Dr. Will Steffen was a pioneering Earth systems scientist who fundamentally established Earth System science as a rigorous interdisciplinary field integrating diverse scientific disciplines. Born in Clearwater, Nebraska in 1947 and raised in Spencer, Iowa, he completed his chemical sciences education in the United States before making Australia his professional home where he became one of the world's most influential climate change experts. He served as Executive Director of the International Geosphere-Biosphere Programme from 1998 to 2004 based in Stockholm, then returned to Canberra where he became Director of the Australian National University's Fenner School of Environment and Society in 2007 and the inaugural Director of ANU's Climate Change Institute from 2008 to 2012. Dr. Steffen held distinguished positions as an Emeritus Professor at ANU, Senior Fellow at the Stockholm Resilience Centre, and Fellow at the Beijer Institute of Ecological Economics.
Dr. Steffen made seminal contributions to global environmental understanding through his co-authorship of the landmark 2005 volume 'Global Change and the Earth System: A Planet under Pressure,' which established the framework for Earth System science and documented the 'Great Acceleration' of human impacts beginning in the 1950s. He pioneered the integration of human processes into Earth System modeling and was pivotal in developing key concepts including the Anthropocene epoch, Planetary Boundaries framework, and the Hothouse Earth hypothesis that explored self-reinforcing feedbacks that could push Earth into a drastically altered climate state. His scientific leadership extended to the Intergovernmental Panel on Climate Change where he contributed to five special reports and studies between 2000 and 2018, significantly shaping global climate science understanding. Dr. Steffen's work provided the scientific foundation for understanding how crossing critical thresholds could lead to large-scale environmental tipping points with potentially irreversible consequences.
Beyond his research, Dr. Steffen was a courageous advocate for science-based climate policy, serving on the Australian government's Climate Commission from 2011 until its abolition in 2013 when he co-founded the Climate Council of Australia to continue this critical work through public donations. He fearlessly challenged government actions that undermined climate science, including public opposition in 2016 to attempts to censor Great Barrier Reef impact information in UNESCO documents. Dr. Steffen also contributed his expertise to legal proceedings, providing expert scientific evidence in climate change cases before Australian courts that established important precedents for considering climate impacts in environmental decision-making. His legacy endures through the ongoing work of researchers worldwide who continue to build upon his integrative approach to Earth System science and through initiatives like the Common Home of Humanity that he championed to establish a stable climate as a global common.
