Complex sentence: Will Steffen (born 1947) was the executive director of the Australian National University (ANU) Climate Change Institute and a member of the Australian Climate Commission until its abolishment in September 2013.
Split into simpler sentences: Will Steffen (born 1947) was the executive director of the Australian National University (ANU) Climate Change Institute. He was a member of the Australian Climate Commission until it was abolished in September 2013.