b.1947) is a climate change expert and researcher at the Australian National University Climate Change Institute, where he was the inaugural director (2008-2012), former Commissioner at Australia’s disbanded Climate Commission, and a Councillor at Australia’s independent Climate Council.  He is also a Senior Research Fellow at the Stockholm Resilience Centre, and former Executive Director of the International Geosphere-Biosphere Program in Stockholm (1998-2004).  He was the second lead author after SRC director Johan Rockström to introduce the seminal concept of planetary boundaries (“A Safe Operating Space for Humanity,” Nature 461, 2009, 472-475), principal author of the government climate report The Crucial Decade (2011), lead author of “Planetary Boundaries: Guiding Human Development on a Changing Planet” (Science, 13 Feb 2015, 1286-1287), and lead author of “The Trajectory of the Anthropocene: The Great Acceleration” (The Anthropocene Review, 2:1, 2015, 81-98), a remarkable dashboard of 24 indicators on environmental and socio-economic trends—most of them moving sharply upward in recent decades.