He has contributed to many of the reports published by the Intergovernmental Panel on Climate Change (IPCC), a body that was recognized in 2007 by the joint award of the 2007 Nobel Peace Prize.
In 1993 he moved to the National Center for Atmospheric Research in Boulder, Colorado, where he was appointed a senior scientist in 1994.
He subsequently moved back to the University of Adelaide where he held an ARC DORA Professorial Fellowship (2012 to 2016).
Wigley has argued in publications and the popular media that the IPCC has been too too optimistic about the prospect of averting harmful climate change by reducing greenhouse gas emissions through the use of renewable technologies alone[17], and argued that any realistic mitigation portfolio must include significant contributions from nuclear energy[18].
In 2015, with other leading experts, he was co-author of an open letter to policy makers, which stated that "continued opposition to nuclear power threatens humanity's ability to avoid dangerous climate change.