Will served as science adviser to the Australian Department of Climate Change and Energy Efficiency. He has been a member of the advisory board of the Australian Bureau of Meteorology and worked with the Prime Minister’s Science, Engineering and Innovation Council. He was also on an advisory panel in Colorado with the National Centre for Atmospheric Research.
Currently, Steffen is on the Science Advisory Committee of the APEC Climate Centre in Korea. He is honorary professor at Copenhagen University Department of Geography and Geology and visiting researcher at the Stockholm Resilience Centre. He is the chair of the Federal Government’s Antarctic Science Advisory Committee, and advises the Australian Government in further roles as scientific adviser to the Department of Climate Change and Energy Efficiency and as expert adviser to the Multi-Party Climate Change Committee. Steffen also sat on the Australian Climate Commission.
In 2011, he was the principal author of a government climate report, The Critical Decade, which advocated a tax should be placed on carbon. In 2018 he was an author of the Special Report on Global Warming of 1.5 °C published by the IPCC.